Document:

Exhibit 4(j)

                             SIGA TECHNOLOGIES, INC.

                      Non-Qualified Stock Option Agreement

                                                     Granting Date: May 23, 2003

To: ___________________________

            We are pleased to notify you that, pursuant to the SIGA
Technologies, Inc. Amended and Restated 1996 Incentive and Non-Qualified Stock
Option Plan (the "Plan"), SIGA TECHNOLOGIES, INC., a Delaware corporation (the
"Company") has granted to you (the "Holder") a Non-Qualified stock option (the
"Option") to purchase all or any part of an aggregate of 100,000 shares of
Common Stock of the Company (the "Optioned Shares"), subject to the terms and
conditions of this Agreement and the Plan. All terms, conditions and
restrictions of the Plan are incorporated herein and made part hereof as if
stated herein. If there is any conflict between the terms and conditions of the
Plan and this Agreement, the terms and conditions of the Plan, as interpreted by
the Committee, shall govern. Except as otherwise provided herein, all
capitalized terms (and any other terms defined in the Plan) used herein shall
have the meaning given to such terms in the Plan.

            1. Term and Exercise of Option. Subject to the provisions of this
Agreement, this Option may be exercised for up to the number of Optioned Shares
(subject to adjustment as provided in Section hereof) by you on or prior to May
23, 2013 ("Last Exercise Date") at an initial exercise price (the "Exercise
Price") of $1.81 per share (subject to adjustment as provided in Section 7
hereof) and all as subject to the Plan and this Agreement. The Holder may
exercise this Option at any time after the date of this Agreement. Any portion
of the Option that you do not exercise shall accumulate and can be exercised by
you any time prior to the Last Exercise Date. You may not exercise your Option
to purchase a fractional share or fewer than 100 shares, and you may only
exercise your Option by purchasing shares in increments of 100 shares unless the
remaining shares purchasable are less than 100 shares.

            This Option may be exercised by delivering to the Secretary of the
Company (i) a written Notice of Intention to Exercise in the form attached
hereto as Exhibit A signed by you and specifying the number of Optioned Shares
you desire to purchase, (ii) payment, in full, of the Exercise Price for all
such Optioned Shares in cash, certified check, surrender of shares of Common
Stock of the Company having a value equal to the exercise price of the Optioned
Shares as to which you are exercising this Option, provided that such
surrendered shares, if previously acquired by exercise of a Company stock
option, have been held by you at least six months prior to their surrender, or
by means of a brokered cashless exercise. As a holder of an option, you shall
have the rights of a shareholder with respect to the Optioned Shares only after
they shall have been issued to you upon the exercise of this Option. Subject to
the terms and provisions of this Agreement and the Plan, the Company shall use
its best efforts to cause the Optioned Shares to be issued as promptly as
practicable after receipt of your Notice of Intention to Exercise.

            2. Non-transferability of Option. This Option shall not be
transferable and may be exercised during your lifetime only by you. Any
purported transfer or assignment of this Option shall be void and of no effect,
and shall give the Company the right to terminate this Option as of the date of
such purported transfer or assignment. No transfer of an Option by will or by
the laws of descent and distribution shall be effective unless the Company shall
have been furnished with written notice thereof, and such other evidence as the
Company may deem necessary to establish the validity of the transfer and
conditions of the Option, and to establish compliance with any laws or
regulations pertaining thereto.

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            3. Certain Rights and Restrictions With Respect to Common Stock. The
Optioned Shares which you may acquire upon the exercise of this Option will not
be registered under the Securities Act of 1933, as amended, or under state
securities laws and the resale by you of such Optioned Shares will, therefore,
be restricted. You will be unable to transfer such Optioned Shares without
either registration under such Act and compliance with applicable state
securities laws or the availability of an exemption therefrom. Accordingly, you
represent and warrant to the Company that all shares of Common Stock you may
acquire upon the exercise of this Option will be acquired by you for your own
account for investment and that you will not sell or otherwise dispose of any
such shares except in compliance with all applicable federal and state
securities laws. The Company may place a legend to such effect upon each
certificate representing Optioned Shares acquired by you upon the exercise of
this Option.

            4. Disputes. Any dispute which may arise under or as a result of or
pursuant to this Agreement shall be finally and conclusively determined in good
faith by the Board of Directors of the Company in its sole discretion, and such
determination shall be binding upon all parties.

            5. Termination of Status.

            (a) This Option is a separate incentive and not in lieu of salary or
other compensation. The Optioned Shares do not vest you with any right to
employment with the Company, nor is the Company's right to terminate your
employment in any way restricted by this Agreement. Subject to the following
provisions of this Section 5, the Option will terminate upon and will not be
exercisable after termination of your employment with the Company ("Employment
Termination Date"). If your employment with the Company is terminated for any
reason other than death or disability, this Option may not be exercised after
the earlier of (i) ninety (90) days from the Employment Termination Date or (ii)
the Expiration Date, and may not be exercised for more than the number of
Optioned Shares purchasable under Section 1 on the Employment Termination Date.

            (b) If you die while this Option is exercisable, or within a period
of three months after the Employment Termination Date, the Option may be
exercised by the duly authorized executor of your last will or by the duly
authorized administrator of your estate, but may not be exercised after the
earlier of (i) one year from the date of your death or (ii) the Expiration Date,
and may not be exercised for more than the number of Optioned Shares purchasable
under Section 1 on the date of your death.

            (c) If your employment is terminated as a result of your permanent
disability, this Option may not be exercised after the earlier of (i) one year
from the Employment Termination Date, or (ii) the Expiration Date, and may not
be exercised for more than the number of Optioned Shares purchasable under
Section 1 on the Employment Termination Date. If you die after the date your
employment is terminated under the provisions of this Section 5(c) but before
the Expiration Date, the provisions of Section 5(b) above shall apply.

            Permanent disability shall mean a disability described in Section
422(c)(6) of the Code. The existence of a Disability shall be determined by the
Committee in its absolute discretion.

            6. Adjustments to Exercise Price and Number of Securities. If the
Company shall at any time subdivide or combine the outstanding shares of Common
Stock, or similar corporate events the Exercise Price and the number of shares
subject to the Option shall be appropriately adjusted.

            7. Reservation and Listing of Securities. The Company shall at all
times reserve and keep available out of its authorized shares of Common Stock,
solely for the purpose of issuance upon the exercise of this Option, such number
of shares of Common Stock or other securities, properties or rights as shall be
issuable upon the exercise thereof. The Company covenants and agrees that, upon
exercise of

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this Option and payment of the Exercise Price therefor, all shares of Common
Stock and other securities issuable upon such exercise shall be duly and validly
issued, fully paid, non-assessable and not subject to the preemptive rights of
any stockholder. As long as this Option shall be outstanding, the Company shall
use its best efforts to cause all shares of Common Stock issuable upon the
exercise of the Option to be listed (subject to official notice of issuance) on
all securities exchanges on which the Common Stock may then be listed and/or
quoted on NASDAQ.

