ANTEX BIOLOGICS INC
8-K, 1999-10-28
BIOLOGICAL PRODUCTS, (NO DIAGNOSTIC SUBSTANCES)
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<PAGE>   1
                       SECURITIES AND EXCHANGE COMMISSION

                             WASHINGTON, D.C. 20549


                                    FORM 8-K


                                 CURRENT REPORT

     PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934


Date of Report (Date of earliest event reported)       September 13, 1999
                                                -------------------------------

                              Antex Biologics Inc.
- --------------------------------------------------------------------------------
             (Exact name of registrant as specified in its charter)

<TABLE>
<S>                                       <C>                                             <C>
   Delaware                                      0-20988                                         52-1563899
- ----------------------------------------------------------------------------------------------------------------------
(State or other jurisdiction              (Commission File Number)                              (IRS Employer
of incorporation)                                                                              Identification No.)
</TABLE>

<TABLE>
<S>                                            <C>                                                          <C>
  300 Professional Drive                       Gaithersburg, MD                                              20879
- ----------------------------------------------------------------------------------------------------------------------
(Address of principal executive offices)                                                                    (Zip Code)
</TABLE>


Registrant's telephone number, including area code     (301) 590-0129
                                                  -----------------------------

- --------------------------------------------------------------------------------
          (Former name or former address, if changed since last report)







<PAGE>   2

ITEM 5.  OTHER EVENTS

            On September 13, 1999, Antex Biologics Inc. (the "Company") entered
into an Omnibus Agreement with SmithKline Beecham plc, an English corporation
("SB plc"), SmithKline Beecham Biologicals Manufacturing s.a., a Belgium
corporation ("SB Bio"), and MicroCarb Human Vaccines Inc., a Delaware
corporation ("MCHV"). Under the Omnibus Agreement and several related
agreements, (i) MCHV, the joint venture between the Company and SB Bio, has been
dissolved, and SB Bio's equity interest in the joint venture has been converted
into common stock, par value $.01 per share, of the Company ("Company Common
Stock"), and (ii) the Company and SB plc have entered into a Research and
Development, Research Support and License Agreement, dated as of September 13,
1999 (the "New License Agreement"), which replaces an agreement having the same
title among the Company, SmithKline Beecham Corporation, a Delaware corporation
("SKB"), and MCHV, dated May 6, 1996 (the "Original License Agreement").

Background

            In 1996, the Company and SmithKline established MCHV, which has been
73.75% owned by the Company and 26.25% owned by SB Bio. The purpose of the joint
venture was to engage in research and development with the goal of developing
human vaccine products for commercial sale. The Company granted to MCHV an
exclusive worldwide, royalty-free (subject to certain third-party license
agreements), perpetual and exclusive right and license to the Company's
proprietary rights with respect to its adhesion receptor technology and
nutriment signal transduction technology for use in the development and sale of
prophylactic and therapeutic human vaccines. In consideration for its interest
in MCHV and this technology transfer, SKB made a $3 million cash payment to the
Company. MCHV, in turn, granted to SB Bio an exclusive worldwide right and
license to the technology to make, use and sell vaccines for several identified
human infectious diseases and for any other human infectious disease for which
SB Bio provided research and development funding. In exchange, SB Bio agreed to
make payments to MCHV based on the achievement of certain product development
milestones and to pay royalties to MCHV based on commercial sales of any human
vaccine product developed by MCHV.

            Included as one of the terms of the joint venture was the right of
SB Bio, prior to September 1, 2003, to exchange its 26.25 % equity interest in
MCHV for 3,595,264 shares of Company Common Stock, as provided for in an
Exchange Option Agreement, dated May 6, 1996, among the Company, SB Bio and MCHV
(the "Exchange Option Agreement").

            Since its inception, the joint venture has engaged in a research and
development program for target products with research services and facilities
supplied by the Company and funded by research and development payments from SB
Bio.

Dissolution of the Joint Venture

            Effective as of September 1, 1999, the joint venture was dissolved
by means of a two-step transaction consisting of (i) the exchange by SB Bio of
its 26.25% interest in MCHV for



                                       2
<PAGE>   3

3,595,264 shares of Company Common Stock, in accordance with the terms of the
Exchange Option Agreement (the "Equity Exchange"), and (ii) and the merger of
MCHV into the Company. As a consequence of the merger, all of the intellectual
property rights of the joint venture have reverted to the Company, subject to
the terms of the New License Agreement (as described below).

New License Agreement

            Under the New License Agreement, the Company has granted to SB plc
an exclusive, worldwide license, with the right to grant sublicenses, to
develop, make, use and sell any product (subject to rights granted by Antex to a
third party) embodying or utilizing the intellectual property of the Company
relating to any and all prophylactic and/or therapeutic human vaccines (but
excluding development of commercial products for use in passive immunization)
for infectious diseases caused or exacerbated by the following targets: (i)
Moraxella catarrhalis, (ii) Neisseria meningitidis, including serotypes A, B and
C, (iii) non-typable Haemophilus influenzae, (iv) Streptococcus pneumoniae and
(v) Chlamydia using the "High Molecular Weight" protein of Chlamydia.

            In consideration for the license, the Company is entitled to receive
milestone payments based on both the successful completion of clinical trials
and subsequent product approvals by the appropriate regulatory authorities. In
addition, the Company will be entitled to receive royalties on SB Bio's net
sales of any product incorporating the licensed technology (subject to a credit
to be taken by SB plc for previous milestone payments).

            Under the New License Agreement, the Company will conduct a research
and development program on behalf of SB plc for the period July 1, 1999 through
December 31, 1999, and will be entitled to receive payments from SB plc of
approximately $1.33 million for budgeted expenses incurred in carrying out the
program. Extension of the research and development program beyond December 31,
1999 for one or more periods of no less than one year each is at the sole
discretion of SB plc.

            All intellectual property rights licensed to SKB under the Original
License Agreement that are not covered by the New License Agreement have
reverted to the Company, including all such rights with respect to Helicobacter
pylori and Campylobacter. However, if either the Helicobacter pylori or
Campylobacter is marketed or licensed by the Company to a third party, SB plc
will be entitled to receive a portion of the proceeds received by the Company
from the third party (but excluding any research and development funding).

New Stock Purchase Warrant

            In connection with the termination of the joint venture, the Company
issued to SB Bio an Amended and Restated Warrant, dated September 13, 1999 (the
"New Warrant"). The New Warrant entitles SB Bio to purchase, at an exercise
price of $.37 per share, 3,865,769 shares of Company Common Stock (which would
have increased to 4,731,958 shares of Company Common Stock had SKB's second
$666,667 payment of research and development funding under the New License
Agreement been received on or before October 1, 1999). The New Warrant, which
replaces the Warrant to Purchase Common Stock, dated May 9, 1996, previously




                                       3
<PAGE>   4

issued to SB Bio by the Company, is exercisable on or before September 1, 2003.

Registration Rights Agreement

            In accordance with the terms of an Amended and Restated Registration
Rights Agreement, dated September 13, 1999, between the Company and SB Bio (the
"Registration Rights Agreement"), the Company has granted to SB Bio demand and
piggyback registration rights with respect to (i) the 3,595,264 shares of
Company Common Stock acquired by SB Bio pursuant to the Exchange Option
Agreement and (ii) the 3,865,769 shares of Company Common Stock issuable upon
the exercise of the New Warrant.

Standstill Agreement and Right of First Offer

            As a result of the Equity Exchange, SB Bio holds, as of the date
hereof, approximately 12.2% of the outstanding shares of Company Common Stock.
In the Omnibus Agreement, SB Bio has agreed that, for a period of ten years
beginning May 6, 1996, except with the prior consent of the Company and subject
to certain limited exceptions, SB Bio and its affiliates will not acquire common
or preferred stock of the Company if the effect of the acquisition would be to
increase the total percentage ownership of SB Bio and its affiliates in any
class of equity securities of the Company to more than 28% of the outstanding
securities of that class.

            If at any time prior to May 6, 2006, SB Bio proposes to sell 5% or
more of the outstanding shares of Company Common Stock, it must first offer the
shares to the Company. The Company, or a designee of the Company, can elect
within 30 days to purchase the shares at the price offered by SB Bio. If the
Company does not elect to purchase the shares, SB Bio can sell the shares to a
third party on the same terms that it offered to the Company.

                            *           *         *

            The foregoing description of the modified arrangement between the
Company and SmithKline is a summary of the material terms and is qualified in
its entirety by reference to the following documents, each of which is filed as
an exhibit to this Report on Form 8-K, and is incorporated herein by reference:
(i) the Omnibus Agreement, (ii) the New License Agreement, (iii) the New
Warrant, and (iv) the Registration Rights Agreement.



                                       4
<PAGE>   5

 ITEM 7.    FINANCIAL STATEMENT AND EXHIBITS


<TABLE>
<CAPTION>
Exhibit No.                    Description
- -----------                    -----------

<S>            <C>
10.1           Omnibus Agreement, dated September 13, 1999, by and among the
               Company, SmithKline Beecham Biologicals Manufacturing s.a.,
               SmithKline Beecham plc, and MicroCarb Human Vaccines Inc.

10.2           Research and Development, Research Support and License Agreement,
               dated September 13, 1999, between the Company and SmithKline
               Beecham plc (certain confidential information has been omitted
               and filed separately with the Securities and Exchange Commission)

10.3           Amended and Restated Warrant, dated September 13, 1999, issued by
               the Company to SmithKline Beecham Biologicals Manufacturing s.a

10.4           Amended and Restated Registration Rights Agreement, dated
               September 13, 1999, between the Company and SmithKline Beecham
               Biologicals Manufacturing s.a.
</TABLE>


                                   SIGNATURES

Pursuant to the requirements of the Securities and Exchange Act of 1934, the
registrant has duly caused this report to be signed on its behalf by the
undersigned hereunto duly authorized.


                                    Antex Biologics Inc.
                                    --------------------
                                    (Registrant)


   October 28, 1999                 /s/ Gregory C. Zakarian
   ----------------                 -----------------------
       (Date)                       Name:   Gregory C. Zakarian
                                    Title:  Vice President, Finance







                                       5
<PAGE>   6




                                  EXHIBIT INDEX

<TABLE>
<CAPTION>
                                                                                               PAGE NUMBER ON
                                                                                               SEQUENTIALLY
EXHIBIT                                                                                        NUMBERED COPY
NO.                                     DESCRIPTION                                            -------------
- ---                                     -----------

<S>                                                                                            <C>
10.1           Omnibus Agreement, dated September 13, 1999, by and among the                        7
               Company, SmithKline Beecham Biologicals Manufacturing s.a.,
               SmithKline Beecham plc, and MicroCarb Human Vaccines Inc.

10.2           Research and Development, Research Support and License Agreement,                    32
               dated September 13, 1999, between the Company and SmithKline
               Beecham plc (certain confidential information has been omitted
               and filed separately with the Securities and Exchange Commission)

10.3           Amended and Restated Warrant, dated September 13, 1999, issued by                    82
               the Company to SmithKline Beecham Biologicals Manufacturing s.a.

10.4           Amended and Restated Registration Rights Agreement, dated                            97
               September 13, 1999, between the Company and SmithKline Beecham
               Biologicals Manufacturing s.a.
</TABLE>





                                       6




<PAGE>   1
                                                                 EXHIBIT 10.1


                                OMNIBUS AGREEMENT

                  This OMNIBUS AGREEMENT dated September 13, 1999 is by and
among SmithKline Beecham Biologicals Manufacturing s.a., a Belgian corporation
("SB Bio"),SmithKline Beecham plc, an English corporation ("SB plc"), Antex
Biologics Inc., a Delaware corporation formerly known as MicroCarb Inc.
("Antex") and MicroCarb Human Vaccines Inc., a Delaware corporation ("MCHV").
This OMNIBUS AGREEMENT shall be effective as of September 1, 1999 (the
"Effective Date").


                                   WITNESSETH:

                  WHEREAS, SmithKline Beecham Corporation, MCHV and Antex were
parties to a Research and Development, Research Support and License Agreement
dated May 6, 1996 (the "Original License Agreement") that was terminated
effective as of September 1, 1999;

                  WHEREAS, SB Bio, Antex and MCHV are parties to a Stock
Purchase Agreement dated May 6, 1996 (the "Stock Purchase Agreement") pursuant
to which, among other things, SB Bio acquired 262.5 shares of the common stock,
par value $.01 per share, of MCHV (the "MCHV Common Stock") and Antex acquired
737.5 shares of the MCHV Common Stock;

                  WHEREAS, SB Bio, Antex and MCHV are parties to an Exchange
Option Agreement dated May 6, 1996 (the "Exchange Option Agreement") pursuant to
which, among other things, Antex granted SB Bio an option to exchange its shares
of the MCHV Common Stock for shares of the common stock, par value $.01 per
share of Antex (the "Common Stock");





                                       7
<PAGE>   2



                  WHEREAS, SB Bio, Antex and MCHV are parties to a Stockholders
Agreement dated May 6, 1996 (the "Stockholders Agreement") which provides, among
other things, for the corporate governance of MCHV;

                  WHEREAS, Antex and SB Bio are parties to a Warrant dated May
6, 1996 (the "Warrant") pursuant to which Antex granted SB Bio the right to
purchase certain shares of the Common Stock;

                  WHEREAS, Antex and SB Bio are parties to a Registration Rights
Agreement dated May 6, 1996 (the "Registration Rights Agreement") pursuant to
which Antex granted SB Bio certain rights to register certain shares of the
Common Stock owned by SB Bio following its exercise of the Warrant; and

                  WHEREAS, the parties hereto desire to (i) enter into a new
research and development, research support and license agreement (ii) terminate
the Stock Purchase Agreement (other than Sections 11.8, 11.9 and 11.10 thereof);
(iii) exchange 262.5 shares of MCHV Common Stock owned by SB Bio for 3,595,264
shares of the Common Stock pursuant to the Exchange Option Agreement and
terminate the Exchange Option Agreement; (iv) merge MCHV with and into Antex;
(v) terminate the Stockholders Agreement; (vi) amend and restate the Warrant;
(vii) amend and restate the Registration Rights Agreement; and (viii) provide SB
Bio with visitation rights for meetings of the Board of Directors of Antex.



                                       8
<PAGE>   3

                  NOW, THEREFORE, in consideration of the premises and of the
representations, warranties and covenants which are to be made and performed by
the respective parties hereto, the parties hereto, intending to be legally
bound, agree as follows.

                                   ARTICLE I


                       Entrance into New License Agreement




                  Section 1.1 Entrance into New License Agreement.
Contemporaneous with the execution and delivery of this Agreement by all of the
parties hereto, SB plc and Antex shall execute and deliver a new Research and
Development, Research Support and License Agreement (the "New License
Agreement") in form of Exhibit A attached hereto.

                                   ARTICLE II

                     Termination of Stock Purchase Agreement


                  Section 2.1 Termination of Stock Purchase Agreement.
Contemporaneous with the execution and delivery of this Agreement by all of the
parties hereto, the Stock Purchase Agreement shall be terminated; provided,
however, that the provisions of Sections 11.8, 11.9 and 11.10 thereof are
restated herein and shall continue in full force and effect. Sections 11.8, 11.9
and 11.10 provide as follows:

                  Section 11.8 Standstill Obligations. For a period of ten (10)
years from May 6, 1996, except with the prior consent of Antex, which consent
may not be unreasonably withheld, SB



                                       9
<PAGE>   4

Bio and its Affiliates, as defined below, shall not, directly or indirectly,
acquire any Equity Securities, as defined below (except by way of (i) stock
splits, stock dividends or other distributions or offerings made available to
other holders of Common Stock generally, or (ii) stock options, warrants or
other rights to purchase Common Stock approved by the Board of Directors of
Antex) if the effect of such acquisition would be to increase the total
percentage interest of SB Bio and its Affiliates, as defined below, in any class
of the Equity Securities to more than twenty-eight percent (28%) (the "Threshold
Percentage") of the then outstanding shares of any class of the Equity
Securities; provided that:

                        (a) SB Bio may acquire Equity Securities without regard
to the limitations set forth above if any of the following events shall
occur:

                                 (i) If a bona fide tender or exchange offer is
made by any Person, as defined below, or 13D Group, as defined below
(other than an Affiliate of SB Bio) to acquire shares of Common Stock which, if
added to the shares of Common Stock, if any, already owned by such Person or 13D
Group, would represent ownership of the then outstanding shares of Common Stock
greater than the Threshold Percentage; or

                                 (ii) If it is publicly disclosed or SB Bio
otherwise learns that shares of Common Stock representing more than twenty
percent (20%) of the then outstanding shares of Common Stock have been acquired
in a nonpublic transaction or that a bona fide offer has been made to acquire
more than twenty percent (20%) of the then outstanding shares of Common Stock in
a nonpublic transaction by any Person or 13D Group (other than an Affiliate of
SB Bio).



                                       10
<PAGE>   5

                        (b) SB Bio shall not be obligated to dispose of any
shares of Common Stock if the aggregate percentage ownership of SB Bio is
increased as a result of (i) a recapitalization of Antex, (ii) a repurchase of
shares of Common Stock by Antex or (iii) any other reason not in violation of
this Agreement.

                        (c)   If any event identified in Section 11.8(a)(i) or
(ii) occurs, SB Bio shall be permitted to take such action and make such offers
as may be considered to be of the same nature and type of action or offer and
directed to the same Person or Persons and for the same resulting number of
shares as that which is being taken by such Person or 13D Group. In proceeding
with any action or offer permitted under this Section 11.8, SB Bio shall be
permitted to offer more favorable terms such as price, cash versus securities or
other such terms as may be consistent with an offer of the same nature and type
of consideration as that which is being proposed by such Person or 13D Group.

                        (d)   In the event that SB Bio or an Affiliate sells,
assigns or otherwise transfers five percent (5%) or more of the then outstanding
shares of Common Stock, or sells, assigns or otherwise transfers any shares of
Common Stock to a Person to whom SB Bio or an Affiliate has previously sold,
assigned or transferred any shares of Common Stock, or to any Person, so that
upon such sale, assignment or transfer, such Person owns in the aggregate five
percent (5%) or more of the then outstanding shares of Common Stock at a price
per share of Common Stock which is greater than the sum of (a) $.37 and (b) the
product of (i) the number of months from May 6, 1996 to the date of such sale,
assignment or other transfer pursuant to Section 11.9(c) and (ii) $.37 and (iii)
 .0167, than the standstill obligations of this Section 11.8 shall be binding
upon



                                       11
<PAGE>   6
the Person who purchases such shares. Except as set forth in the immediately
preceding sentence, the standstill obligations of this Section 11.8(d) shall not
be binding upon any Person who purchases shares of Common Stock from SB Bio or
an Affiliate.

            Section 11.9.  Transfer by SB Bio of Shares of Common Stock.

                       (a) SB Bio may sell, assign or otherwise transfer shares
of Common Stock from time to time owned by it to Affiliates without
restriction. Notwithstanding the preceding sentence, neither SB Bio nor its
Affiliates may sell, assign or otherwise transfer shares of Common Stock except
in accordance with the terms of this Agreement.

                       (b) Except as otherwise provided in Section 11.9(c), SB
Bio may sell, assign or otherwise transfer shares of Common Stock from
time to time owned by it which have been registered with the Securities and
Exchange Commission without restriction. Except as otherwise provided in Section
11.9(c), SB Bio may sell, assign or otherwise transfer shares of Common Stock
from time to time owned by it which have not been registered with the Securities
and Exchange Commission without restriction other than the requirements of Rule
144 promulgated under the Securities Act of 1933, as from time to time in
effect, including the volume limitations under Rule 144 irrespective of whether
Rule 144(k) applies.

                       (c)   If at any time prior to May 6, 2006 SB Bio proposes
to sell five percent (5%) or more of the then outstanding shares of Common
Stock, SB Bio shall give written notice (the "Transfer Notice") to Antex
specifying the number of shares of Common Stock that SB Bio desires to transfer
(the "Transfer Stock") and the price at which SB Bio is offering to sell the



                                       12
<PAGE>   7

Transfer Stock (the "Offering Price"). The Transfer Notice shall constitute an
offer to sell all, but not less than all, of the Transfer Stock to Antex (or its
designee) at the Offering Price with payment in immediately available funds.
Antex or its designee shall have a period of thirty (30) calendar days to accept
SB Bio's offer to sell all, but not less than all, of the Transfer Stock and an
additional period of sixty (60) calendar days after the date that it accepts SB
Bio's offer contained in the Transfer Notice to complete the purchase of all,
but not less than all, of the Transfer Stock at the Offering Price. If Antex or
its designee does not accept the offer contained in the Transfer Notice without
modification within the time period prescribed in the preceding sentence,
declines the offer contained in the Transfer Notice or accepts the offer
contained in the Transfer Notice without modification, but fails to complete the
purchase of all of the Transfer Stock within the time period specified in the
preceding sentence, SB Bio may sell any or all of the Transfer Stock at an
offering price which is not less than the Offering Price for a period of one (1)
year from the date of the Transfer Notice. If SB Bio has not sold the Transfer
Stock within such one (1) year period from the date of the Transfer Notice, SB
Bio must comply with the provisions of this Section 11.9(c) prior to
consummating any sale of such Transfer Stock. If SB Bio proposes to sell any of
the Transfer Stock which constitutes five percent (5%) or more of the then
outstanding shares of Common Stock within such one (1) year period for a price
which is less than the Offering Price specified in the Transfer Notice, SB Bio
must comply with the provisions of this Section 11.9(c) prior to consummating
any sale of such Transfer Stock.

            Section 11.10 Non-Solicitation of Employees. For a period commencing
on the date of this Agreement and ending two (2) years after the expiration of
the New License Agreement (the





                                       13
<PAGE>   8

"Non-Solicitation Period"), SB Bio and Antex each agree that neither they nor
their Affiliates shall solicit, without the prior consent of the other party,
for employment any individual who is employed by such other party during the
Non-Solicitation Period so long as such individual is employed by the other
party.

            Section 2.2 Definitions. For purposes of this Article II, the
following terms shall have the following meanings:

                  (i) "13D Group" means any group of Persons formed for the
purpose of acquiring, holding, voting or disposing of Common Stock (or any other
class of the Equity Securities) which would be required under the Exchange Act
to file a statement on Schedule 13D with the Securities and Exchange Commission
as a "person" within the meaning of Section 13(d)(3) of the Exchange Act if such
group beneficially owned sufficient securities to require such a filing under
the Exchange Act.

                  (ii) "Affiliate" of another Person means a Person which
directly or indirectly owns, is owned by or is under common ownership with
another Person to the extent of at least fifty percent (50%) of the equity (or
such lesser percentage which is the maximum allowed to be owned by a foreign
corporation in a particular jurisdiction) having the power to vote on or direct
the affairs of the entity and any Person actually controlled by, controlling or
under common control with another Person.

                  (iii) "Equity Securities" shall mean the Common Stock and the
Preferred Stock, par value $.01 per share, of Antex.



                                       14
<PAGE>   9

                  (iv) "Exchange Act" means the Securities Exchange Act of 1934,
as amended, and the rules and regulations promulgated thereunder by the
Securities and Exchange Commission.

                  (v) "Person" means and includes an individual, a partnership,
a joint venture, a corporation or trust, an unincorporated organization, a group
or a government or other department or agency thereof.

                                  ARTICLE III


                  Exchange of MCHV Common Stock for Common Stock; Termination of
                  Exchange Option and Stockholders Agreement; Merger of MCHV
                  with and into Antex


                  Section 3.1 Exchange of MCHV Common Stock for Common Stock.
Contemporaneous with the execution and delivery of this Agreement by all of the
parties hereto, (i) SB Bio shall deliver to Antex the original stock certificate
representing 262.5 shares of MCHV Common Stock registered in SB Bio's name and
(ii) Antex shall deliver to SB Bio a duly executed stock certificate
representing 3,595,264 shares of the Common Stock registered in SB Bio's name,
which exchange shall be completed pursuant to the Exchange Option Agreement.
Following the completion of such exchange, the Exchange Option Agreement shall
be terminated, cancelled and of no further force or effect.

                  Section 3.2 Termination of the Stockholders Agreement.
Contemporaneous with the execution and delivery of this Agreement by all of the
parties hereto, the Stockholders Agreement shall be terminated, cancelled and of
no further force or effect.



                                       15
<PAGE>   10

                  Section 3.3 Merger of MCHV with and into Antex.
Contemporaneous with the execution and delivery of this Agreement by all of the
parties hereto, Antex and MCHV shall execute and file with the Secretary of
State of Delaware a Certificate of Merger in the form of Exhibit B attached
hereto.

                                   ARTICLE IV

                            Amendment of the Warrant


                  Section 4.1 Amendment of the Warrant. Contemporaneous with the
execution and delivery of this Agreement by all of the parties hereto, (i) SB
Bio shall deliver to Antex the original Warrant and (ii) Antex shall deliver to
SB Bio a duly executed Amended and Restated Warrant in the form of Exhibit C
attached hereto.

                                   ARTICLE V

                 Amendment of the Registration Rights Agreement


                  Section 5.1 Amendment of the Registration Rights Agreement.
Contemporaneous with the execution and delivery of this Agreement by all of the
parties hereto, SB Bio and Antex shall execute and deliver to one another an
amended and restated Registration Rights Agreement in the form of Exhibit D
attached hereto.

