Document:

Exhibit 10

                       COLLABORATIVE EVALUATION AGREEMENT

This Agreement is made by and between Maxygen, Inc., 515 Galveston Drive,
Redwood City, California 94063 ("Maxygen"), and SIGA Technologies, Inc., 420
Lexington Avenue, Suite 620, New York, NY 10170 ("SIGA"), effective October 17,
2000 (the "Effective Date"), as follows:

                                   BACKGROUND

A. Maxygen has rights in certain genes useful for the production of proteins
that may be useful for vaccines; and

B. SIGA has rights in certain gram-positive commensal bacteria and related
technology useful for the production of proteins on the surface of bacteria that
may be useful for vaccines; and

C. SIGA and Maxygen wish to enter in to this Agreement in order to research and
evaluate the utility of gram-positive commensal bacteria as vectors for
inducing mucosal immunity.

NOW, THEREFORE, in consideration of the mutual covenants contained herein, and
for other good and valuable consideration, the parties hereby agree as follows:

      1. Evaluation. Subject to the terms and conditions set forth herein,
Maxygen and SIGA shall use commercially reasonable efforts to conduct mutually
agreed collaborative research (the "Evaluation") on the utility of gram-positive
commensal bacteria as vectors for inducing mucosal immunity as set forth in the
SIGA/Maxygen Research Project proposal attached hereto as Exhibit A and
incorporated herein (the "Project Proposal"). The parties shall review the
Project Proposal on an ongoing basis and may make mutually agreed upon changes
to the Project Proposal then in effect. SIGA and Maxygen shall conduct research
in accordance with the Project Proposal in a professional manner and each agrees
to commit the personnel, facilities and other resources reasonably necessary to
perform the research. Each party shall be responsible for its own costs in
performing the Evaluation.

      2. Materials:

            2.1 Maxygen Materials: Maxygen shall transfer to SIGA reasonable
quantities of biological materials identified on Exhibit B, and such other
additional materials as Maxygen and SIGA may from time-to-time agree during the
term of the Evaluation (the "Maxygen Materials") for the sole purpose of
performing the Evaluation. All right, title and interest to the Maxygen
Materials shall at all times remain with and be vested in Maxygen.

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                  2.1.1 Restriction on Use and Control. SIGA shall use the
Maxygen Materials for the sole purpose of performing the Evaluation at its
facility located at 420 Lexington Avenue, Suite 620 New York, NY 10170 and/or
SIGA's facility at 4575 SW Research Way, Suite 230, Corvallis, OR 97333 under
the direction of one or more SIGA employees, under scientifically reasonable
containment conditions, and not for any commercial, business or other use or
purpose other than the Evaluation without the prior written consent of Maxygen.
SIGA shall not transfer or provide access to the Maxygen Materials to any other
persons or entity or to any location other than its addresses specified above,
without the prior written consent of Maxygen (which consent may be conditioned
inter alia upon such person or entity duly executing and delivering Maxygen
standard form of material transfer agreement therefor).

                  2.1.2 SIGA represents and warrants that all personnel,
including employees of SIGA and Oregon State University who will be involved in
the performance of the Evaluation are and shall be bound by: (a) confidentiality
obligations at least as strict as those set forth herein; and (b) an obligation
to assign all Inventions (as defined in Section 5 herein) to SIGA and to
cooperate with SIGA in connection with patenting such Inventions. SIGA agrees
that it will not permit persons not bound by such obligations to work on the
Evaluation.

            2.2 SIGA Materials: SIGA owns and/or has licensed certain
gram-positive commensal bacteria and related technology, including without
limitation the gram-positive commensal bacteria and related technology licensed
from Rockefeller University, Oregon State University and/or Emory University and
will make certain of those materials (the "SIGA Materials") available for use in
the Evaluation. All right, title and interest to the SIGA Materials shall at all
times remain with and be vested in SIGA.

            2.3 Joint Materials: Using the SIGA Materials, SIGA shall make
materials as set forth in the Evaluation, including without limitation
recombinant constructs expressing heterologous genes contained within the
Maxygen Materials (the "Joint Materials"). SIGA shall provide, and shall ensure
that Oregon State University provides, reasonable quantities of the Joint
Materials to Maxygen on an ongoing basis during the term of this Agreement.
Subject to Section 7, Maxygen shall use such Joint Materials solely for the
purpose of performing the Evaluation at its facility at 515 Galveston Dr.,
Redwood City, CA 94063 under the direction of one or more Maxygen employees.
Subject to the terms of this Agreement, Maxygen and SIGA shall jointly own the
Joint Materials. Subject to Section 7, neither Maxygen nor SIGA may take, send
or otherwise provide the Joint Materials to any third party without the prior
written approval of both Maxygen and SIGA.

      3. Reports and Records.

            3.1 Reports. Each party shall keep the other party informed of the
progress of the research under the Evaluation and shall provide reasonable
access to all source data and information relating to the Joint Materials and
shall provide the other party with summary written reports of any research under
the Evaluation upon reasonable request. The parties will consult with each other
as needed regarding the proposed course

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of the Evaluation. Within twenty (20) days after completion of the Evaluation,
or termination of the Evaluation in accordance with Article 15, SIGA and Maxygen
will prepare and submit to the other a report that sets forth the results of the
Evaluation and a summary of all data and information related to the Joint
Materials. Such information shall be considered Confidential Information of the
disclosing party as defined in Section 4.

            3.2 Records. SIGA and Maxygen agree to maintain, and SIGA shall
ensure that Oregon State University maintains, records of the activities
conducted in performing the Evaluation (or cause such records to be maintained)
in sufficient detail and in accordance with good scientific practices as will
properly reflect all work done and results achieved in the performance of the
Evaluation (including all data in the form required under any applicable
governmental regulations).

      4. Confidentiality and Non-Use Obligations. During the course of the
Evaluation, Maxygen and SIGA may each provide confidential information,
including but not limited to each party's proprietary materials, research and
development data and plans, proprietary technologies, business or research
strategies, trade secrets and material embodiments thereof (each party's
"Confidential Information"), to the other solely for the recipient's conduct of
the Evaluation. Each party may disclose Confidential Information of the other
party to its employees, agents and consultants, but only to the extent
reasonably required to accomplish the purposes of this Agreement. Each party
will use at least the same standard of care as it uses to protect proprietary or
confidential information of its own to ensure that such employees, agents,
consultants and licensees do not disclose or make any unauthorized use of the
Confidential Information.

            4.1 Confidential Information shall be provided in writing, marked
"confidential", or if disclosed orally, reduced to writing, marked
"confidential", and provided to the recipient within thirty (30) days of such
oral disclosure.

            4.2 The recipient shall maintain the disclosing party's Confidential
Information in confidence during the term of this Agreement and for a period of
five (5) years following the expiration or earlier termination hereof. The
recipient shall use the disclosing party's Confidential Information solely for
its conduct of the Evaluation, unless the recipient has received the prior
written approval of the disclosing party.

            4.3 The recipient's obligations hereunder shall not apply to any
information which: (i) can be shown by contemporaneous documentation of the
recipient to have been in its possession prior to receipt from the disclosing
party; (ii) is or becomes, through no fault of the recipient, publicly known;
(iii) is furnished to the recipient by a third party which is lawfully in
possession of such information and without breach of a duty to the disclosing
party; or (iv) is independently developed by the recipient without access to the
disclosing party's Confidential Information. Notwithstanding the foregoing,
either party may disclose the Confidential Information of the other to the
extent required by an applicable court order or by law; provided, however, that
either party that is so required to disclose the Confidential Information of

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the other party shall give the other party reasonable advance notice of such
disclosure and use reasonable efforts to secure confidential treatment of such
Confidential Information (whether through protective order or otherwise).

      5. Intellectual Property Rights. Maxygen and SIGA acknowledge that the
conduct of the Evaluation may result in Inventions of commercial value, and they
agree to collaborate so as to protect the proprietary nature of such Inventions.
For purposes of this Agreement, "Inventions" shall mean any and all technology,
now existing or hereafter arising, conceived or reduced to practice by Maxygen
and/or SIGA in the performance of the Evaluation, including without limitation,
any idea, discovery, data, compound, molecule, cell line, biological or other
material, know-how, technique, method, process, use, composition, skill,
Confidential Information, trade secret or configuration of any kind, whether or
not any such information or materials would be (i) enforceable as a trade
secret, (ii) protected from copying on the basis of copyright infringement or
unfair competition, or (iii) eligible for protection under the patent laws of
the United States or elsewhere. Inventorship of any Inventions arising from the
conduct of the Evaluation shall be determined by the patent laws of the United
States and, subject to the terms of this Agreement, rights of ownership shall
follow therefrom. SIGA represents and warrants that its conduct of the
Evaluation will not result in the creation of any rights to any third parties.

            5.1 Ownership of Inventions.

                  5.1.1 "Maxygen Inventions" shall mean Inventions invented
solely by Maxygen employees or persons obligated to assign their Inventions to
Maxygen. Maxygen retains all right, title, and interest in and to all Maxygen
Inventions.

                  5.1.2 "SIGA Inventions" shall mean Inventions invented solely
by employees of SIGA or persons obligated to assign their Inventions to SIGA,
including without limitation employees of Oregon State University involved in
the performance of the Evaluation. Subject to the provisions of Section 7
herein, SIGA retains all right, title, and interest in and to all SIGA
Inventions.

                  5.1.3 "Joint Inventions" shall mean Inventions invented
jointly by employees of Maxygen or persons obligated to assign Inventions to
Maxygen, and employees of SIGA or persons obligated to assign Inventions to
SIGA, including without limitation employees of Oregon State University involved
in the performance of he Evaluation. Subject to the provisions of Section 7
herein, Maxygen and SIGA shall jointly own all Joint Inventions.

            5.2 Invention Disclosure; Inventorship. Each party shall promptly
provide a full written disclosure to the other describing any SIGA Inventions
and/or Joint Invention arising out of its conduct of the Evaluation (each an
"Invention Disclosure"). Such disclosure by SIGA shall contain sufficient detail
to enable Maxygen to evaluate the advisability of exercising its option granted
hereunder with respect to each such Invention.

