Document:

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                                                                  Exhibit 10. 20

CERTAIN CONFIDENTIAL INFORMATION CONTAINED IN THIS DOCUMENT, MARKED BY AN
ASTERISK, HAS BEEN OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE
COMMISSION PURSUANT TO RULE 406 UNDER THE SECURITIES ACT OF 1933, AS AMENDED.

                                 AMENDMENT NO. 1
                            TO THE LICENSE AGREEMENT
                                     BETWEEN
                         THE TEXAS A&M UNIVERSITY SYSTEM
                                       AND
                                 INHIBITEX, INC.

         This amendment ("Amendment No. 1") is made and entered into by and
between The Texas A&M University System (hereinafter referred to as "SYSTEM")
with principal offices in College Station, Texas, and Inhibitex, Inc.,
(hereinafter referred to as "INHIBITEX"), a Delaware corporation, having a
principal place of business in Alpharetta, Georgia, parties to the License
Agreement dated February 4, 2000.

                                   WITNESSETH:

         WHEREAS, the parties have entered into a License Agreement regarding
certain intellectual property related to Extracellular Matrix Binding Proteins;
and

         WHEREAS, the original License Agreement between the parties provides
that SYSTEM manage the filing of U.S. and foreign patent applications and
maintenance of patents related to such intellectual property; and

         WHEREAS, INHIBITEX now desires to manage the filing of such patent
applications and maintenance of patents; and

         WHEREAS, SYSTEM agrees to transfer the responsibility of managing U.S.
and foreign patent applications and patents to INHIBITEX; and

         WHEREAS, INHIBITEX now also desires to return its rights in several
technologies, specifically TAM-US 1047 (U.S. Patent Application No.. 09/095/272)
and TAMUS 1609 (U.S. Patent Application No. 09/559,723), to SYSTEM, which was
granted to INHIBITEX under the original License Agreement; and

         WHEREAS, INHTBITEX desires to modify the License Agreement in regards
to specific sublicensee obligations; and

         WHEREAS, SYSTEM agrees to make such modifications.

         NOW THEREFORE, the parties agree that the License Agreement of February
4, 2000 is hereby amended as follows:

1.       DELETE section 1.01(c), 1.01(h) and 1.01(i) in their entirety.

2.       ADD new paragraphs 1.01 (h-o) as follows:

         (h)      United States Provisional Applications 60/189,968, filed March
                  17, 2000, 60/199,370, filed April 25, 2000, and 60/225,402,
                  filed August 15, 2000, entitled "Monoclonal Antibodies to CNA,
                  the Collagen Adhesin of S. aureus, Inhibit

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                  Collagen binding to S. aureus Strains;" all converted to U.S.
                  Application 09/810,428 on March 19, 2001, re-titled
                  "Cross-reactive Displacing Antibodies from Collagen Binding
                  Proteins and Methods of Identification and Use," and also
                  filed as a PCT application on March 19, 2001; and

         (i)      United States Provisional Application 60/260,523 filed January
                  10, 2001 entitled "Suppression of T Cell mediated Responses by
                  the Major Histocompatibility Complex H Analog Protein From S.
                  aureus;" and.

         (j)      United States Provisional Application 60/295,000 filed June 4,
                  2001 entitled "Structural Organization of the
                  Fibrinogen-Binding Region of the Clumping Factor B MSCRAMM of
                  S. aureus and Cross reacting Monoclonal Antibodies from Domain
                  Specific MSCRAMMs;" and

         (k)      United States Provisional Application 60/290,072 filed May 11,
                  2001 entitled "SdrG, A Fibrinogen Binding MSCRAMM from S.
                  epidermidis Targets the Thrombin Cleavage Site of the B beta
                  Chain;" and

         (l)      United States Provisional Application 60/289,132 filed May 8,
                  2001 entitled "Target Surface Proteins for Gram-Positive
                  Bacteria;" and

         (m)      United States Provisional Application 60/275,718 filed March
                  15, 2001 entitled "Collagen Binding Protein from S.
                  epidermidis;" and

         (n)      United States Provisional Application 60/274,611 filed March
                  12, 2001 entitled "S. aureus Anti-CLFA Monoclonal Antibodies;"
                  and

         (o)      Any patent(s) issuing from the foregoing application(s); any
                  divisional, continuations, or continuations-in-part of the
                  foregoing applications; all equivalent foreign patent
                  applications which claim priority under such application(s);
                  any patent(s) issuing from the foregoing application(s); and
                  all extensions or reissues of any such patent(s).

