EXHIBIT 10.28


                         EXECUTIVE EMPLOYMENT AGREEMENT


      THIS EXECUTIVE  EMPLOYMENT  AGREEMENT  ("AGREEMENT") is made as of January
17, 2000 by and between GENETIC VECTORS,  INC., a Florida corporation,  with its
principal executive offices at 5201 N.W. 77th Avenue,  Suite 100, Miami, Florida
33166 (the "COMPANY") and JEROME STREIFEL, an individual residing at the address
set forth in Section 13 hereof (the "EXECUTIVE").

      WHEREAS,  the Executive has been offered the position of Vice President of
Operations  ("VICE  PRESIDENT")  of the  Company and will begin to serve in such
capacities on the Effective Date (as herein defined);

      WHEREAS,  the  Company  wishes to assure  itself  of the  services  of the
Executive  for the period  provided  for herein and the  Executive is willing to
serve in the employ of the Company for said period upon the terms and conditions
hereinafter provided; and

      WHEREAS, the Company's Board has determined that the best interests of the
Company  and its  shareholders  would be served by  providing  for the terms and
conditions of the Executive's employment as set forth herein.

      NOW, THEREFORE,  in consideration of the mutual covenants herein contained
and intending to be legally bound hereby,  the Company and the Executive  hereby
agree as follows:

      Section 1. DEFINITIONS. As used herein, the following terms shall have the
meanings set forth below.

      "DISABILITY"  of the Executive  means that, as a result of the Executive's
incapacity  due to physical or mental  illness,  the  Executive  shall have been
absent  from his duties on a full time  basis for thirty  (30) days in any three
(3) month  period.  If the  Executive is prevented  from  performing  his duties
because of Disability,  upon request by the Company,  the Executive shall submit
to an  examination  by a physician  selected by the  Company,  at the  Company's
expense,  and the  Executive  shall also  authorize  his  personal  physician to
disclose to the selected physician all of the Executive's medical records.

      "FISCAL YEAR" means any fiscal year of the Company, as applicable.

      "PERSON" means any  individual,  sole  proprietorship,  general or limited
partnership,  joint venture, trust,  unincorporated  organization,  association,
corporation, institution, entity, party, limited liability company or government
(whether  territorial,  national,  federal,  state,  provincial,  county,  city,
municipal or otherwise,  including,  without  limitation,  any  instrumentality,
division, agency, body or department thereof).

      Section 2.  EMPLOYMENT AND TERM. The Company hereby employs the Executive,
and the  Executive  hereby  accepts  such  employment  by the  Company,  for the
purposes  and upon the terms and  conditions  contained  in this  Agreement  and

<PAGE>

subject to the  approval of the  Company's  Board of  Directors.  Subject to the
terms and  conditions  contained  herein  and the  approval  of the Board  ("the
"BOARD"), the initial term of this Agreement shall be for a two (2) year period,
commencing on the date on which  Executive  begins his employment at the Company
(the  "EFFECTIVE  DATE"),  and  terminating  on the  second  anniversary  of the
Effective  Date.  Thereafter,  the Company  shall have the  option,  in its sole
discretion to renew this Agreement on its then-current  terms and conditions for
subsequent  one (1) year  extension  terms upon written notice ninety (90) days'
prior to the then applicable term or extension term. The initial term hereof and
any extension term are referred to herein as the "EMPLOYMENT PERIOD."

      Section 3. EMPLOYMENT CAPACITY AND DUTIES. The Executive shall be employed
throughout  the  Employment  Period as the Vice  President of  Operations of the
Company.  The  Executive  shall have the duties  and  responsibilities  normally
associated  and incumbent  with the position of Vice  President of Operations of
the Company and shall  render  services to the Company as its Vice  President of
Operations  and in  connection  therewith  shall  perform  such  duties,  as the
Executive  may  reasonably  be  directed  to  perform  by the CEO and the Board.
Accordingly,  and not by way of  limitation,  as Vice President of Operations of
the  Company,  the  Executive at the request of the Chairman of the Board attend
all meetings of the shareholders of the Company or the Board and, subject to the
direction  or approval of the Board,  the  Executive  shall be  responsible  for
production  and  development  of the Company's  scientific  products,  including
product validation.  In addition,  he will participate in the Company's research
and development projects by providing certain scientific skills as needed.

