<PAGE>

                                                                   Exhibit 10.23

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

                                LICENCE AGREEMENT

                                     between

                               LONZA BIOLOGICS PLC

                                       and

                                 INHIBITEX, INC.

<PAGE>

                                      - 2 -

                                      INDEX

<TABLE>
<CAPTION>
ARTICLE      TITLE                                                    PAGE
-------      -----                                                    ----
<S>                                                                   <C>
1.           Definitions                                                3

2.           Supply of Materials and Know-How                           6

3.           Ownership of Property and Intellectual Property            6

4.           Licences                                                   7

5.           Payments                                                   8

6.           Royalty Procedures                                         9

7.           Liability and Warranties                                  10

8.           Confidentiality                                           11

9.           Patents                                                   13

10.          Term and Termination                                      14

11.          Assignment                                                15

12.          Governing Law and Jurisdiction                            16

13.          Force Majeure                                             16

14.          Illegality                                                17

15.          Miscellaneous                                             17

16.          Notice                                                    18

17.          Interpretation                                            19

SCHEDULE

1            Patent Rights                                             20
</TABLE>

<PAGE>

                                     - 3 -

THIS AGREEMENT is made the 23rd day of December 2002

BETWEEN

LONZA BIOLOGICS PLC of 228 Bath Road, Slough, Berkshire SL1 4DY, England
(hereinafter referred to as "Biologics"), and

INHIBITEX, INC. of 8995 Westside Parkway, Alpharetta, Georgia 30004, USA
(hereinafter referred to as "Licensee")

WHEREAS

A.       Biologics is the proprietor of the System and certain Intellectual
         Property rights in relation thereto (all as hereinafter defined), and

B.       The Licensee wishes to take a Licence under Intellectual Property (as
         hereinafter defined) of which Biologics is the proprietor to
         commercially exploit the Product (as hereinafter defined) in the form
         hereunder.

NOW THEREFORE the parties hereby agree as follows:

1.       Definitions

         1.1      "Affiliate" means any company, partnership or other entity
                  which directly or indirectly controls, is controlled by or is
                  under common control with the relevant party to this
                  Agreement. "control" means the ownership of more than fifty
                  percent (50%) of the issued share capital or the legal power
                  to direct or cause the direction of the general management and
                  policies of the party in question.

         1.2      "Cell Lines" means those cell lines referred to in Clause
                  2.1.1(b).

         1.3      "Effective Date" means the date first above written.

         1.4      "First Commercial Sale" means the date of the first sale or
                  other disposal of Product for consideration by the Licensee or
                  its sublicensee.

<PAGE>

                                     - 4 -

         1.5      "Intellectual Property" means Materials Know-How and Patent
                  Rights owned by Biologics or an Affiliate of Biologics and
                  which Biologics has a right to grant herein.

         1.6      "Know-How" means unpatented technical and other information
                  including but without prejudice to the generality of the
                  foregoing ideas, concepts, inventions, discoveries, data,
                  formulae, specifications, procedures for experiments and tests
                  and other protocols, results of experimentation and testing,
                  fermentation and purification techniques and assay protocols.

         1.7      "Materials" means the System, vectors containing the System,
                  but excluding any gene inserted into the System by Licensee
                  for the purposes of producing Product.

         1.8      "Materials Know-How" means Know-How specifically relating to
                  the Materials of which Biologics is the proprietor.

         1.9      "Net Selling Price" means all monies received by or on behalf
                  of Licensee or its sublicensee hereunder in respect of the
                  sale of Product in the Territory less the following items to
                  the extent that they are paid or allowed and included in the
                  invoice price:

                  1.9.1    normal discounts actually granted;

                  1.9.2    credits allowed for Product or other goods returned
                           or not accepted by customers;

                  1.9.3    packaging, transportation and prepaid insurance
                           charges on shipments or deliveries to customers; and

                  1.9.4    taxes actually incurred and paid by Licensee or its
                           sublicensee hereunder in connection with the sale or
                           delivery of Product or other goods to customers.

                  Upon any sale or other disposal of Product by or on behalf of
                  Licensee or its sublicensee hereunder other than a bona fide
                  arms length transaction exclusively for money or upon any use
                  of the Product for purposes which do not result in a

<PAGE>
                                     - 5 -

                  disposal of such Product in consideration of sales revenue
                  customary in the country of use, such sale, other disposal or
                  use shall be deemed to constitute a sale at the then current
                  maximum selling price in the country in which such sale, other
                  disposal or use occurs.