            8. Forfeiture of Option Gains. If at any time within one year after
the exercise of all or any portion of the Option the Committee determines that
the Company has been materially harmed by you, which harm either (a) results in
your being terminated for Cause or (b) results from your engaging in any
activity determined by the Committee, in its sole discretion, to be in
competition with any activity of the Company, or otherwise inimical, contrary or
harmful to the interests of the Company (including, but not limited to,
violating any non-competition or similar agreements entered into with the
Company or otherwise accepting employment with or serving as a consultant,
adviser or in any other capacity to an entity that is in competition with or
acting against the interests of the Company), then upon notice from the Company
to you any gain ("Gain") realized by you upon exercising such Option shall be
paid by you to the Company. For purposes of this Section 9, such Gain shall be
the excess of the Fair Market Value of the shares of Company Stock obtained
through such exercise as of the date of option exercise over the purchase price
of such shares. The Company shall have the right to offset such Gain against any
amounts otherwise owed to you by the Company (including, but not limited to
wages, vacation pay, or pursuant to any benefit plan or other compensatory
arrangement).

            9. Notices.

            All notices, requests, consents and other communications hereunder
shall be in writing and shall be deemed to have been duly made and sent when
delivered, or mailed by registered or certified mail, return receipt requested:

            (a) If to the registered Holder of this Option, to the address of
the Holder as shown on the books of the Company; or

            (b) If to the Company, to 420 Lexington Avenue, Suite 620, New York,
NY 10017, or to such other address as the Company may designate by notice to the
Holders.

            10. Supplements and Amendments. The Company and the Holder may from
time to time supplement or amend this Agreement in any respect, provided,
however, that no amendment may adversely affect your rights hereunder without
your written consent.

            11. Successors. All the covenants and provisions of this Agreement
shall be binding upon and inure to the benefit of the Company, the Holder and
their respective successors and assigns hereunder.

            12. Governing Law. This Agreement shall be deemed to be a contract
made under the laws of the State of New York and for all purposes shall be
construed in accordance with the laws of the State of New York without giving
effect to the rules of the State of New York governing the conflicts of laws.

            13. Entire Agreement; Modification. This Agreement contains the
entire understanding between the parties hereto with respect to the subject
matter hereof.

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            14. Severabilitv. If any provision of this Agreement shall be held
to be invalid or unenforceable, such invalidity or unenforceability shall not
affect any other provision of this Agreement.

            15. Captions. The caption headings of the Sections of this Agreement
are for convenience of reference only and are not intended, nor should they be
construed as, a part of this Agreement and shall be given no substantive effect.

            16. Benefits of this Agreement. Nothing in this Agreement shall be
construed to give to any person or corporation other than the Company and the
registered Holder of this Option any legal or equitable right, remedy or claim
under this Agreement; and this Agreement shall be for the sole and exclusive
benefit of the Company and the Holder.

            17. Counterparts. This Agreement may be executed in any number of
counterparts and each of such counterparts shall for all purposes be deemed to
be an original, and such counterparts shall together constitute but one and the
same instrument.

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            IN WITNESS WHEREOF, the parties hereto have caused this Agreement to
be dully executed, as of the day and year first written.

                                        SIGA  TECHNOLOGIES, INC.

                                        By: ____________________________________
                                              Thomas N. Konatich
                                              Acting Chief Executive Officer
                                              Chief Financial Officer

                                              __________________________________
                                              Signature of Holder

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                                   Appendix A

                  NOTICE OF INTENTION TO EXERCISE STOCK OPTIONS

The undersigned grantee of a SIGA Technologies, Inc. Stock Option Agreement
dated as of ______________________ to purchase _________ shares of SIGA
Technologies, Inc. common stock hereby gives notice of his or her intention to
exercise the Stock Option (or a portion thereof) and elects to purchase shares
of SIGA Technologies, Inc. common stock.

Shares should be issued in the name of the undersigned and should be sent to the
undersigned at:

_____________________________
_____________________________
_____________________________
_____________________________

Dated this _____ day of ____________________.

Social Security Number: ____________________

Name: ______________________________________

____________________________________________
Signature

INSTRUCTIONS: The exercise of these Stock Options is effective on the date the
Company has received all of (1) this Notice of Intention to Exercise Stock
Options, and (2) payment in full in cash of the exercise price for all shares
being purchased pursuant to this Notice.

                                       6Exhibit 10(eee)

                              EMPLOYMENT AGREEMENT

      This Employment Agreement (the "Agreement") is entered into as of May 23,
2003, between SIGA Technologies, Inc., a Delaware corporation (the
"Corporation"), and Susan K. Burgess, Ph.D. (the "Executive").

      WHEREAS, the Corporation and Plexus Vaccine Inc., a California corporation
("Plexus"), are parties to an Asset Purchase Agreement dated May 14, 2003 (the
"Asset Purchase Agreement");

      WHEREAS, as a condition precedent to the consummation of the transactions
contemplated by the Asset Purchase Agreement (the "Closing"), the parties hereto
have agreed to enter into this Agreement;

      WHEREAS, the Corporation and Executive acknowledge and agree that
immediately prior to the Closing, Executive was employed as president and chief
executive officer of Plexus and was a significant shareholder of Plexus;

      WHEREAS, the Corporation and Executive acknowledge and agree that the
retention of Executive's services and Executive's agreement to enter into and
adhere to the non-competition, non-solicitation and non-disclosure of
proprietary information provisions contained in this Agreement are critical
reasons for the Corporation entering into the Asset Purchase Agreement and
consummating the transactions contemplated thereby; and

      WHEREAS, the Corporation and Executive desire to enter into this Agreement
pursuant to which Executive shall serve as the President of the Corporation on
the terms and conditions hereinafter set forth.

      NOW, THEREFORE, in consideration of the foregoing premises and of the
mutual agreements and covenants hereinafter set forth, the parties hereto agree
to the terms and conditions of this Agreement as follows:

      1. Employment for Term. The Corporation hereby employs Executive and
Executive hereby accepts employment with the Corporation for the period
beginning on May 23, 2003 and ending December 31, 2005 (the "Initial Term"), or
upon the earlier termination of such term pursuant to Section 6 (such term of
employment upon any such earlier termination, being hereinafter referred to as
the "Term"). The termination of Executive's employment under this Agreement
shall end the Initial Term but shall not terminate Executive's or the
Corporation's other agreements in this Agreement, except as otherwise provided
herein.

      2. Position and Duties. During the Term, Executive shall serve as the
President of the Corporation. During the Term, Executive shall also hold such
additional positions and titles as the Board of Directors of the Corporation
(the "Board") may determine from time to time. During the Term, Executive shall
devote her full time and efforts to her duties as an employee of the
Corporation.
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      3. Compensation.

            (a) Base Salary. The Corporation shall pay Executive a base salary,
beginning on the first day of the Term and ending on the last day of the Term,
of not less than $216,000 per annum, payable at least monthly on the
Corporation's regular pay cycle for professional employees (the "Base Salary").

