Document:

PATENT AND TRADEMARK ASSIGNMENT AND SECURITY AGREEMENT

            THIS PATENT AND TRADEMARK  ASSIGNMENT AND SECURITY  AGREEMENT  (this
"Agreement"),  dated as of  November 1, 1999,  is made  between  NORTH  AMERICAN
VACCINE,  INC., a Canadian  corporation  ("Assignor")  and BAXTER  INTERATIONAL,
INC., a Delaware corporation ("Assignee").

         Assignor and Assignee are parties to a Security  Agreement  dated as of
November 1, 1999 (as amended,  modified,  renewed or extended from time to time,
the  "Security  Agreement"),  which  Security  Agreement  provides,  among other
things,  for the  assignment  by Assignor to Assignee,  and grant by Assignor to
Assignee of a security  interest in, certain of Assignor's  property and assets,
including,  without  limitation,  its  patents  and  patent  applications,   its
trademarks, service marks and trade names, and its applications for registration
of such  trademarks,  service  marks  and  trade  names.  Pursuant  to the  Loan
Agreement  Assignor has agreed to execute and deliver this Agreement to Assignee
for filing with the United States  Patent and Trademark  Office (the "PTO") (and
any other relevant  recording systems in any domestic or foreign  jurisdiction),
and as further  evidence of and to effectuate  such assignment of and grant of a
security interest in such patents and patent applications,  trademarks,  service
marks and trade names,  and  applications  for  registration of such trademarks,
service  marks and trade  names,  and the other  general  intangibles  described
herein. Accordingly, Assignor and Assignee hereby agree as follows:

         SECTION 1 DEFINITIONS; INTERPRETATION.

         (a) All  capitalized  terms used in this  Agreement  and not  otherwise
defined  herein  shall  have  the  meanings  assigned  to them  in the  Security
Agreement.

         (b) In this  Agreement,  (i) the  meaning  of  defined  terms  shall be
equally  applicable to both the singular and plural forms of the terms  defined;
and (ii) the captions and headings  are for  convenience  of reference  only and
shall not affect the construction of this Agreement.

         SECTION 2 ASSIGNMENT AND GRANT OF SECURITY INTEREST.

         (a) As security for the payment and  performance of the Obligations (as
defined in the Security  Agreement),  Assignor  hereby  assigns,  transfers  and
conveys and grants a security interest in and mortgage to Assignee, for security
purposes,  all of  Assignor's  right,  title and  interest  in, to and under the
following  property,  whether  now  existing  or  owned or  hereafter  acquired,
developed or arising (collectively, the "Intellectual Property Collateral"):

         (i)   all patents and patent applications,  domestic  or  foreign,  all
licenses  relating to any of the  foregoing  and all income and  royalties  with
respect to any licenses (including,  without limitation, such patents and patent
applications  as  described  in SCHEDULE A hereto),  all rights to sue for past,
present  or future  infringement  thereof,  all  rights  arising  therefrom  and
pertaining  thereto  and  all  reissues,  divisions,  continuations,   renewals,
extensions and continuations-in-part thereof;

                                       1.
<PAGE>

         (ii)  all state (including common law), federal and foreign trademarks,
service  marks  and trade  names,  and  applications  for  registration  of such
trademarks,  service marks and trade names, all licenses  relating to any of the
foregoing and all income and royalties with respect to any licenses  (including,
without limitation,  such marks, names and applications as described in SCHEDULE
B hereto),  whether  registered or  unregistered  and wherever  registered,  all
rights to sue for  past,  present  or future  infringement  or  unconsented  use
thereof,  all rights arising therefrom and pertaining  thereto and all reissues,
extensions and renewals thereof;

         (iii) the entire  goodwill of or associated  with the businesses now or
hereafter  conducted by Assignor  connected  with and  symbolized  by any of the
aforementioned properties and assets;

         (iv)  all  general  intangibles  (as  defined  in  the  UCC)  and   all
intangible intellectual or other similar property of the Assignor of any kind or
nature,  associated with or arising out of any of the aforementioned  properties
and assets and not otherwise described above; and

         (v)   all products and proceeds of any and all of the foregoing.

         (a)   This Agreement shall create a continuing security interest in the
Intellectual  Property  Collateral which shall remain in effect until terminated
in accordance with Section 17 hereof.

         (b)   Notwithstanding  the foregoing  provisions of this Section 2, the
grant of a security  interest  as provided  herein  shall not extend to, and the
term "Intellectual Property Collateral" shall not include, (1) that certain U.S.
Patent No. 5,425,946 which is covered by a security interest in favor of Bankers
Trust Company as evidenced by the filing in the U.S. Patent and Trademark Office
(the "Excluded Patent  Collateral"),  and (2) any general  intangibles of Debtor
(whether owned or held as licensee or lessee, or otherwise),  to the extent that
(i) such general  intangibles are not assignable or capable of being  encumbered
as a matter of law or under the terms of the license,  lease or other  agreement
applicable  thereto (but solely to the extent that any such restriction shall be
enforceable under applicable law), without the consent of the licensor or lessor
thereof or other  applicable  party  thereto and (ii) such  consent has not been
obtained; PROVIDED, HOWEVER, that the foregoing grant of security interest shall
extend to, and the term "Intellectual  Property  Collateral" shall include,  (A)
any  general  intangible  which is an  account  receivable  or a proceed  of, or
otherwise  related to the enforcement or collection of, any account  receivable,
or goods  which  are the  subject  of any  account  receivable,  (B) any and all
proceeds of any general  intangibles which are otherwise  excluded to the extent
that the assignment or  encumbrance  of such proceeds is not so restricted,  and
(C) upon obtaining the consent of any such licensor,  lessor or other applicable
party's consent with respect to any such otherwise excluded general intangibles,
such general intangibles as well as any and all proceeds thereof that might have
theretofore  have been excluded  from such grant of a security  interest and the
term "Intellectual Property Collateral."

         SECTION   3   FURTHER   ASSURANCES;    APPOINTMENT   OF   ASSIGNEE   AS
ATTORNEY-IN-FACT. Assignor at its expense shall execute and deliver, or cause to
be executed and delivered, to Assignee any and all documents and instruments, in

