Exhibit 10.42
                                  -------------

                          PLEDGE AND SECURITY AGREEMENT
                          -----------------------------


      THIS PLEDGE AND SECURITY AGREEMENT,  dated as of December 22, 1999, by and
between GENETIC VECTORS,  INC., a Florida corporation  ("Pledgor"),  and ORBITER
FUND, LTD. (the "Pledgee").

      WHEREAS,  Pledgee is the holder of a Promissory  Note (the "Note") of even
date herewith made by Pledgor in the original principal amount of $300,000;

      WHEREAS, Pledgee desires to obtain a security interest in certain property
owned by Pledgor;

      WHEREAS,  Pledgee  acknowledges  that Pledgor has  previously  pledged and
granted security interests in the Pledged Collateral as defined herein; and

      WHEREAS,  as an inducement to Pledgee's  purchase of the Note, Pledgor has
agreed to grant to Pledgee a security interest in and to the Pledged  Collateral
(as hereinafter defined).

      NOW, THEREFORE,  in consideration of the premises and the mutual covenants
herein contained,  and for other good and valuable  consideration,  the adequacy
and receipt for which are hereby  acknowledged,  the parties hereto hereby agree
as follows:
                                   ARTICLE 1.

                         DEFINITIONS AND INTERPRETATIONS
                         -------------------------------

      Section 1.1.  Interpretations.
                    ---------------

      Nothing  herein  expressed or implied is intended or shall be construed to
confer upon any person other than Pledgee any right, remedy or claim under or by
reason hereof.

      Section 1.2.  Obligations Secured.
                    -------------------

      The  obligations  secured hereby are the obligations of Pledgor to Pledgee
under the Note issued by Pledgor to Pledgee,  in the  maximum  principal  amount
thereof  outstanding from time to time, and any additional amounts payable by or
chargeable to Pledgor thereunder or hereunder (collectively, the "Obligations").


<PAGE>

                                   ARTICLE 2.

                 PLEDGE AND ADMINISTRATION OF PLEDGED COLLATERAL
                 -----------------------------------------------

      Section 2.1.  Pledged Collateral.
                    ------------------

            (a)     Pledgor  hereby  pledges to Pledgee,  and creates in Pledgee
for its benefit, subject to the rights of previous pledgees and other holders of
security  interests in the Pledged  Collateral (as defined  herein),  a security
interest,  for such time as the Obligations shall remain outstanding,  in and to
all of Pledgor's right, title and interest in and to:

                    (i)  the property (the "Pledged Property") listed on Exhibit
1 attached  hereto,  including,  without  limitation,  any securities  described
therein  (which  securities  are  collectively   referred  to  as  the  "Pledged
Securities"), now owned by Pledgor, and all machinery,  equipment,  automobiles,
accounts  receivable,   inventory  and  general  intangibles,   patents,  patent
applications,  licenses and all other  intellectual  property rights owned by or
acquired by Borrower on or after the date of this Agreement; and

                    (ii) all products and proceeds from the Pledged Property.
      The Pledged Property in Section 2.1(a)(i) hereof,  the Pledged  Securities
and the  products  thereof and the  proceeds  of all such items are  hereinafter
collectively  referred to as the "Pledged  Collateral."  The  security  interest
granted by Pledgor to Pledgee in and to the Pledged Collateral is subject to the
rights of  previous  pledgees  and other  holders of security  interests  in the
Pledged Collateral.

            (b)     Simultaneously  with  the  execution  and  delivery  of this
Agreement, Pledgor shall make, execute, acknowledge, file, record and deliver to
Pledgee any  documents  reasonably  requested by Pledgee to perfect its security


                                       2
<PAGE>

interest in the Pledged Collateral.  The Pledgee shall be responsible for filing
any and all documents  required to perfect its security  interest in the Pledged
Collateral.  Simultaneously  with the execution and delivery of this  Agreement,
Pledgor shall make,  execute,  acknowledge and deliver to Pledgee such documents
and  instruments,   including,   without   limitation,   financing   statements,
certificates,  affidavits and forms as may, in Pledgee's reasonable judgment, be
necessary to effectuate,  complete or perfect, or to continue and preserve,  the
security interest of Pledgee in the Pledged  Collateral,  and Pledgee shall hold
such  documents  and  instruments  as  secured  party,  subject to the terms and
conditions contained herein.