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      6. Right to File Patents: Enforcement of Patents/Patent Applications
         Relating to Joint Inventions:

            6.1 Maxygen and SIGA Sole Inventions. Each party shall have the sole
right, but not the obligation, to file, prosecute and maintain patent
applications and patents with respect to its solely owned materials and
Inventions, at its sole expense, in countries selected by such party, and for
conducting interferences, reexaminations, reissues, oppositions, or request for
patent term extension relating thereto. Notwithstanding the foregoing, in the
event that SIGA does not file a patent application covering one or more SIGA
Inventions disclosed in an Invention Disclosure in one or more countries, SIGA
shall so notify Maxygen, and Maxygen may request that SIGA file, and SIGA agrees
to file, a patent application in countries selected by Maxygen to protect
Maxygen's interest in any such SIGA Invention during the Option Period, and
Maxygen agrees to assume SIGA's reasonable costs associated with the filing and
prosecution of such patent applications during the Option Period set forth in
Section 7.2; provided, if prior to the end of such Option Period, Maxygen
notifies SIGA that Maxygen does not wish to acquire a license to such SIGA
Invention, Maxygen's obligation to reimburse SIGA for such costs, and SIGA's
obligation to seek patent protection with respect to such applications, shall
terminate upon such notification.

            6.2 Joint Inventions. With respect to Joint Inventions, the parties
shall confer in good faith to determine whether to seek patent protection for
each Joint Inventions and which party shall file, prosecute and maintain patent
applications and patents on behalf of the parties jointly, including conducting
interferences, reexaminations, reissues, oppositions, or request for patent term
extension relating thereto. For those inventions for which both parties agree to
seek patent protection, the parties shall share equally all reasonable
out-of-pocket patent costs with respect to such Joint Inventions, unless
otherwise agreed in writing. In the event that either party does not desire to
have any such activities undertaken with respect to a particular Joint
Invention, the other party shall have the right, in its discretion and at its
expense, to file, prosecute and/or maintain patent applications and patents with
respect to such joint invention, including conducting interferences,
reexaminations, reissues, oppositions, or request for patent term extension
relating thereto.

            6.3. Cooperation. Except as otherwise expressly provided herein,
applications filed on Joint Inventions shall be written and filed by outside
counsel acceptable to both parties, but under the control of the responsible
party. Each party shall be kept informed of all substantive matters relating to
the preparation and prosecution of all patent applications claiming or
disclosing Joint Inventions. Each party shall have the right to review and
comment upon such documentation and correspondence, as well as all
specifications, claims and responses to office actions related to Joint
Inventions prior to their submission to the relevant government patent office.
In addition, during the term of this Agreement and for ninety (90) days
thereafter, SIGA shall keep Maxygen informed of all substantive matters relating
to the preparation and prosecution of all patent applications claiming or
disclosing SIGA Inventions. Each party shall promptly provide the other with
copies of all patent prosecution and maintenance documentation and
correspondence so that the other shall be currently and promptly informed of the

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continuing prosecution and maintenance of patent applications and patents
claiming or disclosing Joint Inventions and/or, during the term of this
Agreement and for ninety (90) days thereafter, with respect to SIGA Inventions.

            6.4 Enforcement of Joint Inventions. Subject to Section 7, With
respect to any actual or threatened commercially material infringement or use of
any patent or patent applications claiming a Joint Invention (collectively, an
"Infringement"), the parties shall mutually determine which party will have the
rights and responsibilities of abating such an Infringement, and how the
expenses of abating any such Infringement shall be shared. Each party shall have
the right to be represented by counsel of its own selection and its own expense
in any suit initiated under this Section by the other party for an Infringement.
In the event only one party wishes to pursue in such proceeding, it shall have
the right to proceed alone, at its expense, and the other party agrees, at the
request and expense of the party initiating such action, to cooperate and join
in any proceedings in the event that a third party asserts that the co-owner of
such Joint Invention is necessary or indispensable to such proceedings;
provided, neither party may enter into any settlement with respect to any of the
jointly-owned Patent Rights, and may not make any statement which admits that
any of the jointly-owned Patent Rights are invalid or unenforceable, without the
prior consent of other party, which consent shall not be unreasonably withheld.

      7. License and Option Rights.

            7.1 Research License. Subject to the provisions of this Section 7
and each party's obligations hereunder regarding the Joint Materials and each
party's Confidential Information, Maxygen and SIGA each agree to grant to the
other, and hereby grant to the other, a royalty-free co-exclusive license,
without the right to sublicense, to use internally the results of the Evaluation
solely for research purposes.

            7.2 Maxygen Right of Negotiation. SIGA shall grant, and hereby
grants, to Maxygen the right of first negotiation to acquire, on commercially
reasonable terms, an exclusive or non-exclusive commercial license (at Maxygen's
election), with the right to grant and authorize sublicenses, in any patents or
patent applications or other intellectual property rights in and to any SIGA
Invention and/or SIGA's interest in any Joint Invention, and in any patents or
patent applications or other intellectual property rights owned or licensed by
SIGA necessary or reasonably useful to practice the SIGA Inventions and/or Joint
Inventions. Maxygen must notify SIGA in writing of its intent to negotiate such
license within (i) ninety (90) days after its receipt of SIGA's Invention
Disclosure, or (ii) ninety (90) days after completion of the Evaluation, or
(iii) ninety (90) days after the effective date of termination of this
Agreement, whichever is later (the "Option Period"). If Maxygen exercises its
right to negotiate a license to a particular Invention, SIGA shall use its best
efforts to enter into a license with Maxygen for the rights to such Invention
within six (6) months from the date of election, or such longer period as the
parties may agree. If Maxygen does not so notify SIGA that it wishes to acquire
a license to a particular Invention or if the parties are unable to enter into a
license agreement on mutually satisfactory terms with respect to a particular
Invention, then SIGA shall have the right to license any such patents or patent
applications claiming

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such SIGA Inventions, and/or grant licenses under SIGA's interest in such Joint
Inventions, as the case may be, to any third party; provided that SIGA shall not
enter into an agreement which grants any rights to such Invention to any third
party on terms which, taken as a whole, are more favorable to such third party
than those offered to Maxygen, without first offering such terms to Maxygen. If
SIGA offers such terms to Maxygen, then Maxygen shall have sixty (60) business
days in which to notify SIGA as to whether Maxygen accepts such terms. If
Maxygen accepts such terms, then the parties shall promptly enter into such
agreement, granting such rights to Maxygen.

            7.3 Retained Rights. Except as expressly set forth in this
Agreement, no party shall obtain rights in or a license to any patent,
copyright, trademark or other property right of the other party by implication,
estoppel or otherwise.

      8. Publications. Maxygen and SIGA are free to present or publish the
findings of the Evaluation in a thesis, scientific publication, or public,
noncommercial conference provided that: (a) no Maxygen Confidential Information
is revealed by SIGA, and no SIGA Confidential Information is revealed by Maxygen
thereby; and (b) at least forty-five (45) days prior to submission thereof to a
publisher or any third party, the publishing party shall have delivered copies
of the proposed presentation or publication to the other party for review. Said
other party may, within forty five (45) days of such delivery, object to the
publication or presentation because there would be a disclosure of its
Confidential Information, or because there is patentable subject matter in which
said other party has an interest which needs protection. Upon written objection
regarding disclosure of Confidential Information or patentable subject matter,
the publishing party shall: (i) remove any information disclosing patentable
subject matter or, for up to ninety (90) days from initial delivery, delay
disclosing such patentable subject matter in order to permit the filing of
patent applications thereon and (ii) delete the Confidential Information of the
other party contained in the disclosure. The publishing party shall thereafter
be free to publish or disclose the information. The determination of authorship
for any paper shall be in accordance with accepted scientific practice, and the
parties shall, in any publication, acknowledge the contributions and
publications of the other as scientifically appropriate.

      9. Compliance with Law. Each party shall conduct the Evaluation in
compliance with all applicable laws and regulations including, where applicable,
those relating to the treatment of laboratory animals and current NIH
guidelines. Each party shall use any materials received from the other only in
laboratory animals or in in vitro experiments, and not in human beings.

      10. Warranties.

            10.1 Representation and Warranties. Each party hereby warrants and
represents that it has full right and power to enter into this Agreement. SIGA
represents and warrants that (i) the Maxygen Materials and the Joint Materials
will not be used in or for any research that is subject to consulting, licensing
or similar obligations to any third party, including any sponsor, unless written
permission is first obtained from Maxygen (ii) it has the right to grant the
rights, options and licenses herein, and that it has obtained

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any and all necessary written permissions, clearances and/or waivers from all
third parties required in order to grant such rights, options and licenses
herein. Each of Maxygen and SIGA hereby warrants that the rights and obligations
set forth herein do not, and during the term of the Agreement will not, conflict
with any other right or obligation provided under any other agreement that
Maxygen or SIGA, as applicable, has with any third party, including any sponsor
or government entity.

            10.2 Disclaimer of Warranties. Maxygen and SIGA each specifically
disclaim that the Evaluation will be successful, in whole or part. MAXYGEN AND
SIGA EXPRESSLY DISCLAIM ANY WARRANTIES OR CONDITIONS, EXPRESS, IMPLIED,
STATUTORY OR OTHERWISE, WITH RESPECT TO THE CONFIDENTIAL INFORMATION,
INVENTIONS, PATENTS OR KNOW-HOW, MAXYGEN MATERIALS, SIGA MATERIALS, OR JOINT
MATERIALS, INCLUDING, WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY, OR
FITNESS FOR A PARTICULAR PURPOSE, VALIDITY OF ANY MAXYGEN TECHNOLOGY OR SIGA
TEHCNOLOGY, PATENTED OR UNPATENTED, OR NON-INFRINGEMENT OF THE INTELLECTUAL
PROPERTY RIGHTS OF THIRD PARTIES.

      11. Indemnification.

            11.1 Each party (the "Indemnitor") shall indemnify and hold harmless
the other party and their respective employees, agents, officers, directors and
permitted assigns (each an "Indemnitee") from and against any claims by a third
party resulting in any liabilities, damages, settlements, claims, actions,
suits, penalties, fines, costs or expenses incurred (including without
limitation, reasonable attorneys' fees and other expenses of litigation) (any of
the foregoing, a "Claim") arising out of or resulting from (i) the Indemnitor's
conduct of the Evaluation; (ii) a breach of any representations or warranties of
the Indemnitor hereunder, or (iii) the negligence or willful misconduct by the
Indemnitor, except, in each case, to the extent such Claim arises out of the
negligence or willful misconduct of the Indemnitee.

