<PAGE>

                                                                   EXHIBIT 10.17


Portions of this Exhibit have been omitted pursuant to a request for
confidential treatment. The omitted portions, marked by [****], have been
separately filed with the Commission.



                     MASSACHUSETTS INSTITUTE OF TECHNOLOGY

                               LICENSE AGREEMENT

                                  (EXCLUSIVE)

<PAGE>

                              TABLE OF CONTENTS

<TABLE>
<CAPTION>

                                                                                                         PAGE
                                                                                                         ----
<S>                                                                                                       <C>
P R E A M B L E
ARTICLES

1     DEFINITIONS   . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  2
2     GRANT   . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  3
3     DUE DILIGENCE   . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  5
4     ROYALTIES   . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  6
5     REPORTS AND RECORDS   . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  8
6     PATENT PROSECUTION  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  9
7     INFRINGEMENT  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
8     PRODUCT LIABILITY   . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
9     EXPORT CONTROLS   . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
10    NON-USE OF NAMES  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
11    ASSIGNMENT  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
12    DISPUTE RESOLUTION  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
13    TERMINATION   . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
14    PAYMENTS, NOTICES AND OTHER COMMUNICATIONS    . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
15    MISCELLANEOUS PROVISIONS  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

</TABLE>

<PAGE>

                 This Agreement is made and entered into this _________ day of
___________, 199__, (the "Effective Date") by and between MASSACHUSETTS
INSTITUTE OF TECHNOLOGY, a corporation duly organized and existing under the
laws of the Commonwealth of Massachusetts and having its principal office at 77
Massachusetts Avenue, Cambridge, Massachusetts 02139, U.S.A. (hereinafter
referred to as "M.I.T."), and VIRUS RESEARCH INSTITUTE, INC., a corporation duly
organized under the laws of Massachusetts and having its principal office at 840
Memorial Drive Cambridge, MA 02139 (hereinafter referred to as "LICENSEE").

                              W I T N E S S E T H

                 WHEREAS, M.I.T. is the owner of certain PATENT RIGHTS (as
later defined herein) and has the right to grant licenses under said PATENT
RIGHTS, subject only to a royalty-free, nonexclusive license heretofore granted
to the United States Government;

                 WHEREAS, portions of the M.I.T. PATENT RIGHTS are jointly owned
by M.I.T. and Pennsylvania Research Corporation (hereinafter referred to as
"PRC") and PRC has granted M.I.T. exclusive rights to license PRC's rights in
such PATENT RIGHTS in the medical fields of use according to the institutional
agreement dated December 3, 1990 and appended hereto as Appendix C.

                 WHEREAS, M.I.T. desires to have the PATENT RIGHTS utilized in
the public interest and is willing to grant a license thereunder;

                 WHEREAS, LICENSEE has represented to M.I.T., to induce M.I.T.
to enter into this Agreement, that LICENSEE is experienced in the development of
products similar to the LICENSED PRODUCT(s) (as later defined herein) and/or the
use of the LICENSED PROCESS(es) (as later defined herein) and that it shall
commit itself to a thorough, vigorous and diligent program of exploiting the
PATENT RIGHTS so that public utilization shall result therefrom; and

                 WHEREAS, LICENSEE desires to obtain a license under the PATENT
RIGHTS upon the terms and conditions hereinafter set forth.

                 NOW, THEREFORE, in consideration of the premises and the mutual
covenants contained herein, the parties hereto agree as follows:

<PAGE>

                            ARTICLE I - DEFINITIONS

                 For the purposes of this Agreement, the following words and
phrases shall have the following meanings:

                 1.1      "LICENSEE" shall include a related company of VIRUS
RESEARCH INSTITUTE, INC., the voting stock of which is directly or indirectly at
least fifty percent (50%) owned or controlled by VIRUS RESEARCH INSTITUTE, an
organization which directly or indirectly controls more than fifty percent (50%)
of the voting stock of VIRUS RESEARCH INSTITUTE and an organization, the
majority ownership of which is directly or indirectly under common control with
VIRUS RESEARCH INSTITUTE, INC.

                 1.2      "PATENT RIGHTS" shall mean all of the following
M.I.T. intellectual property:

                 (a)      the United States and foreign patents and/or patent
                          applications listed in Appendices A and B;

                 (b)      United States and foreign patents issued from the
                          applications listed in Appendices A and B and from
                          divisionals and continuations of these applications;

                 (c)      claims of U.S. and foreign continuation-in-part
                          applications, and of the resulting patents, which are
                          directed to subject matter specifically described in
                          the U.S. and foreign applications listed in Appendices
                          A and B;

                 (d)      claims of all foreign patent applications, and of the
                          resulting patents, which are directed to subject
                          matter specifically described in the United States
                          patents and/or patent applications described in (a),
                          (b) or (c) above; and

                 (e)      any reissues of United States patents described in
                          (a), (b) or (c)above.

                 1.3      A "LICENSED PRODUCT" shall mean any product or part
thereof which:

                 (a)      is covered in whole or in part by an issued, unexpired
                          claim or a pending claim which has not been declared
                          invalid by a court of Competent Jurisdiction from
                          which there is no appeal or from which no appeal is
                          taken contained in the PATENT RIGHTS in the country in
                          which any such product or part thereof is made, used
                          or sold; or

                                      -2-

<PAGE>

The information below marked by [****] has been omitted pursuant to a request
for confidential treatment. The omitted portion has been separately filed with
the Commission.