      Section 2.2.  Rights; Interests; Etc.
                    -----------------------

            (a)     So long as no  Event of  Default  (as  hereinafter  defined)
shall have occurred and be continuing:

                    (i)  Pledgor  shall  be  entitled  to  exercise  any and all
rights pertaining to the Pledged  Collateral or any part thereof for any purpose
not inconsistent with the terms hereof; and

                    (ii) Pledgor shall be entitled to receive and retain any and
all payments paid or made in respect of the Pledged Collateral.

            (b)     Upon the occurrence  and during the  continuance of an Event
in Default:

                    (i)  Subject to the rights of  previous  pledgees  and other
holders of security  interests in the Pledged  Collateral and subject to Section
2.2(b)(iii)  hereof, all rights of Pledgor to exercise the rights which it would
otherwise be entitled to exercise  pursuant to Section  2.2(a)(i)  hereof and to
receive  payments  which it would  otherwise be authorized to receive and retain
pursuant to Section  2.2(a)(ii)  hereof shall be suspended,  and all such rights


                                       3
<PAGE>

shall thereupon become vested in Pledgee who shall thereupon have the sole right
to  exercise  such  rights and to receive  and hold as Pledged  Collateral  such
payments;  provided,  however,  that if Pledgee shall become  entitled and shall
elect to  exercise  its right to realize on the Pledged  Collateral  pursuant to
Article V hereof, then all cash sums received by Pledgee, or held by Pledgor for
the benefit of Pledgee  and paid over  pursuant  to Section  2.2(b)(ii)  hereof,
shall be applied against any outstanding Obligations.

                   (ii)  Subject to the rights of  previous  pledgees  and other
holders  of  security  interests  in  the  Pledged  Collateral,   all  interest,
dividends,  income and other  payments and  distributions  which are received by
Pledgor contrary to the provisions of Section 2.3(b)(i) hereof shall be received
in trust for the benefit of Pledgee,  shall be segregated from other property of
Pledgor and shall be forthwith paid over to Pledgee;

                  (iii)  notwithstanding   anything   contained  hereto  to  the
contrary, Pledgor shall retain any voting rights it may have with respect to any
of the Pledged  Securities  until such time as Pledgee is entitled and elects to
exercise its rights to realize on the Pledged  Securities  pursuant to Article V
hereof.

            (c)     Each of the  following  events  shall  constitute  a default
under this Agreement (each an "Event of Default"):

                    (i)  any default,  whether in whole or in part, shall occur
in the payment to Pledgee of principal,  interest or other item  comprising  the
Obligations as and when due, which default shall continue for a period of thirty
(30) days after the  receipt  of written  notice  thereof  by  Pledgor;

                   (ii)  any default,  whether in whole or in part, shall occur
in the due observance or performance of any other covenant, term or provision to
be  performed  under this  Agreement by Pledgor,  or the Note,  and all exhibits


                                       4
<PAGE>

thereto which default is not described in any other  subsection of this Section,
and such  default  shall  continue  for a period of thirty  (30) days  after the
receipt of written notice thereof by Pledgor; provided, however, that if Pledgor
shall have commenced to cure such default within such thirty (30) day period and
shall  proceed  continuously  in good faith and with due  diligence to cure such
default, then such period instead shall be sixty (60) days;

                  (iii)  Pledgor 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
insolvent by a court of competent jurisdiction; or

                   (iv)  any case, proceeding or other action shall be commenced
against  Pledgor 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  2.2(c)(iii)  hereof,  or any receiver,
trustee, assignee, custodian,  sequestrator,  liquidator or other official shall
be  appointed  with  respect to Pledgor,  or shall be appointed to take or shall


                                       5
<PAGE>

otherwise  acquire  possession  or control of all or a  substantial  part of the
assets and  properties  of  Pledgor,  and any of the  foregoing  shall  continue
unstayed and in effect for any period of ninety (90) days.

                                   ARTICLE 3.

