EXHIBIT 10.50

                           CONVERTIBLE PROMISSORY NOTE

$75,000                                                         March 3, 2000


      1. AMOUNT; MATURITY. FOR VALUE RECEIVED, the undersigned, GENETIC VECTORS,
INC., a Florida corporation (the "MAKER"),  promises to pay to JACK HIGGINS (the
"HOLDER"),  the principal sum of SEVENTY FIVE THOUSAND  DOLLARS  ($75,000) which
principal  sum shall mature on the day that is one hundred and eighty (180) days
from the date hereof (the "MATURITY DATE") 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.  All accrued but unpaid
interest shall be due and payable on the Maturity Date.

      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.    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)  Subject  to Section 5 hereof,  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



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at least  $5,000,000.  The Maker shall have fifteen (15) business days to make a
mandatory prepayment to the Holder of this Note pursuant to this Section 4(b).

      5.    The Holder hereof shall have the following  conversion  rights:

            (a) Any  Holder of this Note  shall have the right at any time prior
to the payment in full of the principal balance of this Note to convert all (but
not  less  than  all)   amounts   due  under  this  Note  into  fully  paid  and
non-assessable  shares of the Maker's  common stock,  $0.001 par value per share
(the  "COMMON  STOCK").  The number of shares of Common  Stock (the  "CONVERSION
SHARES")  into which this Note may be converted  shall be determined by dividing
(a) the sum of all amounts due under this Note (including,  without  limitation,
all  principal  and  accrued  but  unpaid  interest)  up to  and  including  the
Conversion  Date (as defined below) by (b) Five Dollars (US $5.00) per share (as
adjusted in accordance with Section 5(d) hereof) (the  "CONVERSION  PRICE").  No
fractional shares of Common Stock or scrip representing  fractional shares shall
be issued upon  conversion  of this Note.  Instead of any  fractional  shares of
Common Stock which would  otherwise be issuable upon conversion of the Note, the
Maker shall pay to the Holder a cash adjustment in respect of such fraction.

            (b) To exercise his  conversion  privilege,  the Holder of this Note
shall  surrender  the  original  Note  representing  the debt  obligation  being
converted to the Maker at its principal office, and shall give written notice to
the Maker at the office that the Holder  elects to convert  such Note.  The Note
surrendered  shall  be  accompanied  by  proper  notice  of  waiver  of the debt
obligation in the form required by the Maker.  The date when such written notice
is received by the Maker,  together with the original Note representing the debt
obligation  being  converted  and all other  instruments  required by the Maker,
shall be the "CONVERSION  DATE." As promptly as practicable after the Conversion
Date,  the Maker  shall  issue and  deliver  to and in the name of the  Holder a


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certificate or certificates for the Conversion Shares.  Such conversion shall be
deemed to have been effective on the Conversion  Date and Holder shall be deemed
to have become the Holder of record of the Conversion Shares at such time.

            (c) Upon the effective date of a registration statement filed by the
Maker in connection with the  registration of its securities with the Securities
and Exchange Commission, including, without limitation, a Form SB-2 Registration
Statement, the Holder shall have fifteen (15) business days after such effective
date to provide  written  notice to the Maker electing to have this Note paid in
full in cash upon the receipt by the Maker of a minimum amount of gross proceeds
equal to $5,000,000 in such offering.  In the event the Holder does not make its
election with the  provisions  in this Section 5(c),  all amounts due under this
Note shall automatically convert into Common Stock as provided in Section 5(a).