3.       DELETE paragraph 2.03 in its entirety.

4.       ADD paragraph 3.03 (d) as follows:

         3.03(d)  Notwithstanding the foregoing, the royalty rate to be paid on
                  NET SALES for LICENSED PRODUCTS sold in territories where
                  there is an issued patent having claims covering technology
                  used in the product sold shall be [ *** ] if the product is in
                  the field of active human vaccines containing MSC proteins
                  derived from S. aureus and S.epidermidis for the prevention of
                  S. aureus and S. epidermidis infections.

5.       DELETE paragraph 4.04 in its entirety.

6.       ADD a new paragraph 4.04 as follows:

         4.04     Sublicense obligations. INHIBITEX agrees that any sublicenses
                  granted by it shall provide that the obligations to SYSTEM of
                  paragraphs 10.03, 10.06, 10.07, 12.02, and 12.03 of this
                  Agreement shall be binding upon the sublicensee(s) as if it
                  were a party to this Agreement. INHIBITEX further agrees to
                  include or attach copies of these paragraphs to sublicense
                  Agreements.

7.       DELETE paragraph 5.01 in its entirety.

8.       ADD a new paragraph 5.01 as follows:

                                   Page 2 of 5

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         5.01     Patent Filing and Prosecution. From the effective date of this
                  Amendment, each patent application related to PATENT RIGHTS,
                  i.e. original provisional or regular patent applications,
                  divisionals, continuations, or continuations-in-part, shall be
                  filed by INHIBITEX in the name of SYSTEM using counsel
                  acceptable to SYSTEM. Prior to filing such applications,
                  INHIBITEX shall determine the scope of such applications in
                  consultation with SYSTEM. INHIBITEX agrees to INDEMNIFY and
                  HOLD SYSTEM HARMLESS for the legal fees and expenses INHIBITEX
                  incurs in prosecuting and maintaining PATENT RIGHTS. In the
                  event the Attorney General of Texas (the "AG") rules that
                  counsel pursuing patent protection for SYSTEM must be approved
                  by the AG, INHIBITEX agrees to take all necessary steps to
                  assure compliance with the AG's ruling including, if
                  necessary, modifying this Agreement to allow SYSTEM to hire
                  patent counsel. Prior to filing a patent application related
                  to PATENT RIGHTS, INHIBITEX agrees to provide SYSTEM with the
                  curriculum vitae for each attorney INHIBITEX proposes to use
                  to seek patent protection along with a letter from the firm
                  the attorneys are associated with acknowledging that the firm
                  will look solely to INHIBITEX for the payment of its fees and
                  expenses. Unless exigent circumstances dictate to the
                  contrary, INHIBITEX shall allow SYSTEM at least 30 days to
                  approve of the attorneys INHIBITEX desires to hire to pursue
                  PATENT RIGHTS. INHIBITEX shall also prosecute to completion
                  the U.S. Patent Applications identified in and comprising
                  PATENT RIGHTS. "Prosecution to completion" shall mean
                  prosecution of the original and any continuing or divisional
                  applications to issuance or to a final rejection. INHIBITEX is
                  not required to, but may with the consent of SYSTEM, pursue an
                  appeal to the Board of Patent Appeals and Interferences, or
                  the Federal Circuit Courts, or similar action in foreign
                  countries. Furthermore, INHIBITEX shall maintain any U.S.
                  patent(s) resulting from the prosecution described
                  hereinabove. In the event that INHIBITEX determines not to
                  continue prosecution to completion or maintenance of U.S.
                  Patent Applications comprising PATENT RIGHTS, INHIBITEX will
                  inform SYSTEM of its decision in sufficient time for SYSTEM to
                  make decisions regarding its desire to continue prosecution.
                  In such case, SYSTEM shall have the right to continue the
                  prosecution or maintenance at its own expense. However, any
                  such applications or patents funded by SYSTEM thereafter shall
                  be excluded from PATENT RIGHTS.

9.       DELETE paragraph 5.02 in its entirety.

10.      ADD a new paragraph 5.02 as follows:

         5.02     Foreign Patent Applications. With the cooperation of SYSTEM,
                  INHIBITEX shall file and prosecute, in the name of SYSTEM,
                  foreign patent applications corresponding to U.S. patent
                  applications filed pursuant to paragraph 5.01.

                  (a)      Election not to file. INHIBITEX will inform SYSTEM no
                           less than three (3) months before all foreign filing
                           deadlines [including the one year anniversary of each
                           application filed in the U.S., as well as the
                           national stage filing deadline of each application
                           filed through the Patent Cooperation Treaty (PCT)] as
                           to its selection of foreign countries in which it
                           will seek corresponding patent protection. SYSTEM
                           shall then have the

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                           right to file corresponding foreign patent
                           applications at its own expense in those foreign
                           countries not selected by INHIBITEX. However, such
                           applications funded at SYSTEM's expense shall be
                           excluded from PATENT RIGHTS.