            11.2 An Indemnitee under this Article 11 shall promptly notify the
Indemnitor in writing of any loss, claim, damage, liability or action in respect
of which the Indemnitee intends to claim such indemnification, and the
Indemnitor shall have the right to participate in, and, to the extent the
Indemnitor so desires, to assume the defense thereof with counsel chosen by
Indemnitor, with consent of Indemnitee, which consent shall not be unreasonably
withheld. The Indemnitee shall not enter into negotiations or enter into any
agreement with respect to the settlement of any Claim without the prior written
approval of the Indemnitor, and the indemnity agreement in this Article 11 shall
not apply to amounts paid in settlement of any loss, claim, damage, liability or
action if such settlement is made without the consent of the Indemnitor, which
consent shall not be withheld unreasonably. The failure to deliver written
notice to the Indemnitor within a reasonable time after the commencement of any
such action, if prejudicial to its ability to defend such action, shall relieve
such Indemnitor of any liability to the Indemnitee under this Article 11. At the
Indemnitor's request, the Indemnitee under this Article 11, and its employees
and agents, shall cooperate fully with the Indemnitor and its legal

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representatives in the investigation and defense of any action, claim or
liability covered by this indemnification and provide full information with
respect thereto.

      12. Press Release. All publicity, press releases and other announcements
relating to this Agreement or the transaction contemplated hereby shall be
reviewed in advance by, and shall be subject to the approval of, both parties;
provided, however, that either party may disclose the terms of this Agreement to
the extent required to comply with applicable regulations and laws, without the
prior consent of the other party. Once a particular disclosure has been approved
for disclosure, either party may make disclosures which do not differ materially
therefrom without any need for further consents.

      13. Notices. Routine notices of conditions or situations affecting the
Evaluation shall be given in writing between Drs. Hruby, Fischetti, and/or Jones
of SIGA and Stanley Goldman of Maxygen. All other notices, requests and other
communications hereunder shall be in writing and shall be personally delivered
or sent by nationally recognized overnight express delivery service, registered
or certified mail, return receipt requested, postage prepaid, in each case to
the respective address specified below, or such other address as may be
specified in writing to the other parties hereto as follows:

      In the case of SIGA:

                  SIGA Technologies, Inc.
                  420 Lexington Avenue, Suite 620
                  New York, NY 10170
                  Attn: Joshua D. Schein, Chief Executive Officer

      In the case of Maxygen:

                  Maxygen, Inc.
                  515 Galveston Drive
                  Redwood City, CA 94063
                  Attn: President

      14. Independent Contractor. Neither party, nor their respective employees,
consultants or representatives, shall be considered employees, partners, or
agents of the other party. Neither party may make any representations or
commitments on the other party's behalf nor may one party use the other party's
name or trademarks in any public disclosure, without the named party's prior
written consent.

      15. Term, Termination. Amendment and Survival.

            15.1 Term. This Agreement shall commence on the Effective Date and,
unless terminated earlier pursuant to the other provisions of this Article 15,
shall continue in full force and effect until the first anniversary of the
Effective Date, or such later date as the parties may mutually agree in writing.
This Agreement may be modified, amended or renewed only with the written
agreement of both parties.

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            15.2 Permissive Termination. This Agreement may be terminated by
either party upon thirty (30) days prior written notice to the other party.

            15.3 Effect of Termination.

                  15.3.1 Accrued Rights and Obligations. Termination of this
Agreement for any reason shall not release any party hereto from any liability
which, at the time of such termination, has already accrued to the other party
or which is attributable to a period prior to such termination, nor preclude
either party from pursuing any rights and remedies it may have hereunder or at
law or in equity which accrued or are based upon any event occurring prior to
such termination.

                  15.3.2 Materials. Upon expiration or any termination of the
Agreement, (i) SIGA and Maxygen will cease conducting work on the Evaluation,
(ii) SIGA shall promptly destroy or, at Maxygen's option, return to Maxygen all
Maxygen Materials (except to the extent incorporated into Joint Materials),
(iii) Maxygen shall promptly destroy or, at Maxygen's option, return to SIGA all
SIGA Materials (except to the extent incorporated into Joint Materials), and
(iv) subject to Section 7, each party may retain the Joint Materials generated
in the performance of the Evaluation for internal research and evaluation;
provided, however, that in the event that Maxygen Materials provided to SIGA
hereunder contain genetic material or proteins claimed by Maxygen to be
proprietary and covered by the claims of one or more patent applications or
patents owned or controlled by Maxygen (such materials referred to as
"Proprietary Maxygen Materials"), Maxygen may elect by written notice to have
all Joint Materials incorporating or made from such Proprietary Maxygen
Materials destroyed by both parties, and the parties shall promptly destroy such
Joint Materials upon SIGA's receipt of such notice.

                  15.3.3 Return of Confidential Information. Upon the expiration
or earlier termination of this Agreement, or upon request by the disclosing
party, the recipient shall return to the disclosing party, or provide
satisfactory evidence of the destruction of, all Confidential Information
furnished hereunder and any notes, copies, summaries or extracts thereof,
provided that the recipient may retain one (1) copy of the disclosing party's
Confidential Information in its legal archives in order solely for purposes of
monitoring its obligations hereunder.

                  15.3.4 Survival. Upon the expiration or termination of this
Agreement for any reason, Sections 2, 3, 4, 5, 6, and 7 shall survive; provided,
Section 7.2 shall survive for only ninety (90) days following such expiration or
termination; provided further, Section 11(i) and (ii) shall survive only to the
extent such claims arise from acts or omissions that occurred prior to the
effective date of termination of this Agreement.

      16. Assignment. Neither party may assign or transfer this Agreement
without the written consent of the other party, which consent shall be not be
unreasonably withheld; provided, either party may assign this Agreement, without
such consent, to an entity that acquires all or substantially all of the
business or assets of such party to which

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this Agreement pertains, whether by merger, reorganization, acquisition, sale,
or otherwise. The terms and conditions of this Agreement shall be binding on and
inure to the benefit of the permitted successors and assigns of the parties.

      17. Entire Agreement. This Agreement is the entire agreement of the
parties relating to the Evaluation and supersedes any previous understandings,
representations, acknowledgements, commitments or agreements, oral or written,
regarding such subject matter. This Agreement shall be governed by and construed
under laws of the State of California, without regard to its conflicts of laws
principles. If any provision of this Agreement is held to be unenforceable, the
remaining provisions shall continue unaffected.

      18. Severability. In the event that any provisions of this Agreement are
determined to be invalid or unenforceable by a court of competent jurisdiction,
the remainder of the Agreement shall remain in full force and effect without
said provision. The parties shall in good faith negotiate a substitute clause
for any provision declared invalid or unenforceable, which shall most nearly
approximate the intent of the parties in entering this Agreement; provided, if
the parties are unable to agree on such a substitute clause and the deletion of
the provision held invalid or unenforceable would produce material adverse
financial consequences for one party, such party shall have the right to
terminate the Agreement with thirty (30) days notice.

      19. Compliance with Laws. Each party shall use reasonable efforts to
furnish the other party any information requested or required by that party
during the term of this Agreement or any extensions hereof to enable that party
to comply with the requirements of any U.S. or foreign federal, state and/or
government agency. Each party shall comply with all applicable U.S., foreign,
state, regional and local laws, rules and regulations relating to its activities
to be performed pursuant to this Agreement, including without limitation, the
United States Foreign Corrupt Practices Act, United States export regulations
and such other United States and foreign laws and regulations as may be
applicable, and to obtaining all necessary approvals, consents and permits
required by the applicable agencies of the government of the United States and
foreign jurisdictions.

      20. Headings. The captions to the several Sections and Articles hereof are
not a part of this Agreement, but are included merely for convenience of
reference only and shall not affect its meaning or interpretation.

      21. Binding Effect. This Agreement shall be binding upon and inure to the
benefit of the parties and their respective legal representatives, successors
and permitted assigns.

      22. Counterparts. This Agreement may be executed in two counterparts, each
of which shall be deemed an original and which together shall constitute one
instrument.

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

MAXYGEN, INC.                             SIGA TECHNOLOGIES, INC.

By: /s/ Michael Rabson                    By: /s/ Joshua D. Schein
    ----------------------------------        ----------------------------------
    Michael Rabson                            Joshua D. Schein

Title: Sr. Vice President and             Title: Chief Executive Officer
       General Counsel

MAXY BD Review _____

MAXY Legal Review /s/ DWS
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                                   EXHIBIT A

                                PROJECT PROPOSAL

Objective: Express the Yersinia V antigen on the surface of Streptococcus
gordonii and testing of the derived recombinant as a candidate vaccine.

Procedure:

      1)    Discussions will be held between Maxygen and SIGA research groups to
            determine the exact structure and boundaries of the Yersinia V
            antigen to be expressed.

      2)    Maxygen will provide to SIGA the plasmid containing the gene for the
            Yersinia V antigen along with the necessary sequence information
            pertaining to the gene. Maxygen will also provide purified V antigen
            and antisera to the protein, if available.

      3)    SIGA will construct a recombination plasmid containing the gene for
            the V antigen fused in an appropriate configuration to achieve
            genomic integration and surface expression in Streptococcus
            gordonii. Structure and authenticity of the plasmid will be verified
            by restriction endonuclease digestion and nucleotide sequencing.

      4)    SIGA will transform the recombination plasmid containing the V
            antigen into a recipient Streptococcus gordonii strain. A
            recombinant strain will be selected by acquisition of appropriate
            antibiotic resistance (erythromycin) and surface expression of
            desired protein as measured by streak blot, western blot and ELISA
            if applicable.

      5)    SIGA will provide to Maxygen the verified Streptococcus gordonii V
            antigen recombinant strain in the form of a glycerol stock.

      6)    Maxygen to perform animal studies in mice using the Streptococcus
            gordonii V antigen recombinant strain and perform the necessary
            immunological assays and challenge studies.

      7)    Following the animal trials, Maxygen and SIGA representatives will
            review data and discuss the advisability of continued development of
            this and/or related products.
<PAGE>

                                   EXHIBIT B

                               MAXYGEN MATERIALS

Wild-type V antigen gene from Yersinia pestisExhibit 11

                           EXCLUSIVE LICENSE AGREEMENT

                                     between

                   THE REGENTS OF THE UNIVERSITY OF CALIFORNIA

                                       and

                             SIGA TECHNOLOGIES, INC.