                                   ARTICLE VI

                             Board Visitation Rights


                  Section 6.1 Board Visitation Rights. For so long as SB Bio or
any or its Affiliates own in the aggregate at least ten percent (10%) of the
outstanding shares of Common Stock



                                       16
<PAGE>   11


(such outstanding shares calculated without taking into account any shares of
Common Stock issuable upon exercise or conversion of any exercisable or
convertible securities), Antex shall (i) provide SB Bio notice of each meeting
of Antex's Board of Directors (the "Board") at the same time and in the same
manner as it provides notice of such meeting to any other member of the Board;
(ii) provide SB Bio all written materials provided to members of the Board in
anticipation of, and at, each meeting of the Board at the same time and in the
same manner as it provides such written materials to any other member of the
Board; and (iii) allow one representative of SB Bio (or any of its
Affiliates)(the "SB Bio Representative") to attend in a non-voting, observer
capacity each meeting of the Board in person or, to the extent the meeting of
the Board is to be held by teleconference, to attend such meeting by telephone
conference call. Each SB Bio Representative must be approved by the Board of
Directors of Antex in advance of any meeting of the Board, such approval not to
be unreasonably withheld or delayed; provided, however, that at each annual
meeting of shareholders of Antex, the Board of Directors shall pre-approve three
(3) acceptable SB Bio Representatives who shall be deemed approved by the Board
of Directors until the next annual meeting of shareholders of Antex. Until the
next annual meeting of shareholders of Antex (expected to be in June 2000), the
approved SB Bio Representatives shall be Oliver Boucher, Moncef Slaoui and Jean
Stephenne, with Oliver Boucher designated as the primary SB Bio Representative.
All information which is received by SB Bio in connection with the exercise of
its rights under this Section 6.1 shall be held by it in accordance with the
confidentiality provisions of the New License Agreement. Notwithstanding the
foregoing, it is understood and agreed that Antex reserves the right to withhold
any information and to exclude the SB Bio Representative from any meeting or
portion thereof to the



                                       17
<PAGE>   12

extent access to such information or attendance at such meeting (i) would
adversely affect the attorney-client privilege between Antex and its counsel or
(ii) would violate an obligation of confidentiality to a third party.


                                  ARTICLE VII

                     Representations and Warranties of Antex

                  Antex represents and warrants to SB Bio and SB plc, and SB Bio
and SB plc in agreeing to consummate the transactions contemplated by this
Agreement and each of the agreements attached as exhibits to this Agreement
(collectively the "Related Agreements") have relied upon such representations
and warranties, that, as of the signature date of this Agreement:


                  Section 7.1 Valid and Binding Agreements; Status of Common
Stock. Antex has all requisite corporate power and authority and has taken all
necessary corporate action to enter into this Agreement and the Related
Agreements to which it is a party and to consummate the transactions
contemplated hereby and thereby including without limitation the merger of MCHV
with and into Antex. The shares of the Common Stock delivered to SB Bio pursuant
to Section 3.1 are duly authorized, validly issued, fully paid and nonassessable
shares of the Common Stock, free and clear of all liens, security interests,
pre-emptive rights, claims and other encumbrances. This Agreement and the
Related Agreements to which Antex is a party have been duly and validly executed
and delivered by Antex, and constitute valid and binding agreements of Antex,
enforceable in accordance with their terms, subject to bankruptcy, insolvency,
reorganization or similar laws relating to creditors' rights generally.



                                       18
<PAGE>   13

                  Section 7.2 Corporate Organization.

                  (a) Antex is a corporation duly organized, validly existing
and in good standing under the laws of the State of Delaware and has the
requisite power and authority to carry on its business as currently conducted
and to own the properties and assets it now owns.

                  (b) Antex is duly licensed or qualified to do business as a
foreign corporation, and is in good standing, in Maryland. The nature of Antex's
business does not require it to be qualified to conduct business in any other
jurisdictions.

                  (c) The copies of the certificate of incorporation, and all
amendments thereto, of Antex as certified by the appropriate authorities of
Delaware, and the by-laws, as amended to date, of Antex, as certified by its
Secretary, which have heretofore been delivered to SB Bio, are true, complete
and correct copies of the articles of incorporation and by-laws of Antex, as
amended and in effect on the date hereof.

                  Section 7.3 Capitalization.

                  (a) The authorized capital stock of Antex consists solely of
95,000,000 shares of the Common Stock, of which 25,863,726 shares are issued and
outstanding, and 5,000,000 shares of preferred stock, par value $.01 per share,
of which none are issued or outstanding. The issued and outstanding shares of
the Common Stock are duly authorized, validly issued, fully paid and
nonassessable, and none of the issued and outstanding shares of the Common Stock
were issued in violation of the preemptive rights of any person.


                                       19
<PAGE>   14

                  (b) Except as set forth in Section 7.3(a) and on Schedule 7.3,
(i) there are no shares of capital stock or other equity securities of Antex
outstanding, (ii) there are no outstanding subscriptions, options, warrants or
rights to purchase or acquire any equity securities of, (iii) no equity
securities of Antex are reserved for issuance for any purpose, and (iv) there
are no contracts, commitments, agreements, understandings, arrangements or
restrictions, whether written or oral, to which Antex is a party or by which
Antex is bound relating to any shares of the capital stock or other equity
securities of Antex, whether or not outstanding.

                  Section 7.4 Subsidiaries and Affiliates. Antex owns no capital
stock of any other person or has any other type of interest (whether ownership
or other) in any other person other than MCHV and Antex Pharma Inc. Antex is not
subject to any obligation or requirement to provide funds for, or to make any
investment (in the form of a loan, capital contribution or otherwise) to or in,
any person.


                  Section 7.5 No Violation, Etc. Neither the execution and
delivery of this Agreement or the Related Agreements to which Antex is a party
nor the consummation of the transactions contemplated hereby or thereby nor
compliance by Antex with any of the provisions hereof or thereof will (i)
violate or conflict with any provisions of Antex's certificate of incorporation
or by-laws, (ii) violate or conflict with any statute, code, ordinance, rule,
regulation, judgment, order, writ, decree or injunction applicable to it, or
(iii) violate, or conflict with, or result in a breach in any provision of, or
constitute a default (or any event that, with or without due notice or lapse of
time, or both, would constitute such a default) under, or result in the
termination of, accelerate the performance required by, or result in the
creation of any lien,


                                       20
<PAGE>   15

security interest, charge or other encumbrance upon the 3,595,264 shares of
Common Stock received pursuant to Section 3.1 or any of the properties or assets
of Antex under any of the terms, conditions or provisions of any note, bond,
mortgage, indenture, deed of trust, license, lease, agreement or other
instrument or obligation of which Antex is a party or by which it or any of its
assets is bound.

                  Section 7.6 Consents and Approvals. No permit, consent,
approval or authorization of, or declaration, filing or registration with, any
governmental authority is necessary in connection with the execution and
delivery by Antex of this Agreement or the Related Agreements to which it is a
party or the consummation by Antex of the transactions contemplated hereby or
thereby and no consent of any third party is required to consummate any of the
transactions contemplated hereby or thereby.

                  Section 7.7 Disclosure. No representation or warranty made by
or on behalf of Antex contained in this Agreement or the Related Agreements to
which it is a party, and no statement contained in the Schedules hereto or
thereto or any certificate or other document furnished to SB Bio pursuant to the
provisions hereof or thereof, contains or will contain any untrue statement of a
material fact or omits or will omit to state a material fact necessary in order
to make the statements herein or therein, in light of the circumstances under
which such statements are made, not misleading.

                  Section 7.8 Securities and Exchange Commission Documents.
Antex has timely filed with the Securities and Exchange Commission all material
filings (the "Commission



                                       21
<PAGE>   16

Documents") required to be filed by it pursuant to the Exchange Act and the
Securities Act of 1933, and the Commission Documents complied in all material
respects with the Exchange Act and the Securities Act of 1933, and none of the
Commission Documents contain any untrue statement of a material fact or omitted
to state a material fact necessary to make the statements contained therein not
misleading. Since June 30, 1999, Antex has conducted its business only in the
ordinary course and in substantially the same manner as previously conducted and
there has not been any material adverse change in the business, financial
condition or prospects of Antex.

                  Section 7.9 Authorization of Reserved Shares. On the date
hereof, the issuance, sale and delivery by Antex of the Common Stock issuable
upon the exercise of the Amended and Restated Warrant (the "Reserved Shares")
have been duly authorized by all requisite corporate action of Antex and have
been duly reserved for issuance, and when so issued, sold, paid for and
delivered in accordance with the terms of the Amended and Restated Warrant, the
Reserved Shares will be validly issued, fully paid and nonassessable, and not
subject to any preemptive rights of any stockholder of Antex.

                  Section 7.10 Litigation. There are no (a) legal,
administrative or arbitrable claims, actions, suits, proceedings, investigations
or inquiries pending or threatened by or pending or, to the knowledge of Antex,
threatened against Antex, and (b) judgments, decrees, arbitration awards,
agreements or orders binding upon Antex. No material claims have been asserted
against Antex since its incorporation on September 15, 1992. Antex is not aware
and has no reason to be aware of any basis for any claim, action, suit,
proceeding, investigation or inquiry.



                                       22
<PAGE>   17

                  Section 7.11 Intellectual Property. (a) With the exception of
U.S. Patent No. 5,552,144 and all corresponding foreign patents and patent
applications corresponding hereto and all continuations and divisions thereof
(the "144Patent") which is co-owned by Antex and the United States of America
and certain march-in rights of the United States of America, Department of the
Navy with respect to Campylobacter, and with the exception of rights granted to
Pasteur Merieux Serums et Vaccines S.A. ("Pasteur") pursuant to that certain
license agreement dated December 1, 1994, Antex owns and possesses all right,
title and interest in and to or will have license rights in the Intellectual
Property (as such term in defined in the New License Agreement). With the
exception of the rights granted to Pasteur, the march-in rights of the United
States of America, Department of the Navy, and the rights owned by the United
States of America with respect to the144 Patent, Antex has the sole and
exclusive right to use and license other persons to use the Intellectual
Property and none of the past or present employees, officers, directors or
shareholders of Antex, or any other Person, has any rights with respect thereto.
The consummation of the transactions contemplated hereby will not alter or
impair any rights to use and license others to use the Intellectual Property.
Antex has not received any notice or claim of infringement or any claim
challenging or questioning the validity or effectiveness of Antex's rights in or
to any of the items of Intellectual Property, and Antex is aware of no valid
basis for any such claim. Except as noted above, Antex is not liable, nor has it
made any contract or arrangement whereby it may become liable, to any Person for
any royalty or other compensation for use of any of the items of Intellectual
Property. Following consummation of the Merger of MCHV with and into Antex,
Antex will possess all right, title and interest in all Intellectual Property
that was at any time owned by MCHV. When executed



                                       23
<PAGE>   18

and delivered, the New License Agreement will effectively grant the license and
other rights which are expressly granted to SB plc therein.

                                  ARTICLE VIII

               Representations and Warranties of SB Bio and SB plc

                  SB Bio and SB plc represent and warrant to Antex, and Antex in
agreeing to consummate the transactions contemplated by this Agreement and the
Related Agreements has relied upon such representations and warranties, that, as
of the signature date of this Agreement:


                  Section 8.1 Organization, Standing and Power. SB Bio is a
corporation duly organized under the laws of Belgium and has the requisite
corporate power and authority to carry on its business as now being conducted
and to own the properties and assets it presently owns. SB plc is a corporation
duly organization under the laws of the United Kingdom and has the requisite
corporate power and authority to carry on its business as now being conducted
and to own the properties and assets it presently owns.

                  Section 8.2 Valid and Binding Agreements. All necessary
corporate action on the part of SB Bio and SB plc has been taken to authorize
the execution and delivery of this Agreement and the Related Agreements to which
they are a party, the performance of their obligations hereunder and thereunder
and the consummation of the transactions contemplated hereby and thereby. This
Agreement and the Related Agreements to which they are a party have been duly
and validly executed and delivered by SB Bio and SB plc and constitute valid and
binding agreements of SB Bio and SB plc, enforceable in accordance with their
terms, subject to



                                       24
<PAGE>   19

bankruptcy, insolvency, reorganization or similar laws or equitable principles
relating to creditors' rights generally.

                  Section 8.3 No Violation. Neither the execution and delivery
of this Agreement or the Related Agreements to which SB Bio and SB plc are a
party nor the consummation of the transactions contemplated hereby or thereby
nor compliance by SB Bio and SB plc with any of the provisions hereof or thereof
will (a) violate or conflict with the organizational documents of SB Bio and SB
plc, or (b) violate or conflict with any statute, code, ordinance, rule,
regulation, judgment, order, writ, decree or injunction applicable to SB Bio and
SB plc, or (c) violate or conflict with, or result in a breach of any of the
provisions of, or constitute a default (or any event which, with or without due
notice or lapse of time, or both, would constitute such a default) under, or
result in the termination of, or accelerate the performance required by, or
result in the creation of any lien, security interest, charge or other
encumbrance upon the stock or any of the properties or assets of SB Bio or SB
plc under any of the terms, conditions or provisions of any note, bond,
mortgage, indenture, deed of trust, license, lease, agreement or other
instrument of which SB Bio or SB plc is a party or by which they or any of their
assets are bound.

                  Section 8.4 Consents and Approvals. No permit, consent,
approval or authorization of, or declaration, filing or registration with, any
governmental authority is necessary in connection with the execution and
delivery of this Agreement or the Related Agreements to which they are a party
by SB Bio or SB plc or the consummation by SB Bio or SB plc of the transactions
contemplated hereby or thereby and no consent of any third party is required to
consummate any of the transactions contemplated hereby or thereby.


                                       25
<PAGE>   20

                  Section 8.5 Investor Status. SB Bio is an "accredited
investor" as such term is defined in any of paragraphs (1) through (3), (7), (8)
or Rule 501(a) under the Securities Act of 1933, as amended.

                                   ARTICLE IX

                                  Miscellaneous


                  Section 9.1 Notices. All notices, requests, consents and other
communications hereunder shall be in writing and may be delivered personally
(including by courier or nationally recognized courier), by first class
registered or certified mail (return receipt requested), postage prepaid, or by
facsimile (with written confirmation of receipt) addressed to the following
addresses or facsimile numbers or to other such addresses or facsimile numbers
as may be furnished in writing by one party to the others:

                  (a)     if to Antex:

                         Antex Biologics Inc.
                         300 Professional Drive
                         Gaithersburg, MD  20879, USA
                         Attention:  Chief Executive Officer
                         Facsimile:  (301) 590-1252

                         with a copy to:

                         Covington & Burling
                         1201 Pennsylvania Avenue, N.W.
                         Washington, DC  20004-6000, USA
                         Attention:  Alfred H. Moses, Esq.
                         Facsimile:  (202) 778-5196


                  (b)     if to SB Bio:


                                       26
<PAGE>   21

                         SmithKline Beecham Biologicals Manufacturing s.a.
                         Rue de L'Institut 89
                         B-1330 Rixensart
                         Belgium
                         Attention:  President, General Manager
                         Facsimile:  011-32-2-656-8026

                         if to SB plc:

                         SmithKline Beecham plc
                         c/o SmithKline Beecham Corporation
                         One Franklin Plaza
                         P.O. Box 7929
                         Philadelphia, PA  19101-7929, USA
                         Attention:  Edgar B. Cale III, Esq.
                         Facsimile:  (215) 751-3935

                         with a copy to:

                         Dickstein Shapiro Morin & Oshinsky LLP
                         2101 L Street, N.W.
                         Washington, D.C.  20037, USA
                         Attention:  Neil Lefkowitz, Esq.
                         Facsimile:  (202) 887-0689

Any such notice or communication shall be presumed to have been received (i) in
the case of personal delivery or facsimile transmission, on the date of such
delivery and (ii) in the case of nationally-recognized courier, on the business
day after the date sent.


                  Section 9.2 Governing Law. This Agreement shall be governed
by, and construed in accordance with, the laws of the State of Maryland, without
regard to such jurisdiction's conflicts of laws principles.

                  Section 9.3 Modification; Waiver. This Agreement shall not be
altered or otherwise amended except pursuant to an instrument in writing signed
by SB Bio, SB plc and



                                       27
<PAGE>   22

Antex. Any party may waive any misrepresentation by any other party, or any
breach of warranty by, or failure to perform any covenant, obligation or
agreement of, any other party, provided that mere inaction or failure to
exercise any right, remedy or option under this Agreement, or delaying in
exercising the same, will not operate as nor shall be construed as a waiver, and
no waiver will be effective unless set forth in writing and only to the extent
specifically stated therein.


                  Section 9.4 Entire Agreement. This Agreement, the Related
Agreements, the Schedules and Exhibits hereto and any other agreements or
certificates delivered pursuant hereto constitute the entire agreement of the
parties hereto with respect to the matters contemplated hereby and supersede all
previous written or oral negotiations, commitments, representations and
agreements.

                  Section 9.5 Assignment; Successors and Assigns. This Agreement
may not be assigned by any party, without the prior written consent of the other
parties; provided, however, that SB Bio and SB plc may each assign this
Agreement and any of their rights hereunder to any of their affiliates or to any
corporation with which it may merge or consolidate or sell all or substantially
all of their respective assets without any prior consent; and Antex may assign
this Agreement to any corporation with which Antex may merge, consolidate or
sell all or substantially all of its assets without any prior consent. All
covenants, representations, warranties and agreements of the parties contained
herein shall be binding upon and inure to the benefit of their respective
successors and permitted assigns.




                                       28
<PAGE>   23

                  Section 9.6 Public Announcements. No public announcement of
the transactions contemplated hereby or of the terms hereof at any time shall be
made by any party without the prior written consent of the other parties, not to
be unreasonably withheld or delayed, except to the extent as may be required by
law in the opinion of counsel to SB plc or counsel to Antex and in the latter
case, only upon at least five (5) days prior notification of the proposed
announcement to the other party.

                  Section 9.7 Expenses. The parties shall each pay all costs and
expenses incurred by them or on their behalf in connection with the preparation
of this Agreement and the transactions contemplated hereby, including without
limitation, fees and expenses of their own attorneys, accountants and advisors.

                  Section 9.8 Severability. The provisions of this Agreement are
severable, and in the event that any one or more provisions are deemed illegal
or unenforceable, the remaining provisions shall remain in full force and
effect.

                  Section 9.9 No Third Party Beneficiary. This Agreement is
intended and agreed to be solely for the benefit of the parties hereto, and no
third party shall accrue any benefit, claim or right of any kind whatsoever
pursuant to, under, by or through this Agreement.

                  Section 9.10 Opinion of Counsel to Antex. Within five (5)
business days of the execution and delivery of this Agreement by all of the
parties hereto, Covington & Burling, counsel to Antex, shall deliver its opinion
addressed to SB Bio concerning (i) the transactions



                                       29
<PAGE>   24

contemplated by this Agreement and (ii) the issuance of shares of the Common
Stock and the Amended and Restated Warrant to SB Bio, in the form set forth on
Exhibit E attached hereto.

            Section 9.11 Execution in Counterpart. This Agreement may be
executed in two or more counterparts, each of which shall be deemed an original
but all of which shall constitute one and the same instrument.

          [The balance of this page has been intentionally left blank.]





                                       30
<PAGE>   25




                  IN WITNESS WHEREOF, the parties have executed this Agreement
on the date first above written.


                           MicroCarb Human Vaccines Inc.



                           By:       /s/V. M. Esposito
                                    ----------------------------------
                              Name:       V. M. Esposito
                              Title:      President



                           Antex Biologics Inc.



                           By:       /s/V. M. Esposito
                                    ----------------------------------
                              Name:       V. M. Esposito
                              Title:      Chairman & CEO



                           SmithKline Beecham Biologicals Manufacturing s.a.



                           By:       /s/ Jean Stephenne
                                    ----------------------------------
                              Name:       Jean Stephenne
                              Title:      President, General Manager



                           SmithKline Beecham plc


                           By:       /s/Jean Stephenne
                                    ----------------------------------
                              Name:       Jean Stephenne
                              Title:      Attorney-in-Fact



                                       31

<PAGE>   1

                                                               EXHIBIT 10.2

                                             [XXXX] INDICATES INFORMATION
                                             OMITTED FROM THE EXHIBIT AND
                                             FILED SEPARATELY WITH THE
                                             COMMISSION PURSUANT TO A
                                             CONFIDENTIAL TREATMENT REQUEST








                   RESEARCH AND DEVELOPMENT, RESEARCH SUPPORT
                              AND LICENSE AGREEMENT


                                     BETWEEN


                              ANTEX BIOLOGICS INC.


                                       AND


                             SMITHKLINE BEECHAM PLC













                                        32
<PAGE>   2


                                TABLE OF CONTENTS

<TABLE>
<CAPTION>
ARTICLE                 TITLE                                                                              PAGE
<S>                     <C>                                                                                <C>
    1.                  DEFINITIONS                                                                        4
    2.                  RESEARCH AND DEVELOPMENT                                                           11
    3.                  RESEARCH SUPPORT                                                                   16
    4.                  GRANT OF LICENSE                                                                   18
    5.                  MILESTONE PAYMENTS AND ROYALTIES                                                   19
    6.                  REVERSION AND ROYALTY FOR TARGETS OUTSIDE OF
                        THE FIELD                                                                          23
    7.                  REVERSION AND NON EXCLUSIVE LICENSE ON TARGETS
                        WITHIN FIELD                                                                       25
    8.                  COMPULSORY LICENSES AND THIRD PARTY LICENSES                                       26
    9.                  DILIGENCE                                                                          27
   10.                  DEVELOPMENT, INDEMNIFICATION AND LIABILITY                                         29
   11.                  EXCHANGE OF INFORMATION AND CONFIDENTIALITY                                        30
   12.                  PATENT PROSECUTION AND LITIGATION                                                  33
   13.                  TRADEMARKS                                                                         35
   14.                  STATEMENTS AND REMITTANCES                                                         36
   15.                  TERM AND TERMINATION                                                               37
   16.                  RIGHTS AND DUTIES UPON TERMINATION                                                 39
   17.                  WARRANTIES AND REPRESENTATIONS                                                     39
   18.                  FORCE MAJEURE                                                                      41
   19.                  GOVERNING LAW/JURISDICTION                                                         42
   20.                  SEPARABILITY                                                                       43
   21.                  ENTIRE AGREEMENT                                                                   44
   22.                  NO WAIVER                                                                          44
   23.                  NOTICES                                                                            45
   24.                  ASSIGNMENT                                                                         46
   25.                  GENERAL PROVISIONS                                                                 46
APPENDIX A
APPENDIX B
</TABLE>




                                       33
<PAGE>   3





                   RESEARCH AND DEVELOPMENT, RESEARCH SUPPORT
                              AND LICENSE AGREEMENT


        This Research and Development, Research Support and License Agreement
("Agreement") is dated as of the 13th day of September 1999 and effective as of
the first day of September, 1999, ("Effective Date") between Antex Biologics
Inc., a Delaware corporation having a place of business at 300 Professional
Drive, Gaithersburg, Maryland 20879, USA (herein referred to as "ANTEX") and
SmithKline Beecham plc, having a place of business at New Horizons Court,
Brentford, Middlesex TW8 9EP, United Kingdom (herein referred to as "SB").

                                WITNESSETH THAT:

        WHEREAS, MicroCarb Human Vaccines Inc., MicroCarb Inc., (now ANTEX) and
SmithKline Beecham Corporation, an Affiliate of SB have entered into a Research
and Development, Research Support and License Agreement, dated May 6th, 1996
("Original License") under which the parties have entered into a collaboration
dedicated to the development of commercial human vaccine products for infectious
diseases; and

        WHEREAS, the parties hereto wish to restate the conditions of the
Original License and to replace the Original License by this Agreement; and

        WHEREAS, contemporaneously with the execution of this Agreement,
MicroCarb Human Vaccines Inc., ANTEX, SmithKline Beecham Biologicals
Manufacturing S.A. and SB are entering into an Omnibus Agreement of even date
herewith pursuant to which the parties thereto have agreed, among other things,
to merge MicroCarb Human Vaccines Inc. with and into ANTEX and terminate or
amend certain other agreements between the parties.




                                       34
<PAGE>   4

        NOW, THEREFORE, in consideration of the covenants and obligations
expressed herein and intending to be legally bound, and otherwise to be bound by
proper and reasonable conduct, the parties hereto agree as follows:


1.      DEFINITIONS

        1.01       "Affiliate(s)" shall mean any corporation, firm, partnership
                   or other entity, whether de jure or de facto, which directly
                   or indirectly owns, is owned by or is under common ownership
                   with a party to this Agreement to the extent of at least
                   fifty percent (50%) of the equity (or such lesser percentage
                   which is the maximum allowed to be owned by a foreign
                   corporation in a particular jurisdiction) having the power to
                   vote on or direct the affairs of the entity and any person,
                   firm, partnership, corporation or other entity actually
                   controlled by, controlling or under common control with a
                   party to this Agreement.

        1.02       "Antex Antigen" shall mean any Antigen [XXXXX] that has been
                   developed using the Intellectual Property.

        1.03       "Antigen" shall mean any active ingredient such as (but not
                   limited to) live attenuated micro-organisms, whole killed
                   micro-organisms or sub-unit particles (e.g. polysaccharides,
                   polysaccharide conjugates, peptides, proteins, recombinant
                   proteins, glycolipids), that elicits a specific immune
                   response.

        1.04       "Approval" shall mean any final approval granted by the FDA
                   or other comparable regulatory authority in any country for
                   the lawful manufacture, marketing, sale, administration,
                   distribution and use of a Product.