                  (b)      Prosecution and Maintenance of Foreign Patents.
                           Should INHIBITEX file corresponding foreign patent
                           application(s) and subsequently elects not to
                           continue to prosecute and maintain such foreign
                           patent(s) or patent application(s), it shall so
                           notify the SYSTEM at least three (3) months prior to
                           taking (or not taking) any action which would result
                           in abandonment, withdrawal or lapse of such foreign
                           patent(s) or application(s). SYSTEM shall then have
                           the right to continue maintenance of prosecution of
                           such foreign patent(s) or application(s) at its own
                           expense. However, expenses incurred prior to the
                           point of INHIBITEX taking (or not taking) such action
                           shall remain the responsibility of INHIBITEX and such
                           foreign patent(s) or application(s) shall be excluded
                           from PATENT RIGHTS.

11.      DELETE paragraph 5.03 in its entirety.

12.      ADD a new paragraph 5.03 as follows:

         5.03     Financial Responsibility. INHIBITEX, within thirty (30) days
                  of receipt of a supporting invoice from SYSTEM, shall
                  reimburse SYSTEM for all reasonable expenses incurred prior to
                  the effective date of this Amendment by SYSTEM in filing,
                  prosecuting, and maintaining the U.S. Patent Application(s)
                  and patent(s) under the PATENT RIGHTS, in accordance with
                  paragraph 5.01 hereinabove. Notwithstanding, INHIBITEX shall
                  reimburse SYSTEM for reasonable expenses incurred prior to and
                  henceforth by SYSTEM for legal services comprising the
                  monitoring of the progress of INHIBITEX in filing,
                  prosecuting, and maintaining the U.S. and foreign patent
                  applications and patents under the PATENT RIGHTS. As of the
                  effective date of this Amendment, INHIBITEX shall directly
                  assume one hundred percent (100%) of the expenses it incurs
                  and one hundred percent (100%) of the reasonable expenses
                  incurred by SYSTEM related to filing, prosecution and
                  maintenance of all U.S. and foreign patent application(s) and
                  patent(s) as described in paragraph 5.01 and 5.02. Reasonable
                  expenses incurred by SYSTEM shall not include (1) any
                  substantive analysis of the prosecution of patents, (2)
                  expenses associated with duplication of effort by multiple
                  lawyers in monitoring the progress of the prosecution, and (3)
                  legal fees for services other than the monitoring of the
                  progress of the prosecution.

13.      DELETE paragraph 5.04 in its entirety.

14.      ADD a new paragraph 5.04 as follows:

         5.04     Information. INHIBITEX shall keep SYSTEM promptly and fully
                  informed of the course of patent prosecution or other
                  proceedings related to the protection of PATENT RIGHTS.
                  INHIBITEX shall cooperate with SYSTEM to allow SYSTEM the
                  timely and reasonable opportunity to provide input to the

                                  Page 4 of 5
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                  development of the patent application(s) and any official
                  proceedings prior to filing such applications or other
                  response to proceedings by INHIBITEX. INHIBITEX shall disclose
                  to SYSTEM the complete texts of all patent applications filed
                  by INHIBITEX under the PATENT RIGHTS as well as all
                  information received concerning office actions, the
                  institution or possible institution of any interference,
                  opposition, re-examination, reissue, revocation, nullification
                  or any other official proceeding involving PATENT RIGHTS. All
                  such notifications and disclosures required herein to be made
                  to SYSTEM shall be made no later than ten (10) business days
                  following receipt of such notice. Requests by INHIBITEX or its
                  counsel for documents necessary to effect this Amendment, e.g.
                  powers of attorney, shall be promptly responded to by SYSTEM
                  and its counsel.

15.      ADD a new paragraph 5.05 as follows:

         5.05     Filing of Jointly Owned Foreign Patent Applications. In cases
                  of patent(s) and/or patent application(s) jointly owned by
                  SYSTEM and another parry, 1NHIBITEX shall file such
                  corresponding foreign patent application(s) in the name of
                  SYSTEM and the applicable parry.

16.      ADD a new paragraph 5.06 as follows:

         5.06     Proprietary Rights. All PATENT RIGHTS hereunder are vested in
                  and owned by SYSTEM.

17.      DELETE paragraphs 10.04 and 10.05 in their entirety.

         EXCEPT as provided herein, all terms and conditions of the License
Agreement remain unchanged and in full force and effect.