                                       2.
<PAGE>

form and substance  satisfactory to Assignee, and take any and all action, which
Assignee  may  reasonably  request  from time to time,  to perfect and  continue
perfected,  maintain the priority of or provide  notice of  Assignee's  security
interest in the Intellectual  Property Collateral and to accomplish the purposes
of this  Agreement.  Assignee  shall  have  the  right  to,  in the  name of the
Assignor,  or in the name of Assignee or otherwise,  without notice to or assent
by the Assignor,  and the Assignor hereby  irrevocably  constitutes and appoints
Assignee  (and any of Assignee's  officers or employees or agents  designated by
Assignee) as the Assignor's true and lawful attorney-in-fact with full power and
authority,  (i) to sign the name of the Assignor on all or any of such documents
or  instruments  and perform all other acts that  Assignee  deems  necessary  or
advisable  in order to perfect or continue  perfected,  maintain the priority or
enforceability  of or provide  notice of  Assignee's  security  interest in, the
Intellectual  Property  Collateral,  and  (ii) to  execute  any  and  all  other
documents and instruments, and to perform any and all acts and things for and on
behalf of the  Assignor,  which  Assignee  may deem  necessary  or  advisable to
maintain,  preserve  and protect the  Intellectual  Property  Collateral  and to
accomplish  the purposes of this  Agreement,  including  (A) to defend,  settle,
adjust or (after the  occurrence of any Event of Default)  institute any action,
suit or proceeding with respect to the Intellectual  Property  Collateral,  and,
after the occurrence of any Event of Default, (B) to assert or retain any rights
under any license  agreement for any of the  Intellectual  Property  Collateral,
including  without  limitation any rights of the Assignor  arising under Section
365(n) of the  Bankruptcy  Code,  and (C) after the  occurrence  of any Event of
Default, to execute any and all applications,  documents, papers and instruments
for Assignee to use the Intellectual Property Collateral,  to grant or issue any
exclusive  or   non-exclusive   license  or  sub-license  with  respect  to  any
Intellectual  Property Collateral,  and to assign,  convey or otherwise transfer
title in or dispose of the Intellectual Property Collateral;  provided, however,
that in no  event  shall  Assignee  have  the  unilateral  power,  prior  to the
occurrence  and  continuation  of an  Event of  Default,  to  assign  any of the
Intellectual  Property Collateral to any Person,  including itself,  without the
Assignor's  written  consent.  The  foregoing  shall in no way limit  Assignee's
rights and remedies  upon or after the  occurrence  of an Event of Default.  The
power of attorney set forth in this  Section 3, being  coupled with an interest,
is irrevocable so long as this Agreement shall not have terminated in accordance
with Section 17.

         SECTION 4  FUTURE RIGHTS.  Except as otherwise  expressly  agreed to in
writing by  Assignee,  if and when the Assignor  shall obtain  rights to any new
patentable  inventions or any new trademarks,  or become entitled to the benefit
of any of the  foregoing,  or obtain  rights or  benefits  with  respect  to any
reissue, division,  continuation,  renewal, extension or continuation-in-part of
any patents or trademarks,  or any improvement of any patent,  the provisions of
Section 2 shall  automatically  apply  thereto  and the  Assignor  shall give to
Assignee prompt notice thereof. Assignor shall do all things deemed necessary or
advisable  by  Assignee  to  ensure  the  validity,  perfection,   priority  and
enforceability  of the security  interests  of Assignee in such future  acquired
Intellectual Property Collateral. Assignor hereby authorizes Assignee to modify,
amend,  or supplement the Schedules  hereto and to reexecute this Agreement from
time to time on  Assignor's  behalf and as its  attorney-in-fact  to include any

                                       3.
<PAGE>

such  future  Intellectual  Property  Collateral  and to cause  such  reexecuted
Agreement or such modified,  amended or supplemented  Schedules to be filed with
PTO.

         SECTION 5  ASSIGNEE'S DUTIES.  Notwithstanding any  provision contained
in this Agreement, Assignee shall have no duty to  exercise  any of the  rights,
privileges or powers afforded to it and shall not be responsible to the Assignor
or any other  Person for any  failure to do so or delay in doing so.  Except for
the  accounting  for  moneys  actually  received  by  Assignee  hereunder  or in
connection  herewith,  Assignee  shall have no duty or  liability to exercise or
preserve  any  rights,  privileges  or  powers  pertaining  to the  Intellectual
Property Collateral.

         SECTION 6  REPRESENTATIONS  AND  WARRANTIES.  Assignor  represents  and
warrants to Assignee that:

         (a) A true  and  correct  list  of all  of  the  existing  Intellectual
Property  Collateral  consisting of U.S. patents and patent  applications and/or
registrations  owned  by the  Assignor,  in whole or in  part,  and  pledged  as
collateral hereunder, is set forth in SCHEDULE A.

         (b) A true  and  correct  list  of all  of  the  existing  Intellectual
Property  Collateral  consisting  of U.S.  trademarks,  trademark  registrations
and/or  applications owned by the Assignor,  in whole or in part, and pledged as
collateral hereunder is set forth in SCHEDULE B.

         (c) All patents, trademarks,  service marks and trade names of Assignor
are subsisting and have not been adjudged  invalid or  unenforceable in whole or
in part.

         (d) All maintenance  fees required to be paid on account of any patents
or trademarks of Assignor have been timely paid for maintaining such patents and
trademarks  in force,  and,  to the best of  Assignor's  knowledge,  each of the
patents and trademarks constituting part of the Intellectual Property Collateral
is valid and enforceable.

         (e) To the best of Assignor's  knowledge after due inquiry, no material
infringement  or  unauthorized  use presently is being made of any  Intellectual
Property Collateral by any Person.

         (f) Except as  otherwise  disclosed  in  writing  by  Debtor to Secured
Party,  Assignor is the sole and exclusive  owner of the  Intellectual  Property
Collateral  and  the  past,   present  and  contemplated   future  use  of  such
Intellectual  Property  Collateral  by Assignor  has not,  does not and will not
infringe or violate any right,  privilege  or license  agreement  of or with any
other Person.

         SECTION 7  COVENANTS.

         (a) Assignor  will appear in and defend any action,  suit or proceeding
which may affect to a  material  extent  its title to, or  Assignee's  rights or
interest in, the Intellectual Property Collateral.

                                       4.
<PAGE>

         (b) Assignor  will  not  allow  or  suffer  any  Intellectual  Property
Collateral to become abandoned,  nor any registration  thereof to be terminated,
forfeited, expired or dedicated to the public.

         (c) Assignor will diligently prosecute all applications for patents and
trademarks,    and   file   and   prosecute    any   and   all    continuations,
continuations-in-part, applications for reissue, applications for certificate of
correction and like matters as shall be reasonable and appropriate in accordance
with  prudent  business  practice,  and  promptly  pay any and all  maintenance,
license,  registration and other fees, taxes and expenses incurred in connection
with any Intellectual Property Collateral.

         SECTION 8  ASSIGNEE'S RIGHTS AND REMEDIES.

         (a) Assignee  shall have all rights and remedies  available to it under
the Security  Agreement,  the other Documents and applicable law with respect to
the security  interests in any of the  Intellectual  Property  Collateral or any
other collateral. Assignor agrees that such rights and remedies include, but are
not limited to, the right of  Assignee as a secured  party to sell or  otherwise
dispose of its collateral  after default  pursuant to the UCC.  Assignor  agrees
that Assignee shall at all times have such royalty free licenses,  to the extent
permitted  by law  and to the  extent  of  Assignor's  rights  therein,  for any
Intellectual  Property  Collateral that shall be reasonably  necessary to permit
the  exercise  of any of  Assignee's  rights  or  remedies  upon  or  after  the
occurrence  of an Event of  Default  and  shall  additionally  have the right to
license and/or sublicense any Intellectual Property Collateral upon or after the
occurrence of an Event of Default,  whether general,  special or otherwise,  and
whether  on an  exclusive  or a  nonexclusive  basis,  any of  the  Intellectual
Property  Collateral,  throughout  the world  for such  term or  terms,  on such
conditions,  and in such  manner,  as  Assignee  in its  sole  discretion  shall
determine.  In addition to and without  limiting any of the foregoing,  upon the
occurrence  and during the  continuance  of an Event of Default,  Assignee shall
have the right but shall in no way be obligated  to bring suit,  or to take such
other  action as  Assignee  deems  necessary  or  advisable,  in the name of the
Assignor or  Assignee,  to enforce or protect any of the  Intellectual  Property
Collateral,  in which event the Assignor shall,  at the request of Assignee,  do
any and all lawful acts and execute any and all  documents  required by Assignee
in aid of such enforcement. To the extent that Assignee shall elect not to bring
suit to enforce such Intellectual  Property  Collateral,  Assignor agrees to use
all  reasonable  measures and its  diligent  efforts,  whether by action,  suit,
proceeding  or  otherwise,  to prevent  the  infringement,  misappropriation  or
violations  thereof by others and for that purpose agrees diligently to maintain
any action,  suit or  proceeding  against any Person  necessary  to prevent such
infringement, misappropriation or violation.