      Section 4.  EXECUTIVE  PERFORMANCE  COVENANTS.  The Executive  accepts the
employment  described  in Section 3 herein and agrees to devote his full working
time and efforts (except for absences due to illness and appropriate  vacations)
to the business and affairs of the Company and the  performance of the aforesaid
duties and responsibilities as set forth in Section 3.

      Section  5.  SALARY  AND  BONUS.  The  Executive  shall  be paid a  salary
("SALARY") for the period  commencing on the Effective Date at an annual rate of
One Hundred Thousand ($100,000) payable in equal installments in accordance with
the  Company's  payroll  policies.  The Salary shall be pro-rated for any Fiscal
Year  hereunder  which is less than a full Fiscal Year.  The Executive  shall be
entitled to such bonuses as are determined by the Board of Directors.

      Section 6.  REIMBURSEMENT  OF EXPENSES.  The Company  shall  reimburse the
Executive for expenses incurred in providing  services to the Company,  upon the
Executive's submission of appropriate  documentation evidencing such expenses in
accordance with the Company's  reimbursement policies as determined from time to
time by the Board. If there is a dispute as to the eligibility of an expense for
reimbursement in accordance with the Company's reimbursement policies, then such
expense shall be determined to be  reimbursable if approved by a majority of the
Board.

      Section 7. EMPLOYEE BENEFITS,  VACATIONS. During the Employment Period, in
addition to any and all  compensation  and benefits  required or permitted to be


                                       2
<PAGE>

made by the Company to Executive  hereunder,  the  Executive  shall  receive the
benefits and enjoy the perquisites described below:

            a) VACATION.  The Executive shall be entitled to four (4) weeks paid
vacation per annum. Such vacation shall be taken at such times as are consistent
with the needs and policies of the Company; and

            b)  PARTICIPATION  IN BENEFIT PLANS. The Executive shall be entitled
to participate in any group hospitalization,  health, life or other insurance or
death benefit plan, travel or accident  insurance,  restricted or stock purchase
plan,  stock option plan,  retirement  income or pension  plan,  401(k) plan, or
other  present or future group  employee  benefit plan or program of the Company
for which  executives are or shall become  eligible.  Nothing  contained in this
Agreement  shall prevent the Board from amending or otherwise  altering any such
plan, program or arrangement during the Employment Period; and

            c)   INDEMNIFICATION.   The   Executive   shall   be   entitled   to
indemnification and protection from liability as set forth in Section 11.

      Section 8. TERMINATION OF EMPLOYMENT.

            a) NOTICE OF TERMINATION; EMPLOYMENT TERMINATION DATE.

                  (1)  Any  termination  of the  Executive's  employment  by the
Company or the Executive  shall be communicated by written Notice of Termination
to the other  party  hereto.  For  purposes  of this  Agreement,  a  "NOTICE  OF
TERMINATION"  shall mean a notice  which shall  indicate  the  provision in this
Agreement relied upon.

                  (2) "EMPLOYMENT TERMINATION DATE" shall mean the date on which
the  Employment  Period  and the  Executive's  right and  obligation  to perform
employment  services for the Company shall terminate effective upon the first to
occur of the following:

                        (i) If the  Executive's  employment  is  terminated  for
Disability, the date on which the Notice of Termination is given;

                        (ii) If the  Executive's  employment  is  terminated  by
voluntary  action of the Executive (see Section 8(e)), the date specified in the
Notice of Termination,  which date shall be no more than fifteen (15) days after
the date that the Notice of Termination is given;

                        (iii) The death of the Executive;

                        (iv) The expiration of the Employment Period;

                        (v) If the  Executive's  employment is terminated by the
Company  for  Cause  (see  Section  8(b)(1)),  the  date on  which a  Notice  of
Termination is given; and



                                       3
<PAGE>

                        (vi) If the Executive's  employment is terminated by the
Company  other than for Cause,  Disability or death of the  Executive,  the date
specified in the Notice of Termination  which date shall not be more than thirty
(30) days after the date that the Notice of Termination is given.

            b)  TERMINATION FOR CAUSE:

                  (1) The  Company  may  terminate  the  Executive's  employment
hereunder  and  the  Employment  Period  for  Cause.  For the  purposes  of this
Agreement,  "CAUSE"  shall  mean  termination  because of  Executive's  personal
dishonesty,  willful  misconduct,  breach of fiduciary duty  involving  personal
profit, failure to perform stated duties (after written notice and ten (10) days
to cure),  conviction of a violation of any law, rule or regulation  (other than
traffic violations or similar offenses) or breach of any other provision of this
Agreement (after written notice and ten (10) days to cure).