                          ATTORNEY-IN-FACT; PERFORMANCE
                          -----------------------------

      Section 3.1.  Pledgee Appointed Attorney-In-Fact.
                    ----------------------------------

      Upon the  occurrence of an Event of Default and only as long as such Event
of Default shall be continuing,  and subject to the rights of previous  pledgees
and other  holders of  security  interests  in the Pledged  Collateral,  Pledgor
hereby appoints  Pledgee as Pledgor's  attorney-in-fact,  with full authority in
the place and stead of Pledgor  and in the name of Pledgor  or  otherwise,  from
time to time in  Pledgee's  discretion  to take any action  and to  execute  any
instrument  which  Pledgee may  reasonably  deem  necessary  to  accomplish  the
purposes  of this  Agreement,  including,  without  limitation,  to receive  and
collect all  instruments  made payable to Pledgor  representing  any payments in
respect of the Pledged Collateral or any part thereof and to give full discharge
for the same.  Pledgee may demand,  collect,  receipt for,  settle,  compromise,
adjust,  sue for,  foreclose,  or realize on the Pledged  Collateral as and when
Pledgee may determine.  To facilitate  collection,  and subject to the rights of
previous  pledgees  and  other  holders  of  security  interest  in the  Pledged
Collateral,  Pledgee  may notify  account  debtors  and  obligors on any Pledged
Collateral to make payments directly to Pledgee.

      Section 3.2.  Pledgee May Perform.
                    -------------------

      If Pledgor fails to perform any agreement  contained herein,  Pledgee,  at
its option, may itself perform, or cause performance of, such agreement, and the
reasonable expenses of Pledgee incurred in connection therewith shall be payable
by Pledgor under Section 8.3.


                                       6
<PAGE>

                                   ARTICLE 4.

                         REPRESENTATIONS AND WARRANTIES
                         ------------------------------

      Section 4.1.  Authorization; Enforceability.
                    -----------------------------

      Each of the parties  hereto  represents and warrants that it has taken all
action  necessary to authorize the execution,  delivery and  performance of this
Agreement  and the  transactions  contemplated  hereby;  and upon  execution and
delivery,  this Agreement shall constitute a valid and binding obligation of the
respective party, subject to applicable bankruptcy, insolvency,  reorganization,
moratorium  and similar laws  affecting  creditors'  rights or by the principles
governing the availability of equitable remedies.

      Section 4.2.  Ownership of Pledged Collateral.
                    -------------------------------

      Pledgor  warrants and represents  that Pledgor is the legal and beneficial
owner of the Pledged Collateral.

      Section 4.3.  Due Organization.
                    ----------------

      Pledgor  warrants  and  represents  that  it:  (i) is a  corporation  duly
organized,  validly existing and in good standing under the laws of the State of
Florida;  (ii) has the corporate power and authority  necessary to entitle it to
use its corporate  name and to own,  lease or otherwise  hold its properties and
assets and to carry on its  business as  presently  conducted  or proposed to be
conducted;  and (iii) is duly  qualified  and in good standing to do business as
presently conducted or proposed to be conducted.

                                   ARTICLE 5.

                    DEFAULT; REMEDIES; SUBSTITUTE COLLATERAL
                    ----------------------------------------

      Section 5.1.  Default and Remedies.
                    --------------------

            (a)     If an Event of Default  described in Section  2.2(c)(i)  and
(ii) occurs and is  continuing  for the period set forth  therein,  then in each
such case the Holder may  declare  the  principal  amount to be due and  payable


                                       7
<PAGE>

immediately,  by a  notice  in  writing  to  the  Company,  and  upon  any  such
declaration,  such principal amount shall become immediately due and payable. If
an Event of Default  described  in  Sections  2.2(c)(iii)  or (iv) occurs and is
continuing  for the period set forth therein,  then the principal  amount of the
Note shall automatically  become immediately due and payable without declaration
or other act on the part of any Holder.

            (b)     Upon  the  occurrence  of an Event of  Default,  the  Holder
shall,  subject to the rights of previous pledgees and other holders of security
interests   in  the  Pledged   Collateral,   (i)  be  entitled  to  receive  all
distributions with respect to the Pledged Collateral,  (ii) to cause the Pledged
Collateral to be transferred  into the name of Pledgee or its nominee,  (iii) to
dispose of the Pledged  Collateral,  and (iv) to realize upon any and all rights
in the Pledged Collateral then held by Pledgee.