         (b) The  cash  proceeds  actually  received  from  the  sale  or  other
disposition or collection of  Intellectual  Property  Collateral,  and any other
amounts  received  in  respect  of  the  Intellectual  Property  Collateral  the
application of which is not otherwise  provided for herein,  shall be applied as
provided in the Security Agreement.

         SECTION 9  NOTICES. All notices or other communications hereunder shall
be in writing  (including by facsimile  transmission)  shall be mailed,  sent or

                                       5.
<PAGE>

delivered in accordance  with the Security  Agreement at or to their  respective
addresses  or  facsimile  numbers set forth  below their names on the  signature
pages  hereof,  or at or to such other  address or facsimile  number as shall be
designated  by any party in a written  notice to the other parties  hereto.  All
such  notices and other  communications  shall be  effective  as provided in the
Security Agreement.

         SECTION 10  NO WAIVER; CUMULATIVE  REMEDIES.  No failure on the part of
Assignee to exercise,  and no delay in exercising,  any right,  remedy, power or
privilege  hereunder shall operate as a waiver thereof,  nor shall any single or
partial  exercise of any such right,  remedy,  power or  privilege  preclude any
other or further  exercise  thereof or the exercise of any other right,  remedy,
power or privilege.  The rights and remedies under this Agreement are cumulative
and not  exclusive  of any  rights,  remedies,  powers and  privileges  that may
otherwise be available to Assignee.

         SECTION 11  COSTS AND EXPENSES; INDEMNITY.

         (a)  Assignor  agrees  to pay on  demand  all  costs  and  expenses  of
Assignee,  including without  limitation all attorneys' fees, in connection with
the enforcement or attempted  enforcement of, and  preservation of any rights or
interests under, this Agreement,  and the assignment,  sale or other disposal of
any of the Intellectual Property Collateral.

         (b)  Assignor  hereby  agrees  to  indemnify  Assignee,  any  affiliate
thereof, and their respective directors,  officers,  employees,  agents, counsel
and other advisors (each an "Indemnified Person") against, and hold each of them
harmless from, any and all liabilities,  obligations,  losses, claims,  damages,
penalties,  actions,  judgments,  suits, costs, expenses or disbursements of any
kind or nature whatsoever,  including, without limitation, reasonable attorneys'
fees and attorneys'  fees incurred  pursuant to 11 U.S.C.,  which may be imposed
on, incurred by, or asserted against any Indemnified Person, in any way relating
to  or  arising  out  of  this  Agreement,  including  in  connection  with  any
infringement or alleged  infringement with respect to any Intellectual  Property
Collateral,  or any action  taken or omitted  to be taken by it  hereunder  (the
"Indemnified  Liabilities");  provided that Assignor  shall not be liable to any
Indemnified Person for any portion of such Indemnified Liabilities to the extent
they are found by a final decision of a court of competent  jurisdiction to have
resulted from such Indemnified  Person's gross negligence or willful misconduct.
If and to the extent that the foregoing  indemnification  is for any reason held
unenforceable,  Assignor agrees to make the maximum  contribution to the payment
and  satisfaction  of each of the Indemnified  Liabilities  which is permissible
under applicable law.

         (c) Any amounts  payable to Assignee under this Section 11 or otherwise
under this  Agreement if not paid upon demand shall bear  interest from the date
of such demand until paid in full,  at the default rate of interest set forth in
the Bank Loan Agreement.

         SECTION 12  BINDING EFFECT. This Agreement shall be binding upon, inure
to the benefit of and be enforceable by Assignor,  Assignee and their respective
successors and assigns.

                                       6.
<PAGE>

         SECTION 13  GOVERNING LAW.  This  Agreement  shall  be governed by, and
construed in accordance  with,  the law of the State of New York,  except to the
extent that the validity or perfection of the assignment and security  interests
hereunder in respect of any  Intellectual  Property  Collateral  are governed by
federal law and except to the extent that Assignee  shall have greater rights or
remedies  under federal law, in which case such choice of New York law shall not
be deemed to deprive  Assignee of such rights and  remedies as may be  available
under federal law.

         SECTION 14  AMENDMENT.  This Agreement shall  not be amended  except by
the written agreement of the parties.

         SECTION 15  SEVERABILITY.  Whenever  possible,  each  provision of this
Agreement shall be interpreted in such manner as to be effective and valid under
all  applicable  laws  and  regulations.  If,  however,  any  provision  of this
Agreement  shall be prohibited by or invalid under any such law or regulation in
any  jurisdiction,  it shall,  as to such  jurisdiction,  be deemed  modified to
conform to the minimum  requirements  of such law or regulation,  or, if for any
reason it is not deemed so modified, it shall be ineffective and invalid only to
the extent of such  prohibition  or invalidity  without  affecting the remaining
provisions of this Agreement, or the validity or effectiveness of such provision
in any other jurisdiction.

         SECTION 16  COUNTERPARTS.  This Agreement may be executed in any number
of counterparts and by different parties hereto in separate  counterparts,  each
of which when so  executed  shall be deemed to be an  original  and all of which
taken together shall constitute but one and the same agreement.

         SECTION 17  TERMINATION.  Upon payment and  performance  in full of all
Obligations,  this Agreement shall terminate and Assignee shall promptly execute
and deliver to Assignor such documents and instruments  reasonably  requested by
Assignor as shall be necessary to evidence termination of all security interests
given  by  Assignor  to  Assignee  hereunder,  including  cancellation  of  this
Agreement by written notice from Assignee to the PTO;  PROVIDED,  HOWEVER,  that
the  obligations  of  Assignor  under  Section  11  hereof  shall  survive  such
termination.

         SECTION 18  SECURITY AGREEMENT.  Assignor  acknowledges that the rights
and  remedies  of  Assignee  with  respect  to  the  security  interests  in the
Intellectual  Property Collateral granted hereby are more fully set forth in the
Security  Agreement  [and the other  Documents] and all such rights and remedies
are cumulative.

         SECTION 19  NO INCONSISTENT REQUIREMENTS.  Assignor  acknowledges  that
this Agreement and the Security  Agreement may contain covenants and other terms
and provisions  variously stated regarding the same or similar matters,  and the
Assignor agrees that all such covenants, terms and provisions are cumulative and
all shall be performed and satisfied in accordance with their respective terms.