                  For the avoidance of doubt, the supply of Product free of
                  charge as commercial samples or for use in clinical studies or
                  to third parties for evaluation purposes shall not be included
                  in this provision and shall not be deemed to constitute a
                  sale.

         1.10     "Patent Rights" means the patents and applications which
                  Biologics has a right to grant herein short particulars of
                  which are set out in Schedule 1 hereto and all patents and
                  applications thereof of any kind throughout the world whether
                  national or regional including but without prejudice to the
                  generality of the foregoing, author certificates, inventor
                  certificates, improvement patents, utility certificates and
                  models and certificates of addition and including any
                  divisions, renewals, continuations, continuations in part,
                  extensions of reissue thereof.

         1.11     "Product" means a monoclonal antibody to a bacterial cell
                  surface adhesion known as Aurexis(TM) of which Licensee is the
                  proprietor and which is obtained by the expression of any one
                  gene or of any combination of genes by use of the Materials,
                  or any formulation containing the same.

         1.12     "System" means the glutamine synthetase gene expression system
                  of which Biologics is the proprietor which is described in the
                  Patent Rights and Materials Know-How.

         1.13     "Territory" means world-wide.

         1.14     "Valid Claim" means a claim within the Patent Rights
                  (including any re-issued and unexpired patents) which has not
                  been held unenforceable or invalid by the decision of a court
                  or other governmental agency of competent jurisdiction
                  unappealable or unappealed within the time allowed for appeal
                  and which has not been admitted to be invalid or unenforceable
                  through re-issue or disclaimer or otherwise and which has not
                  expired or been abandoned.

<PAGE>
                                     - 6 -

2.       Supply of Materials and Know-How

         2.1      Immediately following the signature of this Agreement by both
                  parties and receipt of the payment specified in Clause 5.1.1
                  hereof Biologics shall, if requested by Licensee in writing,
                  arrange for supply free of charge ex-works Biologics'
                  premises, Slough, Berkshire (Incoterms 2000) to Licensee the
                  following:

                  2.1.1    Materials

                           (a)      Approximately 20(mu)g of vector pEE12.4.
                                    Approximately 20(mu)g of vector pEE14.4.
                                    Approximately 20(mu)g of vector pEE13.4.
                                    Approximately 20(mu)g of vector pEE6.4.
                                    Approximately 20(mu)g of vector pCon gamma 4
                                    (proline at 241).
                                    Approximately 20(mu)g of vector pCon kappa.
                                    Approximately 20(mu)g of vector pCon gamma
                                    1-f.
                                    Approximately 20(mu)g of vector pCon gamma
                                    1-za.

                           (b)      Two 1ml vials of myeloma cell line NS0.
                                    Two 1ml vials of the Chinese Hamster Ovary
                                    cell line CHO-K1.

                  2.1.2    Materials Know-How

                           Materials Know-How contained as at the date
                           hereinabove in manuals of operating procedures for
                           the System.

                           Licensee shall use the Materials and Cell Lines only
                           in the expression of Product by insertion of gene(s)
                           coding for Product(s) into the Materials and Cell
                           Lines, and shall not use, cause the use of or permit
                           to be used the Materials or the Cell Lines for any
                           purpose not directly authorised by this Agreement.

3.       Ownership of Property and Intellectual Property

         3.1      It is hereby acknowledged and agreed that any and all property
                  and Intellectual Property in the Materials is vested in
                  Biologics.

<PAGE>
                                     - 7 -

         3.2      The provisions of this clause shall survive termination of
                  this Agreement.

4.       Licences

         4.1      Biologics hereby grants to Licensee a world-wide non-exclusive
                  licence under the Intellectual Property to develop,
                  manufacture, market and sell Product in the Territory save as
                  provided by Clause 4.3 below, there shall be no right to
                  sublicense the rights granted hereunder.

         4.2      Save as expressly provided by Clause 2 above, the Licensee
                  hereby undertakes not to make any modifications or adaptations
                  to the Materials or the Cell Lines during the subsistence of
                  this Agreement.