      Section 5.2   Method  of  Realizing  Upon the  Pledged  Collateral:
                    Other Remedies.
                    -----------------------------------------------------

       Upon the occurrence of an Event of Default, in addition to any rights and
remedies  available  at law or in equity,  and subject to the rights of previous
pledgees and other holders of security interests in the Pledged Collateral,  the
following  provisions  shall govern  Pledgee's right to realize upon the Pledged
Collateral;

            (a)     Any item of the Pledged  Collateral  may be sold for cash or
other value in any number of lots at brokers  board,  public  auction or private
sale and may be sold  without  demand,  advertisement  or  notice  (except  that
Pledgee shall give Pledgor  thirty (30) business  days' prior written  notice of
the time and place or of the time  after  which a private  sale may be made (the
"Sale Notice")),  which notice shall in any event be commercially reasonable. At
any sale or sales of the Pledged  Collateral,  Pledgor may bid for and  purchase
the whole or any part of the Pledged  Collateral  and, upon  compliance with the
terms of such sale,  may hold,  exploit and dispose of the same without  further


                                       8
<PAGE>

accountability  to Pledgee.  Pledgor will  execute and  deliver,  or cause to be
executed and  delivered,  such  instruments,  documents,  assignments,  waivers,
certificates,  and  affidavits  and supply or cause to be supplied  such further
information and take such further action as Pledgee  reasonably shall require in
connection with any such sale.

            (b)     Subject to the rights of previous pledgees and other holders
of security interests in the Pledged Collateral,  any cash being held by Pledgee
as Pledged  Collateral and all cash proceeds  received by Pledgee in respect of,
sale  of,  collection  from,  or other  realization  upon all or any part of the
Pledged Collateral shall be applied as follows:

                    (i)  to the  payment of all  amounts  due the Holder for the
expenses  reimbursable to it or them hereunder or owed to it pursuant to Section
8.3 hereof;

                   (ii)  to the payment of the  amounts  then due and unpaid for
principal of and interest on the Note.

                  (iii)  the balance,  if any, to the person or persons entitled
thereto, including, without limitation, Pledgor.


            (c)     Subject to the rights of previous pledgees and other holders
of  security  interests  in the  Pledged  Collateral,  in addition to all of the
rights  and  remedies  which  Pledgor  and  Pledgee  may have  pursuant  to this
Agreement,  Pledgor  and  Pledgee  shall  have all of the  rights  and  remedies
provided  by  law,  including,  without  limitation,  those  under  the  Uniform
Commercial Code.

            (d)

                    (i)  Subject to the rights of  previous  pledgees  and other
holders of security interests in the Pledged Collateral, if Pledgor fails to pay
such amounts due upon the occurrence of an Event of Default which is continuing,


                                       9
<PAGE>

then the Holder may institute a judicial  proceeding  for the  collection of the
sums so due and  unpaid,  may  prosecute  such  proceeding  to judgment or final
decree and may enforce the same against  Pledgor and collect the monies adjudged
or decreed to be payable in the manner  provided  by law out of the  property of
Pledgor, wherever situated.

                   (ii)  Pledgor   agrees  that  it  shall  be  liable  for  any
reasonable  expenses  incurred  by the Holder in  connection  with  enforcement,
collection  and  preservation  of  the  Note,  including,   without  limitation,
reasonable  legal fees and expenses,  and such amounts shall be deemed  included
under Section 8.3 hereof. Section

      Section 5.3.  Proofs of Claim.
                    ---------------

            (a)     In  case of the  pendency of any  receivership,  insolvency,
liquidation, bankruptcy, reorganization, arrangement, adjustment, composition or
other judicial  proceeding  relating to Pledgor or the property of Pledgor or of
such other obligor or their creditors,  the Holder  (irrespective of whether the
principal  of the Note shall then be due and payable as therein  expressed or by
declaration or otherwise and  irrespective of whether the Holder shall have made
any demand on Pledgor for the payment of overdue principal, if any, or interest)
shall,  subject to the rights of previous pledgees and other holders of security
interests in the Pledged Collateral,  be entitled and empowered, by intervention
in such  proceeding  or  otherwise:

                    (i)  to file  and  prove a claim  for the  whole  amount  of
principal of the Note and  interest  owing and unpaid in respect of the Note and
to file such other papers or documents as may be necessary or advisable in order
to have the claims of the Holder  (including any claim for the reasonable  legal
fees and expenses and other  expenses  paid or incurred by the Holder  permitted
hereunder and of the Holder allowed in such judicial proceeding), and


                                       10
<PAGE>

                   (ii)  Subject to the rights of  previous  pledgees  and other
holders of security interests in the Pledged Collateral,  to collect and receive
any monies or other  property  payable or  deliverable on any such claims and to
distribute the same; and any custodian, receiver, assignee, trustee, liquidator,
sequestrator or other similar official in any such judicial proceeding is hereby
authorized  by each Holder to make such payments to the Holder and, in the event
that the Holder  shall  consent to the making of such  payments  directed to the
Holder, to pay to the Holder any amounts for expenses due it hereunder.