                                       7.
<PAGE>

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Agreement, as of the date first above written.

                                       NORTH AMERICAN VACCINE, INC.

                                       By /s/ Lawrence J. Hineline
                                          ---------------------------------
                                             Title: Vice President Finance

                                       10150 Old Columbia Road
                                       Columbia, Maryland  21046

                                       Attn: Vice President Finance
                                             ------------------------------
                                       Fax:  (410) 309-4077
                                             ------------------------------

                                       BAXTER INTERNATIONAL, INC.

                                       By /s/ Steven J. Meyer
                                          ---------------------------------
                                             Title: Corp. Treasurer

                                       8.

<PAGE>

STATE OF CALIFORNIA                   )
                                      ) ss
COUNTY OF ____________________________)

         On ___________ , before me,  _____________,  Notary Public,  personally
appeared ___________________________, personally known to me (or proved to me on
the basis of  satisfactory  evidence) to be the person(s)  whose name(s)  is/are
subscribed to the within  instrument  and  acknowledged  to me that  he/she/they
executed  the  same  in  his/her/their  authorized  capacity(ies),  and  that by
his/her/their  signature(s) on the instrument the person(s),  or the entity upon
behalf of which the person(s) acted, executed the instrument.

         WITNESS my hand and official seal.

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

[SEAL]

                                       9.
<PAGE>

STATE OF CALIFORNIA        )
                           ) ss
COUNTY OF _________________)

         On ___________ , before me,  _____________,  Notary Public,  personally
appeared ___________________________, personally known to me (or proved to me on
the basis of  satisfactory  evidence) to be the person(s)  whose name(s)  is/are
subscribed to the within  instrument  and  acknowledged  to me that  he/she/they
executed  the  same  in  his/her/their  authorized  capacity(ies),  and  that by
his/her/their  signature(s) on the instrument the person(s),  or the entity upon
behalf of which the person(s) acted, executed the instrument.

         WITNESS my hand and official seal.

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

[SEAL]

                                      10.

<PAGE>

<TABLE>
<CAPTION>

                                                                 SCHEDULE A
------------------------------------------------------------------------------------------------------------------------------------
                                                 PATENTS AND PATENT APPLICATIONS OF ASSIGNOR

------------------------------------------------------------------------------------------------------------------------------------
ISSUED U.S. PATENTS
------------------------------------------------------------------------------------------------------------------------------------
<S>                               <C>                <C>                <C>                  <C>                   <C>
Method for the High Level         Blake, et al.      NVX                08/798,760           February 11, 1997     Notice of
Expression, Purification and                         (co-exclusive      (Notice of Allowance                       Allowance issued
Refolding of the Outer Membrane                      license with PMC)  issued Jan. 1999)                          January 1999
Group B Porin Proteins                                                                                             (fee paid April
                                                                                                                   1999)
------------------------------------------------------------------------------------------------------------------------------------
Method for the High Level         Blake, et al.      NVX & Rockefeller  5,439,808            August 8, 1995        Patent
Expression, Purification and                         University
Refolding of the Outer Membrane                      (co-exclusive
Group B Porin Proteins from                          license with PMC)
Neisseria Meningitidis
------------------------------------------------------------------------------------------------------------------------------------
Method for the High Level         Blake, et al.      NVX                5,747,287            May 5, 1998           Patent
Expression, Purification and                         (co-exclusive
Refolding of the Outer Membrane                      license with PMC)
Group B Porin Proteins from
Neisseria Meningitidis
------------------------------------------------------------------------------------------------------------------------------------
Group A Streptococcal             Blake et al.       NVX & Rockefeller  5,866,135            February 2, 1999      Patent
Polysaccharide Immunogenic                           University
Compositions and Methods
------------------------------------------------------------------------------------------------------------------------------------
Method for the High Level         Blake, et al.      NVX                5,879,686            March 9, 1999         Patent
Expression, Purification and                         (co-exclusive
Refolding of the Outer Membrane                      license with PMC)
Group B Porin Proteins from
Neisseria Meningitidis
------------------------------------------------------------------------------------------------------------------------------------
</TABLE>

<TABLE>
<CAPTION>

------------------------------------------------------------------------------------------------------------------------------------
U.S. PATENT APPLICATIONS
------------------------------------------------------------------------------------------------------------------------------------
<S>                                      <C>                     <C>           <C>                <C>                  <C>
Method for the High Level                Tai, et al.             NVX           08/096,181         July 23, 1993        Application
Expression, Purification and
Refolding of the Outer Membrane
Protein P2 from Haemophilus Type b
------------------------------------------------------------------------------------------------------------------------------------
Method for the High Level                Tai, et al.             NVX           08/449,358          May 24, 1995        Application
Expression, Purification and
Refolding of the Outer Membrane
Protein P2 from Haemophilus Type b
------------------------------------------------------------------------------------------------------------------------------------
Antigenic Group B Streptococcus         Michon, et al.           NVX           08/481,883          June 7, 1995        Application
Type II and Type III
Polysaccharide Fragments Having a
2,5-Anhydro-D-Mannose Terminal
Structure and Conjugate Vaccine
Thereof
------------------------------------------------------------------------------------------------------------------------------------
Direct Methods for Molar-Mass          Michon, D'Ambra           NVX           08/753,242       November 22, 1996      Application
Determination of Fragments of
Haemophilus Type b Capsular
Polysaccharides and Vaccine
Preparation
------------------------------------------------------------------------------------------------------------------------------------
Cloning of Non-IgA FC Binding             Tai, Blake             NVX           08/923,992       September 5, 1997      Application
Forms of the Group B Streptococcal
Beta Antigens
------------------------------------------------------------------------------------------------------------------------------------
Antigenic Group B Streptococcus         Michon, et al.           NVX           09/025,225       February 18, 1998      Application
Type II and Type III
Polysaccharide Fragments Having a
2,5-Anhydro-D-Mannose Terminal
Structure and Conjugate Vaccine
Thereof
------------------------------------------------------------------------------------------------------------------------------------

<PAGE>

------------------------------------------------------------------------------------------------------------------------------------
Immunogenic Conjugates Comprising       Blake, et al.            NVX           09/118/180         July 17, 1998        Application
A Group B Meningococcal Porin and
an H. Influenzae Polysaccharide
------------------------------------------------------------------------------------------------------------------------------------
Modified Immunogenic Pneumolysin       Minetti, et al.           NVX           09/120,044         July 21, 1998        Application
Compositions as Vaccines
------------------------------------------------------------------------------------------------------------------------------------
Group A Streptococcal                    Blake et al.           NVX &          09/207,188        December 8, 1998      Application
Polysaccharide Immunogenic                                   Rockefeller
Compositions and Methods                                     University
------------------------------------------------------------------------------------------------------------------------------------
Procedures for the Extraction and       Michon, Blake            NVX           09/221,620       December 23, 1998      Application
Isolation of Bacterial Capsular
Polysaccharides for Use as
Vaccines or Linked to Proteins as
Conjugate Vaccines
------------------------------------------------------------------------------------------------------------------------------------
Gram Positive Bacterial Antigens       Long-Rowe, Blake          NVX           09/399,220       September 17, 1999     Application
and Methods of Purification of the
Streptococcal C-Beta Protein
------------------------------------------------------------------------------------------------------------------------------------
Immunogenic Polysaccharide-Protein      Michon et al.            NVX           09/376,911        August 18, 1999       Application
Conjugate Useful as a Vaccine
Produced Via Conjugation Through a
CZ-3 N-Acyl Portion F A
Polysaccharide
------------------------------------------------------------------------------------------------------------------------------------

</TABLE>

                                      A-1.