            (b) Stock Options. On the date hereof, the Corporation shall grant
Executive an option to purchase an aggregate of 300,000 shares of common stock,
par value $.0001 per share, of the Corporation ("Common Stock"), which shall
vest with respect to the first 100,000 shares on May 23, 2003, with respect to
the second 100,000 shares on May 23, 2004 and with respect to the remaining
100,000 shares on May 23, 2005, pursuant to a Stock Option Grant Agreement of
even date herewith between the Corporation and Executive, in substantially the
form attached hereto as Exhibit A.

            (c) Other and Additional Compensation. The preceding sections
establish the minimum compensation during the Term and shall not preclude the
Board from awarding Executive a higher salary or any bonuses or stock options in
the discretion of the Board during the Term at any time.

            (d) Payment of Deferred Compensation. The parties hereto acknowledge
and agree that the salary payable by Plexus to Executive, in her capacity as
president and chief executive officer of Plexus, during the period from July 1,
2002 through the date hereof, was reduced by an aggregate amount of $83,600 (the
"Deferred Compensation"). The Corporation shall pay Executive 50% of the
Deferred Compensation at the Closing, 25% of the Deferred Compensation on or
before August 10, 2003 and 25% of the Deferred Compensation on or before October
10, 2003.

      4. Employee Benefits. During the Term, Executive shall be entitled to the
employee benefits including vacation, 401(k) plan, health plan and other
insurance benefits made generally available by the Corporation to employees of
the Corporation.

      5. Expenses. The Corporation shall reimburse Executive for actual
out-of-pocket expenses incurred by her in the performance of her services for
the Corporation upon the receipt of appropriate documentation of such expenses.

      6. Termination.

            (a) General. The Initial Term shall end immediately upon Executive's
death. The Initial Term may also end for Cause or Disability, as defined in
Section 7.

            (b) Notice of Termination. Promptly after it ends the Initial Term,
the Corporation shall give Executive notice of the termination, including a
statement of whether the termination was for Cause or Disability (as defined in
Section 7(a) and 7(b) below). The Corporation's failure to give notice under
this Section 6(b) shall not, however, affect the validity of the Corporation's
termination of the Initial Term.

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            (c) Effective Termination by the Corporation. If the Corporation (i)
reassigns Executive's base of operations outside of San Diego, California, or
(ii) materially reduces Executive's duties during the Initial Term, including
replacing Executive as President, or (ii) materially breaches the Corporation's
obligations under this Agreement, then, at her option, Executive may treat such
reduction in duties or relocation or breach as a termination of the Initial Term
without Cause by the Corporation and as "Good Reason" for Executive to resign.

      7. Severance Benefits.

            (a) Cause Defined. "Cause" means (i) willful malfeasance or willful
misconduct by Executive in connection with her employment; (ii) Executive's
gross negligence in performing any of her duties under this Agreement; (iii)
Executive's conviction of, or entry of a plea of guilty to, or entry of a plea
of nolo contendre with respect to, any crime other than a traffic violation or
infraction which is a misdemeanor; (iv) Executive's material breach of any
written policy applicable to all employees adopted by the Corporation which is
not cured to the reasonable satisfaction of the Corporation within fifteen (15)
business days after notice thereof; or (v) material breach by Executive of any
of her agreements in this Agreement which is not cured to the reasonable
satisfaction of the Corporation within fifteen (15) business days after notice
thereof.

            (b) Disability Defined. "Disability" shall mean Executive's
incapacity due to physical or mental illness that results in her being
substantially unable to perform her duties hereunder for six consecutive months
(or for six months out of any nine month period). During a period of Disability,
Executive shall continue to receive the Base Salary hereunder, provided that if
the Corporation provides Executive with disability insurance coverage, payments
of the Base Salary shall be reduced by the amount of any disability insurance
payments received by Executive due to such coverage. The Corporation shall give
Executive written notice of termination which shall take effect sixty (60) days
after the date it is sent to Executive unless Executive shall have returned to
the performance of her duties hereunder during such sixty (60) day period
(whereupon such notice shall become void).

            (c) Termination. If the Corporation ends the Initial Term for Cause
or Disability, or if Executive resigns as an employee of the Corporation for
reasons other than Good Reason as provided in Section 6(c), or if Executive
dies, then the Corporation shall have no obligation to pay Executive any amount,
whether for salary, benefits, bonuses, or other compensation or expense
reimbursements of any kind, accruing after the end of the Term, and such rights
shall, except as otherwise required by law, be forfeited immediately upon the
end of the Term. Payments under Section 3(a) shall continue for the remainder of
the Initial Term unless the Corporation ends the Initial Term for Cause or if
Executive resigns for reasons other than Good Reason as provided in Section
6(c). If the Corporation ends the Initial Term without Cause, or if Executive
resigns for Good Reason as provided in Section 6(c), then the Corporation will
be obligated to continue to pay Executive's salary and all other amounts due
hereunder for the remainder of the Initial Term.

            (d) Change of Control Payment. The provision of this Section 7(d)
set forth the terms of an agreement reached between Executive and the
Corporation regarding Executive's rights and obligations upon the occurrence of
a "Change in Control" (as hereinafter defined) of

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the Corporation. These provisions are intended to assure and encourage in
advance Executive's continued attention and dedication to her assigned duties
and her objectivity during the pendency and after the occurrence of any such
Change in Control. These provisions shall apply in lieu of, and expressly
supersede, the provisions of Section 7(c) if Executive's employment is
terminated or Notice of Termination is given ninety (90) days prior to or within
twelve (12) months after the occurrence of an event constituting a Change in
Control.

                  (i) Escrow. Within ten (10) days after the occurrence of the
      first event constituting a Change in Control (irrespective of whether
      Executive has actual knowledge of such event), the Corporation shall place
      immediately negotiable funds in escrow in an amount equal to the greater
      of (A) Executive's salary and all other amounts due hereunder for the
      remainder of the Term, plus such additional amount as equals the "Gross Up
      Payment" (as hereinafter defined) thereon (the "Change of Control Amount")
      and (B) the amount of Executive's annual base salary at such time (the
      "Annual Salary Amount"). Such escrow shall be conducted pursuant to a
      standard escrow agreement among the Corporation, Executive and an
      independent escrow agent providing for the timely payment to Executive of
      the amounts hold in such escrow in the event Executive becomes entitled
      thereto under the applicable provisions of this Agreement (the "Escrow
      Arrangement"). The Escrow Arrangement shall be maintained until the
      earlier of (A) twelve months and one day after the occurrence of an event
      constituting a Change in Control or (B) the payment to Executive of all
      sums escrowed.