            (b)     Nothing  herein  contained  shall be deemed to authorize the
Holder to  authorize,  consent to or accept or adopt on behalf of any Holder any
plan of  reorganization,  arrangement,  adjustment or composition  affecting the
rights of any Holder  thereof or to  authorize  the Holder to vote in respect of
the claim of any Holder in any such proceeding.

     Section 5.4.   Duties  Regarding  Pledged Collateral.
                    --------------------------------------

      Pledgee  shall  have no duty as to the  collection  or  protection  of the
Pledged Collateral or any income thereon or as to the preservation of any rights
pertaining  thereto,  beyond the safe custody and reasonable  care of any of the
Pledged Collateral actually in Pledgee's possession.

                                   ARTICLE 6.

                              AFFIRMATIVE COVENANTS
                              ---------------------

      Pledgor  covenants  and agrees  that,  from the date  hereof and until the
Obligations  have been fully paid and  satisfied,  unless  Pledgee shall consent
otherwise in writing (as provided in Section 8.4 hereof):

      Section 6.1   Existence, Properties, Etc.
                    ---------------------------

            (a)     Pledgor  shall  do,  or  cause to be done,  all  things,  or
proceed with due  diligence  with any actions or courses of action,  that may be
reasonably  necessary (i) to maintain its due organization,  valid existence and


                                       11
<PAGE>

good standing under the laws of its state of incorporation, and (ii) to preserve
and keep in full force and effect all qualifications, licenses and registrations
in those  jurisdictions  in which the  failure  to do so could  have a  Material
Adverse  Effect (as defined in this Section  6.1(a));  and (b) Pledgor shall not
do, or cause to be done, any act impairing its corporate  power or authority (i)
to carry on its business as now  conducted,  and (ii) to execute or deliver this
Agreement or any other document  delivered in connection  herewith  (which other
loan instruments collectively shall be referred to as the "Loan Instruments") to
which it is or will be a party, or perform any of its  obligations  hereunder or
thereunder.  For purpose of this Agreement,  the term "Material  Adverse Effect"
shall mean any  material  and adverse  affect,  whether  individually  or in the
aggregate,  upon (a)  Pledgor's  assets,  business,  operations,  properties  or
condition, financial or otherwise; (b) the ability of Pledgor to make payment as
and  when  due of all  or any  part  of  the  Obligations;  or (c)  the  Pledged
Collateral.

      Section 6.2.  Accounts and Reports.
                    --------------------

      Pledgor shall maintain a standard  system of accounting in accordance with
generally accepted accounting  principles  consistently  applied and provide, at
its sole expense, to Pledgee the following:

            (a)     as  soon  as  available,  a copy  of  any  notice  or  other
communication  alleging any nonpayment or other material  breach or default,  or
any  foreclosure or other action  respecting any material  portion of its assets
and properties, received respecting any of the indebtedness of Pledgor in excess
of $15,000  (other  than the  Obligations),  or any demand or other  request for
payment under any guaranty, assumption,  purchase agreement or similar agreement
or arrangement respecting the indebtedness or obligations of others in excess of
$15,000,  including  any received from any person acting on behalf of the Holder
or beneficiary thereof; and


                                       12
<PAGE>

            (b)     within  fifteen (15)  business days after the making of each
submission  or  filing,  a copy of any  report,  registration  statement,  proxy
statement,  financial statement,  notice or other document,  whether periodic or
otherwise, submitted to the shareholders of Pledgor, or submitted to or filed by
Pledgor  with  any  governmental   authority  involving  or  affecting  (i)  any
registration  of  Pledgor  or its  securities;  (ii)  Pledgor  that could have a
Material  Adverse Effect;  (iii) the  Obligations;  (iv) any part of the Pledged
Collateral or (v) any of the transactions  contemplated in this Agreement or the
Loan  Instruments,  including,  without  limitation,  those  submitted  or filed
pursuant to the Securities Act of 1933, as amended,  and the Securities Exchange
Act of 1934, as amended.