                  (2) If the  Executive's  employment  shall be  terminated  for
Cause,  the  Company  shall pay the  Executive  his unpaid  Salary  through  the
Employment Termination Date.

            c)  TERMINATION  FOR  DISABILITY.  The  Company  may  terminate  the
Executive's employment because of the Disability of the Executive and thereafter
the Company  shall pay to the Executive  (or his  successors)  his unpaid Salary
through the Employment Termination Date.

            d)  TERMINATION  UPON  EXECUTIVE'S   DEATH.  In  the  event  of  the
Executive's  death,  the Company shall pay to the Executive's  estate any unpaid
amount of Salary through the date of death.

            e) VOLUNTARY  TERMINATION BY EXECUTIVE.  In the event that Executive
voluntarily  terminates his employment  with the Company prior to the expiration
of the Employment  Period, the Company shall pay the Executive his unpaid Salary
through the Employment Termination Date.

            f) COMPENSATION UPON TERMINATION OTHER THAN FOR CAUSE.

                  (1) If the Company shall terminate the Executive's  employment
for any reason  other than  pursuant  to  Sections  8(b),  (c) or (d),  then the
Company  shall,  pay to the Executive his unpaid Salary through the remainder of
the  applicable  term or  extension  term as the case may be and any accrued but
unpaid bonus previously  awarded by the Board of Directors at the same time such
Salary or bonus would have been paid had the Executive not been terminated.

      Section 9. STOCK  OPTIONS.  The Company  shall  provide to  the  Executive
pursuant to the terms and  conditions  of the Stock  Options  Addendum  attached
hereto,  stock options (the "STOCK OPTIONS") to acquire Sixty Thousand  (60,000)
common shares of the Company's  capital stock  ("COMMON  SHARES") at an exercise
price equal to the closing price of the Common Shares on the date of grant.



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<PAGE>

<TABLE>
<CAPTION>
    PERCENTAGE OF STOCK OPTIONS VESTING                           VESTING DATE

                   <S>                                <C>
                   33.3%                                  One year after Effective Date

                   66.6%                               Two years after the Effective Date

                   100%                               Three years after the Effective Date
</TABLE>

      The Stock Options shall be granted under and shall be subject to the terms
and  conditions of the Stock Option  Addendum and the  provisions  thereof shall
control in the event of the termination of Executive's employment.

      Section  10.  CERTAIN  COMPANY   PROTECTION   PROVISIONS.   The  following
provisions  apply  for  the  protection  of  the  Company,   and  shall  survive
indefinitely, beyond the duration of this Agreement:

            (a)  NONCOMPETITION.  During the Employment  Period and for a period
for two (2) years thereafter (the "RESTRICTED PERIOD"),  the Executive shall not
directly or indirectly compete with the Company by owning,  managing,  managing,
controlling or  participating  in the ownership,  management or control of or be
employed by or engaged in any  Competitive  Business (as defined  herein) in any
location in the United States in which the Company is doing business (the "TRADE
AREA").  As used herein,  a  "COMPETITIVE  BUSINESS"  is any other  corporation,
partnership, proprietorship, firm or other business entity which is engaged in a
"core  business  of the  Company."  A  "core  business  of the  Company"  is the
development,  manufacture, distribution or sale of a particular type of product,
reagent or kit involved in the  detection  or  preparation  of nucleic  acids in
which the Company or DNA Sciences, Inc., a California corporation,  has invested
or expended more than Two Hundred  Thousand  Dollars  ($200,000) in the eighteen
(18) months prior to the "Measurement Date" (as defined herein). The MEASUREMENT
DATE shall be the point in time during the Restricted  Period that the Executive
becomes  associated with a Competitive  Business  whether such association is by
employment,   engagement  or  by  directly  or  indirectly   owning,   managing,
controlling  or  participating  in the  ownership,  management  or  control of a
Competitive  Business.  In the event of any period of investment or  expenditure
which  commenced  less than eighteen (18) months from the  Measurement  Date the
amount  invested or expended  shall be  annualized  for such eighteen (18) month
period.