                  (ii) Change in Control. If, within 90 days prior to, or within
      twelve (12) months after the occurrence of an event constituting a Change
      in Control, Executive's employment is terminated or a Notice of
      Termination is given for any reason other than (A) her death, (B) her
      Disability, or (C) by Executive other than for Good Reason, then such
      termination shall be deemed to be a "Termination Due to Change in Control"
      (herein so called), in which event the Corporation shall pay Executive, in
      a lump sum, on or prior to the fifth (5th) day following the date of
      termination of the Term:

                        (A)   an amount equal to the greater of the Change of
                              Control Amount (including any Gross Up Payment)
                              and the Annual Salary Amount; and

                        (B)   Executive's accrued and unpaid Base Salary.

                  (iii) Stock Option Floor. Upon the occurrence of the first
      event constituting a Change in Control, all stock options and other
      stock-based grants to Executive by the Corporation shall, irrespective of
      any provisions of her option agreements, immediately and irrevocably vest
      and become exercisable as of the date of such first event whereupon, at
      any time during the Option Term as defined in the option agreements,
      Executive or her estate may by five (5) days' advance written notice given
      to the Corporation, and irrespective of whether Executive is then employed
      by the Corporation or then living, and solely at the election of Executive
      or her estate, require the Corporation to:

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                        (A)   within thirty (30) days of a request by Executive
                              or her estate file and cause to become effective a
                              Form S-8 (or other appropriate form) with the
                              Securities and Exchange Commission ("SEC")
                              registering for resale all shares underlying stock
                              options granted to Executive and outstanding with
                              all fees and expenses of such filing being paid by
                              the Corporation; or

                        (B)   allow Executive to exercise all or any part of
                              such Stock Options at the option prices therefor
                              specified in the grant of the Stock Options.

                  (iv) Gross Up Payment.

                        (A)   Excess Parachute Payment. If Executive incurs the
                              tax (the "Excise Tax") imposed by Section 4999 of
                              the Internal Revenue Code of 1986 (the "Code") on
                              "Excess Parachute Payments" within the meaning of
                              Section 280G(b)(1) of the Code, the Corporation
                              will pay to Executive an amount (the "Gross Up
                              Payment") such that the net amount retained by
                              Executive, after deduction of any Excise Tax on
                              both the Excess Parachute Payment and any federal,
                              state and local income tax (together with
                              penalties and interest) as well as the Excise Tax
                              upon the payment provided for by this Section
                              7(d)(iv)(A), will be equal to the Change of
                              Control Amount.

                        (B)   Applicable Rates. For purposes of determining the
                              amount of the Gross Up Payment, Executive will be
                              deemed to pay federal income taxes at the highest
                              marginal rate of federal income taxation in the
                              calendar year in which the Gross Up Payment is to
                              be made and state and local income taxes at the
                              highest marginal rates of taxation in the state
                              and locality where taxes thereon are lawfully due,
                              net of the maximum reduction (if any) in federal
                              income taxes that could be obtained from deduction
                              of deductible state and local taxes.

                        (C)   Determination of Gross Up Payment Amount. The
                              determination of whether the Excise Tax is payable
                              and the amount thereof will be based upon the
                              opinion of tax counsel selected by Executive and
                              reasonably approved by the Corporation, which
                              approval will not be unreasonably withheld or
                              delayed. If such opinion is not finally accepted
                              by the Internal Revenue Service (or state and
                              local taxing authorities), then appropriate
                              adjustments to the Excise Tax

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<PAGE>

                              will be computed and additional Gross Up Payments
                              will be made in the manner provided by this
                              Section 7(d)(iv).

                        (D)   Payment. The Corporation will pay the estimated
                              amount of the Gross Up Payment in cash to
                              Executive at the time specified in this Agreement.
                              Executive and the Corporation agree to reasonably
                              cooperate in the determination of the actual
                              amount of the Gross Up Payment. Further, Executive
                              and the Corporation agree to make such adjustments
                              to the estimated amount of the Gross Up Payment as
                              may be necessary to equal the actual amount of the
                              Gross Up Payment, which in the case of the
                              Corporation will refer to refunds of prior
                              overpayments by the Corporation and in the case of
                              Executive will refer to additional payments to
                              Executive to make up for prior underpayments.

                  (v) Definitions. For purposes of this Section 7, the following
      terms shall have the following meanings:

                        (A)   "Change in Control" shall mean any of the
                              following:

                              (1)   the acquisition by any individual, entity,
                                    or group (within the meaning of Section
                                    13(d)(3) or 14(d)(2) of the Exchange Act)
                                    (the "Acquiring Person"), other than the
                                    Corporation, or any of its Subsidiaries or
                                    any Excluded Group (as defined herein), of
                                    beneficial ownership (within the meaning of
                                    Rule l3d-3 promulgated under the Exchange
                                    Act) of 35% or more of the combined voting
                                    power or economic interests of the then
                                    outstanding voting securities of the
                                    Corporation entitled to vote generally in
                                    the election of directors; provided,
                                    however, that any transfer from any director
                                    or executive officer listed in the
                                    Corporation's Form 10-KSB for the year ended
                                    December 31, 2002 under "Security Ownership
                                    of Certain Beneficial Owners" (the "Excluded
                                    Group") will not result in a Change in
                                    Control if such transfer was part of a
                                    series of related transactions the effect of
                                    which, absent the transfer to such Acquiring
                                    Person by the Excluded Group, would not have
                                    resulted in the acquisition by such
                                    Acquiring Person of 35% or more of the
                                    combined voting power or economic interests
                                    of the then outstanding voting securities;
                                    or

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                              (2)   during any period of 12 consecutive months
                                    after the date of this Agreement, the
                                    individuals who at the beginning of any such
                                    12-month period constituted a majority of
                                    the Directors (the "Incumbent Non-Investor
                                    Majority") cease for any reason to
                                    constitute at least a majority of such
                                    Directors; provided that (i) any individual
                                    becoming a director whose election, or
                                    nomination for election by the Corporation's
                                    stockholders, was approved by a vote of the
                                    stockholders having the right to designate
                                    such director and (ii) any director whose
                                    election to the Board or whose nomination
                                    for election by the stockholders of the
                                    Corporation was approved by the requisite
                                    vote of directors entitled to vote on such
                                    election or nomination in accordance with
                                    the Restated Certificate of Incorporation of
                                    the Corporation, shall, in each such case,
                                    be considered as though such individual were
                                    a member of the Incumbent Non-Investor
                                    Majority, but excluding, as a member of the
                                    Incumbent Non-Investor Majority, any such
                                    individual whose initial assumption of
                                    office, is in connection with an actual or
                                    threatened election contest relating to the
                                    election of the directors of the Corporation
                                    (as such terms are used in Rule 14a-2 of
                                    Regulation 14A promulgated under the
                                    Exchange Act) and further excluding any
                                    person who is an affiliate or associate of
                                    an Acquiring Person having acquired within
                                    the preceding 12 months, or proposing to
                                    acquire, beneficial ownership of 25% or more
                                    of the combined voting power of the then
                                    outstanding voting securities of the
                                    Corporation entitled to vote generally in
                                    the election of directors; or

                              (3)   the approval by the stockholders of the
                                    Corporation of a reorganization, merger or
                                    consolidation, in each case, with respect to
                                    which all or substantially all of the
                                    individuals and entities who were the
                                    respective beneficial owners of the voting
                                    securities of the Corporation immediately
                                    prior to such reorganization, merger, or
                                    consolidation do not, following such
                                    reorganization, merger, or consolidation,
                                    beneficially own, directly or indirectly,
                                    more than 50% of the combined voting power
                                    of the then outstanding voting securities
                                    entitled to vote generally in the election
                                    of directors

                                       7
<PAGE>

                                    of. the Corporation resulting from such
                                    reorganization, merger, or consolidation; or

                              (4)   the sale or other disposition of assets
                                    representing 50% or more of the assets of
                                    the Corporation in one transaction or series
                                    of related transactions not initiated or
                                    commenced by any person within the Excluded
                                    Group; or

                              (5)   a "Fundamental Change in Business" as
                                    hereinafter defined; or

                              (6)   a "Hostile Takeover" as hereinafter defined
                                    is declared.