        1.05       "Combination" shall mean Product for one (1) or more Targets
                   in the Field and one (1) or more targets outside the Field.


                                       35
<PAGE>   5


        1.06       "Confidential Information" shall mean all written or tangible
                   information which is (or has been in the course of the
                   discussions leading to this Agreement) designated as
                   confidential and exchanged between the parties and any such
                   information disclosed orally or visually that is confirmed in
                   writing as confidential within thirty (30) days of disclosure
                   (or if such information was disclosed orally or visually
                   prior to the date hereof, it shall be deemed Confidential
                   Information if it was confirmed in writing as confidential on
                   or before the date hereof).

        1.07       "FDA" shall mean the United States Food and Drug
                   Administration.

        1.08       "Field" shall mean any and all prophylactic and/or
                   therapeutic human vaccines (but excluding development of
                   commercial products for use in passive immunization) for
                   infectious diseases caused or exacerbated by the following
                   Targets: Moraxella catarrhalis, Neisseria meningitidis
                   including serotypes A, B and C, non-typable Haemophilus
                   influenzae, Streptococcus pneumoniae and Chlamydia using the
                   "High Molecular Weight" protein ("HMWP") of Chlamydia.

        1.09       "HMWP" means the "High Molecular Weight Protein of Chlamydia
                   trachomatis described in Patents including ANTEX internal
                   reference NO. [XXXXX] with title "Chlamydia protein,
                   gene sequence and uses thereof" and any related foreign
                   filings including PCT application filed on October 1, 1998
                   under the application serial number PCT/US98/20737. For
                   purposes of clarity it is hereby recognized and agreed
                   [XXXXX].

        1.10       "Initial Period" shall have the meaning set forth in
                   Section 2.01.

        1.11       [XXXXX]

        1.12       "Intellectual Property" shall mean all Patents and
                   Technology.

        1.13       "Major European Country" shall mean any of Germany, the
                   United Kingdom, France, Italy and Spain.

                                       36
<PAGE>   6

        1.14.01    "Net Sales" shall mean gross receipts from sales of
                   Product in the Territory by SB and/or its sublicensees
                   under this Agreement less deductions actually taken for:

                      (i)    transportation charges including transportation
                             insurance; and

                      (ii)   the incremental production costs determined as
                             standard, excluding royalties or other licence
                             fees, for formulation, filling and packaging of
                             diluents, adjuvants and/or vehicles (other than
                             aluminium hydroxide) and/or any immune enhancing
                             elements, and for syringes and other administration
                             devices combined with, or contained in, commercial
                             packaging of Product; and

                      (iii)  sales and excise taxes and duties levied on a
                             selling party and any other governmental charges
                             imposed upon the production, importation, use or
                             sale of Product, including without limitation,
                             contributions and payments, required by any
                             governmental authorities, as liability provisions
                             and/or made pursuant to injury compensation schemes
                             and/or as product liability insurance premiums
                             including in the case of the United States of
                             America, contributions and payments required to be
                             made by the United States Government pursuant to
                             the National Childhood Vaccine Injury Act of 1986;
                             and

                      (iv)   normal and customary trade, quantity and cash
                             discounts, commissions to non-Affiliated brokers or
                             agents and other customary rebates accrued, paid
                             and/or allowed in accordance with generally
                             accepted accounting principles consistently
                             applied; and

                      (v)    amounts repaid or credited to customers or charges
                             back from customers on account of rejection or
                             return of Product subject to royalty under this
                             Agreement or on account of retroactive price
                             reductions affecting such Product; and

                                       37
<PAGE>   7

                      (vi)   royalties payable and/or paid by SB to Third
                             Parties on the manufacture, use and/or sale of
                             Product not otherwise deducted or taken into
                             account pursuant to Article 8 hereunder.

        1.14.02       Sales between or among SB and its Affiliates or
                      sublicensees shall be excluded from the computation of Net
                      Sales except where such Affiliates or sublicensees are end
                      users, but Net Sales shall include the subsequent final
                      sales to Third Parties by such Affiliates or sublicensees.

        1.14.03       If Product is sold as part of a Combination, Net Sales for
                      purposes of determining royalties on Product in the
                      Combination shall be calculated by excluding the relative
                      value of vaccines for targets outside the Field , and any
                      such excluded value shall be calculated on the basis of
                      the manufacturer's selling price of technically equivalent
                      vaccines for the same targets . In the event such
                      manufacturer's selling price is not available, ANTEX and
                      SB shall negotiate in good faith the relative value of the
                      vaccines and/or active ingredients included in the
                      Combination.

        1.14.04       In addition to any adjustment to Net Sales pursuant to
                      Section 1.14.03, if any, in the event that a Product
                      incorporates for the same [XXXXX] then Net Sales shall be
                      adjusted on a Target-by-Target basis by multiplying the
                      Net Sales number calculated pursuant to Sections 1.14.01
                      and 1.14.02 adjusted if appropriate pursuant to Section
                      1.14.03 by the [XXXXX], provided that such fraction for
                      any Target which includes at least an Antex Antigen shall
                      not be less than [XXXXX] irrespective of the number of
                      Antigens for such Target included in the Product.

        1.15          "Reverted New Targets" shall have the meaning set forth
                      in Section 7.01.

        1.16          "Other Patents" shall mean any patents and/or patent
                      applications owned and/or controlled by Third Parties
                      having claims which would be infringed by SB




                                       38
<PAGE>   8

                   importing, making, having made, using, having used,
                   offering for sale, selling or having sold Products.

        1.17       "Pasteur License" shall mean that certain License Agreement,
                   dated December 1, 1994 by and between ANTEX and Pasteur
                   Merieux Serums et Vaccins S.A.

        1.18       "Patents" shall mean all patents and patent applications
                   owned and/or controlled and/or used by ANTEX and its
                   predecessors including MicroCarb Human Vaccines Inc.
                   (pursuant to license agreement or otherwise) in or applicable
                   to the Field at anytime prior to the commencement of and
                   during the term of this Agreement, including any
                   continuations, continuations-in-part, divisions, patents of
                   addition, reissues, renewals or extensions (other than SPC)
                   thereof. The current list of patent applications and patents
                   encompassed within Patents is set forth in Appendix A
                   attached hereto and shall be modified from time to time.

        1.19       "Period" shall have the meaning set forth in Section 2.01.

        1.20       "Proceeds" shall have the meaning set forth in Section 6.03.

        1.21       "Product" shall mean any and all products in the Field which
                   embodies or utilizes any Intellectual Property.

        1.22       "R&D Committee" shall have the meaning set forth in
                   Section 2.02.

        1.23       "R&D Program" shall have the meaning set forth in
                   Section 2.01.

        1.24       "Registration" shall mean a filing with an appropriate
                   authority within any country for the purpose of obtaining
                   legal and regulatory approval for the marketing of a Product
                   in such country.

        1.25       "Research Support Facilities" shall have the meaning set
                   forth in Section 3.01.

                                       39
<PAGE>   9

        1.26       "Research Support Services" shall have the meaning set forth
                   in Section 3.01.

        1.27       "Reverted Target" shall have the meaning set forth in
                   Section 6.01.

        1.28       "Royalty Percentage" shall have the meaning set forth in
                   Section 5.03.

        1.29       "SB" shall mean SmithKline Beecham Corp. and its Affiliates.

        1.30       "SPC" shall mean all Supplementary Protection Certificates
                   for medicinal products and their equivalents provided under
                   the Council Regulation (EEC) NO. 1768/92 of June 18, 1992.

        1.31       "Steering Committee" shall have the meaning set forth in
                   Section 2.06.

        1.32       "Target" shall mean an infectious agent at the genus level
                   (unless indicated in Section 1.08 to be at the species level)
                   in the Field and all strains, variants, subtypes and
                   derivatives thereof. For purpose of clarity, HMWP shall
                   throughout this Agreement also be considered as a Target
                   within the Field.

        1.33        "Technology" shall include, to the extent they are not
                    included in Patents, any and all culture media, cell lines,
                    assay systems, DNA fragments, genes, constructs, plasmids,
                    vectors, development strains, expression systems, clones,
                    colonies, promoters, epitopes, micro-organisms, and any
                    other biological materials and deposits thereof (such as,
                    for example, deposits made with the American Type Culture
                    Collection or the European Type Culture Collection under the
                    Budapest Treaty), any and all copyrights, copyright
                    registrations and applications for copyright registrations,
                    any and all inventions, any and all trade secrets, present
                    and/or future data, technical information, know-how, and
                    confidential or proprietary information (including without
                    limitation all chemical, pharmacological, toxicological,
                    clinical, assay, control and manufacturing data and any
                    other similar information) and/or improvements to any of the
                    foregoing, in or applicable to the Field owned and/or
                    controlled and/or used by ANTEX and its predecessors
                    including



                                       40
<PAGE>   10

                   MicroCarb Human Vaccines Inc., (pursuant to license agreement
                   or otherwise) at anytime prior to the commencement of and
                   during the term of this Agreement.

        1.34       "Territory" shall mean all the countries and territories of
                   the world.

        1.35       "Third Party(ies)" shall mean any party which is neither a
                   party to this Agreement nor an Affiliate.

        "Interpretive Rules". For purposes of this Agreement, except as
        otherwise expressly provided herein or unless the context otherwise
        requires : (a) defined terms include the plural as well as the singular
        and the use of any gender shall be deemed to include the other gender;
        (b) references to "Articles", "Sections" and other subdivisions and to
        "Schedules", "Appendices" and "Exhibits" without reference to a
        document, are to designated Articles, Sections and other subdivisions
        of, and to Schedules, Appendices and Exhibits to, this Agreement; (c)
        the use of the term "including" means "including but not limited to";
        and (d) the words "herein", "hereof", "hereunder" and other words of
        similar import refer to this Agreement as a whole and not to any
        particular provision.


2.      RESEARCH AND DEVELOPMENT

        2.01    Subject to the further terms and conditions set forth in this
                Agreement, ANTEX shall, on SB's behalf, conduct a new research
                and development program ("R&D Program") for the period from 1st
                July 1999 to 31st December 1999 ("Initial Period") directed to
                [XXXXX] or other projects as agreed by the R&D Committee and SB
                agrees to pay ANTEX on July 1, 1999 and on October 1, 1999, the
                amount of six hundred sixty-six thousand six hundred and
                sixty-seven US dollars (US $ 666,667) for the performance of
                such activities in line with an R&D plan agreed from time to
                time by the R&D Committee. At SB's sole discretion this R&D
                Program may be extended beyond December 31, 1999, for one (1) or
                more periods of no less than one (1) year (each "Period")



                                       41
<PAGE>   11

                unless mutually agreed between the parties and, if SB so elects,
                the research activities to be performed, the related budget and
                related plan shall be discussed and approved by the R&D
                Committee described in Section 2.02 no later than 1st October
                1999 and, in the case of any further extension, on October 1st
                or ninety(90) days before the end of any Period.

                For any such Period elected by SB, SB shall pay to ANTEX,
                January 1st and July 1st, one half of the related budget for the
                R&D Program agreed upon by the R&D Committee.

        2.02    SB and ANTEX hereby establish a new R&D committee (the "R&D
                Committee") which shall have all powers which are necessary or
                desirable with respect to the implementation and management of
                the R&D Program, including without limitation the power to: (i)
                prepare and approve at the latest ninety (90) days prior to the
                end of the Initial Period or extended Period of the R&D Program
                a plan of specific activities to be performed and related
                deliverables to be achieved by ANTEX during the next Period of
                the R&D Program and the related budget; (ii) make
                recommendations to SB and ANTEX to amend the R&D Program in
                progress; (iii) make decisions with respect to the preparation,
                filing, prosecution and maintenance of Patents; (iv) monitor and
                enforce the budget contained in the relevant R&D Program and to
                verify that all items within the plan of activities have been in
                fact carried out and that the related deliverables have in fact
                been achieved; and (v) the power specified in Section 2.08. The
                R&D Committee shall have no power to : (x) amend, modify, revise
                or waive any provision of this Agreement other than specifically
                provided for herein or; (y) bind ANTEX or any other party hereto
                to any contract or other commitment with a Third Party or grant
                any license or other rights in or with respect to a Product.

        2.03    SB's initial appointees to the R&D Committee are Yves Lobet who
                shall act as SB liaison representative and Jan Poolman and
                ANTEX' initial appointees to the R&D Committee are Larry
                Ellingsworth who shall act as ANTEX liaison representative and
                Theresa Stevens. Meetings of the R&D Committee shall be

                                       42
<PAGE>   12

                held periodically at a place mutually agreed upon, but not less
                frequently than semi-annually. No meeting of the R&D Committee
                shall be convened unless at least two (2) of the members of the
                R&D Committee (one each representing SB and ANTEX) are present
                in person or by telephone conference call. SB and ANTEX shall
                each bear the expenses associated with the attendance at
                meetings of the R&D Committee by members of such committee
                appointed by it. The R&D Committee shall nominate a Chairman to
                call the meetings and a secretary to take the minutes. Other
                than for face-to-face meetings, the parties shall make all
                reasonable efforts to exchange any information on the R&D
                Program and other scientific information to be exchanged between
                or communicated to the parties pursuant to this Agreement
                through their liaison representatives.

        2.04    Each member of the R&D Committee shall be entitled to cast one
                (1) vote on each matter presented for approval at any meeting of
                the R&D Committee. A matter presented for approval at any
                meeting of the R&D Committee shall be considered approved if the
                unanimous consent of the members present at such meeting is
                given in favor of such matter. In the event that any matter
                presented for approval at any meeting of the R&D Committee does
                not receive such unanimous consent, the matter not approved will
                be submitted for resolution to the Steering Committee described
                in Section 2.06 below.

        2.05    For so long as a R&D Program is carried out the R&D Committee
                shall continue to exercise the powers described in Section 2.02
                in accordance with the procedural requirements for approval set
                forth in Section 2.04 and continue to be comprised of four (4)
                members, two (2) of whom are appointed by each of SB and ANTEX
                as described in Section 2.03.

        2.06    ANTEX and SB hereby establish a steering committee (the
                "Steering Committee") composed of two (2) members, one of whom
                shall be appointed by SB and the other appointed by ANTEX, which
                shall be responsible for (i) resolving any dispute or
                disagreement arising at the level of the R&D Committee and/or
                (ii) discussing any business disagreement between the


                                       43
<PAGE>   13

                parties during the R&D Program or after its termination and/or
                (iii) discussing any other matters pertinent to the relationship
                of the parties. Meetings of the Steering Committee shall be
                called by either member of the Steering Committee whenever a
                matter of dispute or disagreement arises between the parties, or
                upon request of either SB or ANTEX. Each party agrees to cause
                its appointee to the Steering Committee to participate in person
                or by telephone conference call in all meetings of the Steering
                Committee. SB's initial representative on the Steering Committee
                is Moncef Slaoui and ANTEX' initial representative on the
                Steering Committee is Vic Esposito.

        2.07    ANTEX shall perform the research and development activities
                allocated to it in the R&D Program as from time to time in
                effect to the best of its abilities and in accordance with: (i)
                this Agreement; and (ii) the scientific, professional and
                commercial standards prevailing in the biotechnology industry at
                the time that such activities are performed. Subject to Section
                2.11, all research and development activities performed by ANTEX
                that are funded by SB are performed by ANTEX on behalf of SB.

        2.08    The R&D Committee shall also have, at its entire discretion, the
                power to allocate and/or switch and/or transfer resources within
                ANTEX to alternative projects within the Field. In addition, SB
                may in its sole discretion (and without the consent of either
                the R&D Committee or ANTEX), at anytime, to transfer any project
                within the Field underway at ANTEX to SB facility in Rixensart
                or to any other SB facility or to any collaborator of SB. Any
                such allocation, switch or transfer will have no impact on the
                overall budget funding approved by the R&D Committee for the
                next six (6) months of the then current period of the R&D
                Program, but ANTEX agrees to apply any unused funds to any other
                activity as may be directed or requested by SB. From January
                1st, 2000, SB agrees to give ANTEX an advance notice of one
                hundred and twenty (120) days before any such different
                allocation or switching of resources or transfer of projects.

        2.09    No later than forty-five (45) days after the last day of the
                Initial Period and any subsequent Period, ANTEX shall furnish to
                SB a written accounting of the



                                       44
<PAGE>   14

                expenditure of all amounts funded by SB, which accounting shall:
                (i) reconcile the expenditure of funds with amounts budgeted for
                expenditure in the R&D Program during such Period; and (ii) make
                available for SB's review a printed listing of all invoices of
                Third Parties related to the expenditure of such R&D Program
                and, upon SB's request, shall also make available invoices
                themselves. In the event that the amounts budgeted by the R&D
                Committee and funded by SB for any such Period of the Research
                Program exceed the amounts expended by ANTEX for activities
                described in the plan for such Period, ANTEX shall pay SB the
                amount of such excess within forty-five (45) days after the last
                day of such Period or if, at SB's discretion, the R&D Program
                continues for a further Period as indicated in Section 2.01,
                such amount shall be reallocated to activities to be performed
                during such Period.

        2.10    ANTEX shall be eligible to be reimbursed for its actual,
                out-of-pocket expenses for clinical trials specifically
                requested by SB and conducted by ANTEX for SB in the Field
                and/or for GMP manufacturing of preclinical or clinical lots to
                be used in said clinical trials which are not covered by the R&D
                Program(s) provided ANTEX receives SB's written approval thereof
                in advance of their disbursement ("Reimbursable Expenses").
                Payment by SB will occur thirty (30) days after SB's approval of
                disbursement and documentary evidence of the disbursement will
                then be submitted by ANTEX to SB for verification within thirty
                (30) days of the disbursement or as soon as possible after
                ANTEX' receipt of such evidence. In addition, and subject to any
                necessary verification by SB, SB agrees to pay the outstanding
                bill for the phase I Helicobacter pylori clinical trial
                undertaken pursuant to the Original License, within a reasonable
                period of time after invoicing by ANTEX and up to a maximum
                amount of [XXXXX].

        2.11    Subject to the next sentence, all improvements to the
                Intellectual Property resulting from the R&D [XXXXX] will be
                owned by ANTEX and shall fall within the scope of the rights and
                licences granted by ANTEX to SB in Article 4 below. All
                improvements of SB's proprietary adjuvants, biological
                material(s), proteins and other materials provided by SB and of
                [XXXXX] and work products,




                                       45
<PAGE>   15

                biological material(s), other intellectual property,
                information, materials and all rights related therein, which
                arise or are derived from the R&D Program or otherwise from
                activities contemplated by or undertaken pursuant to this
                Agreement shall be owned solely and exclusively by SB. In
                particular, it is understood that the results of the R&D Program
                based on [XXXXX] shall be solely and exclusively owned by SBB.




                                       46
<PAGE>   16


3.      RESEARCH SUPPORT

        3.01       ANTEX shall render such research support services (the
                   "Research Support Services") and provide such research
                   support facilities (the "Research Support Facilities") as
                   shall be necessary or desirable to facilitate and implement
                   the R&D Program as from time to time in effect. For the
                   period of performance of the R&D Program ANTEX shall be
                   solely responsible for bearing all expenses relating to
                   provision of such Research Support Services and Research
                   Support Facilities.

        3.02       ANTEX shall render the Research Support Services to the best
                   of its ability and in accordance with the scientific,
                   professional and commercial standards prevailing in the
                   biotechnology industry at the time that the Research Support
                   Services are rendered. ANTEX shall comply with all applicable
                   laws and regulations in rendering the Research Support
                   Services and shall indemnify and hold harmless SB, its
                   Affiliates and their respective directors, officers and
                   employees from any and all liability, loss, damage and
                   expense arising out of or related to the failure by ANTEX to
                   comply with all applicable laws and regulations in rendering
                   the Research Support Services.

        3.03       ANTEX shall promptly notify SB if the employment status of
                   any of the ANTEX employees working on the R&D Program
                   changes. ANTEX shall not subcontract with any Third Parties
                   for the performance of the Research Support Services, except
                   appropriate clinical and preclinical work agreed by the R&D
                   Committee, including, but not limited to, animal studies, GMP
                   or pre-GMP pilot lot production, consultations, and human
                   trials as required. In the case of human trials, trial
                   protocols must be approved by SB prior to filing and must be
                   filed with the competent regulatory authority in the name of
                   SB. ANTEX warrants that it has a binding, written agreement
                   (in the form substantially similar to the form attached
                   hereto as Appendix B) with each ANTEX' scientific employee
                   working on the R&D Program, which agreement shall be in place
                   prior to such employee performing the Research Support
                   Services, and which agreement shall obligate such employee to
                   disclose his work product to



                                       47
<PAGE>   17

                   ANTEX, to not use or disclose such work product to Third
                   Parties, and to assign to ANTEX, (subject to the rights and
                   licences granted to SB under this Agreement), all rights in
                   such work product including without limitation any and all
                   intellectual property rights.

        3.04       ANTEX shall provide the real property required to perform the
                   R&D Program and all of the required fixtures and personal
                   property presently located at 300 Professional Drive,
                   Gaithersburg, Maryland as the Research Support Facilities.
                   All of the Research Support Services shall be performed at
                   the Research Support Facilities, except appropriate clinical
                   and preclinical work agreed by the R&D Committee, including,
                   but not limited to, animal studies, GMP or pre-GMP pilot lot
                   production, consultations, and human trials as required.
                   ANTEX commits to maintain the Research Support Facilities in
                   good operating condition and repair and perform all
                   obligations required to be performed by it under leases,
                   contracts and other commitments relative to the Research
                   Support Facilities. ANTEX shall comply with all applicable
                   laws and regulations in operating the Research Support
                   Facilities and shall indemnify and hold harmless SB, its
                   Affiliates and their respective directors, officers and
                   employees from any and all liability, loss, damage and
                   expense arising out of or related to the failure by ANTEX to
                   comply with all applicable laws and regulations in operating
                   the Research Support Facilities.

        3.05       The parties agree that all persons who perform the Research
                   Support Services shall be employees of ANTEX, and not
                   employees of SB. ANTEX shall be solely responsible for the
                   terms and conditions of the employment of such individuals
                   and the fulfillment of all obligations owed to such
                   employees. ANTEX shall indemnify and hold harmless SB, its
                   Affiliates and their respective directors, officers and
                   employees from any and all liability, loss, damage and
                   expense arising out of or related to any employment-related
                   claims asserted against any of them by any of ANTEX'
                   employees except for any claims that ANTEX demonstrates have
                   arisen out of or relate to actions taken by SB, its
                   Affiliates or their respective directors, officers or
                   employees.


                                       48
<PAGE>   18

4.      GRANT OF LICENSE

        4.01       Subject to the reversion clauses contained in Articles 6 and
                   7 hereof and all the terms and conditions herein contained,
                   ANTEX hereby grants to SB an exclusive and perpetual right
                   and license in the Territory, with the right to grant
                   sublicenses, under the Intellectual Property and any SPC to
                   develop, have developed, import, make, have made, use, have
                   used, offer for sale, sell and have sold any and all Products
                   in any formulation, combination, configuration and/or
                   delivery system.

        4.02       The grant of license by ANTEX pursuant to Section 4.01 shall
                   be subject to the rights granted by ANTEX under the Pasteur
                   License as was in effect on the effective date of the
                   Original License for so long as such rights continue to
                   exist.

        4.03       Any and all Intellectual Property for use in the Field
                   including but not limited to any improvements of Intellectual
                   Property for use in the Field which is developed, conceived,
                   owned, controlled and/or acquired by ANTEX, whether solely or
                   jointly with others, at anytime prior to the commencement and
                   during the term of this Agreement, shall become Intellectual
                   Property licensed to SB under this Agreement, subject in the
                   case of Intellectual Property that is licensed or acquired by
                   ANTEX from Third Parties, or developed in part by Third
                   Parties, to any contractual obligations of ANTEX to such
                   Third Parties existing as of the Effective Date or by the
                   patent laws subsisting in the United States or foreign
                   countries.

        4.04       To the extent not provided for in Section 11.01 ANTEX agrees
                   to promptly transfer without the payment of any additional
                   consideration to SB at SB's request, any material, data,
                   information and/or technology within or covered by
                   Intellectual Property and SB agrees to confirm receipt of any
                   such material, data, information and/or technology transfer.

                                       49
<PAGE>   19

        4.05       SB is free to exercise its rights under the license
                   described in Section 4.01 in any manner SB may deem
                   appropriate, including through working with Third Parties
                   consistent with the terms hereof.


5.      MILESTONE PAYMENTS AND ROYALTIES

        5.01       SB agrees to make the following one-time milestone payments
                   to ANTEX with respect to Product in the Field in the
                   following amounts:

                   (a)       Upon the successful completion of phase I clinical
                             trials as required for Approval of a Product by the
                             FDA or substantially similar trials required for
                             Approval by equivalent regulatory authorities in
                             any Major European Country, SB shall pay to ANTEX
                             the amount of [XXXXX].

                   (b)       Upon the successful completion of phase II clinical
                             trials as required for Approval of a Product by the
                             FDA or substantially similar trials required for
                             Approval by the equivalent regulatory authorities
                             in any Major European Country, SB shall pay to
                             ANTEX the amount of [XXXXX].

                   (c)       Upon the successful completion of phase III
                             clinical trials as required for Approval of a
                             Product by the FDA or substantially similar trials
                             required for Approval by the equivalent regulatory
                             authorities in any Major European Country, SB shall
                             pay to ANTEX the amount of [XXXXX].