            Notwithstanding  the above,  the Executive may become employed by or
engaged  by a  "Competitive  Business"  so  long  as the  Executive  (a) was not
directly  involved with or  participating  in the areas of "core business of the
Company" which makes the other business a "Competitive  Business", or (b) if the
Executive is not involved,  directly,  in that part of the Competitive  Business
which is competitive  with the "core business of the Company." In addition,  the
Executive  may be  employed by or engaged by any  business  which after the date
hereof  becomes  a  "Competitive  Business,"  if the  employment  or  engagement
occurred prior to the Company entering into a new "core business of the Company"
(whether by acquisition or through the Company's own  initiative),  which caused


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<PAGE>

such other business to become a Competitive Business.  Also, this section is not
violated  if the  Executive  owns no more than 5% of the  stock of any  publicly
traded Competitive Business.

            (b)  NON-INTERFERENCE.  During the Restricted  Period, the Executive
shall not for his own  benefit  or the  benefit of any other  person,  induce or
solicit  any  employee  of the  Company or any person  doing  business  with the
Company to terminate  his or her  employment or business  relationship  with the
Company or otherwise interfere with any such relationship.

            (c) CONFIDENTIALITY.  The Executive agrees and acknowledges that, by
reason of the nature of his duties as an officer and  employee,  he will have or
may have access to and become  informed of confidential  and secret  information
which  is a  competitive  asset  of the  Company  ("CONFIDENTIAL  INFORMATION"),
including  without  limitation any lists of customers or subscribers,  financial
statistics,  research data or any other statistics and plans contained in profit
plans,  capital  plans,  critical issue plans,  strategic  plans or marketing or
operation  plans or other trade  secrets of the Company and any of the foregoing
which belong to any person or company but to which the  Executive has had access
by reason of his employment  relationship with the Company. The Executive agrees
faithfully to keep in strict confidence, and not, either directly or indirectly,
to make known, divulge,  reveal,  furnish, make available or use (except for use
in  the  regular  course  of  his  employment   duties)  any  such  Confidential
Information.  The Executive  acknowledges that all manuals,  instruction  books,
price  lists,  experiment  logs or papers,  information  and  records  and other
information and aids relating to the Company's  business,  and any and all other
documents containing Confidential  Information furnished to the Executive by the
Company or otherwise acquired or developed by the Executive,  shall at all times
be the property of the Company.  Upon termination of the Employment  Period, the
Executive  shall return to the Company any such property or documents  which are
in his  possession,  custody or control,  but his obligation of  confidentiality
shall survive such  termination  of the  Employment  Period until and unless any
such  Confidential  Information  shall  have  become,  through  no  fault of the
Executive,  generally known to the trade. The obligations of the Executive under
this  subsection are in addition to, and not in limitation or preemption of, all
other obligations of confidentiality which the Executive may have to the Company
under general legal or equitable principles.

            (d)  REMEDIES.  It is  expressly  agreed  by the  Executive  and the
Company that these  provisions are reasonable for purposes of preserving for the
Company its business,  goodwill and Confidential Information.  It is also agreed
that if any provision is found by a court having jurisdiction to be unreasonable
because  of  scope,  area or time,  then  that  provision  shall be  amended  to
correspond in scope, area and time to that considered  reasonable by a court and
as  amended  shall  be  enforced  and  the  remaining  provisions  shall  remain
effective. In the event of any breach of these provisions by the Executive,  the
parties  recognize and  acknowledge  that a remedy at law will be inadequate and
the Company may suffer irreparable  injury. The Executive  acknowledges that the
services to be rendered by him are of a character  giving them  peculiar  value,
the loss of which cannot be adequately compensated for in damages;  accordingly,
the Executive  consents to injunctive  and other  appropriate  equitable  relief
without  the  posting  of any type of bond or  surety  upon the  institution  of
proceedings  therefor by the Company in order to protect the  Company's  rights.


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<PAGE>

Such relief shall be in addition to any other relief to which the Company may be
entitled at law or in equity.

      Section 11.  INDEMNIFICATION.  As an officer of the Company, the Executive
shall be  indemnified  by the  Company in  accordance  with the  indemnification
provisions  of the  Company's  Bylaws  as in  effect  on the  date  hereof,  and
otherwise to the extent to which officers of a corporation  organized  under the
laws of Florida may be indemnified  pursuant to Section  607.0850 of the Florida
Statutes,  as the  same may be  amended  from  time to time  (or any  subsequent
statute of similar  tenor and effect),  subject to the terms and  conditions  of
such statute.