                        (B)   "Fundamental Change in Business" shall mean that
                              the Corporation, at any time, no longer spends at
                              least fifty percent (50%) of its annual budget on
                              activities related to biotechnology or
                              pharmaceuticals.

                        (C)   "Hostile Takeover" shall mean any Change in
                              Control which at any time is declared by at least
                              a majority of the Board, directly or indirectly,
                              to be hostile or not in the best interests of the
                              Corporation, or in which an attempt is made
                              (irrespective of whether successful) to wrest
                              control away from the incumbent management of the
                              Corporation and, with respect to which, the Board
                              makes efforts to resist.

                  (vi) Satisfactory Alternative. Notwithstanding anything to the
      contrary herein, Executive shall have no rights and the Corporation shall
      have no obligation under this Section 7(d) with respect to a Termination
      Due to Change in Control if, prior to or simultaneously with such
      Termination Due to Change in Control, Executive is offered employment
      within 50 miles of the existing Plexus facility in San Diego, California
      by another business at a level of compensation equal to or greater than
      her compensation hereunder.

      8. Confidentiality, Ownership, and Covenants. Executive acknowledges and
agrees that the Corporation would not consummate the transactions contemplated
by the Asset Purchase Agreement without the assurance that Executive will not
engage in any of the activities prohibited by this Section 8, and will otherwise
comply with this Section 8, for the periods set forth herein. Executive agrees
to restrict her actions as provided for in this Section 8. Executive further
acknowledges that the scope and duration of the covenants set forth in this
Section 8 are reasonable in light of the specific nature and duration of the
transactions contemplated by the Asset Purchase Agreement and the shares of
Common Stock to be issued to her in connection with the liquidation and
dissolution of Plexus pursuant to the terms of the Asset Purchase Agreement. In
consideration thereof, Executive agrees that she will not assert in any forum
that

                                       8
<PAGE>

the provisions of this Section 8 prevent her from earning a living or otherwise
are void or unenforceable or should be held void or unenforceable.

            (a) "Corporation Information" and "Inventions" Defined. "Corporation
Information" means all information, knowledge or data of or pertaining to (i)
the Corporation, its employees and all work undertaken on behalf of the
Corporation, and (ii) any other person, firm, corporation or business
organization with which the Corporation may do business during the Term, that
(as to both (i) and (ii) above) is not in the public domain (and whether
relating to methods, processes, techniques, discoveries, pricing, marketing or
any other matters). "Inventions" collectively refers to any and all inventions,
trade secrets, ideas, processes, formulas, source and object codes, data,
programs, other works of authorship, know-how, improvements, research,
discoveries, developments, designs, and techniques regarding any of the
foregoing.

            (b) Confidentiality. (i) Executive hereby recognizes that the value
of all trade secrets and other proprietary data and all other information of the
Corporation not in the public domain disclosed by the Corporation in the course
of her employment with the Corporation may be attributable substantially to the
fact that such confidential information is maintained by the Corporation in
strict confidentiality and secrecy and would be unavailable to others without
the expenditure of substantial time, effort or money. Executive, therefore,
except as provided in the next two sentences, covenants and agrees that all
Corporation Information shall be kept secret and confidential at all times
during the Term and for the five (5) year period after the end of the Term and
shall not be used or divulged by her outside the scope of her employment as
contemplated by her Agreement, except as the Corporation may otherwise expressly
authorize by action of the Board. In the event that Executive is requested in a
judicial, administrative or governmental proceeding to disclose any of the
Corporation Information, Executive will promptly so notify the Corporation so
that the Corporation may seek a protective order of other appropriate remedy
and/or waive compliance with this Agreement. If disclosure of any of the
Corporation Information is required, Executive may furnish the material so
required to be furnished, but Executive will furnish only that portion of the
Corporation Information that legally is required.

                  (ii) Executive also hereby agrees to keep the terms of this
Agreement confidential to the same extent that the Corporation maintains such
confidentiality (except with regard to any disclosure by the Corporation
required under applicable securities laws).

            (c) Ownership of Inventions, Patents and Technology. Executive
hereby assigns to the Corporation all of Executive's rights (including patent
rights, copyrights, trade secret rights, and all other rights throughout the
world), title and interest in and to Inventions, whether or not patentable or
registrable under copyright or similar statutes, made or conceived or reduced to
practice or learned by Executive, either alone or jointly with others, during
the course of the performance of services for the Corporation. Executive shall
also assign to, or as directed by, the Corporation, all of Executive's right,
title and interest in and to any and all Inventions, the full title to which is
required to be in the United States government of any of its agencies. The
Corporation shall have all right, title and interest in all research and work
product produced by Executive as an employee of the Corporation, including, but
not limited to, all research materials and lab books.

                                       9
<PAGE>

            (d) Non-Competition Period Defined. "Non-Competition Period" means
the period beginning at the end of the Term and ending one (1) year after the
end of the Term.

            (e) Covenants Regarding the Term and Non-Competition Period.
Executive acknowledges and agrees that her services pursuant to this Agreement
are unique and extraordinary; that the Corporation will be dependent upon
Executive for research, development and marketing expertise; and that she will
have access to and control of confidential information of the Corporation.
Executive further acknowledges that the business of the Corporation is
international in scope and cannot be confined to any particular geographic area.
Executive further acknowledges that the scope and duration of the restrictions
set forth in this Section 8(e) are reasonable in light of the specific nature
and duration of the transactions contemplated by the Asset Purchase Agreement
and the shares of Common Stock to be issued to her in connection with the
liquidation and dissolution of Plexus pursuant to the terms of the Asset
Purchase Agreement. For the foregoing reasons and to induce the Corporation to
enter this Agreement, Executive covenants and agrees that, subject to Section
8(h), during the Term and the Non-Competition Period Executive shall not unless
with written consent of the Corporation:

                  (i) engage in any business directly related to the research
      and development of the products or processes in which the Corporation is
      engaged in during the Term or in any other business conducted by the
      Corporation during the Term (collectively the "Prohibited Activity") in
      the World for her own account;

                  (ii) become interested in any individual, corporation,
      partnership or other business entity (a "Person") engaged in any
      Prohibited Activity in the world, directly or indirectly, as an
      individual, partner, shareholder, officer, director, principal, agent,
      employee, trustee, consultant or in any other relationship or capacity;
      provided, however, that Executive may own directly or indirectly, solely
      as an investment, securities of any Person which are traded on any
      national securities exchange if Executive (x) is not a controlling person
      of, or a member of a group which controls, such person or (y) does not,
      directly or indirectly, own 5% or more of any class of securities of such
      person; or

                  (iii) directly or indirectly hire, employ or retain any person
      who at any time during the last two months of the Term was an employee of
      the Corporation or directly or indirectly solicit, entice, induce or
      encourage any such person to become employed by any other person.

