EXHIBIT 10.21

                             FORM OF PROMISSORY NOTE
                             -----------------------

$163,500.00
                                                                January 19, 1999

      1. AMOUNT; MATURITY. FOR VALUE RECEIVED, the undersigned, GENETIC VECTORS,
INC., a Florida  corporation (the "MAKER"),  promises to pay to CAPITAL RESEARCH
LTD., a Delaware  corporation  partnership (the "HOLDER"),  the principal sum of
One Hundred  Sixty-Three  Thousand  Five Hundred  Dollars  ($163,500.00),  which
principal sum shall mature on January 19, 2000 and shall bear simple interest at
the rate set forth herein.

      2.  INTEREST.  Interest  shall  accrue  as of the date of this Note at the
simple interest rate of twelve percent (12%) per annum which rate shall increase
one percent (1%) on the nineteenth  (19th) day of each month that any portion of
this Note remains unpaid commencing on January 19, 2000 up to the maximum amount
permitted by law. Interest shall be payable quarterly in arrears,  commencing on
April 19, 1999 and each  successive  interest  payment shall be due on the first
day of each successive quarter thereafter.

      3. MODE OF PAYMENT.  All payments of principal and interest due under this
Note shall be made in legal tender in the United States of America and delivered
to the Holder at or, at the option of the  Holder,  in such other  manner and at
such other place as the Holder shall have designated to the Maker in writing. 

      4. SECURITY.  The Maker's obligations  hereunder are secured by a security
interest  granted to the Holder  pursuant to a Security  Agreement  of even date
herewith by and between the parties hereto.


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      5. PREPAYMENT.
         ----------

         (a) This Note may be voluntarily  prepaid,  without penalty or premium,
in whole or in part,  at any time and from  time to time.  Any  prepayment  must
include all accrued interest on the principal being prepaid, through the date of
prepayment.

         (b)  Notwithstanding  anything  contained herein to the contrary,  this
Note shall be mandatorily prepaid in the event that the Maker closes an offering
of its securities,  whether through one or more private  placements or secondary
public offerings, in which the Maker raises gross proceeds from such transaction
or transactions of at least $1,500,000.

      6. ACCELERATION UPON EVENT OF DEFAULT. This Note may be accelerated at the
option of the Holder,  upon the  occurrence of any event of default as described
below:

         (a) any  default,  whether  in  whole or in  part,  shall  occur in the
payment to the Holder of principal,  interest or other item  comprising the Note
as and when due which  shall  continue  for a period of ten (10) days  after the
receipt of written notice thereof by the Maker;

         (b) the Maker  shall (1) make a general  assignment  for the benefit of
its  creditors,  (2) apply for or  consent  to the  appointment  of a  receiver,
trustee,  assignee,  custodian sequestrator,  liquidator or similar official for
itself or any of its assets and  properties,  (3) commence a voluntary  case for
relief as a debtor under the United  States  Bankruptcy  Code,  (4) file with or
otherwise  submit to any  governmental  authority any petition,  answer or other
document seeking (A) reorganization, (B) an arrangement with creditors or (C) to
take  advantage  of any  other  present  or  future  applicable  law  respecting
bankruptcy,  reorganization,   insolvency,  readjustment  of  debts,  relief  of
debtors,  dissolution or liquidation, (5) file or otherwise submit any answer or
other  document  admitting or failing to contest the material  allegations  of a
petition  or other  document  filed or  otherwise  submitted  against  it in any
proceeding  under any such  applicable  law, or (6) be adjudicated a bankrupt or


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insolvent by a court of competent jurisdiction; or

         (c) any case, proceeding or other action shall be commenced against the
Maker for the purpose of  effecting,  or an order,  judgment or decree  shall be
entered by any court of competent  jurisdiction  approving (in whole or in part)
anything specified in Section 6(b) hereof, or any receiver,  trustee,  assignee,
custodian,  sequestrator,  liquidator or other  official shall be appointed with
respect to the Maker, or shall be appointed to take or shall  otherwise  acquire
possession or control of all or a substantial  part of the assets and properties
of the Maker, and any of the foregoing shall continue unstayed and in effect for
any period of 60 days.  