         4.3      Subject to the provisions of this Clause 4.3, Licensee shall
                  be entitled to grant a sublicence to the rights granted by
                  Clause 4.1 to a third party for the purposes of that third
                  party producing Product for Licensee provided always:

                  4.3.1    Licensee shall ensure such sublicensee's use of the
                           Materials, the Cell Lines, the Intellectual Property
                           and the Product is undertaken solely for the purpose
                           of establishing a manufacturing process for Product,
                           or producing Product, for Licensee; and

                  4.3.2    The sublicensee shall not, by virtue of this
                           Agreement, be granted any right or licence, either
                           express or implied, under any patent or proprietary
                           right vested in Biologics or otherwise, to use the
                           Materials, the Intellectual Property or the Product
                           other than for the purposes of establishing a
                           manufacturing Process for Product or producing
                           Product for Licensee and Licensee agrees to ensure
                           that such sublicensee shall not assign, transfer,
                           further sublicense or otherwise make over the benefit
                           or the burden of the rights granted to it pursuant to
                           this Agreement; and

                  4.3.3    Any sublicence granted shall be expressly subject and
                           subordinate to the terms of this Agreement, and it
                           shall be Licensee's responsibility to ensure the
                           strict adherence by any sublicensee hereunder to the
                           terms and conditions of this Agreement; and

<PAGE>
                                     - 8 -

                  4.3.4    Promptly following the grant of any sublicensee
                           pursuant to this Clause 4, Licensee shall notify
                           Biologics of the identity of the sublicensee and
                           shall confirm it has complied with the requirements
                           of this Clause 4.3 in respect of the same.

5.       Payments

         5.1      In consideration of the licence granted to Licensee pursuant
                  to Clause 4.1 hereof, Licensee shall pay Biologics as follows:

                  5.1.1    [ *** ] per annum upon the Effective Date of this
                           Agreement; and

                  5.1.2    a royalty of [ *** ] of the Net Selling Price of
                           Product manufactured by the Licensee or Biologics.

         5.2      Upon the grant by Licensee of one or more sublicence(s) in
                  respect of the rights granted by Clause 4.1 pursuant to Clause
                  4.3 and during the continued existence of such sublicence(s)
                  the annual licence fee refered to in clause 5.1.1 shall not
                  become due but rather Licensee shall pay Biologics as follows:

                  5.2.1    [ *** ] per sublicence per annum for use of Materials
                           for production of Product for development services
                           for human clinical studies with initial payment being
                           due on the commencement of manufacture of the first
                           GMP batch for such clinical studies; and

                  5.2.2    [ *** ] per sublicence per annum for use of Materials
                           for production of Product for commercial purposes
                           with initial payment being due on the date of grant
                           of the Biologics Licence Application; and

                  5.2.3    a royalty of [ *** ] of the Net Selling Price of
                           Product manufactured by a sublicensee.

<PAGE>
                                     - 9 -

         5.3      For the avoidance of doubt the annual licence fee refered to
                  in clause 5.1.1 shall not be payable on its anniversary if one
                  or more licence fees have been paid during the preceding 12
                  months in accordance with clauses 5.2.1 or 5.2.2 and in the
                  event that Licensee has previously sub-licensed the rights in
                  accordance with clause 5.2 and subsequently terminates such
                  sub-license, then the annual licence fee referred to in clause
                  5.1.1 shall only become payable upon the anniversary of the
                  Effective Date subsequent to the termination of all
                  sub-licences unless a new sub-licence is granted prior to such
                  anniversary and payment is made in accordance with clause 5.2

         6.       Royalty Procedures

         6.1      Licensee shall keep true and accurate records and books of
                  account containing all data necessary for the calculation of
                  royalties payable to Biologics. Such records and books of
                  account shall, upon reasonable notice having been given by
                  Biologics be open for inspection by Biologics or its duly
                  authorised representative.

         6.2      Licensee shall prepare a statement in respect of each calendar
                  quarter which shall show for the quarter in question details
                  of the sales of Product and the royalty due and payable to
                  Biologics thereon.

                  Such statement shall be submitted to Biologics within thirty
                  (30) days of the end of the calendar quarter to which it
                  relates together with a remittance for the royalties due to
                  Biologics.

         6.3      All sums due under this Agreement:

                  6.3.1    shall be made in pounds sterling to Biologics.
                           Payments due to Biologics in currencies other than
                           pounds sterling shall first be calculated in the
                           relevant local currency before being calculated at
                           the rate of exchange ruling at the close of business
                           on the day payment is due or made, whichever is
                           earlier, provided always that where payment is made
                           after the date provided therefore herein conversion
                           shall be at the rate ruling at the date of payment if
                           this is more favourable to Biologics. The rate of
                           exchange shall be the mean value of the Pound Spot
                           Rate in London first

<PAGE>
                                     - 10 -

                           published in the Financial Times on the day following
                           the day for determining such rates.