                                       for

                         IDENTIFICATION OF SORTASE GENE

                             UC Case No. 1999-262-1

                                                                  --------------
                                                                  U.C. AGREEMENT
                                                                  CONTROL NUMBER
                                                                   2001-04-0279
                                                                  --------------
<PAGE>

                                TABLE OF CONTENTS

Article No. Title                                                          Page

1.   BACKGROUND ...........................................................  1
1.   DEFINITIONS ..........................................................  2
2.   LIFE OF PATENT EXCLUSIVE GRANT .......................................  5
3.   SUBLICENSES ..........................................................  5
4.   PAYMENT TERMS ........................................................  7
5.   LICENSE-ISSUE FEE ....................................................  8
6.   LICENSE-MAINTENANCE FEE ..............................................  8
7.   EARNED ROYALTIES .....................................................  8
8.   MILESTONE PAYMENTS ...................................................  9
9.   DUE DILIGENCE ........................................................  9
10.  PROGRESS AND ROYALTY REPORTS ......................................... 10
11.  BOOKS AND RECORDS .................................................... 11
12.  LIFE OF THE AGREEMENT ................................................ 12
13.  TERMINATION BY THE REGENTS ........................................... 13
14.  TERMINATION BY LICENSEE .............................................. 13
15.  DISPOSITION OF LICENSED PRODUCT ON HAND UPON TERMINATION ............. 14
16.  USE OF NAMES AND TRADEMARKS .......................................... 14
17.  LIMITED WARRANTY ..................................................... 14
18.  PATENT PROSECUTION AND MAINTENANCE ................................... 16
19.  PATENT MARKING ....................................................... 18
20.  PATENT INFRINGEMENT .................................................. 18
21.  INDEMNIFICATION ...................................................... 19
22.  NOTICES .............................................................. 20
23.  ASSIGNABILITY ........................................................ 21
24.  NO WAIVER ............................................................ 22
25.  FAILURE TO PERFORM ................................................... 22
26.  GOVERNING LAWS ....................................................... 22
27.  ARBITRATION .......................................................... 22
28.  PREFERENCE FOR U.S. INDUSTRY ......................................... 23
29.  GOVERNMENT APPROVAL OR REGISTRATION .................................. 23
30.  EXPORT CONTROL LAWS .................................................. 23
31.  SECRECY .............................................................. 24
32.  MISCELLANEOUS ........................................................ 25
<PAGE>

UC Case No. 1999-262-1

                           EXCLUSIVE LICENSE AGREEMENT

                                       for

                         IDENTIFICATION OF SORTASE GENE

      This license agreement ("Agreement") is made effective this 6 day of
December, 2000 ("Effective Date"), between The Regents of the University of
California, a California corporation, having its statewide administrative
offices at 1111 Franklin Street, 12th Floor, Oakland, California 94607-5200
("The Regents"), and SIGA Technologies, Inc., a Delaware corporation, having a
principal place of business at 420 Lexington Avenue, Suite 620, New York, New
York 10170 ("Licensee").

                                   BACKGROUND

      A. Certain inventions, generally characterized as "Identification of
Sortase Gene" (collectively "Invention"), were made in the course of research at
the University of California, Los Angeles ("UCLA"), by Dr. Olaf Schneewind, Mr.
Sarkis Mazmanian, Mrs. Gwen Liu and Mr. Hung Ton-That and are covered by
Regents' Patent Rights as defined below.

      B. The development of the Invention was sponsored in part by the National
Institutes of Health, and, as a consequence, this Agreement is subject to
overriding obligations to the United States ("U.S.") Federal Government under 35
U.S.C. ss.ss. 200-212 and applicable regulations including a non-exclusive,
non-transferable, irrevocable, paid-up license to practice or have practiced the
Invention for or on behalf of the U.S. Government throughout the world (the
"License to the Government").

      C. The Regents has elected to retain title to the Invention under 35
U.S.C.ss.202.

      D. Licensee intends to fund further development of the Invention in the
UCLA laboratory of Dr. Olaf Schneewind under a Sponsored Research Agreement
defined below.

                                                                  --------------
                                                                  U.C. AGREEMENT
                                                                  CONTROL NUMBER
                                                                   2001-04-0279
                                                                  --------------

                                       1
<PAGE>

      E. Licensee has evaluated the Invention under a Secrecy Agreement for Data
with The Regents (UC Control No. 99-20-0510) effective May 5, 1999, and a
Secrecy Agreement for Biological Material with The Regents and American Home
Products Corporation ("AHPC"), Wyeth-Ayerst Research Division (UC Control No.
99-21-0632) effective June 23, 1999.

      F. Licensee wishes to obtain rights from The Regents for the exclusive
commercial development, use and sale of products from the Invention, and The
Regents is willing to grant those rights so that the Invention may be developed
to its fullest and the benefits enjoyed by the general public.

      G. On July 1, 1997, Licensee entered into a Collaborative Research and
License Agreement with AHPC acting through its Wyeth-Ayerst Laboratories
Division, and Licensee desires to utilize and to sublicense AHPC the right to
utilize the Invention and the rights and licenses granted to Licensee hereunder
in connection with such collaboration.

      H. Licensee is a "small business firm" as defined in 15 U.S.C.ss.632.

      I. Both parties recognize and agree that royalties due under this
Agreement on products and methods will be paid by Licensee on both pending
patent applications and issued patents.

                                 - - oo 0 oo - -

      In view of the foregoing, the parties agree:

1. DEFINITIONS

      1.1 "Affiliate" means any corporation, company, partnership, joint venture
and/or firm which controls, is controlled by or is under common control with a
party. For purposes of this Paragraph 1.1, "control" shall mean:

            1.1.1 in the case of corporate entities, direct or indirect
ownership of at least fifty percent (50%) of the stock or shares having the
right to vote for the election of directors, and

            1.1.2 in the case of non-corporate entities, direct or indirect
ownership of at least fifty percent (50%) of the equity interest with the power
to direct the management and policies of such non-corporate entities, provided,
however, that, for purposes of this Agreement, the term "Affiliate" shall not
include any entity with respect to which there is a contractual restriction on
the right to

                                       2
<PAGE>

elect a majority of the directors or to otherwise direct the management and
policies of such entity, until such time as such restrictions are no longer in
effect.

      1.2 "AHPC Agreement" means the Collaborative Research and License
Agreement between Licensee and AHPC that is referenced in Paragraph G of the
Background and is entitled "Collaborative Research and License Agreement,"
effective July 1, 1997 and amended on April 15, 1999, and all past and future
amendments thereto, incorporated herein by reference.

      1.3 "Combination Product" means a product that consists of the Licensed
Product combined with other active components not subject to this Agreement.

      1.4 "Commercially Reasonable Efforts" shall mean those efforts and
resources normally used by a party for development, manufacture, and sale of a
product owned by it or to which it has rights, which is of similar market
potential at a similar stage in its development or product life as is Licensed
Product, taking into account issues of safety and efficacy, product profile, the
competitiveness of the market place, the proprietary position of the compound,
the regulatory structure involved, the profitability of the applicable products
and other relevant factors.

      1.5 "Field of Use" means the use of bacterial sortase genes and proteins
in the development of assays to identify antimicrobial compounds.

      1.6 "Licensed Method" means any method that is covered by a Valid Claim
included within the Regents' Patent Rights, or the use of which would
constitute, but for the license granted to Licensee under this Agreement, an
infringement of any Valid Claim included within Regents' Patent Rights.

      1.7 "Licensed Product" means any material that is either identified or
produced by the use of the bacterial sortase genes and proteins, which are
covered by a Valid Claim included within the Regents' Patent Rights, or any
material that is either identified or produced by or from the use of the
Licensed Method.

      1.8 "Net Sales" means the total of the gross invoice prices from the Final
Sale of Licensed Product to an independent, unaffiliated third party or Licensed
Method performed by Licensee, an Affiliate or a sublicensee, less the sum of the
following actual and customary deductions where applicable: cash, trade or
quantity discounts; sales, use, tariff, import/export duties or other excise
taxes imposed on particular sales (excepting value added taxes or income taxes);
transportation charges, including insurance; and allowances or credits to
customers because of rejections or

                                       3
<PAGE>

returns. Final Sale means the sale or use which is the last act of infringement
of Regents' Patent Rights within the control of Licensee, an Affiliate or
sublicensee, regardless of whether Licensee, an Affiliate or sublicensee had
control over prior infringing acts. For purposes of calculating Net Sales, any
distribution or transfer among the Licensee, an Affiliate or sublicensee for end
use by the Licensee, an Affiliate or sublicensee (which event is the last act of
infringement of Regents' Patent Rights) will be considered a Final Sale at the
price normally charged to independent, unaffiliated third parties.
Notwithstanding the above, any consideration paid Licensee for Licensed Product
or Licensed Method in conjunction with clinical trials before FDA approval shall
not be considered a Net Sale.

      1.9 "Regents' Patent Rights" means The Regents' interest in the following
subject matter:

--------------------------------------------------------------------------------
UC Case Number               U.S. Application Number            Filing Date
--------------------------------------------------------------------------------
1999-262                     09/292,437                         04/15/99
--------------------------------------------------------------------------------

and continuing applications thereof including divisions and substitutions and
including continuation-in-part applications, but only to the extent that the
claims are supported in the parent application; any patents on said applications
including reissues, reexaminations and extensions; and any corresponding foreign
applications or patents.

      1.10 "Sponsored Research Agreement" means the sponsored research agreement
between The Regents and Licensee, entered into on even date herewith, wherein
Licensee will sponsor research related to the Invention in the UCLA laboratory
of Dr. Olaf Schneewind for two (2) years in the total amount of three hundred
thousand and seven dollars ($300,007), which amount is inclusive of all direct
and indirect costs.

      1.11 "Valid Claim" means a claim that (i) in the case of any unexpired
United States or foreign patent, shall not have been donated to the public,
disclaimed, nor held invalid or enforceable by a court or government agency of
competent jurisdiction in an unappealed or unappealable decision, or (ii) in the
case of any United States or foreign patent application, shall not have been
canceled, withdrawn, or abandoned without being refiled in another application
or finally rejected by an administrative agency action from which no appeal can
be taken or shall not have been pending for more than eight (8) years. For
purposes of this definition, this eight-year time period shall be measured
cumulatively for a pending claim in a parent and all subsequent continuing
applications in a given country. If a claim of a patent application that ceased
to be a Valid Claim under (ii) due to

                                       4
<PAGE>

the passage of time later issues as part of a patent described within (i), then
it shall again be considered to be a Valid Claim effective as of the date of the
issuance of such patent.

2. LIFE OF PATENT EXCLUSIVE GRANT

      2.1 Subject to the limitations set forth in this Agreement, The Regents
grants to Licensee a worldwide license under Regents' Patent Rights to make,
have made, use, sell, offer to sell and import Licensed Product and to practice
Licensed Method within the Field of Use to the extent permitted by law.

      2.2 Except as otherwise provided in this Agreement, the license granted in
Paragraph 2.1 is exclusive for the life of the Agreement.

      2.3 The license granted in Paragraphs 2.1 and 2.2 is subject to all the
applicable provisions of any license to the U.S. Government executed by The
Regents and is subject to the overriding obligations to the U.S. Government
under 35 U.S.C.ss.ss.200-2l2 and applicable U.S. governmental implementing
regulations.