      7.  DELAY IN  EXERCISE  OF  RIGHTS.  No delay on the part of the Holder in
exercising  any of its  options,  powers or  rights  nor any  partial  or single
exercise of its options, power or rights shall constitute a waiver thereof or of
any other option, power or right, and no waiver on the part of the Holder of any
of its options,  powers or rights shall constitute a waiver of any other option,
power or right.

      8. WAIVER OF PRESENTMENT;  NO OFFSETS. The Maker hereby waives presentment
for payment, dishonor, protest, notice of protest and any demand whatsoever with
respect  to this Note and the right to  interpose  any  defense  based  upon any
statute of limitation or any claim of laches and any set-off or  counterclaim of
any nature or description.

      9. COLLECTION COSTS; MAXIMUM INTEREST LIMITATIONS.
         ----------------------------------------------

         (a)  The  Maker  agrees  to pay all  reasonable  costs,  including  all
reasonable  attorneys'  fees  and  disbursements   incurred  by  the  Holder  in
collecting or enforcing payment of this Note in accordance with its terms.

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         (b) After this Note becomes due, at stated maturity or on acceleration,
any unpaid balance hereof shall thereafter bear interest until paid at a rate of
sixteen  percent (16%) simple  interest per annum,  but such interest rate shall
not exceed at any time the maximum  interest  rate  allowable  under  applicable
state usury laws.

      10. GOVERNING LAW.
          -------------

         (a) This Note and the rights of the parties hereunder shall be governed
by and  construed in accordance  with the laws of the State of Florida,  without
regard to its conflicts of law principles. All parties hereto (1) agree that any
legal suit,  action or proceeding  arising out of or relating to this note shall
be instituted  only in a Federal or state court in Miami-Dade  County,  Florida,
(2) waive any  objection  which they may now or hereafter  have to the laying of
the venue of any such suit, action or proceeding,  and (3) irrevocably submit to
the jurisdiction of such Federal or state court in Miami-Dade County, Florida in
any such suit,  action or  proceeding,  but such consent shall not  constitute a
general  appearance  or be  available  to any other person who is not a party to
this Note. All parties hereto agree that the mailing of any process in any suit,
action or proceeding in accordance with the notice provisions of this Note shall
constitute personal service thereof.

         (b) THE  MAKER  HEREBY  WAIVES  ANY RIGHT TO TRIAL BY JURY IN ANY LEGAL
PROCEEDING RELATED IN ANY WAY TO THIS NOTE.

      11. NOTICES. All notices or other communications  required or permitted to
be given  pursuant to this Note shall be in writing and shall be  considered  as
duly given on (a) the date of delivery,  if delivered in person or by nationally
recognized  overnight  delivery service or (b) five days after mailing if mailed
by registered or certified mail,  return receipt requested to the party entitled
to receive the same,  if to the  Holder,  at his or its address on the books and
records of the Maker, and if to the Maker, to Genetic  Vectors,  Inc., 5201 N.W.

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77th Avenue,  Suite 100, Miami, Florida 33166,  Attention:  Mead M. McCabe, Jr.,
with a copy to Kirkpatrick & Lockhart LLP, Miami Center - 20th Floor,  201 South
Biscayne Boulevard, Miami, Florida 33131, Attention: Clayton E. Parker, Esq. Any
party may change its address by giving notice to the other party stating its new
address. Commencing on the tenth day after the giving of such notice, such newly
designated  address shall be such party's address for the purpose of all notices
or other communications required or permitted to be given pursuant to this Note.

      12.  SEVERABILITY.  If any provision of this Note shall be held invalid or
unenforceable,  such  invalidity or  unenforceability  shall attach only to such
provision and shall not in any manner affect or render invalid or  unenforceable
any other  severable  provision of this Note, and this Note shall be carried out
as if any such invalid or unenforceable provision were not contained herein.

      13.  AMENDMENT.  This Note shall not be amended  without the prior written
consent of the Holder and the Maker. 

                                      GENETIC VECTORS, INC.



                                      By:   ____________________________________
                                      Its:  ____________________________________






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