                   (d)       Upon Approval of a Product by the FDA, SB shall
                             pay to ANTEX the amount of [XXXXX].

                   (e)       Upon Approval of a Product by the FDA-equivalent
                             authorities of any two (2) Major European
                             Countries, SB shall pay to ANTEX the amount of
                             [XXXXX].



                                       50
<PAGE>   20

                   For the purposes of this Agreement "successful completion"
                   shall mean that, based on the success of such clinical trial,
                   SB decides to enter the next phase of clinical trial or to
                   seek Registration as appropriate.

        5.02       Any milestone payments made by SB pursuant to Section 5.01
                   shall be credited towards SB's obligation to pay any
                   royalties, on a dollar for dollar basis, pursuant to Section
                   5.03 and shall be payable with respect to the first Product
                   incorporating Antex Antigen(s) against each of the Targets
                   within the Field. For the sole purpose of clarification, it
                   is hereby acknowledged and agreed that no milestone payment
                   shall be required to be paid by SB to ANTEX for products
                   against Targets which were licensed to SB under the Original
                   License but which are not within the definition of "Field"
                   contained in this Agreement.

        5.03       As consideration for the license under Intellectual Property
                   granted to SB under this Agreement, and subject to the
                   provisions of Sections 5.02, 8.02 and 8.03, SB shall pay to
                   ANTEX a royalty calculated as a percentage (the "Royalty
                   Percentage") of Net Sales by SB and its sublicensees
                   according to one (1) of the following subsections:

                   (a)       If the Product is covered in the particular country
                             where sales are made by a valid claim of an
                             enforceable granted Patent or by a patent
                             application within Patents listed in Appendix A
                             which has not been pending for more than five (5)
                             years from the date of filing in such country, the
                             Royalty Percentage shall be [XXXXX].

                   (b)       If the Product is not covered by a valid claim of
                             an enforceable granted Patent in the particular
                             country where sales are made, provided SB actually
                             uses, for the making, using or selling of such
                             Product, Technology which is secret, substantial
                             and has been identified in writing by ANTEX, the
                             Royalty Percentage shall [XXXXX].

        5.04       SB's royalty obligation under Section 5.03 (a) shall become
                   effective in each country of the Territory at such time as an
                   enforceable Patent is granted or a




                                       51
<PAGE>   21

                   patent application within Patents listed in Appendix A is
                   pending for less than five (5) years from date of filing in
                   such country covering the Product sold and shall terminate
                   upon the date of lapse, expiration or invalidation of the
                   last remaining Patent in such country or fifteen (15) years
                   from first launch of Product, whichever comes first. Subject
                   to Section 5.03 (b), in the event that any Third Party
                   initiates any legal or administrative proceeding challenging
                   the validity, scope or enforceability of a Patent in any
                   country in the Territory, then such royalty obligation on Net
                   Sales in such country under 5.03(a) shall be suspended during
                   pendency of the proceeding in such country and only the
                   royalty under 5.03(b) shall be paid if applicable. If the
                   enforceability of claims in the Patent covering Product sold
                   are upheld by a court or other legal or administrative
                   tribunal from which no appeal is or can be taken, then the
                   amount of royalties owed during the period of suspension,
                   less any amount already paid, shall be promptly paid by SB
                   with [XXXXX]. If the claims in the Patent are held to be
                   invalid or otherwise unenforceable by a court or other legal
                   or administrative tribunal from which no appeal is or can be
                   taken then the amount of unpaid royalties during the period
                   of suspension shall be retained by SB and no further
                   royalties under 5.03(a) shall be owed with respect to such
                   Patent in such country.

        5.05       SB's royalty obligation under Section 5.03 (b) shall
                   terminate on the seventh (7th) anniversary of the date of the
                   first commercial sale of such Product in two (2) Major
                   European Countries or in the U.S.A., whichever is earlier.

        5.06       Termination of royalty obligations under Section 5.04 and/or
                   5.05 in any country of the Territory shall not preclude SB
                   from continuing to market Product(s) in such country and SB
                   shall be free to use Technology and other Intellectual
                   Property in the Field in relation to such Product without any
                   further financial consideration or royalty payments in
                   relation to such Product to ANTEX in such country.

        5.07       In addition to royalty obligations under Section 5.03(a) as
                   sole remuneration for [XXXXX], SB shall pay to ANTEX a
                   Royalty Percentage of [XXXXX]on the



                                       52
<PAGE>   22

                   proportion of net sales (calculated as specified in Section
                   1.14.01 to 1.14.03) of vaccines incorporating only [XXXXX].
                   The parties agree that [XXXXX] will be incorporated in
                   Product only if there are valid data justifying their
                   preclinical efficacy or if the R&D Committee agrees to the
                   incorporation or addition of [XXXXX] in Products.
                   Notwithstanding the foregoing it is understood and agreed
                   that ANTEX has assigned and will assign to SB any ownership
                   or partial ownership of any intellectual property owned
                   and/or developed by ANTEX when performing work on behalf or
                   at the request of SB relating to [XXXXX].

                   For the purpose of clarity,

                   (a)       if a vaccine other than a Product as sold by SB
                             contains solely [XXXXX], the royalty rate of
                             [XXXXX] described above shall apply irrespective of
                             the number of such [XXXXX] therein;

                   (b)       if a Product as sold by SB contains [XXXXX] and
                             Antex Antigens, the royalty rate shall be
                             determined as per Article 5, with Net Sales
                             calculated and adjusted as per Section 1.14;

                   (c)       if a vaccine other than a Product as sold by SB
                             contains [XXXXX] and at least one other Antigen
                             which is not an Antex Antigen (i.e. Article 5 does
                             not apply) then the effective royalty of [XXXXX]
                             shall be obtained by applying a royalty [XXXXX] to
                             the net sales of such vaccine calculated as per
                             Sections 1.14.01 to 1.14.03 and adjusted as
                             specified in Section 1.14.04.


6.      REVERSION AND ROYALTY FOR TARGETS OUTSIDE OF THE FIELD

        6.01       SB agrees that SB's rights to use the Intellectual Property
                   for products against Targets previously licensed to SB under
                   the Original License and which now fall outside the Field as
                   defined in this Agreement shall hereby revert to ANTEX. In
                   exchange for the reversion of such rights with respect to
                   Helicobacter pylori and Campylobacter ("Reverted Targets")
                   only, ANTEX agrees to make the following future payments to
                   SB:



                                       53
<PAGE>   23

                   (a)       if any Reverted Target is licensed by ANTEX (or any
                             of its Affiliates) to any Third Party, SB shall be
                             entitled to receive [XXXXX] of the Proceeds within
                             thirty (30) days of ANTEX' receipt thereof; and

                   (b)       if any product against any Reverted Target is
                             marketed by ANTEX or by a distributor or agent of
                             ANTEX, SB shall be entitled to receive a royalty of
                             [XXXXX] covered by a patent or [XXXXX] if covered
                             by know-how of net sales (calculated as per Section
                             1.14) of products against the Reverted Target(s)
                             made by ANTEX and/or its distributors and agents.

        6.02       The sharing of Proceeds and/or royalty described in Section
                   6.01 (a) and (b) above shall apply when ANTEX grants any
                   right to and/or interest in, including future right and/or
                   interest, to a Third Party, or uses to develop products
                   marketed by ANTEX or its distributor and agent relating to
                   the Reverted Target(s) licensed to SB under the Original
                   License which is conceived or existing as of the Effective
                   Date hereof or which was developed and/or improved during a
                   period of eighteen (18) months after the Effective Date
                   hereof.

        6.03       For purpose of this Article 6, the term "Proceeds" shall mean
                   any money or other assets at any time received by ANTEX from
                   a Third Party in respect of the Reverted Targets and shall
                   include, without limitation, any licence fees, milestone
                   payments and royalties but shall not include funding received
                   from that Third Party for R&D work performed by ANTEX in
                   relation to the Reverted Target so long as ANTEX can
                   demonstrate to SB that such funding is exclusively used by
                   ANTEX for R&D activities.

        6.04       ANTEX agrees to provide SB with the financial elements of or,
                   if requested by SB the agreement, redacted if reasonably
                   necessary, related to any right, interest, license or
                   sublicense granted by ANTEX to a Third Party relating to the
                   Reverted Target(s) in order and sufficient for SB to
                   determine the extent of Proceeds and/or R&D funding, if any.
                   If the agreement entered by ANTEX and



                                       54
<PAGE>   24

                   the Third Party includes rights to Reverted Targets and other
                   matters, the Proceeds allocated to Reverted Targets shall be
                   determined in good faith by the parties according to the
                   circumstances and shall reflect the relative stage of
                   advancement (e.g. clinical or preclinical) of each Reverted
                   Target compared to any such other matters.

        6.05       Notwithstanding the foregoing, the parties recognize that the
                   current formulation of products against the Reverted [XXXXX].
                   In the latter case, ANTEX and SB agree to negotiate a fair
                   reduction of the payment SB is entitled to receive pursuant
                   to Section 6.01 (a) and/or (b), depending upon the planned
                   extent of the reformulation.


7.      REVERSION AND NON EXCLUSIVE LICENSE ON TARGETS WITHIN FIELD

        7.01       If at any time during the term of this Agreement SB is no
                   longer active or is no longer using Intellectual Property at
                   SB, at ANTEX or elsewhere with respect to a Target within the
                   Field and this situation has lasted for at least eighteen
                   (18) months such Target (hereinafter "Reverted New Target")
                   shall revert on a non-exclusive basis to ANTEX and ANTEX
                   shall be entitled, after it has made the reversion payment
                   described in Section 7.01(a) to grant to (a) Third Party(ies)
                   a non-exclusive license under Intellectual Property with
                   respect to the development of products against such Reverted
                   New Target(s) subject to the following conditions :

                   (a)       SB and ANTEX shall negotiate in good faith
                             reversion payments to be made by ANTEX to SB at the
                             time of reversion, which reversion payments shall
                             reflect among other things, the stage of
                             advancement of the Reverted New Target, funding
                             provided by SB and data, technology and/or
                             information with respect to such Reverted New
                             Target generated and provided by SB to ANTEX.



                                       55
<PAGE>   25

                   (b)       Notwithstanding the foregoing, such reversion shall
                             not take place so long as: (i) SB is funding a R&D
                             Program at ANTEX relating to that Target within the
                             Field and for a period of eighteen (18) months
                             thereafter; (ii) SB is further developing, or
                             otherwise using Intellectual Property relating to
                             that Target, (iii) is undertaking, or has
                             undertaken within a preceding forty-eight (48)
                             month period clinical trials with a Product
                             incorporating an Antex Antigen for that Target (iv)
                             or has launched a Product for that Target on the
                             market, in which cases SB's license for such
                             Target(s) remains exclusive in perpetuity.

                   (c)       SB shall in any event retain a non-exclusive
                             licence with respect to any Reverted New Target
                             under Intellectual Property existing at the time of
                             reversion.

                   (d)       For the purpose of clarity only, and subject to the
                             preceding paragraphs: (i) a reversion may only
                             occur with respect to a Target within the Field for
                             which SB has not undertaken clinical trials within
                             the forty-eight (48) months preceding a possible
                             date for reversion; [XXXXX].


8.      COMPULSORY LICENSES AND THIRD PARTY LICENSES

        8.01       In the event that a governmental agency in any country or
                   territory grants or compels ANTEX to grant a license to any
                   Third Party for product(s) that compete with Product(s)
                   through importation or otherwise, SB shall have the benefit
                   in such country or territory of the terms granted to such
                   Third Party to the extent that such terms are more favorable
                   to the Third Party than those granted to SB under this
                   Agreement to the extent permitted by such governmental
                   agency.

        8.02       The parties recognize that Other Patents may exist. If at any
                   time during the term of this Agreement and/or the Original
                   License, SB, at its sole discretion, but after consultation
                   with ANTEX, deems it necessary to seek a license under



                                       56
<PAGE>   26

                   any Other Patent(s) from any Third Party in order to practice
                   the right and license granted by ANTEX to SB hereunder and
                   avoid infringement during such exercise in any particular
                   country [XXXXX] of any royalties or equivalent fees paid by
                   SB to such Third Party under such license may be deducted
                   from royalties otherwise payable by SB to ANTEX under this
                   Agreement.

        8.03       In the event that royalties are payable by SB to Third
                   Party(ies) on sales of Product, other than pursuant to
                   Section 8.02 above, ANTEX and SB shall evenly share
                   responsibility of any and all such Third Party royalty
                   obligations, which may include, but shall not be limited to,
                   royalties payable for adjuvants and other technology included
                   in the Product. ANTEX' contribution to such share shall be
                   through a reduction in the royalties payable to ANTEX
                   pursuant to Section 5.03, provided however that the Royalty
                   Percentage shall not be reduced by more than [XXXXX].

 9.     DILIGENCE

        9.01       SB will, in accordance with SB's reasonable business, legal,
                   medical, technical and/or scientific judgment, exercise
                   reasonable efforts and diligence in developing,
                   commercializing and selling Product and in undertaking
                   investigations and actions required to obtain appropriate
                   governmental Approvals to market Product. At SB's request,
                   ANTEX shall supply to SB reasonable technical assistance in
                   undertaking such investigations and actions and SB will
                   reimburse ANTEX for its reasonable out-of-pocket expenses
                   associated with the provision of such assistance. The level
                   of effort to be exercised by SB shall be consistent with SB's
                   usual funding level of similar vaccine programs or Products
                   currently under development by SB's Belgian Affiliate
                   SmithKline Beecham Biologicals S.A.

        9.02       The parties acknowledge that it is not consistent with
                   prudent economic behavior and risk management, nor common in
                   the industry, to pursue development of the Intellectual
                   Property for all Products at the same time, but rather to
                   manage the scope and number of development programs and



                                       57
<PAGE>   27

                   respective funding levels as a function of achieving
                   feasibility milestones of a limited number of priority
                   programs. As long as SB is developing one (1) Product in the
                   Field pursuant to the provision of Section 9.01 above, SB
                   shall be deemed to be in full compliance with the diligence
                   requirements under this Agreement.

        9.03       ANTEX shall provide to SB, at SB's request and without the
                   payment of additional consideration, technical assistance
                   concerning development, production and commercialization of
                   Products in the Field. Provision of such technical assistance
                   shall include, but not be limited to, visits by ANTEX and/or
                   ANTEX' personnel to SB at ANTEX' expense, except for
                   reasonable out-of-pocket expenses which will be reimbursed by
                   SB, and visits by SB personnel to ANTEX, at SB's expense, at
                   times and for periods of time upon which the parties will
                   agree. Such provision shall also include, but not be limited
                   to, preparation and processing of INDs, NDAs or similar
                   applications for regulatory Approval and supply of any
                   Technology together with any technology and know-how ANTEX
                   will develop or acquire during the provision of such
                   technical assistance related to the Intellectual Property in
                   the Field, which SB may reasonably require.

        9.04       In the event that SB decides not to pursue Registration or
                   sell a Product that has been approved for sale in a country,
                   including pricing approvals and batch release, and SB is
                   willing to grant distribution rights for such Product in such
                   country to a Third Party, SB will first offer such
                   distribution rights to ANTEX, provided that ANTEX can
                   demonstrate within thirty (30) days of the date that SB
                   offers such distribution rights that it can effectively serve
                   as distributor in such country and is willing to make the
                   necessary commitments to support the selling and distribution
                   of Product in such country, and provided further that there
                   are no adverse effects related to such Product and that such
                   selling activities would not be to the detriment of the
                   commercialization of the same Product by SB in any other
                   country. If ANTEX demonstrates that it can effectively serve
                   as distributor, has made the selling support commitment and
                   its selling activities will not be



                                       58
<PAGE>   28

                   detrimental to the commercialization of the same Product by
                   SB in another country, ANTEX shall have a three (3) month
                   exclusive negotiation period to conclude the distribution
                   agreement. If after this three (3) month period no agreement
                   has been concluded, SB is free to pursue Third Parties to
                   sell such Product in the specified country.


        9.05       ANTEX' failure to comply with any of its obligation(s) under
                   this Agreement, shall be taken into account in establishing
                   whether SB has satisfied its diligence requirements
                   hereunder.


 10.    DEVELOPMENT, INDEMNIFICATION AND LIABILITY

        10.01      SB shall be solely responsible for and shall bear all costs
                   related to the development of Products, including the conduct
                   of clinical trials, and the commercialization of Products,
                   including the manufacturing and marketing of Products. SB
                   shall indemnify and hold harmless ANTEX and its directors,
                   officers and employees from any and all liability, loss,
                   damage and expense arising from any claims, suits,
                   proceedings, demands, recoveries or expenses related to (i)
                   the development of Products, including, with respect to
                   products for Reverted Targets, the conduct of clinical trials
                   initiated by SB or in which SB has been involved between the
                   effective date of the Original License and the Effective Date
                   hereof, and for (ii) the commercialization, manufacture, use
                   or sale of Products, except that ANTEX shall indemnify and
                   hold harmless SB and its Affiliates and their respective
                   directors, officers and employees from any and all liability,
                   loss, damage and expense arising from any claims, suits,
                   proceedings, demands, recoveries or expenses related to the
                   commercialization, manufacture, use or sale of Products
                   resulting from the gross negligence or willful misconduct of
                   ANTEX. ANTEX shall be solely responsible for any and all
                   liabilities out of or relating to clinical trials conducted
                   by or on behalf of ANTEX and/or MicroCarb Human Vaccines
                   Inc., prior to the effective date of the Original License and
                   ANTEX shall indemnify and hold harmless SB and its Affiliates
                   and their respective directors, officers and



                                       59
<PAGE>   29

                   employees from any and all liability, loss, damage and
                   expense arising out of or relating to clinical trials
                   conducted by or on behalf of ANTEX and/or MicroCarb Human
                   Vaccines Inc., prior to the effective date of the Original
                   License.

        10.02      SB shall maintain, at its sole expense, during the term of
                   this Agreement and for a period of at least five (5) years
                   after its termination for any reason, product liability
                   insurance and clinical trial insurance (or a reasonable
                   program of self-insurance) with respect to all Products
                   developed pursuant to the R&D Program (but specifically
                   excluding clinical trial insurance for clinical trials
                   conducted by or on behalf of ANTEX and/or MicroCarb Human
                   Vaccines Inc., prior to the effective date of the Original
                   License ) in amounts comparable to its coverage relating to
                   its other human vaccine products that are manufactured and
                   distributed on a worldwide basis.

        10.03      ANTEX shall maintain, at its sole expense, during the term of
                   this Agreement and for a period of at least five (5) years
                   after its termination for any reason, product liability
                   insurance with respect to any of the activities it will
                   perform hereunder which are not covered by SB under Section
                   10.02.


 11.    EXCHANGE OF INFORMATION AND CONFIDENTIALITY

        11.01      During the term of this Agreement, ANTEX shall promptly
                   disclose to SB and promptly supply SB with all Technology in
                   the Field as requested by SB.

        11.02      During the term of this Agreement and for five (5) years
                   thereafter, irrespective of any termination earlier than the
                   expiration of the term of this Agreement, ANTEX and SB shall
                   not use or reveal or disclose to Third Parties any
                   Confidential Information without first obtaining the written
                   consent of the other party, except as is required to be
                   disclosed to a governmental agency, or is necessary to file
                   or prosecute patent applications concerning Product(s) or to
                   carry out any litigation concerning Product. Any disclosure
                   required for purposes of investigating, developing,
                   manufacturing or marketing Product or



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<PAGE>   30

                   for securing essential or desirable authorizations,
                   privileges or rights from governmental agencies may be made,
                   provided that the disclosing party is satisfied that the
                   proposed Third Party will maintain the confidentiality of the
                   data and information so disclosed. This confidentiality
                   obligation shall not apply or shall cease to apply to such
                   information which is or becomes a matter of public knowledge,
                   or is already in the rightful possession of the receiving
                   party without restriction, or is disclosed to the receiving
                   party without restriction by a Third Party having the right
                   to do so, or is subsequently and independently developed by
                   employees of the receiving party or Affiliates thereof who
                   had no knowledge of nor access to the confidential
                   information disclosed. The parties shall take reasonable
                   measures to assure that no unauthorized use or disclosure is
                   made by others to whom access to such information is granted.

        11.03      Nothing herein shall be construed as preventing SB from
                   disclosing any information received from ANTEX to an
                   Affiliate, sublicensee or distributor of SB, provided such
                   Affiliate, sublicensee or distributor has a written
                   confidentiality undertaking containing confidentiality
                   obligations no less onerous than those set forth in this
                   Article 11.

        11.04      All Confidential Information disclosed by one party to the
                   other shall remain the intellectual property of the
                   disclosing party. In the event that a court or other legal or
                   administrative tribunal, directly or through an appointed
                   master, trustee or receiver, assumes partial or complete
                   control over the assets of a party to this Agreement based on
                   the insolvency or bankruptcy of such party, the bankrupt or
                   insolvent party shall promptly notify the court or other
                   tribunal (i) that Confidential Information received from the
                   other party under this Agreement remains the property of the
                   other party and (ii) of the confidentiality obligations under
                   this Agreement. In addition, the bankrupt or insolvent party
                   shall, to the extent permitted by law, take all steps
                   necessary or desirable to maintain the confidentiality of the
                   other party's Confidential Information and to insure that the
                   court, other tribunal or appointee maintains such information
                   in confidence in accordance with the terms of this Agreement.

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<PAGE>   31

        11.05      No press release, public announcement or other disclosure to
                   Third Parties concerning the existence of, the terms of, or
                   the subject matter covered by, this Agreement, including,
                   without limitation, regarding work on the Targets in the
                   [XXXXX] is expressly mentioned in such press release, public
                   announcement or other disclosure, shall be issued or made,
                   either directly or indirectly, by either party without first
                   obtaining the approval of the other party and agreement upon
                   the nature and text of such announcement or disclosure, which
                   approval and agreement shall not be unreasonably withheld.
                   The other party shall give a response within ten (10) working
                   days which are working days in US, UK and Belgium
                   simultaneously. The party which is legally required to make a
                   public announcement shall use all reasonable efforts to
                   inform the other party of the proposed announcement or
                   disclosure and to provide the other party with a written copy
                   thereof within the abovereferred ten (10) working days delay,
                   in order to allow such other party to comment upon such
                   announcement.

        11.06      Neither SB nor ANTEX shall submit for written or oral
                   publication any manuscript, abstract or the like related to
                   the [XXXXX] which includes data or other information
                   generated and provided by the other party without first
                   obtaining the prior written consent of the other party, which
                   consent shall not be unreasonably withheld and shall be
                   timely provided. The contribution of each party shall be
                   noted in all publications or presentations by acknowledgment
                   or co-authorship, whichever is appropriate.


 12.    PATENT PROSECUTION AND LITIGATION

        12.01      ANTEX shall disclose to SB the complete texts of all patent
                   applications encompassed within Patents filed, owned and/or
                   controlled by ANTEX directly or indirectly together with all
                   prosecution files as well as all information received
                   concerning the institution or possible institution of any
                   interference, opposition, re-examination, reissue,
                   revocation, nullification or any official proceeding
                   involving a Patent anywhere in the Territory. As from the
                   Effective Date, the R&D Committee shall be responsible for
                   decisions regarding the preparation,



                                       62
<PAGE>   32

                   filing, prosecution and maintenance at the expense of SB
                   (which expenses shall be limited to external attorneys' fees
                   and to fees prepaid to national patent offices) of all
                   patents and patents applications within Patents in the
                   Territory. Each party shall have the right to review all such
                   pending applications and other proceedings and make
                   recommendations to the R&D Committee concerning them and
                   their conduct. All Patents shall be filed by a patent counsel
                   selected by the R&D Committee and issued in the name of ANTEX
                   and shall be the sole property of ANTEX subject to the rights
                   and licences granted to SB under this Agreement.

        12.02      Until the sum of [XXXXX] has been reimbursed by SB, the R&D
                   Committee shall also be responsible for decisions regarding
                   the preparation, filing, prosecution and maintenance of all
                   patents and patents applications (other than Patents) which
                   were licensed to SB pursuant to the Original License and
                   which have now reverted to ANTEX pursuant to Article 6. Such
                   responsibility shall be exercised pursuant to the conditions
                   set forth in Section 12.01 above except that SB shall support
                   [XXXXX] expenses linked to the preparation, filing,
                   prosecution and maintenance of such patents which expenses
                   shall be limited to external attorney's fees and to fees
                   prepaid to national patent offices. Furthermore SB's
                   contribution to such patent expenses shall be limited to the
                   expenses incurred during a period [XXXXX] from the Effective
                   Date, as demonstrated by documentary evidence, shall apply
                   only to expenses arising out of actions approved in advance
                   by the R&D Committee, shall not apply to expenses directed to
                   projects for which ANTEX has received R&D funding from a
                   Third Party nor to projects in relation to which ANTEX has
                   granted any rights to a Third Party and shall in no
                   circumstance [XXXXX]

        12.03      SB shall be fully responsible for the filing, prosecution,
                   maintenance and defense of any patent that may [XXXXX] work
                   performed by ANTEX on behalf of SB pursuant to this
                   Agreement. To the extent not provided for under Section 11.01
                   ANTEX shall promptly disclose to SB any and all data,
                   materials and/or other information developed or conceived by
                   ANTEX related to [XXXXX].



                                       63
<PAGE>   33

        12.04      SB shall have the right to assume sole responsibility for
                   any Patent or for any part of Patent thereof which ANTEX
                   intends to abandon or otherwise cause or allow to be
                   forfeited.