      2.4 The license granted in Paragraphs 2.1 and 2.2 is limited to methods
and products that are within the Field of Use. For other methods and products,
Licensee has no license under this Agreement.

      2.5 The Regents reserves the right to use the Invention and associated
technology for clinical, educational and research purposes including publication
of research results and sharing such research results with other non-profit
institutions for their use of similar scope.

3. SUBLICENSES

      3.1 The Regents grants to Licensee the right to issue sublicenses to third
parties to make, have made, use, sell, offer to sell and import Licensed Product
and to practice Licensed Method within the Field of Use, as long as Licensee has
current exclusive rights thereto under this Agreement. To the extent applicable,
such sublicenses must include all of the rights of and obligations due to The
Regents and the U.S. Government contained in this Agreement. For the first three
(3) sublicenses granted by Licensee under this Agreement other than any
sublicense granted to AHPC, Licensee shall be obligated to pay The Regents the
license-issue fee of fifteen thousand dollars ($15,000) provided for in Article
5 (License-Issue Fee) and the license-maintenance fee of ten thousand

                                       5
<PAGE>

dollars ($10,000) provided for in Article 6 (License-Maintenance Fee). For any
and all sublicenses granted by Licensee under this Agreement, Licensee shall be
obligated to pay the amounts set forth in Article 7 (Earned Royalties) and
Article 8 (Milestone Payments). For the sake of clarity, for any sublicense
granted to AHPC under this Agreement, Licensee shall not be obligated to pay The
Regents the amounts set forth in Article 5 (License-Issue Fee) and Article 6
(License-Maintenance Fee) but shall be obligated to pay The Regents the amounts
set forth in Article 7 (Earned Royalties) and Article 8 (Milestone Payments).

      3.2 Licensee shall promptly provide The Regents with a copy of each
sublicense issued; collect and guarantee payment of all payments due The Regents
from sublicensees; and summarize and deliver all reports due The Regents from
sublicensees.

      3.3 Upon termination of this Agreement for any reason, The Regents, at its
sole discretion, shall determine whether Licensee shall cancel or assign to The
Regents any and all sublicenses, provided; however, the parties agree that, upon
termination of Licensee's rights and obligations under this Agreement, for any
reason, if a sublicense to AHPC is in effect, AHPC is the sole sublicensee, and
AHPC is not in breach of its sublicense at the time of such termination, AHPC
may elect, at its option, to be substituted as licensee under this Agreement in
place of current Licensee. Notwithstanding the foregoing, if AHPC is not the
sole sublicensee, The Regents shall have no right to cancel AHPC's sublicense
upon termination of Licensee's rights and obligations under this Agreement
unless AHPC is in breach of its sublicense at the time of such termination. Upon
any such termination, The Regents shall provide AHPC with written notice
thereof, offering AHPC the opportunity to convert its sublicense rights to a
license under this Agreement. Within sixty (60) days of receiving such notice,
AHPC shall notify The Regents, in writing, as to whether it wishes to become the
licensee under this Agreement. If AHPC so elects, then AHPC shall, from the time
of such election and thereafter, assume all of Licensee's rights and obligations
under this Agreement as if it were the original party named as Licensee as of
the Effective Date of this Agreement. In no case is The Regents obligated to
assume duties in an assigned sublicense beyond the duties of The Regents under
this license.

                                       6
<PAGE>

4. PAYMENT TERMS

      4.1 Paragraphs 1.6, 1.7 and 1.9 define Licensed Method, Licensed Product
and Regents' Patent Rights, so that royalties are payable on products and
methods covered by Valid Claims included within the Regent's Patent Rights.
Royalties will accrue in each country for the duration of Regents' Patent Rights
in that country and are payable to The Regents when Licensed Product is invoiced
or if not invoiced, when delivered to a third party.

      4.2 Licensee shall pay to The Regents earned royalties quarterly pursuant
to Article 7 (Earned Royalties) of this Agreement on or before February 28, May
31, August 31 and November 30 of each calendar year. Each payment will be for
earned royalties accrued within Licensee's most recently completed calendar
quarter. Licensee shall pay to The Regents milestone payments pursuant to
Article 8 (Milestone Payments) of this Agreement within thirty (30) days of the
due date of such amounts pursuant to the AHPC Agreement.

      4.3 All monies due The Regents are payable in U.S. dollars. Licensee is
responsible for all bank transfer charges. When Licensed Product is sold for
monies other than U.S. dollars, Licensee shall first determine the earned
royalty in the currency of the country in which Licensed Product was sold and
then convert the amount into equivalent U.S. funds, using the exchange rate
quoted in The Wall Street Journal on the last business day of the reporting
period.

      4.4 All taxes, assessments, and fees of any nature levied or incurred on
account of any payments from Licensee to The Regents accruing under this
Agreement by national, state, or local governments, will be assumed and paid by
Licensee, except taxes levied thereon as income to The Regents and if such taxes
are required to be withheld by Licensee, they will be deducted from payments due
to The Regents and will be timely paid by Licensee to the proper taxing
authority for the account of The Regents, a receipt or other proof of payment
therefor secured and sent to The Regents as soon as practicable.

      4.5 If, due to restrictions or prohibitions imposed by national or
international authority, payments cannot be made as provided in this Article 4
(Payment Terms), the parties shall consult with a view to finding a prompt and
acceptable solution, and Licensee will deal with such monies as The Regents may
lawfully direct at no additional out-of-pocket expense to Licensee.
Notwithstanding the foregoing, if payments arising in connection with the sale
of Licensed Products and Licensed Methods in any country cannot be remitted to
The Regents due to restrictions or

                                       7
<PAGE>

prohibitions imposed by national or international authority within six (6)
months after the calendar quarter during which they are earned, then Licensee
shall be obligated to deposit the royalties in a bank account in such country in
the name of The Regents.

      4.6 No royalties may be collected or paid on Licensed Product sold to the
account of the U.S. Government, or any agency thereof, as provided for in the
License to the Government.

      4.7 In the event payments, rebillings or fees are not received by The
Regents when due, Licensee shall pay to The Regents interest charges at a rate
of ten percent (10%) per annum. Interest is calculated from the date payment was
due until actually received by The Regents.

5. LICENSE-ISSUE FEE

      Licensee shall pay to The Regents a license-issue fee of fifteen thousand
dollars ($15,000) within seven (7) days after the Effective Date. This fee is
non-refundable, non-cancelable and is not an advance against royalties.

6. LICENSE-MAINTENANCE FEE

      Licensee shall also pay to The Regents a royalty in the form of a
license-maintenance fee of ten thousand dollars ($10,000) beginning on the
one-year anniversary of the Effective Date and continuing annually on each
anniversary of the Effective Date. The license-maintenance fee is not due on any
anniversary of the Effective Date if on that date, Licensee is paying an earned
royalty to The Regents under this Agreement in an amount of at least ten
thousand dollars ($10,000). License-maintenance fees are non-refundable and are
not an advance against earned royalties.

7. EARNED ROYALTIES

      Licensee shall pay to The Regents an earned royalty equal to fifteen
percent (15%) of all royalty payments made to Licensee by AHPC, its Wyeth-Ayerst
Laboratories Division or their successors or assignees under Article 7 of the
AHPC Agreement as defined and incorporated herein in Article 1 (Definitions). In
the event the AHPC Agreement is terminated or not renewed or AHPC becomes
Licensee under Article 3 (Sublicenses) or assignee under Article 23
(Assignability), Licensee shall be obligated to pay to The Regents an earned
royalty, based on Net Sales, of fifteen percent (15%) of the royalty rates
specified in Article 7 of the AHPC Agreement.

                                       8
<PAGE>

8. MILESTONE PAYMENTS

      Licensee shall also pay to The Regents fifteen percent (15%) of all funds
it receives from AHPC, its Wyeth-Ayerst Laboratories Division or their
successors or assignees under Article 3.2 of the AHPC Agreement as defined and
incorporated herein in Article 1 (Definitions). In the event the AHPC Agreement
is terminated or not renewed or AHPC becomes Licensee under Article 3
(Sublicenses) or assignee under Article 23 (Assignability), Licensee shall be
obligated to pay to The Regents fifteen percent (15%) of the payments specified
in Article 3.2 of the AHPC Agreement. Notwithstanding the foregoing, the parties
hereto acknowledge that, prior to the Effective Date of this Agreement, Licensee
satisfied the first milestone for which it received one hundred fifty thousand
dollars ($150,000) under Article 3 of the AHPC Agreement and that Licensee is
not obligated to pay The Regents fifteen percent (15%) of such funds.

9. DUE DILIGENCE

      9.1 Licensee, upon execution of this Agreement, shall use Commercially
Reasonable Efforts to proceed with the development, manufacture and sale of
Licensed Product and shall use Commercially Reasonable Efforts to market or
otherwise make commercial use of the same within a reasonable time after
execution of this Agreement and in quantities sufficient to meet market demands.

      9.2 Licensee shall endeavor to obtain all necessary governmental approvals
for the manufacture, use and sale of Licensed Product.

      9.3 Licensee shall:

            9.3.1 sponsor research in the UCLA laboratory of Dr. Olaf Schneewind
for two (2) years in the total amount of three hundred thousand and seven
dollars ($300,007), which amount is inclusive of all direct and indirect costs
under the terms and conditions of the Sponsored Research Agreement;

            9.3.2 market Licensed Product in the U.S. within twelve (12) months
of receiving FDA approval of the NDA for the Licensed Product;

            9.3.3 reasonably fill the market demand for Licensed Product
following commencement of marketing at any time during the exclusive period of
this Agreement; and

                                       9
<PAGE>

            9.3.4 meet all of its duties and obligations under the AHPC
Agreement.

      9.4 If Licensee is unable to perform any of the above provisions, then The
Regents has the right and option to either terminate this Agreement or reduce
Licensee's exclusive license to a nonexclusive license. This right, if exercised
by The Regents, supersedes the rights granted in Article 2 (Life of Patent
Exclusive Grant).

      9.5 In addition to the obligations set forth above, Licensee, along with
its sublicensees, shall spend an aggregate of not less than two hundred fifty
thousand dollars ($250,000) for the development of Licensed Product during each
of the first three (3) years of this Agreement

10. PROGRESS AND ROYALTY REPORTS

      10.1 Beginning February 28, 2001, and semi-annually thereafter, Licensee
shall submit to The Regents a written progress report covering Licensee's (and
any Affiliate or sublicensee's) activities related to the development and
testing of all Licensed Product and the obtaining of the governmental approvals
necessary for marketing. Progress reports are required for each Licensed Product
until the first commercial sale of that Licensed Product occurs in the U.S. and
shall be again required if commercial sales of such Licensed Product are
suspended or discontinued.