                 (b)      is manufactured by using a process or is employed to
                          practice a process which is covered in whole or in
                          part by an issued, unexpired claim or a pending claim
                          which has not been declared invalid by a court of
                          Competent Jurisdiction from which there is no appeal
                          or from which no appeal is taken contained in the
                          PATENT RIGHTS in the country in which any LICENSED
                          PROCESS is used or in which such product or part
                          thereof is used or sold.

                 1.4      A "LICENSED PROCESS" shall mean any process which is
covered in whole or in part by an issued, unexpired claim or a pending claim
which has not been declared invalid by a court of Competent Jurisdiction from
which there is no appeal or from which no appeal is taken contained in the
PATENT RIGHTS.

                 1.5      "NET SALES" shall mean LICENSEE's (and its
sublicensees') billings for LICENSED PRODUCTS and LICENSED PROCESSES produced
hereunder less the sum of the following:

                 (a)      discounts allowed in amounts customary in the trade;

                 (b)      sales, tariff duties and/or use taxes directly
                          imposed and with reference to particular sales;

                 (c)      outbound transportation prepaid or allowed; and

                 (d)      amounts allowed or credited on returns.

                 No deductions shall be made for commissions paid to individuals
whether they be with independent sales agencies or regularly employed by
LICENSEE and on its payroll, or for cost of collections. LICENSED PRODUCTS shall
be considered "sold" when billed out or invoiced.

                 1.6      "TERRITORY" [****]

                 1.7      "FIELD OF USE" shall mean non-injected delivery of
vaccines and immunotherapeutics to all mucosal surfaces (including oral
delivery).

                                      -3-

<PAGE>

The information below marked by [****] has been omitted pursuant to a request
for confidential treatment. The omitted portion has been separately filed with
the Commission.

                               ARTICLE  2 - GRANT

                 2.1      M.I.T. hereby grants to LICENSEE the right and license
to make, have made, use, lease and sell the LICENSED PRODUCTS and to practice
the LICENSED PROCESSES in the TERRITORY for the FIELD OF USE to the end of the
term for which the PATENT RIGHTS are granted unless this Agreement shall be
sooner terminated according to the terms hereof.

                 2.2      LICENSEE agrees that LICENSED PRODUCTS leased or sold
in the United States shall be manufactured substantially in the United States.

                 2.3      [****]

                 2.4      M.I.T. reserves the right to practice under the
PATENT RIGHTS for noncommercial research purposes.

                 2.5      In addition to the options granted in the Sponsored
Research Agreement of Appendix C, M.I.T. further grants to LICENSEE a first
option to an exclusive license in the Field of Use to other new inventions
which:

                 (a)      [****]

                 (b)      [****]

                 (c)      [****]

                 This option for any new invention shall be exercisable within
six months after the date on which M.I.T. notifies LICENSEE that the new
invention has been reported, under the following terms:

                 (i)      [****]

                 (ii)     [****]

                 (iii)    [****]

                 (iv)     [****]

                                      -4-

<PAGE>

The information below marked by [****] has been omitted pursuant to a request
for confidential treatment. The omitted portion has been separately filed with
the Commission.

                 2.6      LICENSEE shall have the right to enter into
sublicensing agreements for the rights, privileges and licenses granted
hereunder.

                 2.7      LICENSEE agrees that any sublicenses granted by it
shall provide that the obligations to M.I.T. of Articles 2, 5, 7, 8, 9, 10, 12,
13, and 15 of this Agreement shall be binding upon the sublicensee as if it were
a party to this Agreement. LICENSEE further agrees to attach copies of these
Articles to sublicense agreements.

                 2.8      LICENSEE agrees to forward to M.I.T. a copy of any
and all sublicense agreements promptly upon execution by the parties.

                 2.9      LICENSEE shall not receive from sublicensees anything
of value in lieu of cash payments in consideration for any sublicense under this
Agreement, without the express prior written permission of M.I.T.

                 2.10     The license granted hereunder shall not be construed
to confer any rights upon LICENSEE by implication, estoppel or otherwise as to
any technology not specifically set forth in Appendix A, Appendix B or Section
2.5 hereof.

                           ARTICLE 3 - DUE DILIGENCE

                 3.1      LICENSEE shall use its best efforts to bring one or
more LICENSED PRODUCTS or LICENSED PROCESSES to market through a thorough,
vigorous and diligent program for exploitation of the PATENT RIGHTS and to
thereafter continue active, diligent marketing efforts for one or more LICENSED
PRODUCTS or LICENSED PROCESSES throughout the life of this Agreement. [****] to
the bringing to market of a LICENSED PRODUCT or LICENSED PROCESS throughout the
term of this Agreement until the first commercial sale of a LICENSED PRODUCT or
commercial use of a LICENSED PROCESS.

                 3.2      In addition, LICENSEE shall adhere to the following
milestones:

                 (a)      [****]

                 (b)      [****]


                                      -5-

<PAGE>

The information below marked by [****] has been omitted pursuant to a request
for confidential treatment. The omitted portion has been separately filed with
the Commission.

                 3.3      LICENSEE's failure to perform in accordance with
Paragraphs 3.1 and 3.2 above shall be grounds for M.I.T. to terminate this
Agreement pursuant to Paragraph 13.3 hereof.