        12.05      In the event of the institution of any suit by a Third Party
                   against ANTEX, SB or its sublicensees for patent infringement
                   involving the manufacture, use, sale, distribution or
                   marketing of Product(s) anywhere in the Territory, the party
                   sued shall promptly notify the other party in writing. SB
                   shall have the first right but not the obligation to defend
                   such suit at its own expense. ANTEX and SB shall assist one
                   another and cooperate in any such litigation at the other's
                   request without expense to the requesting party.

        12.06      In the event that ANTEX or SB becomes aware of actual or
                   threatened infringement of a Patent anywhere in the
                   Territory, that party shall promptly notify the other party
                   in writing. SB shall have the first right but not the
                   obligation to bring, at its own expense, an infringement
                   action against any Third Party and to use ANTEX' name in
                   connection therewith. If SB does not commence a particular
                   infringement action within ninety (90) days, ANTEX, after
                   notifying SB in writing, shall be entitled to bring such
                   infringement action at its own expense. The party conducting
                   such action shall have full control over its conduct,
                   including settlement thereof. In any event, ANTEX and SB
                   shall assist one another and cooperate in any such litigation
                   at the other's request without expense to the requesting
                   party.

        12.07      ANTEX and SB shall recover their respective actual
                   out-of-pocket expenses, or equitable proportions thereof,
                   associated with any litigation or settlement thereof from any
                   recovery made by any party. Any excess amount shall be shared
                   between SB and ANTEX, with the party initiating such
                   litigation receiving [XXXXX] and the other party receiving
                   [XXXXX] of such excess.

        12.08      The parties shall keep one another informed of the status of
                   and of their respective activities regarding any litigation
                   or settlement thereof concerning Products.



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<PAGE>   34

        12.09      ANTEX hereby authorizes SB to act as ANTEX' agent for the
                   purpose of making any application for any extensions of the
                   term of Patents in the Field based on marketing
                   authorization(s) including SPCs and Waxman Hatch extensions
                   and shall provide reasonable assistance therefor to SB, at
                   SB's expense for reasonable out of pocket expenses documented
                   by ANTEX. (In the United States of America as permitted under
                   Title 35 of the United States Code). SB shall decide, at its
                   sole discretion, when and where to file such extensions.


 13.    TRADEMARKS

        13.01      SB, at its expense, shall be responsible for the selection,
                   registration and maintenance of all trademarks which it
                   employs in connection with Products and Combinations and
                   shall solely own and/or control such trademarks. Nothing in
                   this Agreement shall be construed as a grant of rights, by
                   license or otherwise, to ANTEX to use such trademarks for any
                   purpose. During the term of this Agreement, ANTEX will not
                   register or apply to register, in any country of the
                   Territory, any trademark, service mark, trade dress or the
                   like for any good or service related to any Product without
                   the prior written consent of SB unless such Product has
                   reverted back to ANTEX pursuant to Article 7.


 14.    STATEMENTS AND REMITTANCES

        14.01      SB shall keep and require its Affiliates and sublicensees to
                   keep complete and accurate records of all sales of Product
                   under the licenses granted herein. ANTEX shall have the
                   right, through a certified public accountant or like person
                   reasonably acceptable to SB, to examine such records during
                   regular business hours during the life of this Agreement and
                   for one (1) year after its termination, at ANTEX' expense
                   unless such examination reveals a greater than five percent
                   (5%) discrepancy the resolution of which would favor ANTEX,
                   in which



                                       65
<PAGE>   35

                   event SB will pay ANTEX its expense, provided, however, that
                   such examination shall not take place more often than once a
                   year and shall not cover such records for more than the
                   preceding five (5) years and provided further that such
                   accountant shall retain in confidence any information learned
                   in such examination and report to ANTEX only as to the
                   accuracy of the royalty statements and payments and shall
                   simultaneously deliver the same report to SB.

        14.02      Within sixty (60) days after the close of each June 30 and
                   December 31 after launch of the first Product by SB and for
                   the remaining term of this Agreement, SB shall deliver to
                   ANTEX a true accounting of all Products sold by SB and its
                   sublicensees during such six (6) month period and shall at
                   the same time pay all royalties due. Such accounting shall
                   show sales on a country-by-country and Product-by-Product
                   basis.

        14.03      Any tax paid or required to be withheld by SB on account of
                   royalties payable to ANTEX under this Agreement shall be
                   deducted from the amount of royalties otherwise due. SB shall
                   secure and send to ANTEX proof of any such taxes withheld and
                   paid by SB or its sublicensees for the benefit of ANTEX. If
                   there is any change in the withholding tax arrangement
                   between Belgium and the United States of America prevailing
                   at the Effective Date, the parties agree to negotiate in good
                   faith a modification of this Section 14.03 to restore the
                   parties to the same position as they were prior to such
                   change.

        14.04      All royalties due under this Agreement shall be payable in
                   U.S. dollars by wire transfer of immediately available funds
                   to an account at a commercial bank in the U.S. designated by
                   ANTEX. If governmental regulations prevent remittances from a
                   foreign country with respect to sales made in that country,
                   the obligation of SB to pay royalties on sales in that
                   country shall be suspended until such remittances are
                   possible. ANTEX shall have the right, upon giving written
                   notice to SB, to receive payment in that country in local
                   currency.



                                       66
<PAGE>   36

        14.05      Monetary conversions from the currency of a foreign country
                   in which Product is sold into U.S. currency shall be made at
                   the exchange rate in force on the last business day of the
                   period for which the royalties are being paid as published by
                   the Citibank, N.A., New York, U.S.A., or on another basis
                   mutually agreed to by both parties in writing.


 15.    TERM AND TERMINATION

        15.01      If a party hereto substantially fails or neglects to perform
                   covenants or provisions of or a material obligation under
                   this Agreement and if such default is not corrected within
                   sixty (60) days after receiving written notice from the other
                   party with respect to such default, such other party shall
                   have the right to terminate this Agreement by giving written
                   notice to the party in default provided the notice of
                   termination is given within six (6) months of the default and
                   prior to correction of the default.

        15.02      Subject to other provisions herein contained, SB may at its
                   sole discretion terminate this Agreement with respect to any
                   country or all countries of the Territory and/or with respect
                   to any or all Products by giving ANTEX at least thirty (30)
                   days written notice thereof at any time before SB first
                   markets Product in such country(ies). After marketing any
                   Product, SB may terminate this Agreement with respect to any
                   country or all countries of the Territory or with respect to
                   any Product or all Products by giving ANTEX at least three
                   (3) months prior written notice thereof. Upon such
                   termination, SB shall make the relevant Product(s) available
                   to ANTEX as per Section 9.04.

        15.03      Either party may terminate this Agreement if, at any time,
                   the other party shall file in any court or agency pursuant to
                   any statute or regulation of (the United States or of) any
                   (individual) state or (foreign) country, a petition in
                   bankruptcy or insolvency or for reorganization or for an
                   arrangement or for the appointment of a receiver or trustee
                   of the party or of its assets, or if the



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<PAGE>   37

                   other party proposes a written agreement of composition or
                   extension of its debts, or if the other party shall be served
                   with an involuntary petition against it, filed in any
                   insolvency proceeding, and such petition shall not be
                   dismissed within sixty (60) days after the filing thereof, or
                   if the other party shall propose or be a party to any
                   dissolution or liquidation, or if the other party shall make
                   an assignment for the benefit of its creditors.

        15.04      The parties acknowledge that Section 365(n) of Title 11 of
                   the United States Code (collectively, the "Bankruptcy Code")
                   provides, in part that, in the event ANTEX as a licenser of
                   the Intellectual Property undertakes a bankruptcy proceeding
                   under the Bankruptcy Code, SB as a licensee of the
                   Intellectual Property is entitled to retain and continue to
                   exercise its licenses hereunder in accordance with the terms
                   of the Bankruptcy Code. All rights and licenses granted to SB
                   under this Agreement shall be deemed to be for the purpose of
                   such Section 365(n), licenses of right to "intellectual
                   property" as defined under Section 101 of the Bankruptcy
                   Code.


 16.    RIGHTS AND DUTIES UPON TERMINATION

        16.01      Upon termination of this Agreement, ANTEX shall have the
                   right to retain any sums already paid by SB hereunder. Unless
                   otherwise provided for hereunder, termination of this
                   Agreement for any reason shall not affect the rights and
                   obligations of the parties accrued through the effective date
                   of termination, including, without limitation, payment and
                   indemnification provisions relating to Products developed,
                   manufactured or distributed during the term of this
                   Agreement.

        16.02      Upon termination of this Agreement in its entirety or with
                   respect to any country, under Sections 15.02 or 15.03, SB
                   shall notify ANTEX of the amount of Products SB and its
                   sublicensees and distributors then have on hand, the sale of
                   which would, but for the termination, be subject to royalty,
                   and SB and its sublicensees and distributors shall thereupon
                   be permitted to sell that amount



                                       68
<PAGE>   38

                   of Products provided that SB shall pay the royalty thereon at
                   the time herein provided for.

        16.03      Termination of this Agreement shall terminate all outstanding
                   obligations and liabilities between the parties arising from
                   this Agreement except those described in Sections 10.01,
                   10.02, 10.03, 11.02, 11.03, 11.04, 11.05, 11.06, 12.03,
                   12.05, 12.06, 12.07, 12.08, 13.01, 14.01, 14.02, 14.03,
                   14.04, 14.05, 15.03, 16.01, 16.02, 16.03, 17.03, 19.01,
                   23.01, and 23.02.


 17.    WARRANTIES AND REPRESENTATIONS

        17.01      ANTEX warrants it owns the entire right and title to the
                   Intellectual Property and has the right to enter into this
                   Agreement and has not granted to any third party any right
                   granted to SB under the Original License as of the Effective
                   Date. Subject to the rights granted to Pasteur Merieux Serums
                   et Vaccins S.A. pursuant to the Pasteur License ANTEX hereby
                   further represents and warrants to SB that ANTEX has not
                   granted any rights or licences to any Third Party which would
                   interfere with or be in derogation with this Agreement or the
                   Original License and that the Intellectual Property is free
                   and clear from any liens and encumbrances for use in the
                   Field.

        17.02      ANTEX makes no representations or warranties as to the
                   validity or scope of the Patents or that the manufacture,
                   use, sale or other disposal of the Products will be free from
                   infringement of patents of Third Parties. However, ANTEX
                   hereby represents that it has no present knowledge from which
                   it can be inferred that Patents are invalid or that their
                   exercise would infringe patent rights of Third Parties. A
                   holding of invalidity or unenforceability of any Patents,
                   from which no further appeal is or can be taken, shall not
                   affect any obligation already accrued hereunder, but shall
                   only eliminate royalties otherwise due under such Patent from
                   the date such holding becomes final or the date that such
                   royalty obligation becomes suspended pursuant to Section
                   5.03.



                                       69
<PAGE>   39

        17.03      ANTEX acknowledges that, in entering into this Agreement, SB
                   has relied upon information supplied by ANTEX (all of such
                   information being hereinafter referred to collectively as
                   "Product Information") and ANTEX warrants and represents that
                   to the best of its knowledge, the Product Information is
                   accurate in all material respects. ANTEX further warrants and
                   represents that to the best of its knowledge, it has not, up
                   through and including the date of this Agreement, omitted to
                   furnish SB with any information concerning Products or the
                   transactions contemplated by this Agreement which would be
                   material to SB's decision to enter into this Agreement and to
                   undertake the commitments and obligations set forth herein.
                   NOTWITHSTANDING ANYTHING TO THE CONTRARY IN THIS AGREEMENT,
                   ANTEX AND ITS DIRECTORS, OFFICERS AND EMPLOYEES MAKE NO
                   REPRESENTATIONS AND EXTEND NO WARRANTIES OF ANY KIND, EITHER
                   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO WARRANTIES
                   OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE,
                   VALIDITY OF PATENT RIGHTS CLAIMS, ISSUED OR PENDING, AND THE
                   ABSENCE OF LATENT OR OTHER DEFECTS, WHETHER OR NOT
                   DISCOVERABLE, IN NO EVENT SHALL ANTEX AND ITS DIRECTORS,
                   OFFICERS AND EMPLOYEES BE LIABLE FOR ANY CLAIMS (INCLUDING
                   CLAIMS FOR ECONOMIC DAMAGE OR INJURY TO PERSON OR PROPERTY OR
                   FOR LOST PROFITS) ARISING FROM THE PERFORMANCE OF ANY PRODUCT
                   BASED UPON THE INTELLECTUAL PROPERTY, INCLUDING ITS SAFETY,
                   EFFECTIVENESS, COMMERCIAL VIABILITY OR MERCHANTABILITY, AND
                   SB ASSUMES ALL RESPONSIBILITY AND LIABILITY IN THIS REGARD
                   EXCEPT IN CASES OF GROSS NEGLIGENCE OR WILFUL MISCONDUCT OF
                   ANTEX.

        17.04      ANTEX warrants and represents that it has no present
                   knowledge of the existence of any pre-clinical or clinical
                   data or information concerning the Products which suggests
                   that there may exist toxicity, safety and/or efficacy
                   concerns which may materially impair the utility and/or
                   safety of such Products.




                                       70
<PAGE>   40

 18.    FORCE MAJEURE

        18.01      If the performance of any part of this Agreement by either
                   party, or of any obligation under this Agreement, is
                   prevented, restricted, interfered with or delayed by reason
                   of any cause beyond the reasonable control of the party
                   liable to perform, unless conclusive evidence to the contrary
                   is provided, the party so affected shall, upon giving written
                   notice to the other party, be excused from such performance
                   to the extent of such prevention, restriction, interference
                   or delay, provided that the affected party shall use its
                   reasonable best efforts to avoid or remove such causes of
                   non-performance and shall continue performance with the
                   utmost dispatch whenever such causes are removed. When such
                   circumstances arise, the parties shall discuss what, if any,
                   modification of the terms of this Agreement may be required
                   in order to arrive at an equitable solution.


 19.    GOVERNING LAW/JURISDICTION

        19.01      The form, execution, validity, construction and effect of
                   this Agreement shall be determined in accordance with the
                   laws of the State of Delaware.

        19.02(a)        Any controversy or claim arising out of or relating to
                        this Agreement or the breach thereof (hereafter
                        collectively referred to as "Dispute"), shall be first
                        attempted to be settled by the parties, without
                        litigation, in good faith, by submitting details of each
                        such Dispute to the Steering Committee in an effort to
                        effect a mutually acceptable resolution thereof.

        19.02(b)        In the event no mutually acceptable resolution of such
                        Dispute is achieved within a thirty (30) day period as a
                        result of Sub Section 19.02(a) then, at either party's
                        request, such Dispute may be submitted to an
                        unaffiliated expert for resolution. In such event, the
                        parties shall select a mutually acceptable single
                        unaffiliated expert within twenty (20) days of the
                        request of the party invoking this Sub Section 19.02(b).
                        Each party shall have twenty



                                       71
<PAGE>   41

                        (20) days after selection of the unaffiliated expert to
                        submit to such individual such assumptions, methodology,
                        data and information as such party believes necessary to
                        resolve the Dispute in question, provided that such
                        party's submission may not exceed one hundred (100)
                        pages. The unaffiliated expert may then hold a joint
                        meeting with the parties (including any other experts
                        that the parties have engaged in respect of that matter)
                        on the issues that need to be resolved. The
                        unaffiliated expert shall promptly thereafter make a
                        recommendation as to the resolution of the Dispute,
                        which recommendation may either adopt the proposal
                        of either party or adopt an alternative approach. Each
                        party shall bear its own expenses in connection with a
                        procedure under this Sub Section 19.02(b), and the fees
                        and expenses of the unaffiliated expert shall be borne
                        equally by the parties regardless of the ultimate
                        recommendation of such person. The results of a
                        procedure under this Sub Section 19.02(b) shall be used
                        by the parties to guide their own decisions, but shall
                        not have legal effect.

        19.02(c)        Once the results of the procedure set forth in Sub
                        Section 19.02(b) are available, if a Dispute still
                        remains between the parties, then such dispute shall be
                        settled by arbitration in accordance with the Rules of
                        the American Arbitration Association in effect at the
                        time such arbitration is instituted. The arbitration
                        panel shall be composed of three (3) arbitrators, one
                        (1) of whom shall be chosen by ANTEX, one (1) of whom
                        shall be chosen by SB, and one (1) of whom shall be
                        chosen by the two (2) arbitrators previously designated.
                        If both or either of ANTEX and/or SB fail(s) to choose
                        an arbitrator within fourteen (14) calendar days after
                        receiving notice of commencement of arbitration or if
                        the two (2) arbitrators fail to choose a third (3rd)
                        arbitrator within fourteen (14) calendar days of their
                        appointment, such arbitrator(s) shall be chosen by the
                        American Arbitration Association. Unless the parties to
                        the arbitration shall otherwise agree to a different
                        place of arbitration, the place of arbitration shall be
                        Washington, D.C. The arbitration award shall be final
                        and binding upon the parties thereto and may be entered
                        in any court having jurisdiction. Each party shall bear
                        (i) its own expenses in connection with such arbitration
                        and (ii) one-half of the fees and expenses of the



                                       72
<PAGE>   42

                        American Arbitration Association and all arbitrators.
                        No arbitration award shall contain any provision which
                        is inconsistent with the preceding sentence.


 20.    SEPARABILITY

        20.01      In the event any portion of this Agreement shall be held
                   illegal, void or ineffective, the remaining portions hereof
                   shall remain in full force and effect.

        20.02      If any of the terms or provisions of this Agreement are in
                   conflict with any applicable statute or rule of law, then
                   such terms or provisions shall be deemed inoperative to the
                   extent that they may conflict therewith and shall be deemed
                   to be modified to conform with such statute or rule of law.

        20.03      In the event that the terms and conditions of this Agreement
                   are materially altered as a result of Sections 20.01 or
                   20.02, the parties will renegotiate those altered terms and
                   conditions of this Agreement to resolve any inequities.


 21.    ENTIRE AGREEMENT

        21.01      Except for the Confidentiality Agreement between ANTEX and
                   SmithKline Beecham Biologicals S.A. dated August 11, 1995,
                   this Agreement, entered into as of the date written above,
                   constitutes the entire agreement between the parties relating
                   to the subject matter hereof and, as of the Effective Date,
                   supersedes all previous writings and understandings including
                   the Original License. No terms or provisions of this
                   Agreement shall be varied or modified by any prior or
                   subsequent statement, conduct or act of the parties, except
                   that the parties may amend this Agreement by written
                   instruments specifically referring to and executed in the
                   same manner as this Agreement.


                                       73
<PAGE>   43

 22.    NO WAIVER

        22.01      The failure of either party at any time to exercise any of
                   their respective rights under this Agreement shall not be
                   deemed a waiver thereof, nor shall such failure in any way
                   prevent either party, as the case may be, from subsequently
                   asserting or exercising such rights.


 23.    NOTICES

        23.01      Any notice required or permitted under this Agreement shall
                   be sent by registered air mail, return receipt requested and
                   postage pre-paid, or facsimile confirmed in writing via
                   courier, to the following addresses and/or fax numbers of the
                   parties:

                     if to ANTEX
                     ANTEX BIOLOGICS INC.,
                     300 Professional Drive,
                     Gaithersburg, Maryland 20879, USA
                     Attention: Chief Executive Officer
                     Facsimile: 1-301 590 1252

                     if to SB
                     SmithKline Beecham Corp.
                     One Franklin Plaza
                     Philadelphia, Pennsylvania 19101-7929, USA
                     Attention: General Counsel US
                     Facsimile: 1-215 751 5132

                     with a copy to: SMITHKLINE BEECHAM BIOLOGICALS S.A.
                     rue de l'Institut 89
                     B-1330 Rixensart, Belgium
                     Attention: President, General Manager


                                       74
<PAGE>   44

                     Facsimile: 32-2-656 80 25

        23.02      Any notice required or permitted to be given concerning this
                   Agreement shall be effective upon receipt by the party to
                   whom it is addressed.

 24.    ASSIGNMENT

        24.01      This Agreement and the right and licenses herein granted
                   shall be binding upon and inure to the benefit of the
                   successors in interest of the respective parties. Neither
                   this Agreement nor any interest hereunder shall be assignable
                   by either party without the written consent of the others,
                   provided, however, that SB may assign this Agreement to any
                   Affiliate or to any corporation with which it may merge or
                   consolidate, without obtaining the prior written consent of
                   ANTEX and that ANTEX may assign this Agreement to any
                   corporation with which it may merge, consolidate or sell all
                   or substantially all of its assets without the written
                   consent of SB.


25.     GENERAL PROVISIONS

        25.01      Except as otherwise provided in this Agreement, each party
                   shall bear the costs, fees, and expenses incurred by it in
                   connection with, or in anticipation of, this Agreement or the
                   consummation of the transactions contemplated hereby.

        25.02      The parties hereto shall use reasonable diligence to do all
                   such things and provide all such reasonable assurances as may
                   be required to consummate the transactions contemplated
                   hereby, and each party shall execute and deliver to the other
                   parties such further documents, instruments, papers and
                   information as may be reasonably requested by the other
                   parties in order to carry out the purpose and intent of this
                   Agreement.

        25.03      Notwithstanding Section 19.02, each party acknowledges and
                   agrees that a breach of any of its covenants or agreements
                   set forth in this Agreement would



                                       75
<PAGE>   45
                   result in irreparable injury to the other party and that such
                   other party would not have an adequate remedy at law for such
                   breach, and therefore, each party agrees that the other party
                   will be entitled to enforce their respective rights under
                   such covenants and agreements by injunctive proceedings
                   restraining the breaching party from such breaches or
                   threatened breaches without bond.

        25.04      For the convenience of the parties, this Agreement may be
                   executed in two counterparts, each of which when so executed
                   shall be, and be deemed to be, an original instrument and
                   such counterparts together shall constitute one (1) and the
                   same instrument, and notwithstanding their date of execution
                   shall be deemed to be dated as of the date of this Agreement.

        25.05      The descriptive headings of the several Articles and Sections
                   of this Agreement are inserted for convenience only, do not
                   constitute a part of this Agreement and shall not affect in
                   any way the meaning or interpretation of this Agreement.

        25.06      Except as otherwise expressly provided herein, nothing
                   contained in this Agreement, express or implied, is intended
                   to confer upon any person other than the parties to it and
                   their respective successors and permitted assigns any rights
                   or remedies under or by reason of this Agreement.

        25.07      SB and ANTEX each agree that they will not solicit for
                   employment any individual who is employed by the other party
                   during the term of such individual's employment by the other
                   party and for a period of two (2) years after the termination
                   of such individual's employment by the other party. This
                   restriction shall be limited to those individuals who have
                   been actively and directly involved in the R&D Program.



                                       76
<PAGE>   46



IN WITNESS WHEREOF, the parties, through their authorized officers, have
executed this Agreement as of the date first written above.

Antex Biologics Inc.,                              SmithKline Beecham plc





/s/V. M. Esposito                                  /s/Jean Stephenne
BY:     Vic Esposito                               BY:     Jean Stephenne
TITLE:  Chairman and CEO                           TITLE:  Attorney-in-fact






                                       77
<PAGE>   47





                                   APPENDIX A
                                     PATENTS
                         ANTEX CONTROLLED PATENT RIGHTS

                                     [XXXXX]




                                       78
<PAGE>   48



APPENDIX B
                CONFIDENTIAL DISCLOSURE AND INVENTION AGREEMENTS
                        CONFIDENTIAL DISCLOSURE AGREEMENT

This Agreement has been entered into on ___________________ by and between Antex
Biologics Inc. ("Employer") a stock corporation organized and existing under the
laws of the State of Delaware, whose principal place of business is at 300
Professional Drive, Gaithersburg, Maryland 20879 USA; and

____________________ ("Employee"), a citizen of the United States of America,
whose domicile is at _________________ and employed by Employer under a separate
agreement.

Intending to be legally bound, the parties have agreed as follows:

1.          During the term of this Agreement, Employee will have access to, and
            become familiar with Confidential Information such as proprietary
            technology and various trade secrets, including without limitation
            to, financial plans and reports, lists of customers, business plans,
            small business innovation research grants, marketing plans,
            scientific analyses, programs, formulas, patterns, devices, methods,
            models, processes and compilations of information, research and
            development data, patent disclosures and applications, records and
            specifications (Confidential Information) which are owned by the
            Employer and which are regularly used in the course of business
            operations. Employee shall not disclose any of this Confidential
            Information, directly or indirectly, nor use it in any way, either
            during the term of this Agreement or at any time thereafter, except
            as may be required in the course of his/her employment by Employer.

2.          Notwithstanding the foregoing, Employee shall not be required to
            maintain the confidentiality of any information and technology which
            are already known to Employee at the time of its disclosure or which
            is or becomes generally available to the public other than as a
            result of unauthorized disclosure or is or becomes available to
            Employee from a third party not previously, presently, or in the
            future, employed by Employer.

3.          All files, records, documents, drawings, specifications, programs,
            equipment and similar items relating to the business of the Employer
            as described above, whether prepared by Employee or otherwise coming
            into his/her possession, shall remain the exclusive property of the
            Employer.

4.          A confidential relationship is hereby established between the
            Employer and the Employee.

5.          Amendments, additions, or modifications to this Agreement shall be
            valid only if made and executed in writing by both parties.

This Agreement shall be governed by the laws of the State of Maryland applicable
to agreements executed therein. IN WITNESS WHEREOF, the parties hereto have
executed this Agreement on the date first written above.