      10.2 Progress reports submitted under Paragraph 10.1 shall include, but
are not limited to, the following topics:

                  -     summary of work completed
                  -     key scientific discoveries
                  -     summary of work in progress
                  -     current schedule of anticipated events or milestones
                  -     market plans for introduction of Licensed Product and
                  -     a summary of resources (dollar value) spent in the
                        reporting period.

      10.3 Licensee has a continuing responsibility to keep The Regents informed
of the large or small] business entity status (as defined by the U.S. Patent and
Trademark Office) of itself and its sublicensees and Affiliates.

      10.4 Licensee shall report to The Regents in its immediately subsequent
progress and royalty report the date of first commercial sale of a Licensed
Product in each country. In addition, Licensee shall report in its immediately
subsequent progress and royalty report, the occurrence of each event resulting
in any payment becoming due under Article 8 (Milestone Payments) of this
Agreement.

                                       10
<PAGE>

      10.5 After the first commercial sale of a Licensed Product anywhere in the
world, Licensee shall make quarterly royalty reports to The Regents on or before
each February 28, May 31, August 31 and November 30 of each year. Each royalty
report will cover Licensee's most recently completed calendar quarter and will
show:

            10.5.1 the gross sales and Net Sales of Licensed Product sold during
the most recently completed calendar quarter;

            10.5.2 the number of each type of Licensed Product sold;

            10.5.3 the royalties, in U.S. dollars, payable with respect to sales
of Licensed Product;

            10.5.4 the method used to calculate the royalty; and

            10.5.5 the exchange rates used.

      10.6 If no sales of Licensed Product have been made during any reporting
period, a statement to that effect is required.

      10.7 All Progress Reports and Royalty Reports submitted to The Regents
under this Agreement shall be treated by The Regents as Licensee's Confidential
Information in accordance with Article 31 (Secrecy).

11. BOOKS AND RECORDS

      11.1 Licensee shall keep and shall cause its Affiliates and sublicensees
to keep accurate books and accounts of records in connection with the sale of
the Licensed Products in sufficient detail to permit accurate determination of
all figures necessary for verification of payments required to be paid
hereunder. Licensee and its Affiliates and sublicensees shall maintain such
records for a period of at least four (4) years after the end of the year in
which they were generated.

      11.2 Upon forty-five (45) days prior written notice from The Regents,
Licensee shall permit an independent certified public accounting firm of
nationally recognized standing selected by The Regents and reasonably acceptable
to Licensee, to examine, at The Regents sole expense, the relevant books and
records of Licensee and its Affiliates as may be reasonably necessary to verify
the accuracy of the royalty reports and royalties paid hereunder and compliance
with the financial obligations of this Agreement. The examination shall be
limited to pertinent books and records for any year ending not more than four
(4) years prior to the date of such request. An examination under this Section
11.2 shall not occur more than once in any calendar year. Such examination shall

                                       11
<PAGE>

be conducted after reasonable prior written notice to Licensee and during
ordinary business hours. All such accounting firms shall sign a confidentiality
agreement (in form and substance reasonably acceptable to Licensee) as to any of
Licensee's or its Affiliate's confidential information which they are provided,
or to which they have access, while conducting any audit pursuant to this
Section 11.2.

      11.3 If the independent certified public accounting firm concludes that
additional royalties were owed during such period, Licensee shall pay the
additional royalties, together with interest thereon at the rate provided in
Section 4.7, within thirty (30) days of the date Licensee receives such written
report. If such underpayment exceeds five percent (5%) of the total royalty due
The Regents, then the fees charged by the independent certified public
accounting firm for the work associated with the audit shall be paid by
Licensee. If the independent certified public accounting firm concludes that
there has been a royalty overpayment, then Licensee may take a credit for this
overpayment against future royalty payments of up to fifty percent (50%) of the
earned royalty due and payable in any reporting period until the credit is
exhausted.

      11.4 Licensee shall include in any sublicense granted by it pursuant to
this Agreement a provision requiring the sublicensees to make reports to
Licensee, to keep and maintain records of sales made pursuant to such
sublicense, and to grant access to such records to The Regent's independent
certified public accounting firm to the same extent required of Licensee under
this Agreement.

      11.5 The Regents shall treat all financial information provided to The
Regents as Data in accordance with the provisions of Article 31 (Secrecy)
hereof, except when, and only to the extent that, it is necessary to reveal such
information in order to enforce its rights under this Agreement.

12. LIFE OF THE AGREEMENT

      12.1 Unless otherwise terminated by operation of law or by acts of the
parties in accordance with the terms of this Agreement, this Agreement will be
in force on a country-by-country basis, from the Effective Date until the date
of expiration of the last-to-expire patent licensed under this Agreement; or
until the last patent application containing a Valid Claim licensed under this
Agreement is abandoned and no patent in Regents' Patent Rights ever issues.

                                       12
<PAGE>

      12.2 Any termination of this Agreement will not affect the rights and
obligations set forth in the following Articles:

         Article 11     Books and Records
         Article 15     Disposition of Licensed Product on Hand Upon Termination
         Article 16     Use of Names and Trademarks
         Article 21     Indemnification
         Article 25     Failure to Perform
         Article 31     Secrecy

13. TERMINATION BY THE REGENTS

      13.1 If Licensee fails to perform or violates any material term of this
Agreement, then The Regents may give written notice of default ("Notice of
Default") to Licensee. If Licensee fails to repair the default within one
hundred twenty (120) days of the effective date of receipt of Notice of Default,
The Regents may terminate this Agreement and its licenses by a second written
notice ("Notice of Termination"). If a Notice of Termination is sent to
Licensee, this Agreement will automatically terminate on the effective date of
that notice. Such termination will not relieve Licensee of its obligation to pay
any fees owing at the time of termination and will not impair any accrued right
of The Regents. These notices are subject to Article 22 (Notices).

      13.2 In the event Licensee notifies The Regents that:

            13.2.1 the AHPC Agreement is terminated or not renewed;

            13.2.2 a substitute agreement has not been entered into; and

            13.2.3 Licensee does not intend to make, have made, use, sell, offer
to sell and import Licensed Product and practice Licensed Method within the
Field of Use, then The Regents shall have the right to terminate this Agreement.

14. TERMINATION BY LICENSEE

      14.1 Licensee has the right at any time to terminate this Agreement in
whole or as to any portion of Regents' Patent Rights by giving notice in writing
to The Regents. Such notice of termination will be subject to Article 22
(Notices) and termination of this Agreement will be effective sixty (60) days
from the effective date of receipt of such notice.

      14.2 Any termination under the above Paragraph 14.1 does not relieve
Licensee of any obligation or liability accrued under this Agreement prior to
termination or rescind any payment

                                       13
<PAGE>

made to The Regents or anything done by Licensee prior to the time termination
becomes effective. Termination does not affect in any manner any rights of The
Regents arising under this Agreement prior to termination.

15. DISPOSITION OF LICENSED PRODUCT ON HAND UPON TERMINATION

      Upon termination of this Agreement Licensee is entitled to dispose of all
previously made or partially made Licensed Product, but no more, within a period
of one hundred and twenty (120) days provided that the sale of Licensed Product
is subject to the terms of this Agreement, including but not limited to the
rendering of reports and payment of royalties required under this Agreement.

16. USE OF NAMES AND TRADEMARKS

      16.1 Nothing contained in this Agreement confers any right to use in
advertising, publicity or other promotional activities any name, trade name,
trademark or other designation of either party hereto (including contraction,
abbreviation or simulation of any of the foregoing). Unless required by law, the
use by Licensee of the name "The Regents of the University of California" or the
name of any campus of the University of California is prohibited.

      16.2 The Regents is free to release to the inventors and senior
administrators employed by The Regents the terms and conditions of this
Agreement. If such release is made, The Regents shall give notice of the
confidential nature and shall request that the recipient does not disclose such
terms and conditions to others. If a third party inquires whether a license to
Regents' Patent Rights is available, The Regents may disclose the existence of
this Agreement and the extent of the grant in Article 2 (Life of Patent
Exclusive Grant) to such third party, but will not disclose the name of Licensee
or any other terms or conditions of this Agreement, except where The Regents is
required to release information under either the California Public Records Act,
a governmental audit requirement or other applicable law.

17. LIMITED WARRANTY

      17.1 The Regents represents and warrants to Licensee that it has the
lawful right to grant this license.

                                       14
<PAGE>

      17.2 The Licensing Officer for this Agreement, Chester A. Bisbee, Ph.D.,
J.D., represents to Licensee that, to his actual knowledge, The Regents owns the
entire right, title, and interest in and to The Regents' Patent Rights, and that
no third party has asserted it has any right, title, or interest therein, except
for the U.S. Federal Government to the extent described in Paragraph B of the
Background Section of this Agreement.

      17.3 This license and the associated Invention are provided WITHOUT
WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE OR ANY OTHER
WARRANTY, EXPRESS OR IMPLIED. THE REGENTS MAKES NO REPRESENTATION OR WARRANTY
THAT THE LICENSED PRODUCT OR LICENSED METHOD WILL NOT INFRINGE ANY PATENT OR
OTHER PROPRIETARY RIGHT OF ANY THIRD PARTY. HOWEVER, WITH THE EXCEPTION OF
PATENT AND/OR PROPRIETARY RIGHTS OF LICENSEE, THE REGENTS TO THE ACTUAL
KNOWLEDGE OF CHESTER A. BISBEE HAS NO KNOWLEDGE THAT THE LICENSED PRODUCT OR
LICENSED METHOD INFRINGES ANY PATENT OR OTHER PROPRIETARY RIGHT OR THAT ANY
CLAIMS HAVE BEEN MADE THAT THEY DO.

      17.4 IN NO EVENT MAY THE REGENTS BE LIABLE FOR ANY INCIDENTAL, SPECIAL OR
CONSEQUENTIAL DAMAGES RESULTING FROM EXERCISE OF THIS LICENSE OR THE USE OF THE
INVENTION OR LICENSED PRODUCT.

      17.5 This Agreement does not:

            17.5.1 express or imply a warranty or representation as to the
validity or scope of any of Regents' Patent Rights;

            17.5.2 express or imply a warranty or representation that anything
made, used, sold, offered for sale or imported or otherwise disposed of under
any license granted in this Agreement is or will be free from infringement of
patents of third parties;

            17.5.3 obligate The Regents to bring or prosecute actions or suits
against third parties for patent infringement except as provided in Article 20
(Patent Infringement);

            17.5.4 confer by implication, estoppel or otherwise any license or
rights under any patents of The Regents other than Regents' Patent Rights as
defined in this Agreement, regardless of whether those patents are dominant or
subordinate to Regent's' Patent Rights; or

                                       15
<PAGE>

            17.5.5 obligate The Regents to furnish any know-how not provided in
Regents' Patent Rights.