      Section 6.3.  Maintenance and Insurance.
                    -------------------------

            (a)     Pledgor shall maintain or cause to be maintained, at its own
expense,  all of its assets and  properties in good working order and condition,
making all necessary repairs thereto and renewals and replacements thereof.

            (b)     Pledgor shall maintain or cause to be maintained, at its own
expense, insurance in form, substance and amounts (including deductibles), which
Pledgor deems reasonably necessary to Pledgor's business, (i) adequate to insure
all assets and  properties  of Pledgor,  which  assets and  properties  are of a
character  usually  insured by persons  engaged in the same or similar  business
against  loss or  damage  resulting  from  fire or other  risks  included  in an
extended  coverage  policy;  (ii) against public liability and other tort claims
that  may  be  incurred  by  Pledgor;  (iii)  as  may be  required  by the  Loan
Instruments  or  applicable  law and  (iv)  as may be  reasonably  requested  by
Pledgee, all with adequate, financially sound and reputable insurers.


                                       13
<PAGE>

      Section 6.4.  Contracts and Other Collateral.
                    ------------------------------

      Pledgor shall perform all of its obligations under or with respect to each
instrument,  receivable,  contract and other intangible  included in the Pledged
Collateral to which Pledgor is now or hereafter  will be party on a timely basis
and  in  the  manner  therein  required,  including,  without  limitation,  this
Agreement.

      Section 6.5.  Defense of Collateral, Etc.
                    ---------------------------

      Pledgor  shall defend and enforce its right,  title and interest in and to
any part of: (a) the  Pledged  Collateral;  and (b) if not  included  within the
Pledged Collateral, those assets and properties whose loss could have a Material
Adverse Effect,  Pledgor shall,  subject to the rights of previous  pledgees and
other holders of security interests in the Pledged Collateral,  defend Pledgee's
right,  title  and  interest  in and to  each  and  every  part  of the  Pledged
Collateral,  each  against all manner of claims and demands on a timely basis to
the full extent permitted by applicable law.

      Section 6.6.  Payment of Debts, Taxes, Etc.
                    -----------------------------

      Pledgor shall pay, or cause to be paid, all of its  indebtedness and other
liabilities  and perform,  or cause to be performed,  all of its  obligations in
accordance with the respective terms thereof, and pay and discharge, or cause to
be paid or discharged, all taxes, assessments and other governmental charges and
levies  imposed upon it, upon any of its assets and  properties on or before the
last day on which the same may be paid without penalty, as well as pay all other
lawful claims (whether for services, labor, materials, supplies or otherwise) as
and when due; provided,  however,  that it shall not constitute a breach of this
paragraph  if Pledgor  fails to perform any such  obligation  or to pay any such
indebtedness or other liability (except for the Obligations),  tax,  assessment,
or governmental or other charge, levy or claim (i) if the effect of such failure


                                       14
<PAGE>

to pay or perform will not (A) accelerate the maturity thereof,  or of any other
debt or  obligation  of  Pledgor,  or (B)  subject  any part of the  assets  and
properties of Pledgor to sale or forfeiture.

                                   ARTICLE 7.

                               NEGATIVE COVENANTS
                               ------------------

      Pledgor  covenants  and  agrees  that,  from the  date  hereof  until  the
Obligations  have been  fully paid and  satisfied,  Pledgor  shall  not,  unless
Pledgee shall consent otherwise in writing:

      Section 7.1.  Liens and Encumbrances.
                    ----------------------

            incur any liens incurred in respect of  indebtedness  on the Pledged
Collateral which are superior to the Obligations.

                                   ARTICLE 8.