                  6.3.2    are exclusive of any Value Added Tax or of any other
                           applicable taxes, levies, imposts, duties and fees of
                           whatever nature imposed by or under the authority of
                           any government or public authority which shall be
                           paid by Licensee. The parties agree to co-operate in
                           all respects necessary to take advantage of such
                           double taxation agreements as may be available.

         6.4      Where Biologics does not receive payment of any sum by the due
                  date, interest shall accrue thereafter on the sum due and
                  owing to Biologics at the rate of four percent (4%) over the
                  base rate from time to time of HSBC Bank plc, interest to
                  accrue on a day to day basis without prejudice to Biologics'
                  right to receive payment on the due date.

7.       Liability and Warranties

         7.1      Biologics gives no representation or warranty that the Patent
                  Rights which are patent applications will be granted or if
                  granted will be valid nor that the exercise of the rights
                  granted to Licensee hereunder will not infringe other patent
                  rights or intellectual property rights vested in Biologics or
                  any third party. Biologics represents and warrants to Licensee
                  that as of the Effective Date that it has the title to grant
                  the licence granted pursuant to this Agreement and that the
                  licence granted does not conflict with or violate the terms of
                  any agreement between Biologics and any third party.

         7.2      To the best of Biologics' knowledge and belief, as of the date
                  hereof, save for the Patent Rights there are no patent rights
                  or patent applications with respect to the Materials and
                  Materials Know How of which Biologics or its Affiliate is the
                  proprietor and which are necessary to enable the Licensee to
                  exercise the rights granted herein.

                  In the event Biologics becomes the proprietor of patent rights
                  with respect to the Materials and Materials Know How which are
                  necessary to enable Licensee to exercise the rights granted
                  herein, Biologics agrees to grant a licence under the

<PAGE>
                                     - 11 -

                  patent rights to the extent necessary to enable the Licensee
                  to exercise such rights at no additional charge.

                  As of the date of this Agreement Biologics' Legal or Corporate
                  Departments have not received any claim or demand by any third
                  party claiming infringement of its intellectual property
                  rights by use of the Intellectual Property in accordance with
                  the provisions of this Agreement. Biologics agrees to notify
                  Licensee at any time during the term of this Agreement if it
                  receives such notice or demand.

         7.3      The Licensee hereby acknowledges that in order to exploit the
                  rights contained herein the Licensee may require licences
                  under Biologics patent rights other than those herein licensed
                  or under third party patent rights (including those vested in
                  Affiliates of Biologics) that may be infringed by the use by
                  the Licensee of the rights licensed herein and it is hereby
                  agreed that it shall be the Licensee's responsibility to
                  satisfy itself as to the need for such licences and if
                  necessary to obtain such licences. No licence is granted save
                  as expressly provided herein and no licence in addition
                  thereto shall be deemed to have arisen or be implied by way of
                  estoppel or otherwise.

         7.4      Licensee shall indemnify and hold harmless Biologics and its
                  officers, servants and agents at all times in respect of any
                  and all losses, damages, costs and expenses suffered or
                  incurred as a result of any contractual, tortious or other
                  claims or proceedings by third parties against Biologics
                  arising in any way out of the exercise by Licensee of any of
                  the rights granted to it under this Agreement, including, but
                  not limited to, product liability claims or proceedings save
                  to the extent that such third party claims relate solely to
                  the System and Licensee's use of the System in accordance with
                  the scope of this Agreement.

         7.6      Any condition or warranty other than those relating to title
                  which might otherwise be implied or incorporated within this
                  Agreement by reason of statute or common law or otherwise is
                  hereby expressly excluded.

         7.5      The terms of this Clause 7 shall survive termination of the
                  Agreement for whatever reason.

<PAGE>
                                     - 12 -

8.       Confidentiality

         8.1      Licensee expressly acknowledges that the Materials Know-How
                  and any other Know-How with which it is supplied by Biologics
                  pursuant to this Agreement is supplied in circumstances
                  imparting an obligation of confidence and Licensee agrees to
                  keep such Know How or Materials Know-How secret and
                  confidential and to respect Biologics' proprietary rights
                  therein and to use the same for the sole purpose of this
                  Agreement and not during the period of this Agreement or at
                  any time for any reason whatsoever to disclose or permit to be
                  disclosed such Know How or Materials Know-How to any third
                  party other than its sublicensee hereunder for use in
                  accordance with the terms of this Agreement. Licensee shall
                  procure that only its employees and employees of it
                  sublicensee hereunder shall have access to the Know How or
                  Materials Know-How on a need to know basis and that all such
                  employees shall be informed of their secret and confidential
                  nature and shall be subject to the same obligations as
                  Licensee and its sublicensee hereunder pursuant to this Clause
                  8.1.