<PAGE>

<TABLE>
<CAPTION>

---------------------------------------------------------------------------------------------------------------------------
                                                                 SCHEDULE B
---------------------------------------------------------------------------------------------------------------------------
                                                         U.S. TRADEMARKS OF ASSIGNOR
---------------------------------------------------------------------------------------------------------------------------
MARK                               STATUS              APPL NO./     APPL./REGIS. DATE        OWNER OF RECORD
                                                       REGIS. NO.
---------------------------------------------------------------------------------------------------------------------------
     REGISTERED U.S. TRADEMARKS
---------------------------------------------------------------------------------------------------------------------------
<S>                                <C>                 <C>           <C>                      <C>
Globe Design                       Registered          1,932,111     October 31, 1995         North American Vaccine, Inc.
---------------------------------------------------------------------------------------------------------------------------
AMVAX                              Registered          1,967,632     April 16, 1996           North American Vaccine, Inc.
---------------------------------------------------------------------------------------------------------------------------
TRINAVACEL                         Registered          2,101,121     September 30, 1997       American Vaccine Corporation
---------------------------------------------------------------------------------------------------------------------------
TRIVAX                             Registered          2,118,360     December 2, 1997         American Vaccine Corporation
---------------------------------------------------------------------------------------------------------------------------
NAVA                               Registered          2,267,812     August 3, 1999           American Vaccine Corporation
---------------------------------------------------------------------------------------------------------------------------
     PENDING U.S. TRADEMARK APPLICATIONS
---------------------------------------------------------------------------------------------------------------------------
THE IMPORTANCE OF OUR WORK         Pending             75/190,826    October 29, 1996         American Vaccine Corporation
GROWS BIGGER EVERY DAY
---------------------------------------------------------------------------------------------------------------------------
NEISVAC-C                          Pending             Not Avail.    August 26, 1999          American Vaccine Corporation
---------------------------------------------------------------------------------------------------------------------------
NEISIVA                            Pending             Not Avail.    August 26, 1999          American Vaccine Corporation
---------------------------------------------------------------------------------------------------------------------------
MENCIVA                            Pending             Not Avail.    August 26, 1999          American Vaccine Corporation
---------------------------------------------------------------------------------------------------------------------------
</TABLE>

                                      B-1.GUARANTY

      FOR VALUE RECEIVED, the sufficiency of which is hereby acknowledged, and,
in consideration of any credit and/or financial accommodation heretofore or
hereafter from time to time made or granted to North American Vaccine, Inc., a
Canadian corporation ("BORROWER"), by BANK OF AMERICA, N.A. and any other
subsidiaries or affiliates of BankAmerica Corporation and its successors and
assigns (collectively "LENDER"), BAXTER INTERNATIONAL INC., a Delaware
corporation (the "GUARANTOR") hereby furnishes its guaranty of the Guaranteed
Obligations (as hereinafter defined) as follows:

      1.  GUARANTY. Guarantor hereby absolutely and unconditionally guarantees,
as a guarantee of payment and not merely as a guarantee of collection, prompt
payment when due, whether at stated maturity, upon acceleration or otherwise,
and at all times thereafter, of any and all existing and future indebtedness and
liabilities of every kind, nature and character, direct or indirect, absolute or
contingent, liquidated or unliquidated, voluntary or involuntary, of Borrower to
Lender arising under that certain letter loan agreement dated November 1, 1999
between Borrower and Lender (the "BORROWER CREDIT AGREEMENT") and all
instruments, agreements and other documents (including without limitation the
Security Agreement and the IP Security Agreement) of every kind and nature now
or hereafter executed in connection with the Borrower Credit Agreement
(including all renewals, extensions and modifications thereof and all costs,
structuring fees, attorneys' fees and expenses incurred by Lender in connection
with the collection or enforcement thereof) (collectively, the "GUARANTEED
OBLIGATIONS"). Lender's books and records showing the amount of the Guaranteed
Obligations shall be admissible in evidence in any action or proceeding, and
shall be binding upon Guarantor and serve as a rebuttable presumption in favor
of Lender for the purpose of establishing the amount of the Guaranteed
Obligations, subject only to manifest error. This Guaranty shall not be affected
by the genuineness of the Borrower Credit Agreement or the validity, regularity
or enforceability of the Guaranteed Obligations or any instrument or agreement
evidencing any Guaranteed Obligations, or by the existence, validity,
enforceability, perfection, or extent of any collateral therefor, or by any fact
or circumstance relating to the Guaranteed Obligations which might otherwise
constitute a defense to the obligations of Guarantor under this Guaranty. The
obligations of Guarantor hereunder shall be limited to an aggregate amount equal
to the largest amount that would not render its obligations hereunder subject to
avoidance under Section 548 of the Bankruptcy Code (Title 11, United States
Code) or any comparable provisions of any applicable state law.

      2.  NO DEDUCTIONS. All payments by Guarantor hereunder shall be paid in
full, without setoff or counterclaim or any deduction or withholding whatsoever,
including, without limitation, for any and all present and future taxes. In the
event that Guarantor or Lender is required by law to make any such deduction or
withholding, Guarantor agrees to pay on behalf of Lender such amount directly to
the appropriate person or entity, or if the Guarantor cannot legally comply with
the foregoing, Guarantor shall pay to Lender such additional amounts as will
result in the receipt by Lender of the full amount payable hereunder. Guarantor
shall promptly provide Lender with evidence of payment of any such amount made
on Lender's behalf.

<PAGE>

      3.  NO TERMINATION. This Guaranty is a continuing and irrevocable guaranty
of all Guaranteed Obligations now or hereafter existing and shall remain in full
force and effect until all Guaranteed Obligations and any other amounts payable
under this Guaranty are indefeasibly paid and performed in full and any
commitments of Lender or facilities provided by Lender with respect to the
Guaranteed Obligations are terminated.

      4.  WAIVER OF NOTICES. Guarantor waives notice of the acceptance of this
Guaranty and of the extension or continuation of the Guaranteed Obligations or
any part thereof, subject to the provisions of Section 6. Guarantor further
waives presentment, protest, notice, dishonor or default, demand for payment and
any other notices to which Guarantor might otherwise be entitled as a condition
to the satisfaction of its obligations hereunder; provided that Lender shall
provide notice of any Event of Default (as defined in the Borrower Credit
Agreement) in accordance with the terms of Section 23 hereof.