18. PATENT PROSECUTION AND MAINTENANCE

      18.1 As long as Licensee has paid patent costs as provided for in this
Article 18 (Patent Prosecution and Maintenance), The Regents shall diligently
endeavor to prosecute and maintain the U.S. and foreign patents comprising
Regents' Patent Rights using counsel of its choice. The Regents shall provide
Licensee with copies of all relevant documentation, including office actions and
examination reports, shortly after being issued and before a response is due so
that Licensee may be informed and provide The Regents with comments relating to
the continuing prosecution. However, The Regents may always take action to
preserve the Regents' Patent Rights whether or not Licensee has commented.
Licensee agrees to keep this documentation confidential and, if necessary,
Licensee may disclose such information to its sublicensees as long as the
sublicensees agree to be bound by the secrecy provisions of Article 31 (Secrecy)
of this Agreement. The Regents' counsel will take instructions only from The
Regents and all patent applications and patents under this Agreement will be
assigned solely to The Regents provided, however, The Regents shall instruct its
counsel to not unreasonably refuse to consider and take into account any
comments on behalf of Licensee in connection with the prosecution of The
Regents' Patent Rights.

      18.2 The Regents shall use reasonable efforts to amend any patent
application to include claims reasonably requested by Licensee to protect the
products contemplated to be sold under this Agreement.

      18.3 Licensee shall apply for an extension of the term of any patent
included within Regents' Patent Rights if appropriate under the Drug Price
Competition and Patent Term Restoration Act of 1984 and/or European, Japanese
and other foreign counterparts of this Law. Licensee shall prepare all documents
and The Regents agrees to execute the documents and to take additional action as
Licensee reasonably requests in connection therewith.

      18.4 If either party receives notice pertaining to infringement or
potential infringement of any issued patent included within Regents' Patent
Rights under the Drug Price Competition and Patent Term Restoration Act of 1984
and/or foreign counterparts of this Law, that party shall notify the other party
within ten (10) days after receipt of notice of infringement.

                                       16
<PAGE>

      18.5 Licensee shall bear the costs of preparing, filing, prosecuting and
maintaining all U.S. and foreign patent applications contemplated by this
Agreement. Costs billed by The Regents' counsel will be rebilled to Licensee and
are due within thirty (30) days of rebilling by The Regents. These costs include
patent prosecution costs for the Invention incurred by The Regents prior to the
execution of this Agreement and any patent prosecution costs that may be
incurred for patentability opinions, re-examination, re-issue, interferences or
inventorship determinations. Prior prosecution costs will be due upon execution
of this Agreement and billing by The Regents and are at least approximately
thirteen thousand dollars ($13,000) as of October 16, 2000.

      18.6 Licensee may request The Regents to obtain patent protection on the
Invention in foreign countries if available and if it so desires. Licensee shall
notify The Regents of its decision to obtain or maintain foreign patents not
less than sixty (60) days prior to the deadline for any payment, filing or
action to be taken in connection therewith. This notice concerning foreign
filing must be in writing, must identify the countries desired and must reaffirm
Licensee's obligation to underwrite the costs thereof. The absence of such a
notice from Licensee to The Regents will be considered an election not to obtain
or maintain foreign rights.

      18.7 Licensee's obligation to underwrite and to pay patent prosecution
costs will continue for so long as this Agreement remains in effect, but
Licensee may terminate its obligations with respect to any given patent
application or patent upon three (3) months written notice to The Regents. The
Regents will use its best efforts to curtail patent costs when a notice of
termination is received from Licensee. The Regents may prosecute and maintain
such application(s) or patent(s) at its sole discretion and expense, but
Licensee will have no further right or licenses thereunder. Non-payment of
patent costs may be deemed by The Regents as an election by Licensee not to
maintain patent application(s) or patents in the countries for which non-payment
of patent attorney charges and costs occurs.

      18.8 The Regents may file, prosecute or maintain patent applications at
its own expense in any country in which Licensee has not elected to file,
prosecute or maintain patent applications in accordance with this Article 18
(Patent Prosecution and Maintenance) and those applications and resultant
patents will not be subject to this Agreement. At any time during the life of
this Agreement, Licensee may reimburse The Regents for any foreign patent
expenses incurred and retain exclusive license rights in such foreign country if
the rights are available at that time.

                                       17
<PAGE>

19. PATENT MARKING

      Licensee shall mark all Licensed Product made, used or sold under the
terms of this Agreement, or their containers, in accordance with the applicable
patent marking laws.

20. PATENT INFRINGEMENT

      20.1 If Licensee learns of the substantial infringement of any patent
licensed under this Agreement, Licensee shall call The Regents' attention
thereto in writing and provide The Regents with reasonable evidence of
infringement. Neither party will notify a third party of the infringement of any
of Regents' Patent Rights without first obtaining consent of the other party,
which consent will not be unreasonably denied. Both parties shall use their best
efforts in cooperation with each other to terminate infringement without
litigation.

      20.2 Licensee may request that The Regents take legal action against the
infringement of Regents' Patent Rights. Such request must be in writing and must
include reasonable evidence of infringement and damages to Licensee. If the
infringing activity has not abated within thirty (30) days following the
effective date of request, then The Regents has the right to commence suit on
its own account or refuse to participate in the suit.

      20.3 The Regents shall give notice of its election to commence suit in
writing to Licensee by the end of the one hundredth (100th) day after receiving
notice of written request from Licensee. Licensee may thereafter bring suit for
patent infringement, at its own expense, if and only if The Regents elects not
to commence suit and if the infringement occurred during the period and in a
jurisdiction where Licensee had exclusive rights under this Agreement. If,
however, Licensee elects to bring suit in accordance with this Paragraph 20.3,
then The Regents may thereafter join that suit at its own expense.

      20.4 Licensee agrees not to bring suit for patent infringement without
following the procedures of this Article 20 (Patent Infringement), and both
parties agree to be bound by the outcome of a suit for patent infringement
through the pendency of such a suit under Paragraph 20.3.

      20.5 Legal action, as is decided on, will be at the expense of the party
bringing suit and all damages recovered thereby will belong to the party
bringing suit, but legal action brought jointly by The Regents and Licensee and
fully participated in by both will be at the joint expense of the parties

                                       18
<PAGE>

and all recoveries will be shared jointly by them in proportion to the share of
expense paid by each party.

      20.6 Each party shall cooperate with the other in litigation proceedings
instituted hereunder but at the expense of the party bringing suit. Litigation
will be controlled by the party bringing the suit, except that The Regents may
be represented by counsel of its choice in any suit brought by Licensee. In such
case, the costs incurred by The Regents' counsel shall be borne by The Regents.

21. INDEMNIFICATION

      21.1 Licensee shall indemnify, hold harmless and defend The Regents, its
officers, employees and agents; the sponsors of the research that led to the
Invention; and the inventors of the patent applications and patents in Regents'
Patent Rights and their employers (collectively, "The Regents' Indemnitees")
against any and all claims, suits, losses, liabilities, damages, costs, fees and
expenses of a third party (collectively, a "Liability") resulting from or
arising out of the exercise of this Agreement or any sublicense (but not arising
out of or resulting from acts conducted solely by The Regents in the exercise of
this Agreement or any sublicense), provided, however, that Licensee shall have
no obligation to indemnify, hold harmless or defend any of The Regents'
Indemnitees to the extent that a Liability is due to a breach by The Regents of
any of its representations, warranties, covenants or obligations under this
Agreement. This indemnification includes, but is not limited to, any product
liability.

      21.2 Licensee, at its sole cost and expense, shall insure its activities
in connection with the work under this Agreement and obtain, keep in force and
maintain insurance as follows or an equivalent program of self insurance.

      21.3 Comprehensive or commercial form general liability insurance
(contractual liability included) with limits as follows:

            -     Each Occurrence $1,000,000.
            -     Products/Completed Operations Aggregate $5,000,000.
            -     Personal and Advertising Injury $1,000,000.
            -     General Aggregate (commercial form only) $5,000,000.

The coverage and limits referred to under the above do not in any way limit the
liability of Licensee. Licensee shall furnish The Regents with certificates of
insurance showing compliance with all requirements. Certificates must:

                                       19
<PAGE>

            -     provide for thirty (30) days' advance written notice to The
                  Regents of any modification;
            -     indicate that The Regents has been endorsed as an additional
                  Insured under the coverage referred to under the above; and
            -     include a provision that the coverage will be primary and will
                  not participate with nor will be excess over any valid and
                  collectable insurance or program of self-insurance carried or
                  maintained by The Regents.

Notwithstanding the foregoing, in the event that AHPC becomes a direct licensee
in accordance with Section 3.3 hereof, or an assignee in accordance with Article
23 (Assignability), The Regents acknowledges that AHPC maintains a
self-insurance program which would be sufficient to meet AHPC's obligations.

      21.4 The Regents shall notify Licensee in writing of any claim or suit
brought against The Regents in respect of which The Regents intends to invoke
the provisions of this Article 21 (Indemnification). Licensee shall keep The
Regents informed on a current basis of its defense of any claims under this
Article 21(Indemnification).

22. NOTICES

      22.1 Any notice or payment required to be given to either The Regents or
Licensee (and to AHPC for only as long as the AHPC Agreement is in effect and
then only to The Regents and Licensee), shall be deemed to have been properly
given and to be effective:

            22.1.1 on the date of delivery if delivered in person to the
respective addresses given below or to another address as designated in writing
by the party changing its prior address;

            22.1.2 on the date of mailing if mailed by first-class certified
mail, postage paid to the respective addresses given below or to another address
as designated in writing by the party changing its prior address; or

            22.1.3 on the date of mailing if mailed by any global express
carrier service that requires the recipient to sign the documents demonstrating
the delivery of such notice or payment, to the respective addresses given below
or to another address as designated in writing by the party changing its prior
address.

      22.2 For so long as the AHPC Agreement is in effect, both Licensee and The
Regents agree to provide AHPC with a copy of all notices they send to the other
party under this Agreement.