                             ARTICLE 4 - ROYALTIES

                 4.1      For the rights, privileges and license ranted
hereunder, LICENSEE shall pay royalties to M.I.T. in the manner hereinafter
provided to the end of the term of the PATENT RIGHTS or until this Agreement
shall be terminated:

                 a)       [****]

                 b)       [****]

                 (c)      [****]

                 (d)      [****]

                 4.2      [****]

                 4.3      [****]

                 4.4      If LICENSEE sells LICENSED PRODUCTS to or under
arrangement with a governmental or non-profit organization (such as the World
Health Organization), and if such sales [****]

                 4.5      No multiple royalties shall be payable because any
LICENSED PRODUCT, its manufacture, use, lease or sale are or shall be covered by
more than one PATENT RIGHTS patent application or PATENT RIGHTS patent licensed
under this Agreement.

                 4.6      Except as provided in Section 4.7 below, royalty
payments shall be paid in United States dollars in Cambridge, Massachusetts, or
at such other place as M.I.T. may reasonably designate consistent with the laws
and regulations controlling in any foreign country. If any currency conversion
shall be required in connection with the payment of royalties hereunder, such
conversion shall be made by using the exchange rate prevailing at the Chase

                                      -6-

<PAGE>

Manhattan Bank (N.A.) on the last business day of the calendar quarterly
reporting period to which such royalty payments relate.

                 4.7      If by law, regulation, or fiscal policy of a
particular country, conversion into United States dollars or transfer of funds
of a convertible currency to the United States is restricted or forbidden,
LICENSEE shall give M.I.T. prompt notice in writing and shall pay the royalty
and other amounts due through such means or methods as are lawful in such
country as M.I.T. may reasonably designate. Failing the designation by M.I.T. of
such lawful means or methods within thirty (30) days after such notice is given
to M.I.T., LICENSEE shall deposit such royalty payment in local currency to the
credit of M.I.T. in a recognized banking institution designated by M.I.T., or if
none is designated by M.I.T. within the thirty (30) day period described above,
in a recognized banking institution selected by LICENSEE and identified in a
written notice to M.I.T. by LICENSEE, and such deposit shall fulfill all
obligations of LICENSEE to M.I.T. with respect to such royalties.

                        ARTICLE 5 - REPORTS AND RECORDS

                 5.1      LICENSEE shall keep full, true and accurate books of
account containing all particulars that may be necessary for the purpose of
showing the amounts payable to M.I.T. hereunder. Said books of account shall be
kept at LICENSEE's principal place of business or the principal place of
business of the appropriate division of LICENSEE to which this Agreement
relates. Said books and the supporting data shall be open at all reasonable
times for five (5) years following the end of the calendar year to which they
pertain, to the inspection of M.I.T. or its Agents for the purpose of verifying
LICENSEE's royalty statement or compliance in other respects with this
Agreement. Should such inspection lead to the discovery of a greater than ten
percent (10%) discrepancy in reporting, LICENSEE agrees to pay the full cost of
such inspection.

                 5.2      Prior to the first calendar quarter in which Net Sales
occur, LICENSEE shall provide M.I.T. with an annual summary of LICENSEE's
efforts during the preceding year to bring to market a LICENSED PRODUCT or
LICENSED PROCESS. Beginning with the first calendar quarter in which Net Sales
occur, LICENSEE, within ninety (90) days after March 31, June 30, September 30
and December 31, of each year, shall in place of such annual reports

                                      -7-

<PAGE>

deliver to M.I.T. true and accurate reports, giving such particulars of the
business conducted by LICENSEE and its sublicensees during the preceding
three-month period under this Agreement as shall be pertinent to a royalty
accounting hereunder. These quarterly reports shall include at least the
following:

                 (a)      number of LICENSED PRODUCT  manufactured and sold by
                          LICENSEE and all sublicensees;

                 (b)      total billings for LICENSED PRODUCTS sold by LICENSEE
                          and all sublicensees;

                 (c)      accounting for all LICENSED PROCESSES used or sold by
                          LICENSEE and all sublicensees;

                 (d)      deductions applicable as provided in Paragraph 1.5;

                 (e)      total royalties due; and

                 (f)      names and addresses of all sublicensees of LICENSEE.

                 5.3      With each such report submitted, LICENSEE shall pay to
M.I.T. the royalties due and payable under this Agreement. If no royalties shall
be due, LICENSEE shall so report.

                 5.4      On or before the ninetieth (90th) day following the
close of LICENSEE's fiscal year, LICENSEE shall provide M.I.T. with LICENSEE's
certified financial statements for the preceding fiscal year including, at a
minimum, a Balance Sheet and an Operating Statement.

                 5.5      The royalty payments set forth in this Agreement and
amounts due under Article 6 shall, if overdue, bear interest until payment at a
per annum rate two percent (2%) above the prime rate in effect at the Chase
Manhattan Bank (N.A.) on the due date. The payment of such interest shall not
foreclose M.I.T. from exercising any other rights it may have as a consequence
of the lateness of any payment.