      Section  12.  SUCCESSORS  AND  ASSIGNS.  Except as  hereinafter  expressly
provided,  the  agreements,  covenants,  terms and  provisions of this Agreement
shall bind the  respective  heirs,  executors,  administrators,  successors  and
assigns of the parties.

      This  Agreement  is personal  in nature and neither of the parties  hereto
shall,  without the consent of the other,  assign or transfer this  Agreement or
any rights or  obligations  hereunder,  except as provided  in this  Section 12.
Without  limiting  the  foregoing,  the  Executive's  right to receive  payments
hereunder shall not be assignable or transferable,  whether by pledge,  creation
of a  security  interest  or  otherwise,  and in  the  event  of  any  attempted
assignment  or transfer in  contravention  of this Section 12 the Company  shall
have no liability to pay to the purported  assignee or transferee  any amount so
attempted to be assigned or transferred.

      Section  13.  NOTICES.  All  notices  and  other  communications  that are
required or may be given under this  Agreement  shall be in writing and shall be
delivered  personally or by certified mail  addressed to the party  concerned at
the following addresses:

If to the Company:         Genetic Vectors, Inc.
                           5201 N.W. 77th Avenue
                           Suite 100
                           Attn: Mead M. McCabe, Jr., President

With a copy to:            Kirkpatrick & Lockhart LLP
                           201 South Biscayne Boulevard
                           Miami Center, 20th Floor
                           Miami, Florida 33131
                           Attn:  Clayton E. Parker, Esq.

If to Executive:           Jerome Streifel

                           ---------------------
                           ---------------------
                           ---------------------

With a copy to:            William R. Soderstrom, Esquire
                           622 North Water Street, Suite 500
                           Milwaukee, Wisconsin 92024



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<PAGE>

All notices shall be effective upon receipt.

      Section 14. WAIVER; REMEDIES CUMULATIVE.  No waiver of any right or option
hereunder  by any party shall  operate as a waiver of any other right or option,
or the same  right  or  option  as  respects  any  subsequent  occasion  for its
exercise,  or of any legal remedy.  No waiver by any party of any breach of this
Agreement  or of any  agreement  or covenant  contained  herein shall be held to
constitute  a waiver of any other breach or a  continuation  of the same breach.
All remedies  provided by this  Agreement are in addition to all other  remedies
provided under this Agreement or applicable law.

      Section 15.  GOVERNING LAW;  SEVERABILITY.  This Agreement and its various
terms, provisions,  covenants and agreements, and the performance thereof, shall
be construed,  interpreted  and enforced under and with reference to the laws of
the State of Florida.  It is the  intention of the Company and the  Executive to
comply fully with all laws and matters of public  policy  relating to employment
agreements and  restrictive  covenants,  and this  Agreement  shall be construed
consistently with such laws and public policy to the extent possible.  If and to
the extent any one or more covenants,  agreements,  terms and provisions of this
Agreement  or  any  portion  or  portions  thereof  shall  be  held  invalid  or
unenforceable  by a  court  of  competent  jurisdiction,  then  such  covenants,
agreements, terms and provisions (or portions thereof) shall be deemed separable
from the remaining covenants, agreements, terms and provisions of this Agreement
and such holding shall in no way affect the validity or enforceability of any of
the other covenants, agreements, terms and provisions hereof.

      Section  16.   MISCELLANEOUS.   This  Agreement   constitutes  the  entire
understanding  of the parties  hereto with respect to the subject matter hereof.
This  Agreement  may not be  modified,  changed or  amended  except in a writing
signed by each of the parties  hereto.  This Agreement may be signed in multiple
counterparts,  each of which shall be deemed an original hereof. The captions of
the several  sections and  subsections  of this  Agreement are not a part of the
context hereof,  are inserted only for convenience in locating such sections and
subsections and shall be ignored in construing this Agreement.