                                  MISCELLANEOUS
                                  -------------

     Section 8.1.  Notices.
                   -------

      All  notices or other  communications  required or  permitted  to be given
pursuant to this  Agreement  shall be in writing and shall be considered as duly
given on:  (a) the date of  delivery,  if  delivered  in person,  by  nationally
recognized  overnight  delivery  service or (b) five (5) days  after  mailing if
mailed from within the  continental  United  States by  certified  mail,  return
receipt  requested  to the party  entitled to receive  the same,  if to Pledgor,
Genetic Vectors,  Inc., 5201 N.W. 77th Avenue,  Suite 100, Miami, Florida 33166,
Attention:  Mead  M.  McCabe,  Jr.,  with a copy to  Clayton  E.  Parker,  Esq.,
Kirkpatrick  & Lockhart  LLP,  201 S.  Biscayne  Boulevard,  20th Floor,  Miami,
Florida 33131 and if to Pledgee, at the addresses shown on the books of Pledgor.
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 Agreement.


                                       15
<PAGE>

      Section 8.2.  Severability.
                    ------------

      If any provision of this Agreement 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 Agreement,  and this Agreement shall be carried out
as if any such invalid or unenforceable provision were not contained herein.

      Section 8.3.  Expenses.
                    --------

      In the  event of an Event of  Default,  Pledgor  will pay to  Pledgee  the
amount of any and all reasonable  expenses,  including the  reasonable  fees and
expenses of its  counsel,  which  Pledgee or the Holder may incur in  connection
with: (i) the custody or preservation of, or the sale, collection from, or other
realization  upon,  any  of  the  Pledged  Collateral;   (ii)  the  exercise  or
enforcement  of any of the rights of Pledgee  hereunder  or (iii) the failure by
Pledgor to perform or observe any of the provisions hereof.

      Section 8.4.  Waivers, Amendments, Etc.
                    -------------------------

      Pledgee's  delay or  failure  at any time or times  hereafter  to  require
strict performance by Pledgor of any undertakings, agreements or covenants shall
not waiver,  affect,  or diminish any right of Pledgee  under this  Agreement to
demand strict compliance and performance herewith.  Any waiver by Pledgee of any
Event of Default  shall not waive or affect any other Event of Default,  whether
such Event of Default is prior or subsequent  thereto and whether of the same or
a different type. None of the undertakings,  agreements and covenants of Pledgor
contained in this  Agreement,  and no Event of Default,  shall be deemed to have
been waived by Pledgee, nor may this Agreement be amended,  changed or modified,
unless  such  waiver,  amendment,  change or  modification  is  evidenced  by an


                                       16
<PAGE>

instrument in writing specifying such waiver, amendment,  change or modification
and signed by the Holder.

      Section 8.5.  Continuing Security Interest.
                    ----------------------------

      This Agreement shall create a continuing  security interest in the Pledged
Collateral and shall:  (i) remain in full force and effect until payment in full
of the obligations or the conversion of all of the Note as provided therein; and
(ii) be binding upon Pledgor and its  successors  and (iii) inure to the benefit
of  Pledgee  and its  successors  and  permitted  assigns.  Upon the  payment or
satisfaction in full of the Obligations, or such conversion of the Note, Pledgor
shall  be  entitled  to the  return,  at its  expense,  of such  of the  Pledged
Collateral as shall not have been sold in accordance  with Section 5.2 hereof or
otherwise applied pursuant to the terms hereof.

      Section 8.6.  Applicable Law:  Jurisdiction.
                    -----------------------------

      This Agreement 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. Pledgee and Pledgor hereto: (i) agree
that any legal  suit,  action or  proceeding  arising out of or relating to this
Agreement  shall be  instituted  only in a federal or state court in  Miami-Dade
County,  Florida;  (ii) waive any objection which they may now or hereafter have
to the laying of the venue of any such  suit,  action or  proceeding;  and (iii)
irrevocably  submit  to the  jurisdiction  of any  federal  or  state  court  in
Miami-Dade County, Florida, in any such suit, action or proceeding.  Pledgee and
Pledgor  hereto  agree that the  mailing of any  process in any suit,  action or
proceeding in accordance  with the notice  provisions  of this  Agreement  shall
constitute personal service thereof.


                                       17
<PAGE>

      Section 8.7.  Entire Agreement.
                    ----------------

      This  Agreement  constitutes  the entire  agreement  among the parties and
supersedes any prior agreement or  understanding  among them with respect to the
subject matter hereof.

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

                                    GENETIC VECTORS, INC.


                                    By:________________________________
                                    Title:_____________________________


                                    ORBITER FUND, LTD.


                                    By:________________________________
                                    Title:_____________________________