         8.2      Licensee hereby undertakes and agrees to keep the Materials
                  and the Cell Lines secure and safe from loss, damage, theft,
                  misuse and unauthorised access and shall procure that the
                  Materials and the Cell Lines shall be made available only to
                  employees of Licensee and employees of its sublicensee
                  hereunder on a need to know basis and subject to the same
                  obligations of confidence as provided in Clause 8.1 hereof,
                  and to use the same for the sole purpose of this Agreement.

         8.3      Both parties undertake and agree not to at any time for any
                  reason whatsoever disclose or permit to be disclosed to any
                  third party or otherwise make use of or permit to be made use
                  of any trade secrets or confidential information relating to
                  the business affairs or finances of the other or of any
                  suppliers, agents, distributors, licensees or other customers
                  of the other which comes into their possession pursuant to
                  this Agreement.

         8.4      The obligations of confidence referred to in this Clause 8
                  shall not extend to any information which:

<PAGE>
                                     - 13 -

                  8.4.1    is or shall become generally available to the public
                           otherwise than by reason of a breach by the recipient
                           party of such information of the provisions of this
                           Clause 8;

                  8.4.2    is known to the recipient party of such information
                           and is at its free disposal prior to its receipt from
                           the other;

                  8.4.3    is subsequently disclosed to the recipient party
                           without obligations of confidence by a third party
                           owing no such obligations in respect thereof; and

                  8.4.4    Biologics or Licensee may be required to disclose to
                           a government agency for the purpose of any statutory,
                           regulatory or similar legislative requirement
                           applicable to the production of Product or to meet
                           the requirements of any Stock Exchange to which the
                           parties may be subject but only to the extent such
                           disclosure is required, and subject to obligations of
                           secrecy wherever possible; and

                  8.4.5    can be demonstrated by competent written evidence as
                           having been independently developed by the recipient
                           of the information in questions without reference to
                           that information.

         8.5      The obligations of both parties under this Clause 8 shall
                  survive the expiry or termination of this Agreement for
                  whatever reason.

9.       Patents

         9.1      Biologics hereby undertakes and agrees that at its own cost
                  and expense it will:

                  9.1.1    prosecute or procure prosecution of such of the
                           Patent Rights which are patent applications
                           diligently to grant so as to secure the best
                           commercial advantage obtainable so far as it is
                           reasonable to do so with reference to Biologics'
                           commercial considerations; and

                  9.1.2    pay or procure payment of all renewal fees in respect
                           of the Patent Rights valid and subsisting for the
                           full term thereof and in particular will procure

<PAGE>
                                     - 14 -

                           such renewal of the registrations thereof as may be
                           necessary from time to time so far as it is
                           reasonable to do so with particular reference to
                           commercial considerations.

         9.2      Licensee shall promptly notify Biologics in writing of any
                  infringement or improper or unlawful use of or of any
                  challenge to the validity of the Patent Rights and/or
                  Know-How. Biologics undertakes and agrees to take all such
                  steps and proceedings and to do all other acts and things as
                  may in Biologics' sole discretion be necessary to restrain any
                  such infringement or improper or unlawful use or to defend
                  such challenge to validity and Licensee shall permit Biologics
                  to have the sole conduct of any such steps and proceedings
                  including the right to settle them whether or not Licensee is
                  a party to them.

10.      Term and Termination

         10.1     Unless terminated earlier in accordance with the provisions of
                  this Clause 10 or Clause 13 or 14, this Agreement shall
                  continue in force in each country of the world, until expiry
                  of the last to expire of a period of fifteen (15) years from
                  the date of First Commercial Sale or until expiry of the last
                  Valid Claim, whichever is later always provided that this
                  Agreement shall terminate before the expiry of the said
                  fifteen (15) year period and after the expiry of the last
                  Valid Claim if Biologics makes publicly available the
                  Materials and the Materials Know-How.

         10.2     Licensee may terminate this Agreement by giving sixty (60)
                  days notice in writing to Biologics.

         10.3     Either Biologics or Licensee may terminate this Agreement
                  forthwith by notice in writing to the other upon the
                  occurrence of any of the following events:

                  10.3.1   if the other commits a breach of this Agreement which
                           in the case of a breach capable of remedy shall not
                           have been remedied within sixty (60) days of the
                           receipt by the other of a notice identifying the
                           breach and requiring its remedy.