                                --------------------------------------
                                Employee

ATTEST                                      Antex Biologics Inc.



_______________________________ by
Witness                                     Gregory Zakarian
                                            Vice President and
                                              Chief Financial Officer






                                       79
<PAGE>   49


                               INVENTION AGREEMENT


            WHEREAS, Antex Biologics Inc., a Delaware corporation (the
"Company"), whose place of business is 300 Professional Drive, Gaithersburg,
Maryland 20879, is engaged in a continuous program of research, development and
production respecting its business, present and future.

            I understand that as part of my employment by the Company, I may
make new contributions and inventions of value to the Company. In consideration
of my employment or continued employment, as the case may be, and the
compensation received by me from the Company from time to time, I hereby agree
as follows:

            1. Disclosure of Inventions. I will promptly disclose to the
Company, or any persons designated by it, all improvements, modifications,
developments, documentation, data, inventions, designs, ideas, copyrightable
works, discoveries, trademarks, copyrights, trade secrets, formulae, processes,
techniques, programs, and know-how, whether or not patentable or registrable
under copyright or similar statute, made or conceived or reduced to practice or
learned by me, either alone or jointly with others, during the period of my
employment (whether or not during normal working hours) with the Company
(whether prior to, on or after the date hereof) which are related to or useful
in the actual or anticipated business of the Company, or result from tasks
assigned me by the Company or result from use of premises or equipment owned,
leased or contracted for by the Company (all said improvements, inventions,
designs, ideas, copyrightable works, discoveries, trademarks, copyrights, trade
secrets, formulae, processes, techniques, programs, know-how and data shall be
collectively hereinafter called "Inventions").

            2. Assignment of and Assistance on Inventions. I hereby assign to
the Company any rights I may have or acquire in all Inventions and agree that
all Inventions shall be the sole property of the Company and its assigns, and
the Company and its assigns shall be the sole owner of all patents, copyrights,
and other rights in connection therewith. I further agree to assist the Company
in every proper way (but at the Company's expense) to obtain and from time to
time enforce patents, copyrights or other rights on said Inventions in any and
all countries, and to that end I will execute all documents necessary:

                        (a) to apply for, obtain and vest in the name of the
            Company alone (unless the Company otherwise directs) letters patent,
            copyrights or other analogous protection in any country throughout
            the world and when so obtained or vested to renew and restore the
            same; and

                        (b) to defend any opposition proceedings in respect of
            such applications and any opposition proceedings or petitions or
            applications for revocation of such letters patent, copyright or
            other analogous protection.

            In the event the Company is unable, after reasonable effort, to
secure my signature on any letters patent, copyright or other analogous
protection relating to an Invention, whether because of my physical or mental
incapacity or for any other reason whatsoever, I hereby irrevocably designate
and appoint the Company and its duly authorized officers and agents as my agent
and attorney-in-fact, to act for and in my behalf and in good stead to execute
and file any such application or applications and to do all other lawfully
permitted acts to further the prosecution and issuance of letters patent,
copyright or other analogous protection thereon with the same legal force and
effect as if executed by me. My obligation to assist the Company in obtaining
and enforcing patents and copyrights for such Inventions in any and all
countries shall continue beyond the termination of my employment, but the
Company shall compensate me at a reasonable rate after such termination for time
actually spent by me at the Company's request on such assistance.

            I acknowledge that all original works of authorship which are made
by me (solely or jointly with others) within the scope of employment and which
are protectable by copyright are being created at the instance of the Company
and are "works made for hire," as that term is defined in the United States
Copyright Act (17 U.S.C.A. Section 101). If such laws are inapplicable or in the
event that such works, or any part thereof, are determined by a court of
competent jurisdiction not to be a work made for hire under the United States
copyright laws, this Agreement shall operate as an irrevocable and unconditional
assignment by me to the Company of all of my right, title and interest
(including, without limitation all rights in and to the copyrights through the
world, including the right to prepare derivative works and the right to all
renewals and extensions) in the works in perpetuity.

            3. Remedies for Breach. I agree that any breach of this Agreement by
me would cause irreparable damage to the Company and that, in the event of such
breach, the Company shall have, in addition to any and all




                                       80
<PAGE>   50

remedies of law, the right to an injunction, specific performance or other
equitable relief to prevent or redress the violation of my obligations
hereunder.

            4. Assignability. This Agreement shall be binding upon me, my heirs,
executors, assigns and administrators, shall inure to the benefit of the
Company, its successors, and assigns, and shall survive the termination of my
employment by the Company, regardless of the manner of such termination.

            5. Entire Agreement. This Agreement constitutes the entire agreement
between the parties and supersedes all prior agreements and understandings,
whether written or oral, relating to the subject matter of this Agreement.

            6. Applicable Law. This Agreement shall in all respects be governed
by, and contained and enforced in accordance with the laws of the State of
Maryland.

            7. In case any provision of this Agreement shall be invalid, illegal
or otherwise unenforceable, the validity, legality and enforceability of the
remaining provisions shall in no way be affected or impaired thereby.



Date:__________________________          By:__________________________________
                                                  (Employee)

ACCEPTED AND AGREED TO:
ANTEX BIOLOGICS INC.


- -------------------------------------
By:  Gregory C. Zakarian

Title:      Vice President and
            Chief Financial Officer






                                       81

<PAGE>   1
                                                                 EXHIBIT 10.3



                  This Amended and Restated Warrant and the Common Stock
                  issuable upon exercise hereof have not been registered or
                  qualified for sale under the Securities Act of 1933, as
                  amended, or any state securities law and may not be sold or
                  transferred in the absence of such registration or an
                  exemption therefrom under said Act or any such state laws
                  which may be applicable.

No. of Shares: 3,865,769 (which number is subject to adjustment as provided
herein)



                          AMENDED AND RESTATED WARRANT

                           To Purchase Common Stock of

                              ANTEX BIOLOGICS INC.

                  WHEREAS, in connection with the execution and delivery of that
certain Research and Development, Research Support and License Agreement (the
"Original License Agreement") dated May 6, 1996, by and among MicroCarb Human
Vaccines, Inc., MicroCarb, Inc. (the former name of Antex Biologics Inc.) and
SmithKline Beecham Corporation, MicroCarb, Inc. granted SmithKline Beecham
Biologicals Manufacturing s.a. a warrant (the "Original Warrant") dated May 6,
1996 to purchase certain shares of its common stock, $.01 par value per share;
and

                  WHEREAS, MicroCarb Human Vaccines, Inc., Antex Biologics Inc.
and SmithKline Beecham Corporation have terminated the Original License
Agreement on the date hereof and, in connection with the termination of the
Original License Agreement, Antex Biologics Inc. has entered into a new research
and development, research support and license agreement (the "New License
Agreement") with SmithKline Beecham plc, and has also agreed in a separate
omnibus agreement (the "Omnibus Agreement") dated the date hereof between Antex
Biologics Inc., MicroCarb Human Vaccines, Inc. and SmithKline Beecham
Biologicals Manufacturing s.a. to among other things amend and restate the
Original Warrant as set forth herein.

                  THIS AMENDED AND RESTATED WARRANT CERTIFIES THAT, for value
received, the registered holder hereof, SmithKline Beecham Biologicals
Manufacturing s.a., a Belgian company, whose address is Rue de L'Institut 89,
B-1330 Rixensart Belgium, or its successors and assigns, is entitled to purchase
from ANTEX BIOLOGICS INC., a corporation organized and existing under the laws
of Delaware, 3,865,769 shares of the Common Stock (as hereinafter defined) at
the Basic Purchase Price (as hereinafter defined) at any time on or before 5:00
p.m., Eastern Standard time on September 1, 2003. Notwithstanding the
immediately preceding sentence, the number of shares of the Common Stock
purchasable hereunder shall be cumulatively increased by the following number of
shares of the Common Stock in the following circumstance: the number of shares
of the Common Stock purchasable hereunder shall be




                                       82
<PAGE>   2

immediately increased by an additional 866,189 shares of the Common Stock if
SmithKline Beecham Corporation provides Antex Biologics Inc. an additional U.S.
$666,667 in research and development funding under the Amended License Agreement
on or before October 1, 1999. The number of shares of the Common Stock
purchasable hereunder and the Basic Purchase Price therefor are subject to
further adjustment as hereinafter provided in Section 5.

            Section 1. Definitions. For all purposes of this Amended and
Restated Warrant, the following terms shall have the meanings indicated:

                   "Basic Purchase Price" shall mean the price of U.S. $0.37 per
share of the Common Stock, at which price the registered holder hereof may
exercise this Amended and Restated Warrant prior to any adjustments being made
as provided in Section 5. Notwithstanding the immediately preceding sentence,
the Basic Purchase Price for the 866,189 additional shares of the Common Stock
purchasable hereunder if SmithKline Beecham Corporation provides Antex Biologics
Inc. an additional U.S. $666,667 in research and development funding under the
New License Agreement on or before October 1, 1999 shall be the Market Price of
the Common Stock as of October 1, 1999 prior to any adjustments being made as
provided in Section 5.

                  "Business Day" shall mean any day except a Saturday, a Sunday,
or a legal holiday in the City of New York other than a legal holiday on which
the New York Stock Exchange is open for trading on a regular basis.

                  "Commission" shall mean the Securities and Exchange Commission
and any other similar or successor agency of the federal government then
administering the Securities Act or the Exchange Act.

                  "Common Stock" shall mean and include the Company's authorized
common stock, $.01 par value per share, as constituted on the date of this
Amended and Restated Warrant, and shall also include any class of the capital
stock of the Company hereafter authorized which shall neither (i) be limited to
a fixed sum or a percentage of par value in respect of the rights of the holders
thereof to receive dividends and to participate in the distribution of assets
upon the voluntary or involuntary liquidation, dissolution or winding-up of the
Company, nor (ii) be subject at any time to redemption by the Company.

                  "Company" shall mean Antex Biologics Inc. and its successors.

                  "Convertible Securities" shall mean any stock or securities
convertible into or exchangeable for shares of the Common Stock.

                  "Exchange Act" shall mean the Securities Exchange Act of 1934,
and any similar or successor federal statute, and the rules and regulations of
the Commission thereunder, all as the same shall be in effect at the time.

                  "Market Price" shall mean, as of any date, 5% of the sum for
each of the 20 consecutive Trading Days immediately prior to such date, of the
average of either:

                  (i) the high and low sales prices of the Common Stock on such
Trading Day on the New York Stock Exchange or;



                                       83
<PAGE>   3

                  (ii)  if the Common Stock shall not on such Trading Day then
be listed on such Exchange, such high and low sales prices on the principal
(determined by the highest volume of the Common Stock during the month
immediately preceding the month in which occurs the date as of which Market
Price is being determined) national securities exchange (as defined in the
Exchange Act) on which the Common Stock may then be listed, or;

                  (iii) if there shall have been no sales on any such Exchange
or exchange on any such Trading Day, the bid and asked prices on such Exchange
or exchange at the end of such Trading Day, or;

                  (iv)  if the Common Stock shall not be so listed on any such
Trading Day, the representative bid and asked prices at the end of such Trading
Day in the over-the-counter market as reported by the National Association of
Securities Dealers Automated Quotations System ("Nasdaq"), or;

                  (v)   if there be no such representative prices reported by
Nasdaq, the bid and asked prices at the end of such Trading Day in the
over-the-counter market.

For purposes of determining Market Price, the term "Trading Day" shall mean a
Business Day on which the amount greater than zero can be calculated with
respect to the Common Stock under any one or more of the foregoing categories
(i) , (ii), (iii), (iv) or (v), and the end of the Trading Day, for the purposes
of categories (iv) and (v), shall mean the exact time at which trading shall end
on the New York Stock Exchange.

                  "Person" shall mean any individual, partnership, joint
venture, limited liability company, unincorporated organization, government or
department or agency of a government.

                  "Purchase Price" shall mean as of any date, the Basic Purchase
Price, as the same has been adjusted from time to time pursuant to the
provisions of Section 5.

                  "Registrable Securities" shall mean the Warrants and the
Warrant Shares.

                  "Securities Act" shall mean the Securities Act of 1933, and
any similar or successor federal statute, and the rules and regulations of the
Commission thereunder, all as the same shall be in effect at the time.

                  "Warrantholders" shall mean, as of any date, the then
registered holders of the Warrants and the then registered holders of the
Warrant Shares.

                  "Warrants" shall mean this Amended and Restated Warrant and
any other warrant of the Company hereafter issued to SmithKline Beecham
Biologicals Manufacturing s.a., including all amendments thereto, and together
with all Warrants issued in exchange, transfer or replacement of any thereof.

                  "Warrant Shares" shall mean all shares of the Common Stock
purchased or purchasable by the registered holders of the Warrants upon the
exercise thereof pursuant to Section 4 thereof.



                                       84
<PAGE>   4

                  All terms used in this Amended and Restated Warrant which are
not defined in this Section 1 have the meanings respectively set forth therefor
elsewhere in this Amended and Restated Warrant.

            Section 2. Ownership of this Amended and Restated Warrant. The
Company may deem and treat the Person in whose name this Amended and Restated
Warrant is registered as the holder and owner hereof, notwithstanding any
notations of ownership or writing hereon made by anyone other than the Company,
for all purposes and shall not be affected by any notice to the contrary, until
presentation of this Amended and Restated Warrant for registration or transfer
as provided in Section 3. The Company shall maintain, at its office or agency at
300 Professional Drive, Gaithersburg, Maryland 20879 (or at such other office or
agency of the Company as the Company shall designate from time to time by notice
to the registered holder of this Amended and Restated Warrant), a register for
the Warrants, in which the Company shall record the name and address of the
Person in whose name each Warrant has been issued, as well as the name and
address of each transferee and each prior owner of such Warrant.


            Section 3. Exchange, Transfer and Replacement. This Amended and
Restated Warrant is exchangeable, upon the surrender hereof by the registered
holder to the Company at its office or agency provided for in Section 2, for new
Warrants of like tenor, representing in the aggregate the right to purchase the
number of shares of the Common Stock purchasable hereunder, each of such new
Warrants to represent the right to purchase such number of shares of the Common
Stock as shall be designated by said registered holder at the time of such
surrender. This Amended and Restated Warrant and all rights hereunder are
transferable without the necessity of obtaining any consent to such transfer, in
whole or in part, only upon the register provided for in Section 2, by the
registered holder hereof in Person or by duly authorized attorney, and a new
Warrant shall be made and delivered by the Company, of the same tenor as this
Amended and Restated Warrant but registered in the name of the transferee, upon
surrender of this Amended and Restated Warrant with the Assignment Form attached
hereto duly completed, at said office or agency of the Company. Upon receipt by
the Company at its office or agency provided for in Section 2 of evidence
reasonably satisfactory to it of the loss, theft, destruction or mutilation of
this Amended and Restated Warrant, the Company will make and deliver a new
Warrant of like tenor in replacement of this Amended and Restated Warrant. This
Amended and Restated Warrant shall be promptly cancelled by the Company upon the
surrender hereof in connection with any exchange, transfer or replacement. The
Company shall pay all taxes and all other expenses and charges payable in
connection with the preparation, execution and delivery of Warrants pursuant to
this Section 3.

            Section 4. Exercise of this Amended and Restated Warrant.

            A. Procedure for Exercise. In order to exercise this Amended and
Restated Warrant in whole or in part, the registered holder hereof shall
complete the Subscription Form attached hereto, and deliver this Amended and
Restated Warrant to the Company, at its office or agency provided for in Section
2, together with one or more of the following types of consideration in an
aggregate amount equal to the aggregate Purchase Price of the shares of the
Common Stock then being purchased: (i) cash or check; and (ii) shares of the
Common Stock (which shall be valued at their Market Price on the date of
exercise). In addition to delivering the consideration specified in the
preceding sentence, the registered holder of the Amended and Restated Warrant
may make a "cashless" exercise of this Amended and Restated Warrant by
instructing the Company to withhold Warrant Shares that would otherwise be
issued upon the exercise of this




                                       85
<PAGE>   5

Amended and Restated Warrant (which shall be valued at their Market Price on the
date of exercise). The exercise of this Amended and Restated Warrant shall be
deemed to have been effected and the Purchase Price and the number of shares of
the Common Stock issuable in connection with such exercise shall be determined
as of the close of business on the Business Day prior to the date on which such
completed Subscription Form shall have been delivered at such office or agency.
Upon receipt of such Form and the consideration referenced in the first sentence
of this Section 4, the Company shall, as promptly as practicable, and in any
event within 10 Business Days thereafter, execute or cause to be executed and
delivered to said holder by an air courier which guarantees next day delivery a
certificate or certificates representing the aggregate number of shares of the
Common Stock specified in such Form. Each stock certificate so delivered shall
be in such authorized denomination as may be requested by the registered holder
hereof and shall be registered in the name of said holder or such other name as
shall be designated by said holder, and the Person in whose name any such stock
certificate shall be issued upon such exercise shall be deemed to have become
the holder of record of the shares represented thereby as of the time when the
exercise of this Amended and Restated Warrant with respect to such shares shall
be deemed to have been effected. If this Amended and Restated Warrant shall have
been exercised only in part, the Company shall, at its expense at the time of
delivery of said stock certificate or certificates, deliver to such holder a new
Warrant of like tenor evidencing the rights of such holder to purchase the
remaining shares of the Common Stock covered by this Amended and Restated
Warrant. The Company shall pay all taxes, other expenses and charges payable in
connection with the preparation, execution and delivery of stock certificates
pursuant to this Section 4.

            B. Acknowledgment of Continuing Obligation. The Company will, at the
time of the exercise of this Amended and Restated Warrant, in whole or in part,
upon request of the registered holder hereof but at the expense of the Company,
acknowledge in writing its continuing obligation to said holder in respect of
any rights to which said holder shall continue to be entitled after such
exercise in accordance with this Amended and Restated Warrant.

            C. Character of Warrant Shares. All shares of the Common Stock
issuable upon the exercise of this Amended and Restated Warrant shall, when
issued, be duly authorized, validly issued, previously unissued, fully paid and
non-assessable.

            Section 5. Anti-Dilution Provisions.

            A. Adjustment of Purchase Price and Number of Warrant Shares. The
Purchase Price shall be subject to adjustment from time to time as hereinafter
in this Section 5 provided. Except as otherwise expressly provided in Section
5E, upon each adjustment of the Purchase Price pursuant to this Section 5, the
registered holder of this Amended and Restated Warrant shall thereafter be
entitled to purchase, at the Purchase Price resulting from such adjustment, the
number of shares of the Common Stock (calculated to the nearest whole share)
obtained by multiplying the Purchase Price in effect immediately prior to such
adjustment by the number of shares of the Common Stock purchasable pursuant
hereto immediately prior to such adjustment and dividing the product thereof by
the Purchase Price resulting from such adjustment.

            B. Purchase Price Adjustment Formulas. If and whenever after the
date of this Amended and Restated Warrant, the Company shall (i) declare a
dividend or other distribution upon any capital stock of the Company which is
payable in shares of the Common Stock or Convertible Securities, (ii) declare a
dividend or any other distribution upon the Common Stock payable



                                       86
<PAGE>   6

otherwise than out of the current earnings, retained earnings or earned surplus
or (iii) subdivide or combine the shares of the Common Stock, then in each such
case the Purchase Price shall be forthwith changed as provided in Sections 5C,
5D and 5E, respectively.

            C. Stock Dividends. In case at any time the Company shall declare a
dividend or any other distribution upon the Common Stock of the Company which is
payable in shares of the Common Stock or Convertible Securities, then the
Purchase Price in effect immediately prior to the declaration of such dividend
or distribution shall be reduced to the quotient obtained by dividing (1) the
product of (x) the number of shares of the Common Stock outstanding and deemed
(in accordance with the last sentence of this Section 5C) to be outstanding
immediately prior to such declaration, multiplied by (y) the then effective
Purchase Price, by (2) the total number of shares of the Common Stock
outstanding and deemed (in accordance with the last sentence of this Section 5C)
to be outstanding immediately after such declaration (but in no event shall the
Purchase Price be reduced to less than the par value per share of the Common
Stock). All shares of the Common Stock and all Convertible Securities issuable
in payment of any dividend or other distribution upon the Common Stock of the
Company shall be deemed after such declaration to have been issued or sold
without consideration. The number of shares of the Common Stock deemed to be
outstanding shall be the total maximum number of shares of the Common Stock
issuable upon (i) the exercise of all outstanding rights or options to subscribe
for or to purchase shares of the Common Stock and (ii) the conversion or
exchange of (A) all outstanding Convertible Securities and (B) all Convertible
Securities issuable upon the exercise of rights or options to subscribe for or
purchase Convertible Securities.

            D. Extraordinary Dividends and Distributions. In case at any time
the Company shall declare a dividend or any other distribution upon the Common
Stock payable otherwise than out of current earnings, retained earnings or
earned surplus and otherwise than in shares of the Common Stock or Convertible
Securities, the Purchase Price in effect immediately prior to such declaration
shall be reduced by an amount equal, in the case of a dividend or distribution
in cash, to the amount thereof payable per share of the Common Stock or, in the
case of any other dividend or distribution, to the fair value thereof per share
of the Common Stock at the time such dividend or distribution was declared, as
determined by the Board of Directors of the Company (but in no event shall the
Purchase Price be reduced to less than the par value per share of the Common
Stock). For the purposes of the foregoing a dividend or distribution other than
in cash shall be considered payable out of earnings, retained earnings or earned
surplus only to the extent that such current earnings, retained earnings or
earned surplus are charged an amount equal to the fair value of such dividend or
distribution at the time of the declaration thereof, as determined by the Board
of Directors of the Company. Such reductions shall take effect as of the date on
which a record is taken for the purposes of such dividend or distribution, or,
if a record is not taken, the date as of which the holders of record of the
Common Stock entitled to such dividend or distribution are to be determined.

            E. Stock Splits and Reverse Splits. In case at any time the Company
shall subdivide its outstanding shares of the Common Stock into a greater number
of shares, the Purchase Price in effect immediately prior to such subdivision
shall be proportionately reduced and the number of Warrant Shares purchasable
upon the exercise of this Amended and Restated Warrant immediately prior to such
subdivision shall be proportionately increased, and conversely, in case at any
time the Company shall combine the outstanding shares of the Common Stock into a
smaller number of shares, the Purchase Price in effect immediately prior to such
combination shall be proportionately increased and the number of Warrant Shares
purchasable upon the




                                       87
<PAGE>   7

exercise of this Amended and Restated Warrant immediately prior to such
combination shall be proportionately reduced.

            F. Adjustments for Consolidation, Merger, Sale of Assets,
Reorganization, Etc. If at any time the Company shall be a party to any
transaction (including without limitation a merger, consolidation, sale of all
or substantially all of the Company's assets or a recapitalization of the Common
Stock) in which the previously outstanding shares of the Common Stock shall be
changed into or exchanged for different securities of the Company or changed
into or exchanged for common stock or other securities of another corporation or
other property (including cash) or any combination of any of the foregoing (each
such transaction being hereinafter referred to as the "Transaction"; the Company
(in the case of a recapitalization of the Common Stock) or such other
corporation being hereinafter referred to as the "Acquiring Company"; and the
common stock of the Acquiring Company being hereinafter referred to as the
"Acquiror's Stock"), then, as a condition to the consummation of the
Transaction, lawful and adequate provisions shall be made so that, upon the
basis and the terms and in the manner provided in this Section 5F, each holder
of any Warrants, upon the exercise of such Warrants at any time after the
consummation of the Transaction, shall be entitled to receive, in lieu of the
shares of the Common Stock issuable upon such exercise prior to such
consummation, at the election of such holder given by notice to the Company on
or before the later of (x) the day on which the holders of the Common Stock
approve the Transaction, or (y) the thirtieth day following the date of delivery
or mailing to such holder of the last proxy statement relating to the vote on
the Transaction by the holders of the Common Stock:

                        (i) the stock and other securities, cash and property to
                  which such holder would have been entitled upon the
                  consummation of the Transaction if such holder had exercised
                  this Amended and Restated Warrant immediately prior thereto
                  (subject to adjustments from and after) the date of the
                  consummation of the Transaction (the "Consummation Date") as
                  nearly equivalent as possible to the adjustments provided for
                  in Sections 5A and 5F); or

                        (ii) if the Acquiring Company meets the requirements set
                  forth in this Section 5F, the number of shares of the
                  Acquiror's Stock or, if the Acquiring Company fails to meet,
                  but a Parent (as defined in this Section 5F) does meet such
                  requirements, the number of shares of such Parent's common
                  stock (subject to adjustments from and after the Consummation
                  Date as nearly equivalent as possible to the adjustments
                  provided for in Sections 5A and 5F), determined by dividing
                  (i) the product obtained by multiplying (a) the number of
                  shares of the Common Stock to which the holder of this Amended
                  and Restated Warrant would have been entitled had such holder
                  exercised this Amended and Restated Warrant immediately prior
                  to the consummation of the Transaction, times (b) the greater
                  of the Purchase Price or the Acquisition Price (as defined in
                  this Section 5F) in effect on the date immediately preceding
                  the Consummation Date, by (ii) the Market Value of the
                  Acquiror's Stock on the date immediately preceding the
                  Consummation Date.