         IN WITNESS WHEREOF, the parties have caused this Amendment No. 1 to
become effective on the date executed below by the last signatory to this
Amendment.

INHIBITEX, INC.                         THE TEXAS A&M UNIVERSITY SYSTEM

     /s/ William D. Johnston            By:  /s/ T. D. Kale
     ---------------------------             -------------------------------
     By:                                     Name: Tom D. Kale
     Title:                                  Title: Vice Chancellor for Business
                                                    Services

Date: 4/16/02                           Date: 4/29/02

                                   Page 5 of 5<PAGE>

                                                                   Exhibit 10.21

                                 AMENDMENT NO. 2
                            TO THE LICENSE AGREEMENT
                                     BETWEEN
                         THE TEXAS A&M UNIVERSITY SYSTEM
                                       AND
                                 INHIBITEX, INC.

         This amendment ("Amendment No. 2") is made and entered into by and
between The Texas A&M University System (hereinafter "SYSTEM") with principal
offices in College Station, Texas, and Inhibitex, Inc. (hereinafter
"INHIBITEX"), a Delaware Corporation, having a principal place of business in
Alpharetta, Georgia, parties to the License Agreement dated February 4, 2000,
and Amendment No. 1.

                                   WITNESSETH:

         WHEREAS, the parties have entered into a License Agreement regarding
certain intellectual property related to Extracellular Matrix Binding Proteins;
and

         WHEREAS, the original License Agreement between the parties provides
that INHIBITEX return rights in individual technologies that INHIBITEX fails to
devote reasonable business efforts to the development and commercialization of
certain technology or products claimed in one or more of the patents comprising
PATENT RIGHTS; and

         WHEREAS, SYSTEM understands the principles of patent portfolio
management; and

         WHEREAS, INHIBITEX desires to modify the License Agreement in regard
to its return of rights in individual technologies; and

         WHEREAS, INHIBITEX also desires to modify the License Agreement in
regards to specific sublicensee obligations; and

         WHEREAS, SYSTEM agrees to make such modifications.

         NOW THEREFORE, the parties agree that the License Agreement of February
4, 2000 is hereby amended as follows:

1.       DELETE paragraph 3.01 in its entirety.

2.       ADD a new paragraph 3.01 as follows:

         3.01     Commercial Development and Sales. In consideration of the
                  license grant made to INHIBITEX by SYSTEM herein, INHIBITEX
                  agrees to use commercially reasonable efforts to accomplish
                  commercial development of LICENSED PRODUCTS. INHIBITEX or its
                  sublicensee(s) shall record first NET SALES no later than
                  December 31, 2006, unless failure to reach this development
                  milestone is due to unanticipated or unexpected commercial
                  circumstances, such as but not limited to unforeseen delays in
                  U.S. Government regulatory approval; or unexpected technical,
                  manufacturing scale up, clinical trial or regulatory issues.

<PAGE>

                  Once product sales begin, INHIBITEX shall record NET SALES
                  every consecutive Calendar Year.

3.       ADD new sentences to the end of paragraph 4.01 as follows:

         4.01     For example only and by way of clarification, the parties
                  agree that fees attributable to PATENT RIGHTS shall not
                  include reimbursements by a sublicensee to INHIBITEX of its
                  patent expenses or development expenses and shall not include
                  payments made to INHIBITEX by a sublicensee for achievement of
                  regulatory milestones with the FDA or similar foreign
                  governmental agencies. Payments made to INHIBITEX for
                  achievement o(pound) progress in patent prosecution, such as
                  issuance of a patent application shall be fees attributable to
                  PATENT RIGHTS.

4.       ADD a new sentence to the end of paragraph 7.06 as follows:

         Diligence respecting one or more patent applications or patents within
         the PATENT RIGHTS would constitute diligence as to the PATENT RIGHTS as
         a whole.

         EXCEPT as provided herein, all terms and conditions of the License
Agreement and Amendment No. 1 remain unchanged and in full force and effect.

         IN WITNESS WHEREOF, the parties have caused this Amendment No. 2 to
become effective on the date executed below by the last signatory to this
Amendment.

INHIBITEX, INC.                          THE TEXAS A&M UNIVERSITY SYSTEM

By:     /s/ William D. Johnston          By:     /s/ T.D. Kale
      ---------------------------              -----------------------------
            William D. Johnston                       Tom D. Kale
             President & CEO                          Vice Chancellor for
                                                      Business Services

Date: 4/16/02                            Date: 4/29/02

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