                                       20
<PAGE>

         In the case of Licensee:    SIGA Technologies, Inc.
                                     420 Lexington Avenue, Suite 620
                                     New York, NY 10170
                                     Attention: Joshua D. Schein, Ph.D.
                                                Chief Executive Officer

          In the case of AHPC:       Wyeth-Ayerst Laboratories
                                     555 East Lancaster Avenue
                                     St. Davids, PA 19087
                                     Attention: Senior Vice President
                                                Global Business Development

             with a copy to:         Associate General Counsel
                                     American Home Products Corporation
                                     One Campus Drive
                                     Parsippany, NJ 07054

         In the case of The Regents: The Regents of the University of California
                                     Office of Technology Transfer
                                     1111 Franklin Street, 5th Floor
                                     Oakland, CA 94607-5200
                                     Attention: Executive Director
                                                Research Administration and
                                                  Technology Transfer
                                     RE:        UC Case No. 1999-262-1

23.  ASSIGNABILITY

      This Agreement may be assigned by The Regents, but is personal to Licensee
and assignable by Licensee only with the written consent of The Regents, which
consent will not be unreasonably withheld except that the Licensee may, without
such consent, assign this Agreement and all its rights and obligations hereunder
in connection with the transfer or sale of substantially all of its business or
a division or in the event of its merger, consolidation, change in control or
similar transactions. The above notwithstanding, The Regents hereby consents to
an assignment to AHPC and/or to its Wyeth-Ayerst Laboratories Division or any
successors thereto provided that the AHPC sublicense is in effect, AHPC is the
sole sublicensee, AHPC is not in breach of its sublicense, and AHPC assumes all
liabilities and obligations to The Regents required of Licensee by this
Agreement, including past due obligations existing at the time of assumption of
this Agreement by AHPC. In the event the AHPC Agreement is not renewed or
extended, Licensee may assign this

                                       21
<PAGE>

Agreement to any other entity, with the written consent of The Regents, provided
the payments called for hereunder are made and The Regents receive the full
amount of all payments due them pursuant to Article 3 and Article 7 of the AHPC
Agreement as if the AHPC Agreement were still a valid contract.

24. NO WAIVER

      No waiver by either party of any default of this Agreement may be deemed a
waiver of any subsequent or similar default. A suspension of duty under this
Agreement due to force majeure shall not be for a period longer than one year.

25. FAILURE TO PERFORM

      If either party finds it necessary to undertake legal action against the
other on account of failure of performance due under this Agreement, then the
prevailing party is entitled to reasonable attorneys' fees in addition to costs
and necessary disbursements.

26. GOVERNING LAWS

      THIS AGREEMENT WILL BE INTERPRETED AND CONSTRUED IN ACCORDANCE WITH THE
LAWS OF THE STATE OF CALIFORNIA WITHOUT REGARD TO WHICH PARTY DRAFTED PARTICULAR
PROVISIONS OF THIS AGREEMENT, but the scope and validity of any patent
application or patent will be governed by the applicable laws of the country of
the patent application or patent. Disputes between the parties regarding this
Agreement will utilize only courts within California for disputes that go to
court.

27. ARBITRATION

      Any and all controversies, claims or disputes arising out of or relating
to Article 9 (Due Diligence), or the breach thereof, shall be solely and
exclusively settled by arbitration in accordance with the Commercial Arbitration
Rules then in effect (the "Arbitration Rules") of the American Arbitration
Association ("AAA"). The arbitration shall take place in Los Angeles,
California, and the arbitrator shall be appointed by the mutual consent of the
parties. If the parties are unable to agree upon the appointment of an
arbitrator, then the arbitration shall take place before an arbitrator

                                       22
<PAGE>

selected in accordance with the Arbitration Rules. The arbitrator appointed by
the parties or by the AAA, as the case may be, is sometimes referred to herein
as the "Arbitrator." Each party hereby irrevocably consents to the sole and
exclusive jurisdiction and venue of the State and Federal courts located in the
City of Los Angeles, State of California, in connection with any matter arising
out of the foregoing arbitration or this Agreement, including but not limited to
confirmation of the award rendered by the Arbitrator and enforcement thereof by
entry of judgment thereon or by any other legal remedy. Service of process in
connection with any such arbitration or any proceeding to enforce an arbitration
award may be made in the manner set forth in Article 22 (Notices) or in any
other manner permitted by applicable law. All costs and expenses of the
Arbitration shall be shared equally by the parties hereto.

28. PREFERENCE FOR U.S. INDUSTRY

      Because this Agreement grants the exclusive right to use or sell the
Invention in the U.S., Licensee agrees that any products sold in the U.S.
embodying this Invention or produced through the use thereof will be
manufactured substantially in the U.S.

29. GOVERNMENT APPROVAL OR REGISTRATION

      Each party hereto shall promptly notify the other if it becomes aware that
this Agreement is subject to any U.S. or foreign government reporting or
approval requirement. Licensee shall make all necessary filings and pay all
costs including fees, penalties and all other out-of-pocket costs associated
with such reporting or approval process. However, Licensee shall not be liable
for any fines or penalties arising from acts occurring prior to the date hereof

30. EXPORT CONTROL LAWS

      The Licensee shall observe all applicable U.S. and foreign laws with
respect to the transfer of Licensed Product and related technical data to
foreign countries, including, without limitation, the International Traffic in
Arms Regulations ("ITAR") and the Export Administration Regulations.

                                       23
<PAGE>

31. SECRECY

      31.1 With regard to confidential information ("Data"), which can be oral
or written or both, received by one party from the other party regarding the
Invention, this Agreement or any of the transactions contemplated hereby or the
performance of any party under this Agreement, the parties agree:

            31.1.1 not to use the Data except for the sole purpose of performing
under the terms of this Agreement;

            31.1.2 to safeguard Data against disclosure to others with the same
degree of care as it exercises with its own data of a similar nature;

            31.1.3 not to disclose Data to others (except to its employees,
agents, consultants or commercial partners who are bound to such party by a like
obligation of confidentiality) without the express written permission of the
disclosing party, except that the receiving party is not prevented from using or
disclosing any of the Data that:

                        31.1.3.1    the receiving party can demonstrate by
                                    written records was previously known to it;

                        31.1.3.2    is now or becomes in the future, public
                                    knowledge other than through breach of this
                                    Agreement by the receiving party;

                        31.1.3.3    is lawfully obtained by Licensee from
                                    sources independent of the receiving party;

                        31.1.3.4    is independently developed by the receiving
                                    party without the aid, use or application of
                                    Data received from the disclosing party
                                    hereunder;

                        31.1.3.5    is required to be disclosed to a
                                    governmental entity or agency in connection
                                    with seeking any governmental or regulatory
                                    approval or pursuant to the lawful
                                    requirement or request of a governmental
                                    entity or agency; or

                        31.1.3.6    is disclosed under the California Public
                                    Records Act or other requirements of law;
                                    and

            31.1.4 that the secrecy obligations of the parties with respect to
Data will continue for a period ending five (5) years from the termination date
of this Agreement.

      31.2 The obligations of confidentiality and limited use hereunder apply to
any Data whether supplied under this Agreement or the Secrecy Agreements
indicated in Article 32.3 (Miscellaneous).

      31.3 Upon the termination of this Agreement, the receiving party shall
within thirty (30) days following the effective date of termination destroy or
return to the disclosing party any Data received from the disclosing party which
Data is in its possession. However, the receiving party may retain one copy of
Data solely for archival purposes, provided that such Data is subject to the

                                       24
<PAGE>

confidentiality provisions set forth in this Article 31 (Secrecy). Within sixty
(60) days following termination, the receiving party must provide the disclosing
party with a written notice that Data has been returned or destroyed.

      31.4 With regard to biological material received by Licensee from The
Regents, if any, including any cell lines, vectors, genetic material,
derivatives, products progeny or material derived therefrom ("Biological
Material"), Licensee agrees:

            31.4.1 not to use Biological Material except for the sole purpose of
performing under the terms of this Agreement;

            31.4.2 not to transfer Biological Material to others (except to its
employees, agents, consultants or commercial partners who are bound to Licensee
by like obligations conditioning and restricting access, use and continued use
of Biological Material) without the express written permission of The Regents,
except that Licensee shall not be prevented from transferring Biological
Material which:

                        31.4.2.1    becomes publicly available other than
                                    through acts or omissions of Licensee; or

                        31.4.2.2    is lawfully obtained by Licensee from
                                    sources independent of The Regents;

            31.4.3 to safeguard Biological Material against disclosure and
transmission to others with the same degree of care as it exercises with its own
biological materials of a similar nature; and

            31.4.4 to destroy all copies of Biological Material at the
termination of this Agreement.

32. MISCELLANEOUS

      32.1 The headings of the several sections are inserted for convenience of
reference only and are not intended to be a part of or to affect the meaning or
interpretation of this Agreement.

      32.2 This Agreement is not binding on the parties until it has been signed
below on behalf of each party. It is then effective as of the Effective Date.

      32.3 No amendment or modification of this Agreement is valid or binding on
the parties unless made in writing and signed on behalf of each party. This
Agreement embodies the entire understanding of the parties and supersedes all
previous communications, representations or understandings, either oral or
written, between the parties relating to the subject matter hereof. The Secrecy
Agreement for Data with The Regents (UC Control No. 99-20-0510) effective May 5,
1999, and a Secrecy Agreement for Biological Material with The Regents and
American Home

                                       25
<PAGE>

Products Corporation, Wyeth-Ayerst Research Division (UC Control No. 99-21-0632)
effective June 23, 1999, are hereby terminated.

      32.4 In case any of the provisions contained in this Agreement are held to
be invalid, illegal or unenforceable in any respect, that invalidity, illegality
or unenforceability will not affect any other provisions of this Agreement and
this Agreement will be construed as if the invalid, illegal or unenforceable
provisions had never been contained in it.

      32.5 None of the provisions of this Agreement is intended to create any
form of joint venture between the parties, rights in third parties or rights
that are enforceable by any third party.

      IN WITNESS WHEREOF, both The Regents and Licensee have executed this
Agreement, in duplicate originals, by their respective and duly authorized
officers on the day and year written.

SIGA TECHNOLOGIES, INC.              THE REGENTS OF THE UNIVERSITY
                                         OF CALIFORNIA

By: /s/ Joshua D. Schein             By: /s/ Alan B. Bennett
    --------------------------           -----------------------
         (Signature)                         (Signature)

Name: Joshua D. Schein               Name: Alan B. Bennett
      ------------------------
         (Please Print)

Title: Chief Executive Officer       Title: Executive Director
       -----------------------              Research Administration and
                                              Technology Transfer

Date: 11/29/2000                     Date: December 6, 2000
      -----------------------              ---------------------

        Approved as to legal form: /s/ P. Martin Simpson, Jr. 11/14/2000
                                   -------------------------------------
                             P. Martin Simpson, Jr.              Date
                             University Counsel
                             Office of General Counsel

                                       26

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