                  10.3.2   if the other is unable to pay its debts or enters
                           into compulsory or voluntary liquidation (other than
                           for the purpose of effecting a

<PAGE>
                                     - 15 -

                           reconstruction or amalgamation in such manner that
                           the company resulting from such reconstruction or
                           amalgamation if a different legal entity shall agree
                           to be bound by and assume the obligations of the
                           relevant party under this Agreement) or compounds
                           with or convenes a meeting of its creditors or has a
                           receiver appointed over all or any part of its assets
                           or takes or suffers any similar action in consequence
                           of a debt, or ceases for any reason to carry on
                           business.

         10.4     If at any time during this Agreement Licensee directly or
                  indirectly opposes or assists any third party to oppose the
                  grant of letters patent or any patent application within any
                  of the Patent Rights or disputes or directly or indirectly
                  assists any third party to dispute the validity of any patent
                  within any of the Patent Rights or any of the claims thereof
                  Biologics shall be entitled at any time thereafter to
                  terminate all or any of the licences granted hereunder
                  forthwith by notice to Licensee.

         10.5     If this Agreement is terminated for any reason any and all
                  licences granted hereunder shall terminate with effect from
                  the date of termination and Licensee shall destroy all
                  Materials, Cell Lines and Product forthwith and shall certify
                  such destruction immediately thereafter in writing to
                  Biologics.

         10.6     Termination for whatever reason or expiration of this
                  Agreement shall not affect the accrued rights of the parties
                  arising in any way out of this Agreement as at the date of
                  termination. The right to recover damages against the other
                  and all provisions which are expressed to survive this
                  Agreement shall remain if full force and effect.

11.      Assignment

         11.1     Save as expressly provided by Clause 4. neither party shall be
                  entitled to assign, transfer, charge or in any way make over
                  the benefit and/or burden of this Agreement without the prior
                  written consent of the other which consent shall not be
                  unreasonably withheld or delayed save that Company shall be
                  entitled without the prior written consent of Biologics to
                  assign, transfer, charge, sub-contract, deal with or in any
                  manner make over the benefit and/or burden of this Agreement
                  to an entity to which Company has assigned its entire business
                  in the

<PAGE>
                                     - 16 -

                  field relevant to the Research Evaluation and Biologics shall
                  be entitled without the prior written consent of the other
                  party to assign transfer, charge, sub-contractor deal with or
                  in any other manner make over the benefit and/or burden of
                  this Agreement to an Affiliate or to any 50/50 joint venture
                  company of which Biologics is the beneficial owner of fifty
                  per cent (50%) of the issued share capital thereof or to any
                  company with which Biologics may merge or to any company to
                  which that party may transfer its assets and undertakings.

         11.2     This Agreement shall be binding upon the successors and
                  assigns of the parties and the name of a party appearing
                  herein shall be deemed to include the names of its successors
                  and assigns provided always that nothing herein shall permit
                  any assignment by either party except as expressly provided
                  herein.

12.      Governing Law and Jurisdiction

         12.1     The validity, construction and performance of this Agreement
                  shall be governed by English law to the jurisdiction of whose
                  courts the parties hereto submit.

         12.2     Either party shall have the right to take proceedings in any
                  other jurisdiction for the purposes of enforcing a judgement
                  or order obtained from the Court in England.

13.      Force Majeure

         Neither party shall be in breach of this Agreement if there is any
         total or partial failure of performance by it of its duties and
         obligations under this Agreement occasioned by acts and events beyond
         its control such as any act of God, fire, act of government or state,
         war, civil commotion, insurrection, embargo, prevention from or
         hindrance in obtaining any raw materials, energy or other supplies,
         labour disputes of whatever nature and any other reason beyond the
         control of either party. If either party is unable to perform its
         duties and obligations under this Agreement as a direct result of the
         effect of one of the reasons set out in this Clause 13 such party shall
         give written notice to the other of such inability stating the reason
         in question. The operation of this Agreement shall be suspended during
         the period (and only during the period) in which the reason continues.
         Forthwith upon the reason ceasing to exist the party relying upon it
         shall give written advice to the other of this fact. If the reason
         continues for a period of more than ninety

<PAGE>
                                     - 17 -

         (90) days and substantially affects the commercial basis of this
         Agreement the party not claiming under this Clause 13 shall have the
         right to terminate this Agreement by giving sixty (60) days written
         notice of such termination to the other party.