                         ARTICLE 6 - PATENT PROSECUTION

                 6.1      Except as provided in Section 6.4, M.I.T. shall apply
for, seek prompt issuance of, and maintain during the term of this Agreement the
PATENT RIGHTS in the United States and in the foreign countries listed in
Appendix B hereto. Appendix B may be amended by

                                      -8-

<PAGE>

The information below marked by [****] has been omitted pursuant to a request
for confidential treatment. The omitted portion has been separately filed with
the Commission.

verbal agreement of both parties, such agreement to be confirmed in writing
within ten (10) days. The prosecution, filing and maintenance of all PATENT
RIGHTS patents and applications shall be the primary responsibility of M.I.T.;
provided, however, that patent counsel selected by M.I.T. is reasonably
acceptable to LICENSEE. M.I.T. (and by instruction its patent counsel) shall
consult with LICENSEE and its patent counsel as to the preparation and filing,
prosecution and maintenance of PATENT RIGHTS, and shall furnish to LICENSEE and
its patent counsel copies of documents relevant to such preparation, filing,
prosecution or maintenance sufficiently prior to filing such documents or making
any payment due thereunder to allow for review and comment by LICENSEE and its
patent counsel. If, as a result of any such consultation, LICENSEE shall elect
not to pay the expenses of any patent application or patent included in PATENT
RIGHTS (which election may be limited to a specific country or countries),
LICENSEE shall so notify M.I.T. within thirty (30) days of such consultation and
shall thereby surrender its rights under PATENT RIGHTS in the country or
countries affected, provided, however, that LICENSEE shall remain obligated to
reimburse M.I.T. for any costs incurred with respect to such patent application
or patent prior to said election. M.I.T. agrees that it shall not abandon the
prosecution of any patent applications under PATENT RIGHTS nor shall it fail to
make any payment or fail to take any other action necessary to obtain or
maintain a patent under PATENT RIGHTS unless it has notified LICENSEE in
sufficient time for LICENSEE to assume such prosecution, make such payment or
take such action, and LICENSEE shall thereafter have the right to prosecute
and/or maintain such PATENT RIGHTS at its expense in M.I.T.'s name, and M.I.T.
shall thereafter render to LICENSEE all necessary assistance in order to
facilitate such prosecution and/or maintenance.

                 6.2      LICENSEE shall reimburse M.I.T. for payment of all
fees and costs relating to the filing, prosecution, and maintenance of the
PATENT RIGHTS incurred by M.I.T. after the Effective Date of this Agreement.

                 6.3      [****]

                                      -9-

<PAGE>

                 6.4      If, pursuant to Section 8.B.2 of the Research
Agreement, LICENSEE obtains an exclusive license to a new invention which is
added to PATENT RIGHTS, and if such new invention is jointly owned pursuant to
Section 8.F. of the Research Agreement ("JOINT PATENT RIGHTS"), LICENSEE shall
apply for, seek prompt issuance of, and maintain during the term of this
Agreement at its own expense such JOINT PATENT RIGHTS in the United States and
in such other countries as LICENSEE shall have elected. The prosecution, filing
and maintenance of JOINT PATENT RIGHTS shall be the primary responsibility of
LICENSEE; provided, however that patent counsel selected by LICENSEE is
reasonably acceptable to M.I.T. LICENSEE (and by instruction its patent counsel)
shall consult with M.I.T. and its patent counsel as to the preparation and
filing, prosecution and maintenance of JOINT PATENT RIGHTS, and shall furnish to
M.I.T. and its patent counsel copies of documents relevant to such preparation,
filing, prosecution or maintenance sufficiently prior to filing such documents
or making any payment due thereunder to allow for review and comment by M.I.T.
and its patent counsel. If, at any time, LICENSEE shall elect not to pay the
expenses of any patent application or patent included in JOINT PATENT RIGHTS
(which election may be limited to a specific country or countries), LICENSEE
shall so notify M.I.T. within thirty (30) days of such consultation and shall
thereby surrender its rights under JOINT PATENT RIGHTS in the country or
countries affected, provided, however, that LICENSEE shall remain obligated for
any COSTS incurred with respect to such patent application or patent prior to
said election. LICENSEE agrees that it shall not abandon the prosecution of any
patent applications under JOINT PATENT RIGHTS nor shall it fail to make any
payment or fail to take any other action necessary to obtain or maintain, in a
patent under JOINT PATENT RIGHTS unless it has notified M.I.T. in sufficient
time for M.I.T. to assume such prosecution, make such payment or take such
action, and M.I.T. shall thereafter have the right to prosecute and/or maintain
such JOINT PATENT RIGHTS at its expense in LICENSEE's name, and LICENSEE shall
thereafter render to M.I.T. all necessary assistance in order to facilitate such
prosecution and/or maintenance.

                                      -10-

<PAGE>

The information below marked by [****] has been omitted pursuant to a request
for confidential treatment. The omitted portion has been separately filed with
the Commission.

                            ARTICLE 7 - INFRINGEMENT

                 7.1      LICENSEE shall inform M.I.T. promptly in writing of
any alleged infringement of the PATENT RIGHTS by a third party of which LICENSEE
becomes aware and of any available evidence thereof.

                 7.2      During the term of this Agreement, M.I.T. shall have
the right, but shall not be obligated to prosecute at its own expense all
infringements of the PATENT RIGHTS and, in furtherance of such right, LICENSEE
hereby agrees that M.I.T. may include LICENSEE as a party plaintiff in any such
suit, without expense to LICENSEE. M.I.T.'s choice of counsel in any such suit
shall be subject to LICENSEE's approval, providing that such approval shall not
be unreasonably withheld. The total cost of any such infringement action
commenced or defended [****]

                 7.3      If within six (6) months after having been notified of
any alleged infringement, M.I.T. shall have been unsuccessful in persuading the
alleged infringer to desist and shall not have brought and shall not be
diligently prosecuting an infringement action, or if M.I.T. shall notify
LICENSEE at any time prior thereto of its intention not to bring suit against
any alleged infringer in the TERRITORY for the FIELD OF USE, then, and in those
events only, LICENSEE shall have the right, but shall not be obligated, to
prosecute at its own expense any infringement of the PATENT RIGHTS in the
TERRITORY for the FIELD OF USE, and LICENSEE may, for such purposes, use the
name of M.I.T. as party plaintiff; provided, however, that such right to bring
such an infringement action shall remain in effect only for so long as the
license granted herein remains exclusive. No settlement, consent judgment or
other voluntary final disposition of the suit may be entered into without the
consent of M.I.T., which consent shall not unreasonably be withheld. LICENSEE
shall indemnify M.I.T. against any order for costs that may be made against
M.I.T. in such proceedings.