                           [SIGNATURE PAGE TO FOLLOW]






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<PAGE>




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


                                   EXECUTIVE:

                                   JEROME STREIFEL


                                   ----------------------------------------




                                    COMPANY:

                                    GENETIC VECTORS, INC.,
                                    A FLORIDA CORPORATION


                                    By:
                                   ----------------------------------------
                                        Its:
                                             ------------------------------




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<PAGE>


                              STOCK OPTION ADDENDUM
                                       TO
                         EXECUTIVE EMPLOYMENT AGREEMENT
                                     BETWEEN
                              GENETIC VECTORS, INC.
                                       AND
                                 JEROME STREIFEL


      Subject  to  all  of  the  terms  and  conditions  contained  herein,  the
undersigned,  Genetic  Vectors,  Inc., a Florida  corporation  (the  "COMPANY"),
hereby grants to JEROME  STREIFEL  (the  "Executive")  the following  options to
purchase shares (the "EXECUTIVE OPTION SHARES") of the Company's $.001 par value
common stock (the "COMMON SHARES") as follows:

      The Company and the Executive hereby agree as follows:

      Subject to all of the terms and conditions  contained herein,  the Company
hereby grants to Executive the following options to purchase Common Shares:

      OPTIONS.  The Company  hereby  grants to  Executive  the right and option,
pursuant to the  Company's  1999 Stock  Incentive  Plan,  to  purchase  from the
Company Sixty Thousand (60,000) Common Shares (the "OPTIONS") upon the following
terms and conditions:

       TERM OF OPTIONS. The Options shall be effective throughout the Employment
Period and for a period of ten years from the date of grant.

       PURCHASE  PRICE.  The purchase price for the Option shall be equal to the
Closing Price of the Common Shares on the date of grant.

       OPTIONS  NON-TRANSFERABLE.  The option rights with respect to the Options
are  non-transferable and are personal to Executive and may be exercised only by
Executive and non one else.

       TIME OF EXERCISE.  Except as set forth herein, there are no conditions to
the exercise or the exercisability by the Executive of the Options.

      VESTING OF OPTIONS.  Subject to the  provisions  of Section 3 hereof,  the
Options  shall vest as follows:  (1) one-third on the first  anniversary  of the
date first  written above (2)  one-third on the second  anniversary  of the date
first written above and (3) one third on the third anniversary of the date first
written  above,  provided,  however,  that  if  the  executive's  employment  is
terminated  for any reason other than death or permanent  disability (as defined
in the  Company's  1999 Stock  Option  Plan),  any and all Options that have not
vested  as of the  Employment  Termination  Date (as  defined  in the  Executive
Employment Agreement) shall expire on such Employment Termination Date.

      SECURITIES ACT, ETC. In the absence of an effective Registration Statement
under the  Securities  Act of 1933,  as from time to time in effect (the "ACT"),
relating  thereto,  the Company  shall not be required to register a transfer of
shares  delivered  or  deliverable  upon  exercise  of the  Options  ("DELIVERED
SHARES")  on its books  unless  the  Company  shall have been  provided  with an
opinion of counsel  satisfactory to it prior to such transfer that  registration
under the Act is not required in connection  with the  transaction  resulting in
such transfer.  Each certificate  evidencing Delivered Shares or issued upon any
transfer of  Delivered  Shares  shall bear an  appropriate  restrictive  legend,
except that such  certificate  shall not bear such a  restrictive  legend if the


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<PAGE>

opinion of counsel  referred to above is to the further  effect that such legend
is not required in order to establish compliance with the provisions of the Act.
Nothing in this  paragraph 2 shall  modify or  otherwise  affect the  provisions
applicable to the Delivered Shares.

      TERMINATION, EXERCISE, ETC.

      Except as set forth herein, the Options shall expire and terminate, to the
extent  not  previously  exercised,  as to all  Executive  Option  Shares on the
Employment Termination Date.

      Unless the Board of Directors  (the  "BOARD")  determines  otherwise,  the
Executive's  rights in  respect of any  outstanding  Options  shall  immediately
terminate and no shares (or cash) shall be delivered with respect to the Options
if prior to the delivery of the Executive  Option  Shares,  (i) the Executive is
terminated  for cause or (ii) the Executive  engages in conduct as determined by
the Board to violate the non-competition or non-disclosure  provisions set forth
in Section 10 of the Executive  Employment Agreement or (iii) failure to provide
the representations and certifications required in Section 3 hereof.