            (f) Remedies. Executive hereby acknowledges that the covenants and
agreements contained in Section 8 are reasonable and valid in all respects and
that the Corporation is entering into this Agreement, inter alia, on such
acknowledgement. If Executive breaches, or threatens to commit a breach, of any
of the restrictive covenants set forth in this Agreement (the "Restrictive
Covenants"), the Corporation shall have the following rights and remedies, each
of which rights and remedies shall be independent of the other and severally
enforceable, and all of which rights and remedies shall be in addition to, and
not in lieu of, any other rights and remedies available to the Corporation under
law or in equity: (i) the right and remedy to have the Restrictive Covenants
specifically enforced by any court having equity jurisdiction, it being
acknowledged and agreed that any such breach or threatened breach will

                                       10
<PAGE>

cause irreparable injury to the Corporation and that money damages will not
provide an adequate remedy to the Corporation; and (ii) the right and remedy to
require Executive to account for and pay over to the Corporation such damages as
are recoverable at law as the result of any transactions constituting a breach
of any of the Restrictive Covenants.

            (g) Jurisdiction. The parties intend to and hereby confer
jurisdiction to enforce the Restrictive Covenants upon the courts of any
jurisdiction within the geographical scope of such Covenants. If the courts of
any one or more such jurisdictions hold the Restrictive Covenants wholly
unenforceable by reason of the breadth of such scope or otherwise, it is the
intention of the parties that such determination not bar or in any way affect
the Corporation's right to the relief provided above in the courts of any other
jurisdiction, within the geographical scope of such Covenants, as to breaches of
such Covenants in such other respective jurisdiction such Covenants as they
relate to each jurisdiction being, for this purpose, severable into diverse and
independent covenants.

            (h) Executive's agreements and covenants under Section 8(e) shall
automatically terminate if (i) the Corporation ends the Initial Term without
Cause, (ii) Executive resigns for Good Reason as provided in Section 6(c) or
(iii) the Initial Term expires on December 31, 2005 in accordance with the terms
of this Agreement.

      9. Successors and Assigns.

            (a) Executive. This Agreement is a personal contract, and the rights
and interests that the Agreement accords to Executive may not be sold,
transferred, assigned, pledged, encumbered, or hypothecated by her. All rights
and benefits of Executive shall be for the sole personal benefit of Executive,
and no other person shall acquire any right, title or interest under this
Agreement by reason of any sale, assignment, transfer, claim or judgement or
bankruptcy proceedings against Executive. Except as so provided, this Agreement
shall inure to the benefit of and be binding upon Executive and her personal
representatives, distributes and legatees.

            (b) The Corporation. This Agreement shall be binding upon the
Corporation and inure to the benefit of the Corporation and of its successors
and assigns, including (but not limited to) any corporation that may acquire all
or substantially all of the corporation's assets or business or into or with
which the Corporation may be consolidated or merged. In the event that the
Corporation sells all or substantially all of its assets, merges or
consolidates, otherwise combines or affiliates with another business, dissolves
and liquidates, or otherwise sells or disposes of substantially all of its
assets and Executive does not elect to treat any such transaction as a
termination by the Corporation without Cause pursuant to Section 7(c), then this
Agreement shall continue in full force and effect. The Corporation's obligations
under this Agreement shall cease, however, if the successor to, the purchaser or
acquirer either of the Corporation or of all or substantially all of its assets,
or the entity with which the Corporation has affiliated, shall assume in writing
the Corporation's obligations under this Agreement (and deliver and executed
copy of such assumption to Executive), in which case such successor or
purchaser, but not the Corporation, shall thereafter be the only party obligated
to perform the obligations that remain to be performed on the part of the
Corporation under this Agreement.

                                       11
<PAGE>

      10. Entire Agreement. This Agreement represents the entire agreement
between the parties concerning Executive's employment with the Corporation and
supersedes all prior negotiations, discussions, understanding and agreements,
whether written or oral, between Executive and the Corporation relating to the
subject matter of this Agreement.

      11. Amendment or Modification, Waiver. No provision of this Agreement may
be amended or waived unless such amendment or waiver is agreed to in writing
signed by Konatich and by a duly authorized officer of the Corporation. No
waiver by any party to this Agreement or any breach by another party of any
condition or provision of this Agreement to be performed by such other party
shall be deemed a waiver of a similar or dissimilar condition or provision at
the same time, any prior time or any subsequent time.

      12. Notices. Any notice to be given under this Agreement shall be in
writing and delivered personally or sent by overnight courier or registered or
certified mail, postage prepaid, return receipt requested, addressed to the
party concerned at the address indicated below, or to such other address of
which such party subsequently may give notice in writing:

            If to Executive:            Susan K. Burgess, Ph.D.
                                        14321 Twin Peaks Road
                                        Poway, CA 92064

            If to the Corporation:      SIGA Technologies, Inc.
                                        420 Lexington Avenue
                                        Suite 601
                                        New York, NY 10170
                                        Fax: 212-697-3130
                                        Attention: Thomas N. Konatich

                   with a copy to:      Kramer Levin Naftalis & Frankel LLP
                                        919 Third Avenue
                                        New York, NY 10022
                                        Attention: James A. Grayer, Esq.

Any notice delivered personally or by overnight courier shall be deemed given on
the date delivered and any notice sent by registered or certified mail, postage
prepaid, return receipt requested, shall be deemed given on the date mailed.

      13. Severability. If any provision of this Agreement or the application of
any such provision to any party or circumstances shall be determined by any
court of competent jurisdiction to be invalid and unenforceable to any extent,
the remainder of this Agreement or the application of such provision to such
person or circumstances other than those to which it is so determined to be
invalid and unenforceable shall not be affected, and each provision of this
Agreement shall be validated and shall be enforced to the fullest extent
permitted by law. If for any reason any provision of this Agreement containing
restrictions is held to cover an area or to be for a length of time that is
unreasonable or in any other way is construed to be too broad or to any extent
invalid, such provision shall not be determined to be entirely null, void and of
no effect; instead, it is the intention and desire of both the Corporation and
Executive that, to the extent that the provision is or would be valid or
enforceable under applicable law, any court of

                                       12
<PAGE>

competent jurisdiction shall construe and interpret or reform this Agreement to
provide for a restriction having the maximum enforceable area, time period and
such other constraints or conditions (although not greater than those contained
currently contained in this Agreement) as shall be valid and enforceable under
the applicable law.