                  For the purposes of this Section 5F: the term "Market Value"
shall mean, for any share of common stock on any date specified herein, the last
sale price, regular way, on such date



                                       88
<PAGE>   8

or, if no sale takes place on such date, the average of the closing bid and
asked prices on such date, in each case as reported on the New York Stock
Exchange or, if such common stock is not listed on the New York Stock Exchange
but is authorized for quotation on the Nasdaq National Market, the last
transaction price per share of common stock as reported by the Nasdaq National
Market on such date; and the term "Acquisition Price" shall mean the
consideration per share to be paid for or received by the holders of the
previously outstanding shares of the Common Stock in accordance with the terms
of the Transaction, determined (x) in the case where the holders of the
previously outstanding shares of Common Stock received solely shares of the
Acquiror's Stock in the Transaction, by multiplying the Market Value of the
Acquiror's Stock as of the date immediately preceding the Consummation Date by a
fraction the numerator of which shall be the aggregate number of shares of the
Acquiror's Stock to be received in the Transaction in exchange for all of the
previously outstanding shares of the Common Stock and the denominator of which
shall be the aggregate number of such previously outstanding shares of the
Common Stock, and (y) in any other case, by dividing the aggregate fair market
value (using Market Value for any shares of the Acquiror's Stock), as of the
date immediately preceding the Consummation Date of the aggregate consideration
to be received by the holders of such previously outstanding shares of Common
Stock by the number of shares of such previously outstanding Common Stock. The
requirements referred to in clause (ii) of this Section 5F with reference to the
Acquiring Company or to a corporation (herein referred to as a "Parent") which
directly or indirectly controls the Acquiring Company are as follows: (AA) its
common stock is listed on the New York Stock Exchange or quoted on the Nasdaq
National Market and such common stock continues to meet such requirements for
listing or quotation thereon, (BB) it is required to file, and in each of its
three fiscal years immediately preceding the Consummation Date has filed,
reports with the Commission pursuant to Section 13 or 15(d) of the Exchange Act,
and (CC) in the case of a Parent, such Parent is required to include the
Acquiring Company in the consolidated financial statements contained in the
Parent's Annual Report on Form 10-K and is not itself included in the
consolidated financial statements of any other Person (other than its
consolidated subsidiaries). Notwithstanding anything contained in this Amended
and Restated Warrant to the contrary, the Company shall not effect any
Transaction unless prior to or simultaneously with the consummation of such
Transaction the survivor or successor corporation (if other than the Company)
resulting from such Transaction shall assume by written instrument executed and
delivered to each Warrantholder, the obligation to deliver to such Warrantholder
such shares of stock, securities or assets as, in accordance with the foregoing
provisions, such Warrantholder may be entitled to receive, and containing the
express assumption by such successor corporation of the due and punctual
performance and observance of every provision of this Amended and Restated
Warrant to be performed and observed by the Company and of all liabilities and
obligations of the Company hereunder.

            G. Statement Regarding Adjustments. Upon each adjustment of the
Purchase Price and upon each change in the number of shares of the Common Stock
issuable upon exercise of this Amended and Restated Warrant, and in the event of
any change in the rights of the holder of this Amended and Restated Warrant by
reason of other events herein set forth, then and in each such case, the Company
will promptly obtain an opinion of a firm of independent certified public
accountants of recognized national standing (who may be the regular auditors of
the Company) selected by the Company's chief financial officer, stating the
adjusted Purchase Price and the new number of shares so issuable, or specifying
the other shares of stock, securities or assets and the amount thereof
receivable as a result of such change in rights, and setting forth in reasonable
detail the method of calculation and the facts upon which such calculation is
based. The




                                       89
<PAGE>   9

Company will promptly mail a copy of such accountants' opinion to the registered
holder of this Amended and Restated Warrant.

            H. Outside Opinion. In case at any time or from time to time
conditions arise by reason of action taken by the Company, which in the opinion
of its Board of Directors, are not adequately covered by the provisions of this
Section 5, and which might materially and adversely affect the exercise rights
of the registered holders of the Warrants, the Board of Directors of the Company
may appoint a firm of independent certified public accountants of recognized
national standing, which may be the firm regularly retained by the Company,
which shall give their opinion upon the adjustment, if any, on a basis
consistent with the standards established in the other provisions of this
Section 5, necessary with respect to the Purchase Price, so as to preserve,
without dilution, the exercise rights of the registered Warrantholders. If the
Board of Directors of the Company does not appoint a firm of independent
certified public accountants to give the opinion described in the preceding
sentence, the Company's chief financial officer shall render such opinion. Upon
receipt of such opinion from either the independent certified public accountants
or the Company's chief financial officer, the Board of Directors of the Company
shall forthwith make the adjustments described herein.

            Section 6. Certain Agreements of the Company. The Company covenants
and agrees that:

            A. Will Reserve Shares. The Company will authorize, reserve and set
apart and have available for issuance at all times, free from preemptive rights,
that number of the shares of the Common Stock which are deliverable upon the
exercise of this Amended and Restated Warrant, and the Company will have at all
times such other rights or privileges which are necessary to enable it at any
time to fulfill all of its obligations hereunder.

            B. Will Avoid Certain Actions. The Company will not, by amendment of
its certificate of incorporation or through any reorganization, transfer of
assets, consolidation, merger, issue or sale of securities or otherwise, avoid
or take any action which would have the effect of avoiding the observance or
performance of any of the terms to be observed or performed hereunder by the
Company, but will at all times in good faith assist in carrying out all of the
provisions of this Amended and Restated Warrant. Without limiting the generality
of the foregoing, the Company will not take any action to revoke, call, redeem,
cancel or otherwise terminate this Amended and Restated Warrant or the rights
granted under this Amended and Restated Warrant.

            C. Will Secure Governmental Approvals. If any shares of the Common
Stock required to be reserved for the purposes of exercise of this Amended and
Restated Warrant require registration with or approval of any governmental
authority under any federal law (other than the Securities Act) or under any
state law before such shares of the Common Stock may be issued upon exercise of
this Amended and Restated Warrant, the Company will, at its expense, as
expeditiously as possible use its best efforts to cause such shares to be duly
registered or approved, as the case may be.

            D. Will Pay Certain Taxes and Fees. The Company will pay all issue
or transfer taxes with respect to the issuance or transfer of shares of the
Common Stock to each holder of the Warrants in connection with each exercise of
the Warrants, as well as all fees and expenses incurred by the Company in
connection with each such issuance or transfer.



                                       90
<PAGE>   10

            E. Will Bind Successors. This Amended and Restated Warrant will be
binding upon any corporation succeeding to the Company by merger, consolidation
or acquisition of all or substantially all of the Company's assets.

            Section 7. Notifications by the Company. In case at any time:

            (1) the Company shall declare upon the Common Stock any dividend or
      other distribution (except out of current earnings, retained earnings or
      earned surplus) to the holders of the Common Stock;

            (2) the Company shall make an offer for subscription pro rata to the
      holders of the Common Stock of any additional shares of stock of any class
      or other rights;

            (3) the Board of Directors of the Company shall authorize (whether
      definitively or subject to any conditions) any capital reorganization, or
      reclassification of the capital stock of the Company, or consolidation or
      merger of the Company with, or sale of all or substantially all of its
      assets to, another Person;

            (4) the Board of Directors of the Company shall authorize (whether
      definitively or subject to any conditions) a voluntary dissolution,
      liquidation or winding-up of the Company; or

            (5) the Company shall become subject to involuntary dissolution,
      liquidation or winding-up;

then, in each of such cases, the Company shall give notice to the registered
holder of this Amended and Restated Warrant of the date on which (a) the books
of the Company shall close or a record shall be taken for such dividend,
distribution or subscription rights, or (b) such reorganization,
reclassification, consolidation, merger, sale, dissolution, liquidation or
winding-up shall take place or be voted upon by stockholders of the Company, as
the case may be. Such notice shall also specify the date as of which the holders
of record of shares of the Common Stock shall participate in such dividend,
distribution or subscription rights, or shall be entitled to exchange their
shares of the Common Stock or securities for other property deliverable upon
such reorganization, reclassification, consolidation, merger, sale, dissolution,
liquidation or winding-up, as the case may be. Such notice shall be given not
less than 30 and not more than 90 days prior to the action in question and not
less than 30 days and not more than 90 days prior to the record date or the date
on which the Company's transfer books are closed in respect thereto and such
notice shall state that the action in question or the record date is subject to
the effectiveness of a registration statement under the Securities Act, or to a
favorable vote of stockholders, if either is required.

            Section 8. Rights of a Stockholder. This Amended and Restated
Warrant shall not entitle any Warrantholder to any voting rights or any other
rights, or subject any Warrantholder to any liabilities, as a stockholder of the
Company.

            Section 9. Modification; Waivers. This Amended and Restated Warrant
may be modified or amended only with the written consent of each Warrantholder.
The Company shall not be released from its obligations hereunder without the
written consent of each Warrantholder. The observance of any term of this
Amended and Restated Warrant may be waived (either




                                       91
<PAGE>   11

generally or in a particular instance and either retroactively or prospectively)
by the Person entitled to enforce such term, but any such waiver shall be
effective only if in a writing signed by the Person against which such waiver is
to be asserted. Except as otherwise specifically provided herein, no delay on
the part of any Person in exercising any right, power or privilege hereunder
shall operate as a waiver thereof, nor shall any waiver on the part of any party
hereto of any right, power or privilege hereunder operate as a waiver of any
other right, power or privilege hereunder nor shall any single or partial
exercise of any right, power or privilege hereunder preclude any other or
further exercise thereof or the exercise of any other right, power or privilege
hereunder.

            Section 10. Entire Agreement. This Amended and Restated Warrant, the
Omnibus Agreement, the New License Agreement, and that certain Amended and
Restated Registration Rights Agreement dated the date hereof between the Company
and SmithKline Beecham Biologicals Manufacturing s.a.and SmithKline Beecham plc
represent the entire understanding and agreement between the parties thereto
with respect to the subject matter hereof and supersede all other prior
agreements and understandings, both written and oral, between the parties
thereto with respect to the subject matter hereof and thereof.

            Section 11. Severability. If any provision of this Amended and
Restated Warrant, or the application of such provision to any Person or
circumstance, shall be held invalid, the remainder of this Amended and Restated
Warrant or the application of such provision to other Persons or circumstances
shall not be affected thereby; provided, that the parties shall negotiate in
good faith with respect to an equitable modification of the provision or
application thereof held to be invalid.

            Section 12. Notices.

            A. Any notice or communication to any Person shall be duly given if
in writing and delivered in Person, receipt requested, or overnight air courier
guaranteeing next day delivery or by facsimile (with written confirmation of
receipt), to such other party's address (or to such other address as such other
party shall have specified in a notice given in accordance with this Section
12.)


                    If to the Company:

                    300 Professional Drive
                    Gaithersburg, Maryland  20879
                    Attention:  President and Chief Executive Officer
                    Facsimile:  (301) 590-1252

                    If to SmithKline Beecham Biologicals Manufacturing s.a.:

                    Rue de L'Institut 89
                    B-1330 Rixensart
                    Belgium
                    Attention:  President, General Manager
                    Facsimile:  011-32-2-656-8026

                                       92
<PAGE>   12

                    with a copy to:

                    SmithKline Beecham Corporation
                    One Franklin Plaza
                    P.O. Box 7929
                    Philadelphia, Pennsylvania  19101-7929
                    Attention:  Edgar B. Cale III, Esq.

                    Facsimile:  (215) 751-3935

            B. All notices and communications will be deemed to have been duly
given: at the time delivered by hand, if personally delivered; and the next
business day after timely delivery to the courier, if sent by overnight air
courier guaranteeing next day delivery.

            Section 13. Headings. The Section headings in this Amended and
Restated Warrant are for convenience of reference only, and shall not be deemed
to alter or affect the meaning or interpretation of any provision hereof.

            Section 14. Construction. This Amended and Restated Warrant shall be
governed, construed and enforced in accordance with the laws of the State of
Delaware, without regard to its principles of conflict of laws.

            Section 15. No Adverse Agreements. The Company has not previously,
and will not hereafter, enter into any agreement with respect to its securities
which is adverse to the rights granted to SmithKline Beecham Biologicals
Manufacturing s.a. and its successors and assigns under this Amended and
Restated Warrant.

            Section 16. Specific Performance. The Company agrees that this
Amended and Restated Warrant cannot be purchased or sold in the open market and
that, for these reasons, among others, each Warrantholder will be irreparably
damaged in the event that this Amended and Restated Warrant is not specifically
enforceable. Accordingly, in the event of any controversy concerning this
Amended and Restated Warrant, or any right or obligation hereunder, such right
or obligation shall be enforceable in a court of equity by specific performance.
The rights granted in this Section 16 shall be cumulative and not exclusive, and
shall be in addition to any and all other rights which the Warrantholder may
have hereunder, at law or in equity.

            Section 17. Transfer and Assignment. The registered holder of this
Warrant may transfer and assign this Warrant and its rights hereunder without
the necessity of obtaining any consent to such transfer or assignment, provided
that the registered holder is permitted to transfer or assign its shares of the
Common Stock under the terms of Section 2.1 of the Omnibus Agreement.

               [The Balance of This Page Intentionally Left Blank]


                                       93
<PAGE>   13



                    IN WITNESS WHEREOF, Antex Biologics Inc. has caused this
Amended and Restated Warrant to be executed and delivered by its duly authorized
officer under its corporate seal, attested by its duly authorized officer and to
be dated September 1, 1999.


                                         ANTEX BIOLOGICS INC.



                                         By:    /s/V. M. Esposito
                                               -------------------------------
                                               Name:       V. M. Esposito
                                               Title:      Chairman & CEO


[Corporate Seal]

Attest:



/s/Gregory C. Zakarian
- --------------------------------
Name:     Gregory C. Zakarian
Title:    Secretary





                                       94
<PAGE>   14




                                SUBSCRIPTION FORM

                     To be Executed by the Registered Holder
                   Desiring to Exercise the Within Warrant of

                              ANTEX BIOLOGICS INC.



                  The undersigned registered holder hereby exercises the right
to purchase _______ shares of the Common Stock covered by the within Warrant,
according to the conditions thereof, and herewith makes payment in full of the
Purchase Price of such shares, $__________________ by delivery of
__________________________________.

[Alternatively. The undersigned registered holder hereby exercises the right to
purchase ___ shares of the Common Stock covered by the within Warrant, according
to the terms thereof and herewith makes a "cashless" exercise of the within
Warrant and instructs Antex Biologics Inc. to withhold ___ shares of the Common
Stock that would otherwise be issued upon the exercise of the within Warrant.]



                                      -------------------------------
                                      Name of Registered Holder


                                      -------------------------------
                                      Signature


                                      -------------------------------
                                      Title


                                      Address
                                                 ------------------------

                                                 ------------------------





Dated:  ___________________





                                       95
<PAGE>   15



                                 ASSIGNMENT FORM

                     To Be Executed by the Registered Holder
                   Desiring to Transfer the Within Warrant of

                              ANTEX BIOLOGICS INC.

                  FOR VALUE RECEIVED, the undersigned registered holder hereby
sells, assigns and transfer unto _________________ the right to purchase
____________________ shares of the Common Stock covered by the within Warrant,
and does hereby irrevocably constitute and appoint ______________________
Attorney to transfer the said Warrant on the books of the Company (as defined in
said Warrant), with full power of substitution.


                                      -------------------------------
                                      Name of Registered Holder

                                      -------------------------------
                                      Signature

                                      -------------------------------
                                      Title

                                      Address
                                                ------------------------

                                                ------------------------



Dated:  _________________

In the presence of

- -------------------------



                                     NOTICE:

                  The signature to the foregoing Assignment Form must correspond
to the name as written upon the face of the within Warrant in every particular,
without alteration or enlargement or any change whatsoever.





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<PAGE>   1


                                                                 EXHIBIT 10.4

               AMENDED AND RESTATED REGISTRATION RIGHTS AGREEMENT


                  AMENDED AND RESTATED REGISTRATION RIGHTS AGREEMENT dated
September 13, 1999, and effective as of September 1, 1999 (the "Effective Date")
between ANTEX BIOLOGICS INC., a Delaware corporation (the "Company") and
SMITHKLINE BEECHAM BIOLOGICALS MANUFACTURING S.A., a Belgian company ("SB Bio").

                              W I T N E S S E T H:


                  WHEREAS, pursuant to an Omnibus Agreement (the "Omnibus
Agreement") dated the date hereof, among the Company, SB Bio and MicroCarb Human
Vaccines Inc., a Delaware corporation ("MCHV"), SB Bio has acquired 3,595,264
shares of the common stock of the Company, par value $.01 per share (the "Common
Stock");

                  WHEREAS, pursuant to an Amended and Restated Warrant (the
"Warrant") dated the date hereof between the Company and SB Bio, the Company has
granted SB Bio a warrant to purchase up to 4,731,958 shares of the Common Stock;
and

                  WHEREAS, the Company desires to provide SB Bio and its
successors and permitted assigns with certain rights regarding the registration
of (i) 3,595,264 shares of the Common Stock acquired on the date hereof and (ii)
up to 4,731,958 shares of the Common Stock issuable upon the exercise of the
Warrant.

                  NOW, THEREFORE, in consideration of the mutual covenants and
agreements made herein, and other good valuable consideration, the receipt and
sufficiency of which are hereby acknowledged and accepted, the parties hereto
agree as follows:

                   1. Definitions. As used herein, unless the context otherwise
requires, the following terms have the following respective meanings:

                  "Affiliate" has the meaning set forth in Rule 12b-2 under the
Exchange Act.

                  "Closing Price" means the last sale price, regular way, as
reported in the principal consolidated transaction reporting system with respect
to securities listed or admitted to trading on the principal national securities
exchange on which the Registrable Securities shall be listed or admitted to
trading on a Trading Day or, if the Registrable Securities shall not be listed
or admitted to trading on any national securities exchange on such Trading Day,
the last reported transaction price on such Trading Day or, if not so quoted,
the closing bid price in the over-the-counter market on such Trading Day, as
reported by Nasdaq or such other system then in use.

                  "Commission" means the United States Securities and Exchange
Commission or any other federal agency at the time administering the Securities
Act.

                  "Common Stock" has the meaning set forth in the first WHEREAS
clause of the Recitals.


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<PAGE>   2



                  "Demand" has the meaning set forth in Section 2.1.1.

                  "Exchange Act" means the Securities Exchange Act of 1934, as
amended, or any similar federal statute, and the rules and regulations of the
Commission thereunder, as the same shall be in effect at the time. Reference to
a particular section of the Securities Exchange Act of 1934, as amended, shall
include reference to the comparable section, if any, of any such subsequent
similar federal statute.

                  "Nasdaq" means the National Association of Securities Dealers
Automated Quotations System or such other securities trading system then in use.

                  "Person" means any individual, partnership, joint venture,
corporation, trust, unincorporated organization, government or department or
agency of a government.

                  "Registrable Common Securities" means the 3,595,264 shares of
Common Stock acquired on the date hereof and the shares of Common Stock issued
upon any exercise of the Warrant.

                  "Registrable Securities" means collectively the Registrable
Common Securities and any other securities issuable in connection therewith or
in replacement thereof by way of a dividend, distribution, recapitalization,
exchange, merger, consolidation or other reorganization. As to any particular
Registrable Securities, once issued such securities shall cease to be
Registrable Securities when (a) a registration statement with respect to the
sale of such securities shall have become effective under the Securities Act and
such securities shall have been disposed of in accordance with such registration
statement, (b) they shall have been sold as permitted by, and in compliance
with, Rule 144 (or any successor provision) promulgated under the Securities Act
or (c) they shall have ceased to be outstanding.

                  "Registration Expenses" means all expenses incident to the
Company's performance of or compliance with Section 2, including, without
limitation, all registration, filing and National Association of Securities
Dealers, Inc. fees, all listing fees, all fees and expenses of complying with
securities or blue sky laws (including, without limitation, reasonable fees and
disbursements of counsel for the underwriters in connection with blue sky
qualifications of the Registrable Securities), all word processing, duplicating
and printing expenses, messenger and delivery expenses, the fees and
disbursements of counsel for the Company and of its independent public
accountants, including the expenses of "comfort" letters required by or incident
to such performance and compliance, and any fees and disbursements of
underwriters customarily paid by issuers or sellers of securities.

                  "Securities Act" means the Securities Act of 1933, as amended,
or any subsequent similar federal statute, and the rules and regulations of the
Commission thereunder, all as the same shall be in effect at the time.
References to a particular section of the Securities Act of 1933, as amended,
shall include a reference to the comparable section, if any, of any such
subsequent similar federal statute.

                  "Trading Day" means a day on which the principal national
securities exchange on which the Registrable Securities in question shall be
listed or admitted to trading shall be open for the transaction of business or,
if the Registrable Securities shall not be listed or admitted to




                                       98
<PAGE>   3

trading on any national securities exchange, any day on which trading takes
place in the over-the-counter market.

            "Warrant" has the meaning set forth in the second WHEREAS clause of
the Recitals.

            2. Registration Rights.

               2.1. Registration on Demand.

               2.1.1. Demand. Subject to Section 2.1.7, upon the written request
(the "Demand") of SB Bio that the Company effect the registration under the
Securities Act of all or part of SB Bio's Registrable Securities, the Company
shall effect, as soon as practicable and in any event within 120 days after the
Demand is received from SB Bio, the registration under the Securities Act, of
the Registrable Securities which the Company has been so requested to register
by SB Bio.

               2.1.2. Registration of Other Securities. Whenever the Company
shall effect a registration pursuant to this Section 2.1 in connection with an
underwritten offering by SB Bio of Registrable Securities, holders of securities
of the Company who have "piggyback" registration rights may include all or a
portion of such securities in such registration, offering or sale. If the
managing underwriter of any such offering shall inform the Company by letter of
its belief that the number or type of securities of the Company requested by
holders of the securities of the Company other than SB Bio to be included in
such registration would materially and adversely affect the underwritten
offering, then the Company shall include in such registration, to the extent of
the number and type of securities which the Company is so advised can be sold in
(or during the time of) such offering, first, all of the Registrable Securities
specified by SB Bio in the Demand and second, for each holder of the Company's
securities other than SB Bio, the fraction of such holder's securities proposed
to be registered which is obtained by dividing (i) the number of the securities
of the Company that such holder proposes to include in such registration by (ii)
the total number of securities proposed to be included in such registration by
all holders other than SB Bio.

               2.1.3. Registration Statement Form. Registrations under this
Section 2.1 shall be on such appropriate registration form of the Commission as
shall be selected by the Company. The Company shall include in any such
registration statement all information which, in the opinion of counsel to the
Company, is required to be included.

               2.1.4. Expenses. The Company shall pay the Registration Expenses
in connection with the first Demand registration requested pursuant to this
Section 2.1, but excluding underwriting discounts and selling commissions
relating to the sale or disposition of SB Bio's Registrable Securities, and the
fees and expenses of SB Bio's own counsel. SB Bio shall pay all the Registration
Expenses in connection with the second and third Demand registrations requested
pursuant to this Section 2.1. If the registration pursuant to the first Demand
is withdrawn at the request of SB Bio and if SB Bio elects not to have such
registration count as the first Demand registration under this Section 2.1, SB
Bio shall pay all the Registration Expenses of such registration.

               2.1.5. Effective Registration Statement. A registration requested
pursuant to this Section 2.1 shall not be deemed to have been effected (i)
unless a registration statement with




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<PAGE>   4

respect thereto has become effective, (ii) if after it has become effective,
such registration is interfered with by any stop order, injunction or other
order or requirement of the Commission or other governmental agency or court for
any reason and has not thereafter become effective, or (iii) in the case of an
underwritten offering, if the conditions to closing specified in the
underwriting agreement, if any, entered into in connection with such
registration are not satisfied or waived.

               2.1.6. Selection of Underwriters. In connection with each
underwritten offering, SB Bio shall promptly select an underwriter subject to
the approval of the Company (which approval shall not be unreasonably withheld
by the Company).

               2.1.7. Limitations on Registration on Demand. The Company shall
not be required to prepare and file a registration statement pursuant to this
Section 2.1 which would become effective within 120 days following the effective
date of a registration statement (other than a registration statement filed on
Form S-8) filed by the Company with the Commission pertaining to an underwritten
public offering of convertible debt securities or equity securities for cash for
the account of the Company or another holder of securities of the Company if SB
Bio was afforded the opportunity to include at least fifty (50%) percent of its
Registrable Securities in such registration pursuant to Section 2.2. In no event
shall the Company be required to effect (i) in the aggregate, more than three
registrations pursuant to this Section 2.1, (ii) more than one registration
pursuant to this Section 2.1 in any 180 day period and (iii) any registration,
if, in the good faith determination of the Company's Board of Directors, such
registration would adversely affect certain activities of the Company to the
material detriment of the Company, then the Company may at its option direct
that such Demand be delayed for a period not in excess of 90 days from the date
of the Company's receipt of the Demand, such right to delay a Demand shall be
exercised by the Company not more than once in any twelve month period.