            (d) In the event that the Maker  shall (A) pay a stock  dividend  in
and on shares of its Common  Stock;  (B)  subdivide  its  outstanding  shares of
Common Stock into a greater number of shares; (C) combine its outstanding shares
of  Common   Stock  into  a  smaller   number  of   shares,   or  (D)  issue  by
reclassification  of its shares of Common Stock any shares of its capital stock,
then the Conversion Price in effect  immediately prior thereto shall be adjusted
so that the Holder of this Note surrendered for conversion after the record date
fixing  shareholders  to be  affected by such event shall be entitled to receive
upon conversion the number of such shares of Common Stock which the Holder would
have been  entitled to receive  after the  happening of such event had this Note
been  converted  immediately  prior to such record  date.  Such  adjustment,  if
applicable,  shall be made on the effective date of such event and shall also be
effective  retroactively  as to the  principal  amount  of this  Note  converted
between such record date and the effective date of the event.



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      6. ACCELERATION UPON EVENT OF DEFAULT. Upon the occurrence of any event of
default as  described  below,  the Holder  shall have the  remedies set forth in
Section 7 hereof, which remedies shall be exclusive:

            (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 fifteen  business (15) 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  bankrupt or
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 5(b) hereof, or any receiver,  trustee,  assignee,
custodian,  sequestrator,  liquidator or other  official shall be appointed with


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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 ninety (90) days.

      7.  EXCLUSIVE  REMEDIES UPON EVENT OF DEFAULT.  Upon the  occurrence of an
event of default as described  in Section 6 hereof,  any Holder of this Note may
exercise one of the following  exclusive remedies by providing the Maker written
notice of the Holder's choice of remedies hereunder within fifteen (15) business
days  after the  occurrence  of an event of default  as  described  in Section 6
hereof and upon the expiration of any notice or cure period described herein:

            (a) The Holder of this Note shall have the right to convent all (but
not less than all) amounts due under this Note into Common  Stock in  accordance
with the conversion  procedures as set forth in Section 5(b) hereof.  The number
of shares of Common Stock into which this Note may be converted pursuant to this
Section  7(a) shall be  determined  by  dividing  (i) the sum of all amounts due
under this Note (including,  without  limitation,  all principal and accrued but
unpaid  interest) up to and including the Conversion Date (ii) Three Dollars (US
$3.00) per share (as  adjusted in  accordance  with  Section  5(d)  hereof).  No
fractional shares of Common Stock or scrip representing  fractional shares shall
be issued upon  conversion  of this Note.  Instead of any  fractional  shares of
Common Stock which would  otherwise be issuable upon conversion of the Note, the
Maker shall pay to the Holder a cash adjustment in respect of such fraction; or

            (b) The Holder of this Note shall have the right to the repayment in
cash of all  amounts  due under this Note,  in which case such  Holder  shall be
entitled  to  receive a warrant  from the Maker  that  entitles  such  Holder to
purchase  from the Maker  shares of Common Stock of the Maker in an amount equal


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to one percent (1%) of the principal amount of this Note at a purchase price per
share of Five  Dollars (US $5.00) (as adjusted in  accordance  with Section 5(d)
hereof)  for each  month  that such  principal  balance  remains  unpaid up to a
maximum of six (6) months.  Any warrants  issuable pursuant to this Section 7(b)
shall be issued to the Holder on the last  business  day of each month each such
warrant is due. By way of example only, if the principal balance of this Note is
$100,000,  then the Holder would be entitled to receive a warrant from the Maker
to purchase 1,000 shares for $5.00 per share.

      8.  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.

      9. WAIVER OF PRESENTMENT. The Maker hereby waives presentment for payment,
dishonor,  protest,  notice of protest and any demand whatsoever with respect to
this Note.

      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,  including,  without
limitation,  any  objection  based  on  the  assertion  that  such  venue  is an
inconvenient  forum  and (3)  irrevocably  submit  to the  jurisdiction  of such
Federal or state court in Miami-Dade County, Florida in any such suit, action or


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proceeding.  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) ten (10) days  after  mailing if
mailed by 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.
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  (10th) 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.  AMENDMENT.  This Note shall not be amended  without the prior written
consent of the Holder and the Maker.

                                      GENETIC VECTORS, INC.


                                       By:
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                                      Its:
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