                 7.4      In the event that LICENSEE shall undertake the
enforcement and/or defense of the PATENT RIGHTS by litigation, [****] Any
recovery of damages by LICENSEE

                                      -11-

<PAGE>

The information below marked by [****] has been omitted pursuant to a request
for confidential treatment. The omitted portion has been separately filed with
the Commission.

for each such suit shall be applied first in satisfaction of any unreimbursed
expenses and legal fees of LICENSEE relating to such suit, [****]

                 7.5      For any patent of the PATENT RIGHTS jointly owned by
M.I.T. and LICENSEE, LICENSEE shall have the first right to enforce and/or
defend the patent. Other provisions of such enforcement or defense by LICENSEE
shall be in accordance with Paragraphs 7.3 and 7.4 above. If LICENSEE chooses
not to enforce or defend such patent, M.I.T. shall then have the right to do so,
in accordance with the provisions of Paragraph 7.2 above.

                 7.6      In the event that a declaratory judgment action
alleging invalidity or noninfringement of any of the PATENT RIGHTS shall be
brought against LICENSEE, M.I.T., at its option, shall have the right, within
thirty (30) days after commencement of such action, to intervene and take over
the sole defense of the action at its own expense.

                 7.7      In any infringement suit as either party may institute
to enforce the PATENT RIGHTS pursuant to this Agreement, the other party hereto
shall, at the request and expense of the party initiating such suit, cooperate
in all respects and, to the extent possible, have its employees testify when
requested and make available relevant records, papers, information, samples,
specimens, and the like.

                         ARTICLE 8 - PRODUCT LIABILITY

                 8.1      LICENSEE shall at all times during the term of this
Agreement and thereafter, indemnify, defend and hold M.I.T. and PRC, their
trustees, officers, employees and affiliates, harmless against all claims and
expenses, including legal expenses and reasonable attorneys' fees, rising out of
the death of or injury to any person or persons or out of any damage to property
and against any other claim, proceeding, demand, expense and liability of any
kind whatsoever resulting from the production, manufacture, sale, use, lease,
consumption or advertisement of the LICENSED PRODUCT(s) and/or LICENSED
PROCESS(es) or arising from any obligation of LICENSEE hereunder.

                                      -12-

<PAGE>

                 8.2      Commencing not later than commencement of human trials
of any LICENSED PRODUCT, LICENSEE shall obtain and carry in full force and
effect liability insurance which shall protect LICENSEE and M.I.T. in regard to
events covered by Paragraph 8.1 above, providing that such insurance is
available at commercially acceptable rates.

                 8.3      M.I.T. warrants that it owns above or jointly with PRC
the PATENT RIGHTS and that it has the right to grant the rights and licenses
granted in this agreement. M.I.T.'s total liability under this warranty shall be
limited to the amounts paid by LICENSEE to M.I.T. under this License Agreement.

                 8.4      EXCEPT AS OTHERWISE EXPRESSLY SET FORTH IN THIS
AGREEMENT, M.I.T. MAKES NO REPRESENTATIONS AND EXTENDS NO WARRANTIES OF ANY
KIND, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND VALIDITY OF PATENT RIGHTS
CLAIMS, ISSUED OR PENDING. NOTHING IN THIS AGREEMENT SHALL BE CONSTRUED AS A
REPRESENTATION MADE OR WARRANTY GIVEN BY M.I.T. THAT THE PRACTICE BY LICENSEE OF
THE LICENSE GRANTED HEREUNDER SHALL NOT INFRINGE THE PATENT RIGHTS OF ANY THIRD
PARTY.

                          ARTICLE 9 - EXPORT CONTROLS

                 It is understood that M.I.T. is subject to United States laws
and regulations controlling the export of technical data, computer software,
laboratory prototypes and other commodities (including the Arms Export Control
Act, as amended and the Export Administration Act of 1979), and that its
obligations hereunder are contingent on compliance with applicable United States
export laws and regulations. The transfer of certain technical data and
commodities may require a license from the cognizant agency of the United States
Government and/or written assurances by LICENSEE that LICENSEE shall not export
data or commodities to certain foreign countries without prior approval of such
agency. M.I.T. neither represents that a license shall not be required nor that,
if required, it shall be issued.

                                      -13-

<PAGE>

                         ARTICLE 10 - NON-USE OF NAMES

                 LICENSEE shall not use the names or trademarks of the
Massachusetts Institute of Technology nor of Pennsylvania Research Corporation
nor of Pennsylvania State University, nor any adaptation thereof, nor the names
of any of their employees, in any advertising, promotional or sales literature
without prior written consent obtained from M.I.T., PRC or said employee, in
each case, except that LICENSEE may state that it is licensed by M.I.T. under
one or more of the patents and/or applications comprising the PATENT RIGHTS.

                            ARTICLE 11 - ASSIGNMENT

                 This Agreement is not assignable except by LICENSEE in
conjunction with substantially all of the assets of LICENSEE which relate to the
business of vaccines and immunotherapeutics. Any other attempt to do so is void.