      14. Survivorship. The respective rights and obligations of the parties
hereunder shall survive any termination of this Agreement to the extent
necessary to the intended preservation of such rights and obligations.

      15. Headings. All descriptive headings of sections and paragraphs in this
Agreement are intended solely for convenience of reference, and no provision of
this Agreement is to be construed by reference to the heading of any section or
paragraph.

      16. Withholding Taxes. All salary, benefits, reimbursements and any other
payments to Executive under this Agreement shall be subject to all applicable
payroll and withholding taxes and deductions required by any law, rule or
regulation of and federal, state or local authority.

      17. Counterparts. This Agreement may be executed in one or more
counterparts, each of which shall be deemed to be an original but all of which
together constitute one and same instrument.

      18. Applicable Law; Arbitration. The validity, interpretation and
enforcement of this Agreement and any amendments or modifications hereto shall
be governed by the laws of the State of New York, as applied to a contract
executed within and to be performed in such State. The parties agree that any
disputes shall be definitively resolved by binding arbitration before in
accordance with the Rules of the American Arbitration Association, with the
arbitration hearing to be held in New York, New York. The parties hereby consent
to the jurisdiction to the federal courts of the Southern District of New York
or, if there shall be no jurisdiction, to the state courts located in New York
County, New York, to enforce any arbitration award rendered with respect
thereto. Each party shall choose one neutral arbitrator and the two neutral
arbitrators shall choose a third neutral arbitrator. All costs and fees related
to such arbitration (and judicial enforcement proceedings, if any) shall be
borne and allocated by and between the parties as the arbitrators decide is
appropriate, with the intent that the party who is the most unsuccessful should
bear most (or all) of said costs and fees.

                  [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK]

                                       13
<PAGE>

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

                                        SIGA TECHNOLOGIES, INC.

                                           By: /s/ Thomas N. Konatich
                                               ---------------------------------
                                               Thomas N. Konatich
                                               Chief Executive Officer and
                                               Chief Financial Officer

                                               /s/ Susan K. Burgess
                                               ---------------------------------
                                               Susan K. Burgess, Ph.D.

                                       14
<PAGE>

                                                                       EXHIBIT A

                             SIGA TECHNOLOGIES, INC.

                        Incentive Stock Option Agreement

                                                     Granting Date: May 23, 2003

To: Susan K. Burgess, Ph.D.:

            We are pleased to notify you that SIGA TECHNOLOGIES, INC., a
Delaware corporation (the "Corporation"), has granted to you (the "Holder") an
incentive stock option (the "Option") under the Corporation's Amended and
Restated 1996 Incentive and Non-Qualified Stock Option Plan (the "Plan") to
purchase all or any part of an aggregate of 300,000 shares of Common Stock of
the Corporation (the "Optioned Shares"), subject to the terms and conditions of
this Agreement.

            1. Vesting, Term and Exercise of Option. Subject to the provisions
of this Agreement, this Option may be exercised for up to the number of vested
Optioned Shares (subject to adjustment as provided in Section 6 hereof) by you
on or prior to the tenth anniversary of the Granting Date ("Last Exercise Date")
at an initial exercise price (the "Exercise Price") of $1.81 per share (subject
to adjustment as provided in Section 6 hereof) and all as subject to Plan and
this Agreement. The Holder may exercise this Option according to the following
vesting schedule: this Option shall become exerciseable with respect to the
first 100,000 Optioned Shares on May 23, 2003, with respect to the second
100,000 Optioned Shares on May 23, 2004 and with respect to the remaining
100,000 Optioned Shares on May 23, 2005. Any portion of the Option that you do
not exercise shall accumulate and can be exercised by you any time prior to the
Last Exercise Date. You may not exercise your Option to purchase a fractional
share or fewer than 100 shares, and you may only exercise your Option by
purchasing shares in increments of 100 shares unless the remaining shares
purchasable are less than 100 shares.

            This Option may be exercised by delivering to the Secretary of the
Corporation (i) a written Notice of Intention to Exercise in the form attached
hereto as Appendix A signed by you and specifying the number of Optioned Shares
you desire to purchase, (ii) payment, in full, of the Exercise Price for all
such Optioned Shares in cash, certified check, surrender of shares of Common
Stock of the Corporation having a value equal to the exercise price of the
Optioned Shares as to which you are exercising this Option, provided that such
surrendered shares, if previously acquired by exercise of a Company stock
option, have been held by you at least six months prior to their surrender, or
by means of a brokered cashless exercise. As a holder of an option, you shall
have the rights of a shareholder with respect to the Optioned Shares only after
they shall have been issued to you upon the exercise of this Option. Subject to
the terms and provisions of this Agreement and the Plan, the Corporation shall
use its best efforts to cause the Optioned Shares to be issued as promptly as
practicable after receipt of your Notice of Intention to Exercise.

            2. Non-transferability of Option. This Option shall not be
transferable and may be exercised during your lifetime only by you. Any
purported transfer or assignment of this Option shall be void and of no effect,
and shall give the Corporation the right to terminate this Option as of the date
of such purported transfer or assignment. No transfer of an Option by will

<PAGE>

or by the laws of descent and distribution shall be effective unless the
Corporation shall have been furnished with written notice thereof, and such
other evidence as the Corporation may deem necessary to establish the validity
of the transfer and conditions of the Option, and to establish compliance with
any laws or regulations pertaining thereto.

            3. Certain Rights and Restrictions With Respect to Common Stock. The
Optioned Shares which you may acquire upon the exercise of this Option will not
be registered under the Securities Act of 1933, as amended, or under state
securities laws and the resale by you of such Optioned Shares will, therefore,
be restricted. You will be unable to transfer such Optioned Shares without
either registration under such Act and compliance with applicable state
securities laws or the availability of an exemption therefrom. Accordingly, you
represent and warrant to the Corporation that all shares of Common Stock you may
acquire upon the exercise of this Option will be acquired by you for your own
account for investment and that you will not sell or otherwise dispose of any
such shares except in compliance with all applicable federal and state
securities laws. The Corporation may place a legend to such effect upon each
certificate representing Optioned Shares acquired by you upon the exercise of
this Option.

            4. Disputes. Any dispute which may arise under or as a result of or
pursuant to this Agreement shall be finally and conclusively determined in good
faith by the Board of Directors of the Corporation in its sole discretion, and
such determination shall be binding upon all parties.

            5. Termination of Status.

                  (a) This Option is a separate incentive and not in lieu of
salary or other compensation. The Optioned Shares do not vest you with any right
to employment with the Corporation, nor is the Corporation's right to terminate
your employment in any way restricted by this Agreement. Subject to the
following provisions of this Section 5, the Option will terminate upon and will
not be exercisable after termination of your employment with the Corporation
("Employment Termination Date"). If your employment with the Corporation is
terminated for any reason other than death or disability, this Option may not be
exercised after the earlier of (i) ninety (90) days from the Employment
Termination Date or (ii) the Expiration Date, and may not be exercised for more
than the number of Optioned Shares purchasable under Section 1 on the Employment
Termination Date.