               2.2. Piggyback Registration.

               2.2.1. Right to Include Registrable Securities. If the Company at
any time proposes to register any of its securities under the Securities Act by
registration on Forms S-1, S-2, S-3 or any successor or similar form(s) (except
registrations on such Forms or similar forms solely for registration of
securities in connection with (i) an employee benefit plan or dividend
reinvestment plan or a merger or consolidation or (ii) debt securities which are
not convertible into Common Stock), whether or not for sale for its own account,
it shall each such time give written notice to SB Bio of its intention to do so
and of SB Bio's rights under this Section 2.2 at least 30 days prior to the
anticipated filing date of a registration statement with respect to such
registration with the Commission. Upon the written request of SB Bio made as
promptly as practicable and in any event within 10 business days after the
receipt of any such notice, which request shall specify the Registrable
Securities intended to be disposed of by SB Bio, the Company shall use its best
efforts to effect the registration under the Securities Act of all Registrable
Securities which the Company has been so requested to register by SB Bio;
provided, that if, at any time after giving written notice of its intention to
register any securities and prior to the effective date of the registration
statement filed in connection with such registration, the Company shall
determine for any reason not to register or to delay registration of such
securities, the Company may, at its election, give written notice of such
determination to SB Bio and (i) in the case of a determination not to register,
shall be relieved of its obligation to register any Registrable Securities in
connection with such registration (but not from any obligation of the Company to
pay the Registration Expenses in connection therewith), without




                                       100
<PAGE>   5

prejudice, (provided, however, that SB Bio may request that such registration be
effected as a registration under Section 2.1 hereof) and (ii) in the case of a
determination to delay registering, shall be permitted to delay registering any
Registrable Securities for the same period as the delay in registering such
other securities.

               2.2.2. Priority in Piggyback Registrations. Notwithstanding
anything in Section 2.2.1 above to the contrary, if the managing underwriter of
any underwritten offering shall inform the Company by letter of its belief that
the number or type of Registrable Securities requested to be included in such
registration would materially and adversely affect such offering, then the
Company shall notify SB Bio of such fact and give SB Bio the opportunity to
negotiate with the managing underwriter regarding the inclusion in such
registration of all of the Registrable Securities requested by SB Bio to be
included therein. If the managing underwriter does not agree to include more
than eighty (80%) percent (or such lesser percentage as SB Bio shall, in its
sole discretion, agree to) of the number of the Registrable Securities initially
requested by SB Bio to be included in such registration, then the Company shall
include in such registration, to the extent of the number and type which the
Company is so advised can be sold in (or during the time of) such offering,
first, all securities proposed by the Company to be sold for its own account or
by the holder of securities who initiated a demand registration, and second, for
each holder of the Company's securities other than the holder of the securities
who initiated a demand registration, the fraction of such holder's securities
proposed to be registered which is obtained by dividing (i) the number of the
securities of the Company that such holder proposes to include in such
registration by (ii) the total number of securities proposed to be sold in such
offering by such holders.

               2.3. Registration Procedures.

               2.3.1. In connection with the registration of any Registrable
Securities under the Securities Act as provided in Sections 2.1 and 2.2, the
Company shall as expeditiously as possible:

               (i) prepare and file with the Commission the requisite
registration statement to effect such registration and thereafter use its best
efforts to cause such registration statement to become and remain effective;

               (ii) prepare and file with the Commission such amendments and
supplements to such registration statement and the prospectus used in connection
therewith as may be necessary to keep such registration statement effective and
to comply with the provisions of the Securities Act with respect to the
disposition of all Registrable Securities covered by such registration statement
for such period as shall be required for the disposition of all of such
Registrable Securities;

               (iii) furnish to SB Bio such number of conformed copies of such
registration statement and of each such amendment and supplement thereto (in
each case including all exhibits), such number of copies of the prospectus
contained in such registration statement (including each preliminary prospectus
and any summary prospectus) and any other prospectus filed under Rule 424 under
the Securities Act, in conformity with the requirements of the Securities Act,
and such other documents as SB Bio may reasonably request;



                                      101
<PAGE>   6

               (iv) use its best efforts (x) to register or qualify all
Registrable Securities and other securities covered by such registration
statement under such other securities or Blue Sky laws of such States of the
United States of America where an exemption is not available and as SB Bio shall
reasonably request, (y) to keep such registration or qualification in effect for
so long as such registration statement remains in effect, and (z) to take any
other action which may reasonably be necessary or advisable to enable SB Bio to
consummate the disposition in such jurisdictions of the Registrable Securities
to be sold by SB Bio, except that the Company shall not for any such purpose be
required to qualify generally to do business as a foreign corporation in any
jurisdiction wherein it would not, but for the requirements of this paragraph
(iv), be obligated to be so qualified or to consent to general service of
process in any such jurisdiction;

               (v) use its best efforts to cause all Registrable Securities
covered by such registration statement to be registered with or approved by such
other federal or state governmental agencies or authorities as may be necessary
in the opinion of counsel to the Company and counsel to SB Bio to consummate the
disposition of such Registrable Securities in accordance with their intended
method of disposition;

               (vi) furnish to SB Bio, (x) an opinion of outside counsel for the
Company, and (y) a "comfort" letter signed by the certified independent public
accountants who have certified the Company's financial statements included or
incorporated by reference in such registration statement, each covering
substantially the same matters with respect to such registration statement (and
the prospectus included therein) and, in the case of the accountant's comfort
letter, with respect to events subsequent to the date of such financial
statements, as are customarily covered in opinions of issuer's counsel and in
accountant's comfort letters delivered to the underwriters in underwritten
public offerings of securities (and dated the dates such opinions and comfort
letters are customarily dated);

               (vii) notify SB Bio when a prospectus relating thereto is
required to be delivered under the Securities Act, upon discovery that, or upon
the happening of any event as a result of which, the prospectus included in such
registration statement, as then in effect, includes an untrue statement of a
material fact or omits to state any material fact required to be stated therein
or necessary to make the statements therein not misleading, in the light of the
circumstances under which they were made, and at the request of SB Bio promptly
prepare and furnish to SB Bio such number of copies of a supplement to or an
amendment of such prospectus as may be necessary so that, as thereafter
delivered to the purchasers of such securities, such prospectus shall not
include an untrue statement of a material fact or omit to state a material fact
required to be stated therein or necessary to make the statements therein not
misleading in the light of the circumstances under which they were made;

               (viii) otherwise use its best efforts to comply with all
applicable rules and regulations of the Commission, and make available to its
securityholders, as soon as reasonably practicable, an earnings statement
meeting the requirements of Section 11(a) of the Securities Act, which the
Company shall be entitled to satisfy by complying with the requirements of Rule
158 promulgated thereunder, and promptly furnish a copy of the same to SB Bio;

               (ix) provide and cause to be maintained a transfer agent and
registrar for all Registrable Securities covered by such registration statement
from and after a date not later than the effective date of such registration
statement; and



                                      102
<PAGE>   7

               (x) use its best efforts to list all Registrable Securities
covered by such registration statement on any national securities exchange or
over-the-counter market, if any, on which Registrable Securities of the same
class, and if applicable, series, covered by such registration statement are
then listed.

               SB Bio agrees that upon receipt of any notice from the Company of
the happening of an event of the kind described in Section 2.3.1(vii), SB Bio
will forthwith discontinue its disposition of Registrable Securities pursuant to
the registration statement relating to such Registrable Securities until SB
Bio's receipt of the copies of the supplemented or amended prospectus
contemplated by Section 2.3.1(vii).

               2.4. Underwritten Offerings.

               2.4.1. Requested Underwritten Offerings. If requested by the
underwriters for any underwritten offering by SB Bio pursuant to a registration
requested under Section 2.1, the Company will enter into an underwriting
agreement with such underwriters for such offering, such agreement to be
reasonably satisfactory in substance and form to the Company, SB Bio and the
underwriters, and to contain such representations and warranties by the Company
and SB Bio and such other terms as are generally prevailing in agreements of
that type, including, without limitation, indemnities to the effect and to the
extent provided in Section 2.6. SB Bio will cooperate with the Company in the
negotiation of the underwriting agreement and will give consideration to the
reasonable suggestions of the Company regarding the form and substance thereof.
SB Bio shall be a party to such underwriting agreement. SB Bio shall not be
required to make any representations or warranties to or agreements with the
Company or the underwriters other than representations, warranties or agreements
regarding SB Bio, SB Bio's Registrable Securities, SB Bio's intended method of
distribution and any other representations or warranties required by law or
customarily given by selling shareholders in an underwritten public offering.


               2.4.2. Piggyback Underwritten Offerings. If the Company proposes
to register any of its securities under the Securities Act as contemplated by
Section 2.2 and such securities are to be distributed by or through one or more
underwriters, subject to the priority and other provisions of Section 2.2.2 the
Company will, if requested by SB Bio, arrange for such underwriters to include
all the Registrable Securities to be offered and sold by SB Bio among the
securities of the Company to be distributed by such underwriters. SB Bio shall
become a party to the underwriting agreement negotiated between the Company and
such underwriters. SB Bio shall not be required to make any representations or
warranties to or agreements with the Company or the underwriters other than
representations, warranties or agreements regarding SB Bio, SB Bio's Registrable
Securities and SB Bio's intended method of distribution or any other
representations or warranties required by law or customarily given by selling
shareholders in an underwritten public offering.


               2.4.3. Holdback Agreements.

               (i) If any registration of Registrable Securities shall be in
connection with an underwritten public offering, SB Bio agrees if required by
the underwriter or underwriters not to effect any public sale or distribution,
including any sale pursuant to Rule 144 under the Securities Act, of any
Registrable Securities, and not to effect any such public sale or distribution
of any other equity security of the Company or of any security convertible into
or exchangeable or exercisable for any equity security of the Company (in each
case, other than as part of such




                                      103
<PAGE>   8

underwritten public offering) during the 15 days prior to, and during the 90-day
period beginning on, the effective date of such registration statement, provided
that SB Bio has received written notice of such registration at least 15 days
prior to such effective date.

               (ii) If any registration of Registrable Securities shall be in
connection with an underwritten public offering, the Company agrees (x) if
required by the underwriter or underwriters not to effect any public sale or
distribution of any of its equity securities or of any security convertible into
or exchangeable or exercisable for any equity security of the Company (other
than in connection with any employee stock option or other benefit plan which
has been duly adopted by the Company and which provides for the distribution to
participants in the plan of equity securities of the Company or securities
convertible or exchangeable or exercisable for equity securities of the Company)
during the 15 days prior to, and during the 90-day period beginning on the
effective date of such registration statement (except as part of such
registration) and (y) that any agreement entered into after the date of this
Agreement pursuant to which the Company issues or agrees to issue any privately
placed equity securities shall contain a provision under which holders of such
securities agree that, if required by the underwriter or underwriters, they will
not effect any public sale or distribution of any such securities during the
period referred to in the foregoing clause (x), including any sale pursuant to
Rule 144 under the Securities Act (except as part of such registration, if
permitted), if such holder is participating in the offering pursuant to such
registration.

               2.5. Preparation; Reasonable Investigation. In connection with
the preparation and filing of each registration statement under the Securities
Act pursuant to this Agreement, the Company will give SB Bio not less than 30
days prior written notice of the preparation of such registration statement and
give SB Bio and its counsel and accountants the opportunity to participate, at
SB Bio's expense, in the preparation of such registration statement, each
prospectus included therein or filed with the Commission, and each amendment
thereof or supplement thereto, and give each of them such access to its books
and records, such opportunities to discuss the business of the Company with
officers and the independent public accountants who have certified its financial
statements as shall be necessary, in the opinion of SB Bio's counsel, to conduct
a reasonable investigation within the meaning of the Securities Act. Any
expenses incurred by SB Bio in connection with any such investigation shall be
borne by SB Bio.

               2.6. Indemnification.

               2.6.1. Indemnification by the Company. In the event of any
registration of any securities of the Company under the Securities Act, the
Company will, and hereby does, indemnify and hold harmless, in the case of any
registration statement filed pursuant to Sections 2.1 or 2.2, SB Bio, its
directors, officers, employees, agents and affiliates and, to the extent
required by any underwriting agreement entered into by the Company, each other
Person who participates as an underwriter in the offering or sale of such
securities and each other Person who controls SB Bio or any such underwriter
within the meaning of the Securities Act, insofar as losses, claims, damages, or
liabilities (or actions or proceedings, whether commenced or threatened, in
respect thereof) arise out of or are based upon any untrue statement or alleged
untrue statement of any fact contained in any registration statement under which
such securities were registered under the Securities Act, any preliminary
prospectus, final prospectus, or summary prospectus contained therein, or any
amendment or supplement thereto, or any omission or alleged omission to state
therein a fact required to be stated therein or necessary to




                                      104
<PAGE>   9

make the statements therein in light of the circumstances in which they were
made not misleading, and the Company will reimburse SB Bio and each such
director, officer, agent or affiliate, and, to the extent required by any
underwriting agreement entered into by the Company, underwriter and controlling
Person for any legal or any other expenses reasonably incurred by them in
connection with investigating or defending any such loss, claim, liability,
action or proceeding; provided that the Company shall not be liable in any such
case to the extent that any such loss, claim, damage, liability (or action or
proceeding in respect thereof) or expense arises out of or is based upon an
untrue statement or alleged untrue statement or omission or alleged omission
made in such registration statement, any such preliminary prospectus, final
prospectus, summary prospectus, amendment or supplement in reliance upon and in
conformity with written information furnished to the Company through an
instrument duly executed by SB Bio, specifically stating that it is for use in
the preparation thereof. Such indemnity shall remain in full force and effect
regardless of any investigation made by or on behalf of SB Bio or any such
director, officer, agent or affiliate or controlling Person and shall survive
the transfer of such securities by SB Bio.


               2.6.2. Indemnification by SB Bio. If any Registrable Securities
are included in any registration statement, SB Bio will indemnify and hold
harmless (in the same manner and to the same extent as set forth in Section
2.6.1 above) the Company, each director of the Company, each officer of the
Company and each employee of the Company with respect to any statement or
alleged statement in or omission or alleged omission from such registration
statement, any preliminary prospectus, final prospectus or summary prospectus
contained therein, or any amendment or supplement thereto, if such statement or
alleged statement or omission or alleged omission was made in reliance upon and
in conformity with written information furnished to the Company through an
instrument duly executed by SB Bio specifically stating that it is for use in
the preparation of such registration statement, preliminary prospectus, final
prospectus, summary prospectus, amendment or supplement.

               2.6.3. Notice of Claims, Etc. Promptly after receipt by an
indemnified party of notice of the commencement of any action or proceeding
involving a claim referred to in the preceding paragraphs of this Section 2.6,
such indemnified party will, if a claim in respect thereof is to be made against
an indemnifying party, immediately give written notice to the latter of the
commencement of such action; provided, however, that the failure of any
indemnified party to give notice as provided herein shall not relieve the
indemnifying party of its obligations under the preceding paragraphs of this
Section 2.6, except to the extent that the indemnifying party is materially
prejudiced by such failure. The indemnified party shall be entitled to receive
the indemnification payments described in Section 2.6.6 after providing such
written notice to the indemnifying party. In case any such action is brought
against an indemnified party, unless in such indemnified party's reasonable
judgment a conflict of interest between such indemnified and indemnifying
parties may exist in respect of such claim, the indemnifying party shall be
entitled to participate in and to assume the defense thereof, jointly with any
other indemnifying party similarly notified to the extent that it may wish, with
counsel reasonably satisfactory to such indemnified party, and after notice from
the indemnifying party to such indemnified party of its election so to assume
the defense thereof, the indemnifying party shall not be liable to such
indemnified party for any legal or other expenses subsequently incurred by the
latter in connection with the defense thereof other than reasonable costs
related to the indemnified party's cooperation with the indemnifying party,
unless in such indemnified party's reasonable judgment a conflict of interest
between such indemnified and indemnifying parties arises in respect of such
claim after the assumption of the defense thereof. No indemnifying party shall
be liable for any




                                      105
<PAGE>   10

settlement of any action or proceeding effected without its written consent,
which consent shall not be unreasonably withheld. No indemnifying party shall,
without the consent of the indemnified party, consent to entry of any judgment
or enter into any settlement which does not include as an unconditional term
thereof the giving by the claimant or plaintiff to such indemnified party of a
release from all liability in respect to such claim or litigation.

               2.6.4. Contribution. If the indemnification provided for in this
Section 2.6 shall for any reason be held by a court to be unavailable to an
indemnified party under Section 2.6.1 or 2.6.2 hereof in respect of any loss,
claim, damage or liability, or any action in respect thereof, then, in lieu of
the amount paid or payable under Sections 2.6.1 or 2.6.2 hereof, the indemnified
party and the indemnifying party under Sections 2.6,1 or 2.6.2 hereof shall
contribute to the aggregate losses, claims, damages and liabilities (including
legal or other expenses reasonably incurred in connection with investigating the
same), (i) in such proportion as shall be appropriate to reflect the relative
benefits received by the Company on one hand and SB Bio on the other or (ii) if
the allocation provided by clause (i) above is not permitted by applicable law,
in such proportion as is appropriate to reflect the relative fault of the
Company on one hand and SB Bio on the other which resulted in such loss, claim,
damage or liability, or action in respect thereof, as well as any other relevant
equitable considerations. No Person guilty of fraudulent misrepresentation
(within the meaning of the Securities Act) shall be entitled to contribution
with respect to such fraudulent misrepresentation from any Person who was not
guilty of such fraudulent misrepresentation. In addition, no Person shall be
obligated to contribute hereunder any amounts in payment for any settlement of
any action or claim, effected without such Person's written consent, which
consent shall not be unreasonably withheld.


               2.6.5. Other Indemnification. Indemnification and contribution
similar to that specified in the preceding paragraphs of this Section 2.6 (with
appropriate modifications) shall be given by the Company and SB Bio with respect
to any required registration or other qualification of securities under any
federal or state law or regulation of any governmental authority other than the
Securities Act.

               2.6.6. Indemnification Payments. The indemnification and
contribution required by this Section 2.6 shall be made by periodic payments of
the amount thereof during the course of the investigation or defense, as and
when bills are received or expense, loss, damage or liability is incurred by the
indemnified party.

               3. Rule 144. With a view to making available the benefits of
certain rules and regulations of the Commission which may at any time permit the
sale of the Registrable Securities to the public without registration, the
Company agrees to:

                  (a) use its best efforts to facilitate the sale of the
Registrable Securities to the public, without registration under the Securities
Act, pursuant to Rule 144 promulgated under the Securities Act;

                  (b) make and keep public information available, as those terms
are understood and defined in Rule 144 promulgated under the Securities Act at
all times;

                  (c) use its best efforts to file with the Commission in a
timely manner all reports and other documents required of the Company under the
Securities Act and the Exchange Act; and



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<PAGE>   11

                  (d) deliver a written statement as to whether it has complied
with such requirements of this Section, to SB Bio upon SB Bio's request.

               4. Legend. Any certificate evidencing Registrable Securities
shall bear the following legend in addition to any other legend that may be
required by law:

               "THE SECURITIES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO A
               REGISTRATION RIGHTS AGREEMENT, DATED SEPTEMBER 13, 1999 AND
               EFFECTIVE AS OF SEPTEMBER 1, 1999, BETWEEN ANTEX BIOLOGICS INC.
               AND SMITHKLINE BEECHAM BIOLOGICALS MANUFACTURING, S.A. A COPY OF
               SUCH AGREEMENT SHALL BE FURNISHED WITHOUT CHARGE BY ANTEX
               BIOLOGICS INC. TO THE HOLDER HEREOF UPON SUCH HOLDER'S WRITTEN
               REQUEST."


               5. Modification; Waivers. This Agreement may be modified or
amended only with the written consent of each party hereto. No party hereto
shall be released from its obligations hereunder without the written consent of
the other party. The observance of any term of this Agreement may be waived
(either generally or in a particular instance and either retroactively or
prospectively) by the party entitled to enforce such term, but any such waiver
shall be effective only if in a writing signed by the party against which such
waiver is to be asserted. Except as otherwise specifically provided herein, no
delay on the part of any party hereto in exercising any right, power or
privilege hereunder shall operate as a waiver thereof, nor shall any waiver on
the part of any party hereto of any right, power or privilege hereunder operate
as a waiver of any other right, power or privilege hereunder nor shall any
single or partial exercise of any right, power or privilege hereunder preclude
any other or further exercise thereof or the exercise of any other right, power
or privilege hereunder.

               6. Entire Agreement. This Agreement represents the entire
understanding and agreement between the parties hereto with respect to the
subject matter hereof and supersedes all other prior agreements and
understandings, both written and oral, between the parties with respect to the
subject matter hereof.

               7. Severability. If any provision of this Agreement, or the
application of such provision to any Person or circumstance, shall be held
invalid, the remainder of this Agreement or the application of such provision to
other Persons or circumstances, to the extent permitted by law, shall not be
affected thereby; provided, that the parties shall negotiate in good faith with
respect to an equitable modification of the provision or application thereof
held to be invalid.

               8. Notices.

                  (a) Any notice or communication to any party hereto shall be
duly given if in writing and delivered in person, receipt requested, or air
courier guaranteeing two (2) day delivery, or facsimile (with written
confirmation of receipt) to such other party's address or facsimile number set
forth below.

                  If to Antex Biologics Inc.:



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<PAGE>   12

                  300 Professional Drive
                  Gaithersburg, Maryland  20879
                  Attention:  Chief Executive Officer
                  Facsimile:  (301) 590-1252

                  If to SmithKline Beecham Biologicals
                  Manufacturing s.a.:

                  Rue de L'Institut 89
                  B-1330 Rixensart
                  Belgium
                  Attention: President, General Manager
                  Facsimile:  011-32-2-656-8026

with a copy to:

                  SmithKline Beecham Corp.
                  One Franklin Plaza
                  P.O. Box 7929
                  Philadelphia, Pennsylvania  19101-7929
                  Attention:  Edgar B. Cale, III, Esq.
                  Facsimile:  (215) 751-3935

                  (b) All notices and communications will be deemed to have been
duly given: at the time delivered by hand, if personally delivered or facsimiled
(with written confirmation of receipt); and the next business day after timely
delivery to the courier, if sent by air courier guaranteeing two (2) day
delivery.

               9. Successors and Assigns. This Agreement shall inure to the
benefit of and shall be binding upon the Company and SB Bio and their respective
successors and permitted assigns. SB Bio may assign its rights under this
Agreement to any Person to whom SB Bio transfers any of the Registrable
Securities, the Omnibus Agreement, the Warrant or any interest therein without
the necessity of obtaining any consent to such assignment.. In the event that SB
Bio assigns its rights to a holder or holders of only a portion of the
Registrable Securities, then all references to SB Bio herein shall also be
deemed to refer to such other holder or holders, but in such event SB Bio will
have the sole right to make all decisions by and give notices for such holder or
holders under this Agreement; provided, that if SB Bio no longer owns any
Registrable Securities, then all decisions and notices hereunder shall be made
by the holders of not less than a majority of the Registrable Securities
outstanding and all other holders of Registrable Securities shall be bound by
any such decision.

               10. Counterparts. This Agreement may be executed in two or more
counterparts, each of which for all purposes shall be deemed to be an original
and all of which together shall constitute the same agreement.


               11. Headings. The Section headings in this Agreement are for
convenience of reference only, and shall not be deemed to alter or affect the
meaning or interpretation of any provisions hereof.



                                      108
<PAGE>   13

               12. Construction. This Agreement shall be governed, construed and
enforced in accordance with the laws of the State of Delaware, without regard to
its principles of conflict of laws.

               13. No Adverse Agreements. The Company has not previously, and
will not hereafter, enter into any agreement with respect to its securities
which adversely affects the rights granted to SB Bio in this Agreement.

               14. Recapitalizations, etc. In the event that any capital stock
or other securities are issued in respect of, in exchange for, or in
substitution of, any Registrable Securities by reason of any reorganization,
recapitalization, reclassification, merger, consolidation, spin-off, partial or
complete liquidation, stock dividend, split-up, sale of assets, distribution to
stockholders or combination of the shares of Registrable Securities or any other
similar change in the Company's capital structure, appropriate adjustments shall
be made in this Agreement so as to fairly and equitably preserve, as far as
practicable, the original rights and obligations of the parties hereto under
this Agreement.

               15. Specific Performance. The parties hereto agree that the
Registrable Securities of the Company cannot be purchased or sold in the open
market other than pursuant to Rule 144 or pursuant to an effective registration
statement and that, for these reasons, among others, the holder or holders of
the Registrable Securities will be irreparably damaged in the event that this
Agreement is not specifically enforceable. Accordingly, in the event of any
controversy concerning the Registrable Securities which are the subject of this
Agreement, or any right or obligation to register such securities, such right or
obligation shall be enforceable in a court of equity by specific performance.
The rights granted in this Section 15 shall be cumulative and not exclusive, and
shall be in addition to any and all other rights which the parties hereto may
have hereunder, at law or in equity. SB Bio consents to the jurisdiction of the
federal courts of the State of Delaware in any suit, action or proceeding
brought pursuant to this Section 15, waives any objection it may have to the
laying of venue in any such suit, action or proceeding in any of such court, and
agrees that service of any court paper may be made in such manner as may be
provided under applicable laws or court rules governing service of process.

               16. Term. This Agreement shall continue in full force and effect
until the earlier of (i) seven (7) years after the Effective Date and (ii) the
first date on which SB Bio and its permitted assigns may sell all of the
Registrable Securities held by them in a ninety (90) day period pursuant to Rule
144 under the Securities Act.


                                      109
<PAGE>   14



                    IN WITNESS WHEREOF, the parties have caused this Agreement
to be executed on September 13, 1999, and effective as of September 1, 1999, and
delivered by their respective duly authorized officers.

                             ANTEX BIOLOGICS INC.



                             By:    /s/V. M. Esposito
                                   ---------------------------------------
                                  Name:   V. M. Esposito
                                  Title:  Chairman & CEO



                             SMITHKLINE BEECHAM BIOLOGICALS MANUFACTURING S.A.



                             By:    /s/Jean Stephenne
                                   ---------------------------------------
                                  Name:   Jean Stephenne
                                  Title:  President, General Manager

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