      5.  SUBROGATION. Guarantor shall exercise no right of subrogation,
contribution or similar rights with respect to any payments it makes under this
Guaranty until (a) all of the Guaranteed Obligations and any amounts payable
under this Guaranty are indefeasibly paid and performed in full and any
commitments of Lender or facilities provided by Lender with respect to the
Guaranteed Obligations are terminated or (b) Guarantor exercises Guarantor's
Call Option (or Lender exercises Lender's Put Option) in accordance with and as
more specifically described in Section 23 hereof. If any amounts are paid to
Guarantor in violation of the foregoing limitation, then such amounts shall be
held in trust for the benefit of Lender and shall forthwith be paid to Lender to
reduce the amount of the Guaranteed Obligations, whether matured or unmatured.

      6.  WAIVER OF SURETYSHIP DEFENSES. Guarantor agrees that Lender may, at
any time and from time to time, and without notice to Guarantor, make any
agreement with Borrower or with any other person or entity liable on any of the
Guaranteed Obligations or providing collateral as security for the Guaranteed
Obligations, for the extension, renewal, payment, compromise, discharge or
release of the Guaranteed Obligations, or for any modification or amendment of
the terms thereof or of any instrument or agreement evidencing the Guaranteed
Obligations or the provision of collateral, all without in any way impairing,
releasing, discharging or otherwise affecting the obligations of Guarantor under
this Guaranty; provided that Lender shall not (a) extend the final maturity date
of the Guaranteed Obligations or any portion thereof, (b) reduce the rate or
extend the time for payment of interest, (c) waive the principal amount of any
Loan, (d) increase the Commitment or (e) release all or substantially all of any
collateral given to secure the Guaranteed Obligations, without in each case the
written consent of Guarantor. Guarantor waives any defense arising by reason of
any disability or other defense of Borrower or any other guarantor, or the
cessation from any cause whatsoever of the liability of Borrower, or any claim
that Guarantor's obligations exceed or are more burdensome than those of
Borrower and waives the benefit of any statute of limitations affecting the
liability of Guarantor hereunder. Guarantor waives any right to enforce any
remedy which Lender now has or may hereafter have against Borrower and waives
any benefit of and any right to participate in any security now or hereafter
held by Lender, subject to the provisions of Sections 23 and 24 hereof. Further,
Guarantor consents to the taking of, or failure to take, any action which might
in any manner or to any extent vary the risks of Guarantor under this Guaranty

                                       2
<PAGE>

or which, but for this provision, might operate as a discharge of Guarantor.

      7.  EXHAUSTION OF OTHER REMEDIES NOT REQUIRED. The obligations of
Guarantor hereunder are those of primary obligor, and not merely as surety, and
are independent of the Guaranteed Obligations. Guarantor waives diligence by
Lender and action on delinquency in respect of the Guaranteed Obligations or any
part thereof, including, without limitation any provisions of law requiring
Lender to exhaust any right or remedy or to take any action against Borrower,
any other guarantor or any other person, entity or property before enforcing
this Guaranty against Guarantor.

      8.  REINSTATEMENT. Notwithstanding anything in this Guaranty to the
contrary, this Guaranty shall continue to be effective or be reinstated, as the
case may be, if at any time any payment of any portion of the Guaranteed
Obligations is revoked, terminated, rescinded or reduced or must otherwise be
restored or returned upon the insolvency, bankruptcy or reorganization of
Borrower or any other person or entity or otherwise, as if such payment had not
been made and whether or not Lender is in possession of or has released this
Guaranty and regardless of any prior revocation, rescission, termination or
reduction.

      9.  SUBORDINATION. Guarantor hereby subordinates the payment of all
obligations and indebtedness of Borrower owing to Guarantor, whether now
existing or hereafter arising, including but not limited to any obligation of
Borrower to Guarantor as subrogee of Lender or resulting from Guarantor's
performance under this Guaranty, to the indefeasible payment in full of all
Guaranteed Obligations. If Lender so requests, any such obligation or
indebtedness of Borrower to Guarantor shall be enforced and performance received
by Guarantor as trustee for Lender and the proceeds thereof shall be paid over
to Lender on account of the Guaranteed Obligations, but without reducing or
affecting in any manner the liability of Guarantor under this Guaranty.

      10. INFORMATION. Guarantor agrees to furnish promptly to Lender any and
all financial or other information regarding Guarantor or its property as Lender
may reasonably request in writing; provided, Guarantor shall not be obligated to
furnish or deliver information to Lender in addition to the requirements set
forth in the Existing Credit Agreement (as defined in Section 20 hereof).

      11. STAY OF ACCELERATION. In the event that acceleration of the time for
payment of any of the Guaranteed Obligations is stayed, upon the insolvency,
bankruptcy or reorganization of Borrower or any other person or entity, or
otherwise, all such amounts shall nonetheless be payable by Guarantor
immediately upon demand by Lender.

      12. EXPENSES. Guarantor shall pay on demand all out-of-pocket expenses
(including reasonable attorneys' fees and expenses and the allocated cost and
disbursements of internal legal counsel) in any way relating to the enforcement
or protection of Lender's rights under this Guaranty, including any incurred in
the preservation, protection or enforcement of any rights of Lender in any case
commenced by or against Guarantor under the Bankruptcy Code (Title 11, United

                                       3
<PAGE>

States Code) or any similar or successor statute. The obligations of Guarantor
under the preceding sentence shall survive termination of this Guaranty.

      13. AMENDMENTS. No provision of this Guaranty may be waived, amended,
supplemented or modified, except by a written instrument executed by Lender and
Guarantor.

      14. NO WAIVER. No failure by Lender to exercise, and no delay in
exercising, any right, remedy or power hereunder shall operate as a waiver
thereof; nor shall any single or partial exercise of any right, remedy or power
hereunder preclude any other or further exercise thereof or the exercise of any
other right. The remedies herein provided are cumulative and not exclusive of
any remedies provided by law or in equity. The unenforceability or invalidity of
any provision of this Guaranty shall not affect the enforceability or validity
of any other provision herein.

      15. ASSIGNMENT; GOVERNING LAWS; JURISDICTION. This Guaranty shall (a) bind
Guarantor and its successors and assigns, PROVIDED that Guarantor may not assign
its rights or obligations under this Guaranty without the prior written consent
of Lender (and any attempted assignment without such consent shall be void), (b)
inure to the benefit of Lender and its successors and assigns and Lender may,
without notice to Guarantor and without affecting Guarantor's obligations
hereunder, assign or sell participations in the Guaranteed Obligations and this
Guaranty, in whole or in part, and (c) be governed by the internal laws of the
State of New York. Guarantor hereby irrevocably (i) submits to the non-exclusive
jurisdiction of any United States Federal or State court sitting in New York,
New York in any action or proceeding arising out of or relating to this
Guaranty, and (ii) waives to the fullest extent permitted by law any defense
asserting an inconvenient forum in connection therewith. Service of process by
Lender in connection with such action or proceeding shall be binding on
Guarantor if sent to Guarantor by registered or certified mail at its address
specified below. Guarantor agrees that Lender may disclose to any prospective
purchaser and any purchaser of all or part of the Guaranteed Obligations any and
all information in Lender's possession concerning Guarantor, this Guaranty and
any security for this Guaranty.

      16. CONDITION OF BORROWER. Guarantor acknowledges and agrees that it has
the sole responsibility for, and has adequate means of, obtaining from Borrower
such information concerning the financial condition, business and operations of
Borrower as Guarantor requires, and that Lender has no duty, and Guarantor is
not relying on Lender at any time to disclose to Guarantor any information
relating to the business, operations or financial condition of Borrower.