14.      Illegality

         If any provision or term of this Agreement or any part thereof shall
         become or be declared illegal, invalid or unenforceable for any reason
         whatsoever including but without limitation by reason of the provisions
         of any legislation or other provisions having the force of law or by
         reason of any decision of any Court or other body or authority having
         jurisdiction over the parties hereto or this Agreement including the EC
         Commission or the European Court of Justice, such terms or provisions
         shall be divisible from this Agreement and shall be deemed to be
         deleted from this Agreement in the jurisdiction in question provided
         always that if any such deletion substantially affects or alters the
         commercial basis of this Agreement either party shall have the right to
         terminate this Agreement by giving sixty (60) days written notice of
         such termination to the other party.

15.      Miscellaneous

         15.1     This Agreement embodies and sets forth the entire agreement
                  and understanding of the parties and supersedes all prior oral
                  and written agreements, understanding or arrangements relating
                  to the subject matter of this Agreement. Neither party shall
                  be entitled to rely on any agreement, understanding or
                  arrangement which is not expressly set forth in this
                  Agreement.

         15.2     This Agreement shall not be amended, modified, varied or
                  supplemented except in writing signed by duly authorised
                  representatives of the parties.

         15.3     No failure or delay on the part of either party hereto to
                  exercise any right or remedy under this Agreement shall be
                  construed or operated as a waiver thereof nor shall any single
                  or partial exercise of any right or remedy under this
                  Agreement preclude the exercise of any other right or remedy
                  or preclude the further exercise of such right or remedy as
                  the case may be. The rights and remedies provided in this
                  Agreement are cumulative and are not exclusive of any rights
                  or remedies provided by law.

<PAGE>
                                     - 18 -

         15.4     The text of any press release or other communication to be
                  published by or in the media whether of a scientific nature or
                  otherwise and concerning the subject matter of this Agreement
                  shall require the prior written approval of Biologics.
                  Notwithstanding the foregoing, nothing herein shall be
                  construed as limiting Licensee's rights or ability to publish,
                  present or use in any way data and results relating solely and
                  exclusively to the Research Evaluation without reference to
                  the System, the Materials, the Intellectual Property or
                  Biologics. Such publication, presentation or use by Company
                  shall not require prior review or written approval of
                  Biologics.

         15.5     Each of the parties hereto shall be responsible for its
                  respective legal and other costs incurred in relation to the
                  preparation of this Agreement.

         15.6     The parties to this Agreement do not intend that any term
                  hereof should be enforceable by virtue of the Contracts
                  (Rights of Third Parties) Act 1999 by any person who is not a
                  party to this Agreement.

16.      Notice

         16.1     Any notice or other document to be given under this Agreement
                  shall be in writing and shall be deemed to have been duly
                  given if left at or sent by registered post, courier,
                  facsimile or other electronic media to a party or delivered in
                  person to a party at the address or facsimile number set out
                  below for such party or such other address as the party may
                  from time to time designate by written notice to the other(s):

                  Address of Biologics
                  Lonza Biologics plc, 228 Bath Road, Slough, Berkshire SL1 4DY
                  Facsimile: 01753 777001
                  For the attention of the Head of Legal Services

                  Address of Licensee
                  Inhibitex, Inc., 8995 Westside Parkway, Alpharetta,
                  Georgia 30004, USA
                  Facsimile: 001 678 336 2612

<PAGE>
                                     - 19 -

                  For the attention of President and Chief Operating Officer
                  with a copy to Chief Scientific Officer

         16.2     All such notices and documents shall be in the English
                  language. Any such notice or other document shall be deemed to
                  have been received by the addressee seven (7) working days
                  following the date of despatch of the notice or other document
                  by post or, where the notice or other document is sent by hand
                  or is given by facsimile or other electronic media,
                  simultaneously with the transmission or delivery. To prove the
                  giving of a notice or other document it shall be sufficient to
                  show that it was despatched.

17.      Interpretation

         17.1     The headings in this Agreement are inserted only for
                  convenience and shall not affect the construction hereof.

         17.2     Where appropriate words denoting a singular number only shall
                  include the plural and vice versa.

         17.3     Reference to any statute or statutory provision includes a
                  reference to the statute or statutory provision as from time
                  to time amended, extended or re-enacted.