                  (b) If you die while this Option is exercisable, or within a
period of three months after the Employment Termination Date, the Option may be
exercised by the duly authorized executor of your last will or by the duly
authorized administrator of your estate, but may not be exercised after the
earlier of (i) one year from the date of your death or (ii) the Expiration Date,
and may not be exercised for more than the number of Optioned Shares purchasable
under Section 1 on the date of your death.

                  (c) If your employment is terminated as a result of your
permanent disability, this Option may not be exercised after the earlier of (i)
one year from the Employment Termination Date, or (ii) the Expiration Date, and
may not be exercised for more than the number of Optioned Shares purchasable
under Section 1 on the Employment Termination Date.

<PAGE>

If you die after the date your employment is terminated under the provisions of
this Section 5(c) but before the Expiration Date, the provisions of Section 5(b)
above shall apply.

            Permanent disability shall mean a disability described in Section
422(c)(6) of the Code. The existence of a Disability shall be determined by the
Committee in its absolute discretion.

            6. Adjustments to Exercise Price and Number of Securities. If the
Corporation shall at any time subdivide or combine the outstanding shares of
Common Stock, or similar corporate events the Exercise Price and the number of
shares subject to the Option shall be appropriately adjusted.

            7. Reservation and Listing of Securities. The Corporation shall at
all times reserve and keep available out of its authorized shares of Common
Stock, solely for the purpose of issuance upon the exercise of this Option, such
number of shares of Common Stock or other securities, properties or rights as
shall be issuable upon the exercise thereof. The Corporation covenants and
agrees that, upon exercise of this Option and payment of the Exercise Price
therefor, all shares of Common Stock and other securities issuable upon such
exercise shall be duly and validly issued, fully paid, non-assessable and not
subject to the preemptive rights of any stockholder. As long as this Option
shall be outstanding, the Corporation shall use its best efforts to cause all
shares of Common Stock issuable upon the exercise of the Option to be listed
(subject to official notice of issuance) on all securities exchanges on which
the Common Stock may then be listed and/or quoted on NASDAQ.

            8. Forfeiture of Option Gains. If at any time within one year after
the exercise of all or any portion of the Option the Committee determines that
the Corporation has been materially harmed by you, which harm either (a) results
in your being terminated for Cause or (b) results from your engaging in any
activity determined by the Committee, in its sole discretion, to be in
competition with any activity of the Corporation, or otherwise inimical,
contrary or harmful to the interests of the Corporation (including, but not
limited to, violating any non-competition or similar agreements entered into
with the Corporation or otherwise accepting employment with or serving as a
consultant, adviser or in any other capacity to an entity that is in competition
with or acting against the interests of the Corporation), then upon notice from
the Corporation to you any gain ("Gain") realized by you upon exercising such
Option shall be paid by you to the Corporation. For purposes of this Section 7,
such Gain shall be the excess of the Fair Market Value of the shares of Company
Stock obtained through such exercise as of the date of option exercise over the
purchase price of such shares. The Corporation shall have the right to offset
such Gain against any amounts otherwise owed to you by the Corporation
(including, but not limited to wages, vacation pay, or pursuant to any benefit
plan or other compensatory arrangement).

            9. Notices. All notices, requests, consents and other communications
hereunder shall be in writing and shall be deemed to have been duly made and
sent when delivered, or mailed by registered or certified mail, return receipt
requested:

                  (a) If to the registered Holder of this Option, to the address
      of the Holder as shown on the books of the Corporation; or

<PAGE>

                  (b) If to the Corporation, to 420 Lexington Avenue, Suite 601,
      New York, NY 10017, or to such other address as the Corporation may
      designate by notice to the Holders.

            10. Supplements and Amendments. The Corporation and the Holder may
from time to time supplement or amend this Agreement in any respect, provided,
however, that no amendment may adversely affect your rights hereunder without
your written consent.

            11. Successors. All the covenants and provisions of this Agreement
shall be binding upon and inure to the benefit of the Corporation, the Holder
and their respective successors and assigns hereunder.

            12. Governing Law. This Agreement shall be deemed to be a contract
made under the laws of the State of New York and for all purposes shall be
construed in accordance with the laws of the State of New York without giving
effect to the rules of the State of New York governing the conflicts of laws.

            13. Entire Agreement; Modification. This Agreement, together with
the Asset Purchase Agreement, including all schedules and exhibits hereto and
thereto, contains the entire understanding between the parties hereto with
respect to the subject matter hereof.

            14. Severability. If any provision of this Agreement shall be held
to be invalid or unenforceable, such invalidity or unenforceability shall not
affect any other provision of this Agreement.

            15. Captions. The caption headings of the Sections of this Agreement
are for convenience of reference only and are not intended, nor should they be
construed as, a part of this Agreement and shall be given no substantive effect.

            16. Benefits of this Agreement. Nothing in this Agreement shall be
construed to give to any person or corporation other than the Corporation and
the registered Holder of this Option any legal or equitable right, remedy or
claim under this Agreement; and this Agreement shall be for the sole and
exclusive benefit of the Corporation and the Holder.

            17. Counterparts. This Agreement may be executed in any number of
counterparts and each of such counterparts shall for all purposes be deemed to
be an original, and such counterparts shall together constitute but one and the
same instrument.

                      [Signature page follows immediately]

<PAGE>

            IN WITNESS WHEREOF, the parties hereto have caused this Agreement to
be dully executed, as of the day and year first written.

                                        SIGA TECHNOLOGIES, INC.

                                        By:
                                            ------------------------------------
                                            Name:  Thomas N. Konatich
                                            Title: Acting Chief Executive
                                                   Officer and Chief Financial
                                                   Officer

                                        ----------------------------------------
                                        Susan K. Burgess, Ph.D.

<PAGE>

                                   Appendix A

                  NOTICE OF INTENTION TO EXERCISE STOCK OPTIONS

The undersigned grantee of a SIGA Technologies, Inc. Stock Option Agreement
dated as of ______________________ to purchase _________ shares of common stock,
par value $.0001 per share, of SIGA Technologies, Inc. ("Common Stock") hereby
gives notice of her or her intention to exercise the Stock Option (or a portion
thereof) and elects to purchase shares of Common Stock.

Shares should be issued in the name of the undersigned and should be sent to the
undersigned at:

_____________________________
_____________________________
_____________________________
_____________________________

Dated this _____ day of __________________.

Social Security Number: __________________

Name: ____________________________________

__________________________________________
Signature

INSTRUCTIONS: The exercise of these Stock Options is effective on the date SIGA
Technologies, Inc. has received (1) this Notice of Intention to Exercise Stock
Options, and (2) payment in full in cash of the exercise price for all shares
being purchased pursuant to this Notice.

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