      17. SETOFF. If and to the extent any payment is not made when due
hereunder, Lender may setoff and charge from time to time any amount so due
against any or all of Guarantor's accounts or deposits with Lender.

      18. OTHER GUARANTEES. Unless otherwise agreed by Lender and Guarantor in
writing, this Guaranty is not intended to supersede or otherwise affect any
other guaranty now or hereafter given by Guarantor for the benefit of Lender or
any term or provision thereof.

                                       4
<PAGE>

      19. REPRESENTATIONS AND WARRANTIES. Guarantor represents and warrants that
(i) it is duly organized and in good standing under the laws of the jurisdiction
of its organization and has full capacity and right to make and perform this
Guaranty, and all necessary authority has been obtained; (ii) this Guaranty
constitutes its legal, valid and binding obligation enforceable in accordance
with its terms; (iii) the making and performance of this Guaranty does not and
will not violate the provisions of any applicable law, regulation or order, and
does not and will not result in the breach of, or constitute a default or
require any consent under, any agreement, instrument, or document to which it is
a party or by which it or any of its property may be bound or affected; (iv) all
consents, approvals, licenses and authorizations of, and filings and
registrations with, any governmental authority required under applicable law and
regulations for the making and performance of this Guaranty have been obtained
or made and are in full force and effect; (v) by virtue of its relationship with
Borrower, the execution, delivery and performance of this Guaranty is for the
direct benefit of Guarantor and it has received adequate consideration for this
Guaranty; and (vi) the financial information that has been delivered to Lender
by or on behalf of Guarantor is complete and correct in all respects and
accurately presents the financial condition and the operational results of
Guarantor and since the date of the most recent financial statements delivered
to Lender, there has been no material adverse change in the financial or
operational condition of Guarantor.

      20. INCORPORATION OF COVENANTS. Reference is made to that certain Credit
Agreement (Facility A) dated as of November 24, 1998 (as amended or modified
prior to the date of the Guaranty, the "EXISTING CREDIT AGREEMENT") among
Guarantor, the financial institutions named therein, Bank of America, N.A.
(formerly Bank of America National Trust and Saving Association) and The Chase
Manhattan Bank, as Co-Arrangers, and The First National Bank of Chicago, as
administrative agent. Reference is further made to the covenants contained in
Article VIII of the Existing Credit Agreement (hereinafter referred to as the
"INCORPORATED COVENANTS"). So long as principal of and interest on any Loan (as
defined in the Borrower Credit Agreement) or any other amount payable under the
Borrower Credit Agreement or under any other Loan Document remains unpaid or
unsatisfied or the Commitment (as defined in the Borrower Credit Agreement) has
not been terminated, Guarantor shall comply with the Incorporated Covenants, it
being agreed that such covenants and agreements shall survive any termination,
cancellation or discharge of the Existing Credit Agreement. Guarantor agrees
with Lender that the Incorporated Covenants (and all other relevant provisions
of the Existing Credit Agreement related thereto, including without limitation
all exhibits, schedules and the defined terms contained in Section 1.01 thereof,
which are used in the Incorporated Covenants) are hereby incorporated by
reference into this Guaranty to the same extent and with the same effect as if
set forth fully herein and shall inure to the benefit of Lender, without giving
effect to any waiver, amendment, modification or replacement of the Existing
Credit Agreement or any term or provision of the Incorporated Covenants
occurring subsequent to the date of this Guaranty, except to the extent
otherwise specifically provided for in the following paragraph of this Section.

      In the event a waiver is granted under the Existing Credit Agreement or an
amendment or modification is executed with respect to the Existing Credit
Agreement, and such waiver, amendment and/or modification affects the

                                       5
<PAGE>

Incorporated Covenants, then such waiver, amendment or modification shall be
effective with respect to the Incorporated Covenants as incorporated by
reference into this Guaranty only if consented to in writing by the Lender. In
the event of any replacement of the Existing Credit Agreement with a similar
credit facility (the "NEW FACILITY") the covenants contained in the New Facility
which correspond to the covenants contained in Sections 8.01 and 8.02,
respectively, of the Existing Credit Agreement shall become the Incorporated
Covenants hereunder only if consented to in writing by Lender and, if such
consent is not granted or if the Existing Credit Agreement is terminated and not
replaced, then covenants contained in Sections 8.01 and 8.02, respectively, of
the Existing Credit Agreement (together with any modifications or amendments
approved in accordance with this paragraph) shall continue to be the
Incorporated Covenants hereunder.

      21. GUARANTY EVENTS OF DEFAULT. Each of the following shall be a "Guaranty
Event of Default" for purposes of this Guaranty:

      (a)            Any "Event of Default" specified in Section 9.01 of the
                Existing Credit Agreement occurs and is continuing, without
                giving effect to any waiver thereof pursuant to the Existing
                Credit Agreement; or
      (b)            Guarantor fails to perform or observe any other covenant or
                agreement  (not  specified  in  (a)  above)  contained  in  this
                Guaranty or any Loan Document (as defined in the Borrower Credit
                Agreement)  on its part to be performed or observed  (including,
                without limitation,  the failure of Guarantor to comply with any
                of its payments  obligations  in  accordance  with and under the
                terms of this Guaranty); or
      (c)            Any representation or warranty in this Guaranty or in any
                certificate, agreement, instrument or other document made or
                delivered by Guarantor pursuant to or in connection with this
                Guaranty or the Borrower Loan Agreement proves to have been
                incorrect when made or deemed made.

      22. WAIVER OF JURY TRIAL; FINAL AGREEMENT. TO THE EXTENT ALLOWED BY
APPLICABLE LAW, GUARANTOR AND LENDER EACH WAIVE TRIAL BY JURY WITH RESPECT TO
ANY ACTION, CLAIM, SUIT OR PROCEEDING ON OR ARISING OUT OF THIS GUARANTY. THIS
GUARANTY REPRESENTS THE FINAL AGREEMENT BETWEEN THE PARTIES AND MAY NOT BE
CONTRADICTED BY EVIDENCE OF PRIOR, CONTEMPORANEOUS, OR SUBSEQUENT ORAL
AGREEMENTS BETWEEN THE PARTIES. THERE ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN
THE PARTIES.

      23. CALL/PUT PROVISIONS.

      (a) GUARANTOR'S CALL OPTION. Guarantor (or any Affiliate identified by
      Guarantor) shall have the right, upon three Business Days' prior written
      notice to Lender, to purchase all (but not less than all) of Lender's
      rights, interests and obligations in and to the Borrower Credit Agreement
      at par value and subject in all cases to the representations, warranties

                                       6
<PAGE>

      and disclaimers set forth in Section 24 hereof (as set forth herein,
      "GUARANTOR'S CALL OPTION"). Notwithstanding (I) Guarantor's exercise of
      its call option pursuant to this section or (II) any other provision of
      this Guaranty to the contrary, the Guaranty shall continue to be effective
      or be reinstated, as the case may be, if at any time any payment of any
      portion of the Guaranteed Obligations received by Lender is (x) revoked,
      terminated, rescinded or reduced or (y) subject to a request or an action
      filed by Borrower, or any of its successors in bankruptcy (including a
      trustee or any official committee), seeking the return or restoration of
      any or all of such payment pursuant to the avoidance provisions of the
      United States Bankruptcy Code, specifically including but not limited to
      11 U.S.C. ss.ss. 544, 547, 548 and 550, as if such payment had not been
      made and whether or not Lender is in possession of or has released this
      Guaranty and regardless of any prior revocation, rescission, termination
      or reduction. Guarantor shall be responsible for all costs and expenses
      (including without limitation Breakage Costs) associated with Guarantor's
      exercise of its rights hereunder.