      Subject to the preceding  paragraph 3(a) and the other  provisions of this
addendum,  the  Options  may,  to the  extent  exercisable  but  not  previously
exercised,  be exercised at any time and from time to time, in whole or in part,
by written notice delivered to the Company signed by the Executive or the Estate
thereof. Such notice shall state the number of Option Shares in respect to which
the Options are being  exercised,  and shall  contain such  representations  and
warranties of the  Executive or the Estate  thereof as the Company may then deem
necessary or desirable in order to comply with federal or state  securities laws
or as may  otherwise  be  reasonably  requested  by the  Company  and  shall  be
accompanied  either (i) by payment in full (in cash, by personal check or by any
other method  acceptable to the Company) of the full  Exercise  Price in respect
thereof or (ii)  delivery to the  Company of a number of shares of Common  Stock
owned by the Executive and having a fair market value (determined reasonably and
in good faith by the Board of Directors  and, if reasonably  possible,  prior to
such exercise) equal to the full Exercise Price in respect thereof. In addition,
the Company  shall have the right to require  that the  Executive  or the Estate
thereof,  when exercising the Options in whole or in part,  remit to the Company
an amount  sufficient  to satisfy any federal,  state or local  withholding  tax
requirements  (or make other  arrangements  satisfactory  to the  Company)  with
regard to such taxes prior to the delivery of any Delivered  Shares  pursuant to
such exercise,  including,  without limitation,  by withholding Delivered Shares
otherwise deliverable upon such exercise,  and, if requested by the Executive or
such Estate, the Company shall so withhold at least a number of Delivered Shares
requested to be so withheld by the  Executive at the time of such  exercise.  As
soon as practicable after such notice and payment shall have been received,  the
Company shall deliver a certificate or certificates  representing  the number of
Delivered Shares with respect to which the Options were exercised, registered in
the name of the Executive or such other name as the Executive shall direct.

      All  Delivered  Shares that shall be  purchased  upon the  exercise of the
options as provided herein shall be fully paid and non-assessable.

      CERTAIN CONDITIONS.  In the event the Company (i) pays a dividend or makes
a distribution on its Common Stock,  (ii)  subdivides its outstanding  shares of
Common Stock into a greater  number of shares,  (iii)  combines its  outstanding
shares  of  Common  Stock  into  a  smaller  number  of  shares,  (iv)  makes  a
distribution  on its  Common  Stock in shares of its  capital  stock  other than
Common Stock, (v) issues by  reclassification  of its Common Stock any shares of
its  capital  stock,   or  (vi)   consummates  any  merger   reorganization   or
consolidation  pursuant to which any securities or other consideration is issued
to the holders of  outstanding  shares of capital  stock of the Company (each an
"ADJUSTMENT  EVENT"),  then the Options granted to the Executive hereunder shall


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<PAGE>

be so adjusted and upon the exercise of such  Options,  the  Executive  shall be
entitled to receive such securities of the Company or other consideration as the
Executive would have held immediately  after the consummation of such Adjustment
Event had the  Delivered  Shares  issuable  upon such  exercise been held by the
Executive on such record date.

      5. RIGHT OF OFFSET. The Company shall have the right to offset against the
obligation to deliver  Executive Option Shares (or cash) under this Stock Option
Addendum (i) any amounts or  liabilities of the Executive to the Company or (ii)
any claims of the Company against the Executive.

      6. NO  RIGHTS  TO  CONTINUED  EMPLOYMENT.  Nothing  in this  Stock  Option
Addendum  or the 1999  Stock  Incentive  Plan shall be  construed  as giving the
Executive any right to continue employment or affect any right which the Company
may have to  terminate  or alter  the terms and  conditions  of the  Executive's
Employment.

      7. BOARD OF DIRECTORS.  The Board shall have full  discretion with respect
to any  actions to be taken or  determined  to be made in  connection  with this
Stock  Option  Addendum  and its  determinations  shall be  final,  binding  and
conclusive.

      8.  AMENDMENT BY BOARD.  The Board reserves the right at any time to amend
the terms and conditions  set forth in this Stock Option  Addendum and the Board
may amend the 1999 Stock Incentive Plan in any respect.

      9. MISCELLANEOUS.  Except as specifically  otherwise provided in Section 4
hereof as to exercise by the Executive's Estate, the Options may not be assigned
or transferred,  in whole or in part, whether by operation of law, upon death or
otherwise, by the Executive without the written consent of the Company which the
Company may  withhold in its sole and absolute  discretion,  with or without any
reason.  The Options are not intended to constitute and "incentive stock option"
as that term is used in Section 422 of the  Internal  Revenue  Code of 1986,  as
amended,  and shall not be treated as incentive stock options. The Options shall
be  governed  by and  construed  in  accordance  with the  laws of the  State of
Florida.

                                          GENETIC VECTORS, INC.


                                          By:
                                             ---------------------------------
                                          Name:
                                               -------------------------------
                                          Title:
                                                ------------------------------





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