AS WITNESS the hands of the duly authorised representatives of the parties
hereto

Signed for and on behalf of                             [ILLEGIBLE]
LONZA BIOLOGICS PLC                              -------------------------

                                                         Secretary         TITLE

Signed for and on behalf of                         /s/ Joseph M. Patti
INHIBITEX, INC.                                  -------------------------

                                       CSO and VP Preclinical Development. TITLE

<PAGE>
                                     - 20 -

                                   SCHEDULE 1

                                  PATENT RIGHTS

Biologics Ref:          LBP07 (formerly known as PA98)

Priority Dates:         01.04.85 and 03.09.85

Title:                  Transformed Myeloma Cell-Line and a Process for the
                        Expression of a Gene Coding for a Eukaryotic Polypeptide
                        employing same

Inventors:              John Henry Kenten
                        Michael Alan Boss

<TABLE>
<CAPTION>
                         Patent Application
Territory                or * Patent Number          Patent Expiry Date
---------                ------------------          ------------------
<S>                      <C>                         <C>
Australia                     * 584417                    01.04.06

Bulgaria                      *  60107                    01.04.06

Canada                        *1319120                    15.06.10

Europe+                       * 216846                    01.04.06

Russia                        *2079553                    01.04.06

United Kingdom                *2183662                    01.04.06

USA (cont III)                *5981216                    09.11.16
</TABLE>

+        includes Austria, Belgium, France, Germany, Italy, Luxembourg,
         Netherlands, Sweden and Switzerland.

<PAGE>
                                     - 21 -

Celltech Ref. No:                PA 108

Subject Matter:                  Expression systems containing a glutamine
gene                             synthetase

Title:                           Recombinant DNA Sequences, Vectors containing
                                 them and method for the use thereof

Origin:                          Celltech/University of Glasgow joint invention
Registered Owner:                Celltech Limited/University of Glasgow
Beneficial Owner:                Celltech R&D Limited/University of Glasgow

Priority Application Date:       23rd January 1986
Earliest Publication Date/No:    30th July 1987/WO87/04462

<TABLE>
<CAPTION>
Territory              Application Date       Application No.       Patent No.      Expiry Date
---------              ----------------       ---------------       ----------      -----------
<S>                    <C>                    <C>                   <C>             <C>
Australia                  23.01.87              68935/87             599081          23.01.07
Canada                     23.01.87              528011               1338901         11.02.14
*Europe                    23.01.87              87900856.3           0256055         23.01.07
Japan                      23.01.87              500891/87            7032712         23.01.07
USA                        23.01.87              07/595733            5122464         16.06.09
USA (divisional)           23.01.87              08/302241            5770359         16.06.09
USA (divisional)           23.01.87              08/476567            5827739         16.06.09
</TABLE>

*includes: Austria, Belgium, France, Germany, Italy, Liechtenstein, Luxembourg,
Netherlands, Sweden, Switzerland, United Kingdom

<PAGE>
                                     - 22 -

Biologics Ref:       LBP09 (formerly known as PA 140)

Priority Date:       23.07.87

Title:               Recombinant DNA Product and Processes using it

Inventors:           Christopher Robert Bebbington

<TABLE>
<CAPTION>
                          Patent Application
Territory                 or * Patent Number          Patent Expiry Date
---------                 ------------------          ------------------
<S>                       <C>                         <C>
Europe+                        * 323997                    22.07.08

Japan                          *2505268                    22.07.08

USA (cont II)                  *5591639                    07.01.14

USA (divisional)               *5658759                    19.08.14
</TABLE>

+        includes Austria, Belgium, France, Germany, Italy, Luxembourg,
         Netherlands, Sweden, Switzerland and United Kingdom

<PAGE>
                                     - 23 -

Biologics Ref:       LBP10 (formerly known as PA 177)

Priority Date:       18.04.88

Title:               Recombinant DNA Methods, Vectors and Host Cells

Inventors:           Christopher Robert Bebbington
                     Geoffrey Thomas Yarranton

<TABLE>
<CAPTION>
                          Patent Application
Territory                 or * Patent Number          Patent Expiry Date
---------                 ------------------          ------------------
<S>                       <C>                         <C>
Australia                      * 624616                    18.04.09

Canada                         *1338891                    04.02.14

Europe+                        * 338841                    18.04.09

Japan                          *2007380                    18.04.09

USA (cont I)                   *5879936                    09.03.16

USA (cont II)                  *5891693                    06.04.16
</TABLE>

+        includes Austria, Belgium, France, Germany, Greece, Italy, Luxembourg,
         Netherlands, Spain, Sweden, Switzerland and United Kingdom