                         ARTICLE 12- DISPUTE RESOLUTION

                 12.1     For any and all claims, disputes or controversies
arising under, out of, or in connection with this Agreement, including any
dispute relating to patent validity or infringement, which the parties shall be
unable to resolve within sixty (60) days, the party raising such dispute shall
promptly advise the other party of such claim, dispute or controversy in a
writing which describes in reasonable detail the nature of such dispute. By not
later than five (5) business days after the recipient has received such notice
of dispute, each party shall have selected for itself a representative who shall
have the authority to bind such party, and shall additionally have advised the
other party in writing of the name and title of such representative. By not
later than ten (10) business days after the date of such notice of dispute, such
representatives shall schedule a date for a mediation hearing with the Cambridge
Dispute Settlement Center or Endispute Inc. in Cambridge, Massachusetts. If the
representatives of the parties have not been able to resolve the dispute within
fifteen (15) business days after such mediation hearing, the parties shall have
the right to pursue any other remedies legally available to resolve such dispute
in either the Courts of the Commonwealth of Massachusetts or in the United
States District Court for the District of Massachusetts, to whose jurisdiction
for such purposes M.I.T. and LICENSEE each hereby irrevocably consents and
submits.

                                      -14-

<PAGE>

The information below marked by [****] has been omitted pursuant to a request
for confidential treatment. The omitted portion has been separately filed with
the Commission.

                 12.2     Notwithstanding the foregoing, nothing in this Article
shall be construed to waive any rights or timely performance of any obligations
existing under this Agreement.

                            ARTICLE 13 - TERMINATION

                 13.1     If LICENSEE shall cease to carry on its business, this
Agreement shall terminate upon notice by M.I.T.

                 13.2     Should LICENSEE fail to make any payment whatsoever
due and payable to M.I.T. hereunder, M.I.T. shall have the right to terminate
this Agreement effective on thirty (30) days' notice, unless LICENSEE shall make
all such payments to M.I.T. within said thirty (30) day period. Upon the
expiration of the thirty (30) day period, if LICENSEE shall not have made all
such payments to M.I.T., the rights, privileges and license granted hereunder
shall automatically terminate.

                 13.3     Upon any material breach or default of this Agreement
by LICENSEE, other than those occurrences set out in Paragraphs 13.1 and 13.2
hereinabove, which shall always take precedence in that order over any material
breach or default referred to in this Paragraph 13.3, M.I.T. shall have the
right to terminate this Agreement and the rights, privileges and license granted
hereunder effective on ninety (90) days' notice to LICENSEE. Such termination
shall become automatically effective unless LICENSEE shall have cured any such
material breach or default prior to the expiration of the ninety (90) day
period. The above notwithstanding, if LICENSEE is in breach of Article 3, but
otherwise in compliance with the terms of this Agreement [****]

                 13.4     [****]

                 13.5     LICENSEE shall have the right to terminate this
Agreement at any time on six (6) months' notice to M.I.T., and upon payment of
all amounts due M.I.T. through the effective date of the termination.

                 13.6     Upon termination of this Agreement for any reason,
nothing herein shall be construed to release either party from any obligation
that matured prior to the effective date of

                                      -15-

<PAGE>

such termination. LICENSEE and any sublicensee thereof may, however, after the
effective date of such termination, sell all LICENSED PRODUCTS, and complete
LICENSED PRODUCTS in the process of manufacture at the time of such termination
and sell the same, provided that LICENSEE shall pay to M.I.T. the Running
Royalties thereon as required by Article 4 of this Agreement and shall submit
the reports required by Article 5 hereof on the sales of LICENSED PRODUCTS.

                 13.7     Upon termination of this Agreement for any reason, any
sublicensee not then in default shall have the right to seek a license from
M.I.T., M.I.T. agrees to negotiate such licenses in good faith under reasonable
terms and conditions.

             ARTICLE 14- PAYMENTS, NOTICES AND OTHER COMMUNICATIONS

                 Any payment, notice or other communication pursuant to this
Agreement shall be sufficiently made or given on the date of mailing if sent to
such party by certified first class mail, postage prepaid, addressed to it at
its address below or as it shall designate by written notice given to the other
party:

                 In the case of M.I.T.:

                 Director
                 Technology Licensing Office
                 Massachusetts Institute of Technology
                 Room E32-300
                 Cambridge, Massachusetts 02139

                 In the case of LICENSEE:

                 President
                 Virus Research Institute
                 840 Memorial Drive
                 Cambridge, MA 02139

                     ARTICLE 15 - MISCELLANEOUS PROVISIONS

                 15.1     This Agreement shall be construed, governed,
interpreted and applied in accordance with the laws of the Commonwealth of
Massachusetts, U.S.A., except that questions

                                      -16-

<PAGE>

affecting the construction and effect of any patent shall be determined by the
law of the country in which the patent was granted.

                 15.2     The parties hereto acknowledge that this Agreement
sets forth the entire Agreement and understanding of the parties hereto as to
the subject matter hereof, and shall not be subject to any change or
modification except by the execution of a written instrument subscribed to by
the parties hereto.

                 15.3     The provisions of this Agreement are severable, in the
event that any provisions of this Agreement shall be determined to be invalid or
unenforceable under any controlling body of the law, such invalidity or
unenforceability shall not in any way affect the validity or enforceability of
the remaining provisions hereof.

                 15.4     LICENSEE agrees to mark the LICENSED PRODUCTS sold in
the United States with all applicable United States patent numbers. All LICENSED
PRODUCTS shipped to or sold in other countries shall be marked in such a manner
as to conform with the patent laws and practice of the country of manufacture or
sale.