      (b) LENDER'S PUT OPTION. Upon the occurrence of any Event of Default and
      written notice thereof provided by Lender to Guarantor, Lender shall sell
      to Guarantor all (but not less than all) of Lender's rights, interests and
      obligations in and to the Borrower Credit Agreement at par value and
      subject in all cases to the representations, warranties and disclaimers
      set forth in Section 24 hereof (as set forth herein, "LENDER'S PUT
      OPTION"). Notwithstanding (I) Lender's exercise of its put option pursuant
      to this section or (II) any other provision of this Guaranty to the
      contrary, the Guaranty shall continue to be effective or be reinstated, as
      the case may be, if at any time any payment of any portion of the
      Guaranteed Obligations is (x) revoked, terminated, rescinded or reduced or
      (y) subject to a request or an action filed by Borrower, or any of its
      successors in bankruptcy (including a trustee or any official committee),
      seeking the return or restoration of any or all of such payment pursuant
      to the avoidance provisions of the United States Bankruptcy Code,
      specifically including but not limited to 11 U.S.C. ss.ss. 544, 547, 548
      and 550, as if such payment had not been made and whether or not Lender is
      in possession of or has released this Guaranty and regardless of any prior
      revocation, rescission, termination or reduction. Guarantor shall be
      responsible for all costs and expenses (including without limitation
      Breakage Costs) associated with Lender's exercise of its rights hereunder.

      PROVIDED, HOWEVER, that, (a) notwithstanding Borrower's and Guarantor's
good faith efforts, if the Guarantor and Borrower do not execute a definitive
agreement for the North American Vaccine Acquisition on or prior to November 16,
1999, and (b) between the date hereof and November 16, 1999, Borrower has not,
directly or indirectly solicited, initiated or encouraged (including by way of
furnishing or disclosing nonpublic information) any inquiries or the making or
any proposal or offer (including, without limitation, any offer to its
stockholders), with any third party other than Guarantor relating to any Company
Competing Transaction or knowingly encouraged or otherwise entered into or
maintained any discussions or negotiations with respect to any Company Competing
Transaction, or agreed or endorsed any agreement, arrangement or understanding
with respect to a Company Competing Transaction, or authorized or permitted any
representative of Borrower to take any such action, then Guarantor agrees that
it shall not, in connection with the exercise of Guarantor's Call Option or the

                                       7
<PAGE>

exercise of Lender's Put Option, commence the exercise of remedies set forth in
the Borrower Credit Agreement if Borrower repays all amounts owing under or in
connection with the Borrower Credit Agreement and any related agreements within
20 days thereafter. For purposes of this Guaranty, a "Company Competing
Transaction" shall mean any of the following involving Borrower:

           (i)     any merger, consolidation, share exchange, recapitalization,
business combination, material issuance of equity or other similar transaction;

           (ii)    any sale, lease, exchange, transfer or other disposition of
10% or more of the assets of Borrower and its subsidiaries taken as a whole in a
single transaction or series of related transactions;

           (iii)   any license, sublicense, sale or similar transaction,
arrangement or agreement with respect to any material patents, trademarks, trade
secrets, patent applications, know how or other intellectual property of
Borrower or any of its subsidiaries;

           (iv)    any tender offer or exchange offer for any of the outstanding
voting securities of Borrower;

           (v)     any acquisition by any person or group of persons of 10% or
more of the voting securities (or securities convertible or exchangeable
therefor)of Borrower; or

           (vi)    any public announcement of a proposal, plan or intention to
do any of the foregoing or any agreement to engage in any of the foregoing.

      24. ASSIGNMENT PROVISIONS. To the extent that Borrower's obligations under
the Borrower Credit Agreement are secured by a lien or pledge of collateral to
Lender in Borrower's property or assets (of whatever nature) (collectively,
"BORROWER COLLATERAL"), Lender hereby agrees that upon payment in full by
Guarantor of the Guaranteed Obligations (as determined by Lender), Lender shall,
if requested in writing by Guarantor, assign to Guarantor or its designee all or
a portion of Lender's rights (if any, and of whatever nature) in and to such
Borrower Collateral. Lender does not make, shall not be obligated to make nor
shall be deemed to have made any representation or warranty of any kind as to
the value of the Borrower Collateral or any portion thereof, including but not
limited to any representation or warranty with respect to the value of Lender's
Lien in such Borrower Collateral or the attachment, perfection or priority of
Lender's Lien with respect thereto. Lender hereby specifically disclaims any
such representations or warranties. Lender shall not warrant nor be obligated to
defend Lender's Lien or the attachment, perfection or priority of such Lien.
GUARANTOR HEREBY SPECIFICALLY ACKNOWLEDGES AND AGREES THAT LENDER DOES NOT MAKE,
SHALL NOT BE OBLIGATED TO MAKE NOR SHALL BE DEEMED TO HAVE MADE ANY
REPRESENTATION OR WARRANTY WITH RESPECT TO THE BORROWER COLLATERAL, INCLUDING
WITHOUT LIMITATION THE ATTACHMENT, PERFECTION OR PRIORITY OF LENDER'S LIEN WITH
RESPECT THERETO. Lender agrees to reasonably cooperate with Guarantor to execute
UCC assignments and such other legal documentation as may be necessary to effect

                                       8
<PAGE>

the purposes of this paragraph. Guarantor shall be responsible for the costs and
expenses (including without limitation reasonable attorneys' fees and expenses
and the allocated cost and disbursements of internal legal counsel) associated
with the assignment and/or transfer by Lender of its rights with respect to the
Borrower Collateral in accordance with the terms hereof.

      25. DEFINED TERMS. Capitalized terms used herein but not otherwise defined
shall have the respective meaning set forth in the Borrower Credit Agreement.

                                       9
<PAGE>

Duly executed and delivered under seal this 1st day of November, 1999.

                                          BAXTER INTERNATIONAL INC.

                                          By:  /s/ Steven J. Meyer
                                               -----------------------
                                               Name:  Steven J. Meyer
                                               Title: Corp. Treasurer

Acknowledged and Agreed:

BANK OF AMERICA, N.A.

By:    /s/ Lawrence J. Gordon
       ----------------------

Name:  Lawrence J. Gordon

Title: Vice President

Acknowledged and Agreed:

NORTH AMERICAN VACCINE, INC.

By:    /s/ Randal Chase
       -----------------------

Name:  Randal Chase, Ph.D.
       -------------------
Title: Chief Executive Officer & President
       -----------------------------------

                                       10

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00003-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00003-of-00352.parquet"}]]