                 15.5     The failure of either party to assert a right
hereunder or to insist upon compliance with any term or condition of this
Agreement shall not constitute a waiver of that right or excuse a similar
subsequent failure to perform any such term or condition by the other party.

                 IN WITNESS WHEREOF the parties have duly executed this
Agreement the day and year set forth below.

MASSACHUSETTS INSTITUTE OF                         VIRUS RESEARCH INSTITUTE
TECHNOLOGY

By /s/ JOHN T. PRESTON                             By /s/ JOHN W. LITTLECHILD
   --------------------------------------             -------------------------
Title Director, Technology License Office          Title President
      -----------------------------------                ----------------------
Date  12/5/91                                      Date  12/6/91
      -----------------------------------                ----------------------




                                      -17-

<PAGE>

The information below marked by [****] has been omitted pursuant to a request
for confidential treatment. The omitted portion has been separately filed with
the Commission.

                                   APPENDIX A

                                     [****]





                                      -18-

<PAGE>

The information below marked by [****] has been omitted pursuant to a request
for confidential treatment. The omitted portion has been separately filed with
the Commission.

                                   APPENDIX B

                                     [****]





                                      -19-

<PAGE>

The information below marked by [****] has been omitted pursuant to a request
for confidential treatment. The omitted portion has been separately filed with
the Commission.

                                   APPENDIX C

                     MASSACHUSETTS INSTITUTE OF TECHNOLOGY

                          OFFICE OF SPONSORED PROGRAMS

RESEARCH AGREEMENT between the MASSACHUSETTS INSTITUTE OF TECHNOLOGY,
         hereinafter referred to as "the Institute" and the VIRUS RESEARCH
         INSTITUTE, hereinafter referred to as "the Sponsor".

WHEREAS, the research program contemplated by this Agreement is of mutual
         interest and benefit to the Institute and to the Sponsor, and will
         further the instructional and research objectives of the Institute in a
         manner consistent with its status as a non-profit, tax-exempt,
         educational institution.

NOW, THEREFORE, the parties hereto agree as follows:

         1.      STATEMENT OF WORK. [****]

         2.      PRINCIPAL INVESTIGATOR. [****]

         3.      PERIOD OF PERFORMANCE. [****]

         4.      REIMBURSEMENT OF COSTS. [****]

                                      -20-

<PAGE>

The information below marked by [****] has been omitted pursuant to a request
for confidential treatment. The omitted portion has been separately filed with
the Commission.

         5.      PAYMENT. Payments shall be made to the Institute by the
                 Sponsor in advance on the following basis:

                 [****]

         6.      TERMINATION.  Performance under this Agreement may be
                 terminated by the Sponsor upon six months written notice;
                 performance may be terminated by the Institute if
                 circumstances beyond its control preclude continuation of the
                 research. Upon termination, the Institute will be reimbursed
                 as specified in Article 4 for all costs and non-cancelable
                 commitments incurred in the performance of the research, such
                 reimbursement not to exceed the total estimated project cost
                 specified in Article 4.

         7.      PUBLICATIONS.  The Institute will be free to publish the
                 results of research under this Agreement; provided that a copy
                 of each publication will be provided to the Sponsor at least
                 thirty (30) days in advance of publication and, if the
                 publication would disclose a patentable invention, the
                 Institute will delay publication for an additional sixty (60)
                 days to enable the Institute or Sponsor to file a patent
                 application in accordance with Section 8.

         8.      INTELLECTUAL PROPERTY.

                 A.       Title to any invention conceived or first reduced to
                          practice in the performance of the research program
                          shall remain with the Institute which shall have the
                          sole right to determine the disposition of any
                          inventions or other rights resulting therefrom,
                          including the right to determine whether or not a
                          patent application will be filed, and shall so notify
                          the Sponsor.


                                      -21-

<PAGE>

The information below marked by [****] has been omitted pursuant to a request
for confidential treatment. The omitted portion has been separately filed with
the Commission.

                 B.       In the event that a patent application on such an
                          invention is filed by the Institute, the Sponsor
                          (subject to third party rights, if any, in such
                          invention) shall be entitled to elect one of the
                          following alternatives by notice in writing to the
                          Institute within six (6) months after notification to
                          the Sponsor that a patent application has been filed:

                          1.      [****]

                          2.      [****]

                          3.      [****]

                 C.       In the event that the Sponsor has not elected any of
                          the foregoing alternatives within six (6) months after
                          notification that a patent application has been filed,
                          the Sponsor shall be deemed to have elected alterative
                          3. above.

                 D.       [****]

                 E.       In the event that the Institute declines to file a
                          patent application, the Sponsor may file in the United
                          States and/or elsewhere, in the name of the Institute,
                          and shall be entitled to elect between the above
                          alternatives no later than six (6) months after such
                          filing date.

                 F.       Inventions made jointly by employees of the Institute
                          and employees of the Sponsor shall be owned jointly by
                          the Institute and the Sponsor and, in the absence of
                          any further agreement, the Institute and the Sponsor
                          shall

                                      -22-

<PAGE>

                          each have the independent right to use and/or license
                          the jointly owned invention(s). The Institute shall
                          grant to Sponsor the same option and license rights to
                          the Institute's rights in jointly owned invention(s)
                          as are granted to the Sponsor in Paragraph 8B above.

                 G.       The Sponsor shall retain all invention disclosures
                          submitted by the Institute in confidence and use its
                          best efforts to prevent their disclosure to third
                          parties. The Sponsor shall be relieved of this
                          obligation only when this information becomes publicly
                          available through no fault of the Sponsor.

                 H.       Title to and the right to determine the disposition
                          of any copyrights or copyrightable material first
                          produced or composed in the performance of this
                          research shall remain with the Institute.  The
                          Institute shall grant to the Sponsor an irrevocable,
                          royalty-free, non-transferable, non-exclusive right
                          and license to use, reproduce, display, distribute,
                          translate and perform, all such copyrightable
                          materials other than computer software and its
                          documentation. The Institute shall grant to the
                          Sponsor an irrevocable, royalty-free, non-
                          transferable, non-exclusive right and license to use,
                          reproduce, display, translate and perform computer
                          software and its documentation specified to be
                          developed and delivered under the Statement of Work
                          for Sponsor's internal (non-commercial) research
                          purposes. Sponsor may elect to negotiate a
                          non-exclusive (or exclusive subject to third party
                          rights, if any) royalty-bearing license to use,
                          reproduce, display, distribute, translate and perform
                          such computer software and its documentation for
                          commercial purposes (in a designated field of use,
                          where appropriate).  Computer software for which a
                          patent application is filed shall be subject to
                          paragraph B.  above.


                                      -23-

<PAGE>

                 I.       In the event that the Institute elects to establish
                          property rights other than patents to any tangible
                          research property (TRP), e.g., biological materials,
                          developed during the course of the research, the
                          Institute and the Sponsor will determine disposition
                          of rights to such property by separate agreement. The
                          Institute will, at a minimum, reserve the right to
                          use and distribute TRP for non-commercial research
                          purposes.

                 J.       All licenses elected by Sponsor pursuant to this
                          clause become effective as of the date the parties
                          sign a subsequent license agreement, and shall survive
                          termination or expiration of this Agreement.

         9.      USE OF NAMES. Neither party will use the name of the other in
                 any advertising or other form of publicity without the written
                 permission of the other, in the case of the Institute, that of
                 the Director of the News Office.

         10.     NOTICES. Any notices required to be given or which shall be
                 given under this Agreement shall be in writing delivered by
                 first class air mail or telex addressed to the parties as
                 follows:

                 MASSACHUSETTS INSTITUTE                    SPONSOR
                 OF TECHNOLOGY

                 Mr. George H. Dummer, Director             Virus Research
                 Office of Sponsored Programs, E19-702      Institute, Inc.
                 Massachusetts Institute of Technology      840 Memorial Drive
                 77 Massachusetts Avenue                    Cambridge, MA 02139
                 Cambridge, MA 02139

                 In the event notices, statements and payments required under
                 this Agreement are sent by certified or registered mail by one
                 party to the party entitled thereto at its

                                      -24-

<PAGE>

                 above address, they shall be deemed to have been given or made
                 as of the date so mailed.

         11.     ASSIGNMENT. This agreement shall be binding upon and inure to
                 the benefit of the parties hereto and the successors to
                 substantially the entire business and assets of the respective
                 parties hereto. This Agreement shall not be assignable by
                 either party without the prior written consent of the other
                 party; any attempted assignment is void.

         12.     GOVERNING LAW. The validity and interpretation of this
                 agreement and the legal relation of the parties to it shall be
                 governed by the laws of the Commonwealth of Massachusetts.

         13.     ENTIRE AGREEMENT. Unless otherwise specified, this Agreement
                 embodies the entire understanding between the Institute and
                 the Sponsor for this project, and any prior or contemporaneous
                 representations, either oral or written are hereby superseded.
                 No amendments or changes to this Agreement including without
                 limitation, changes in the statement of work, total estimated
                 cost, and period of performance, shall be effective unless
                 made in writing and signed by authorized representatives of
                 the parties.


                 MASSACHUSETTS INSTITUTE            SPONSOR
                 OF TECHNOLOGY

                 By /s/ DAVID J. HARRIGAN           By /s/ JOHN W. LITTLECHILD
                    ----------------------------       -------------------------
                        Associate Director/
                        Office of Sponsored

                 Title  Programs                    Title  President
                        ------------------------           ---------------------

                 Date   12/5/91                     Date   12/6/91
                        ------------------------           ---------------------


                                      -25-

<PAGE>

The information below marked by [****] has been omitted pursuant to a request
for confidential treatment. The omitted portion has been separately filed with
the Commission.

                                FIRST AMENDMENT

                 This Amendment is to the License Agreement with the Effective
Date of December 6, 1991 between MASSACHUSETTS INSTITUTE OF TECHNOLOGY and VIRUS
RESEARCH INSTITUTE, INC.

                 The parties thereto now further agree as follows:

1.       [****]

2.       LICENSEE shall pay to M.I.T., in addition to the fees and royalties due
under Article IV of the License Agreement, the following fees:

         a)      [****]

         b)      [****]

3.       [****]

4.       The effective date of this Amendment shall be the last date of the
         signatures below. Agreed to for:

     MASSACHUSETTS INSTITUTE OF            VIRUS RESEARCH INSTITUTE, INC.
                 TECHNOLOGY

By /s/ JOHN T. PRESTON                     By /s/ BRYAN E. ROBERTS
   ---------------------------------          ----------------------------------

Title Director, Technology Licensing       Title V.P., Research & Development
      ------------------------------             -------------------------------

Date 9-17-92                               Date 9-17-92
     -------------------------------            --------------------------------


                                      -26-