JOINDER AGREEMENT

                  This Joinder  Agreement (the  "JOINDER") is entered into as of
June 23,  2000 by and among GENE FUND,  LP,  KENSON  VENTURE,  LLC AND VITALBIO
HOLDINGS, INC. (the "NEW NON-PREFERRED HOLDERS") and INFORMAX,  INC., a Delaware
corporation (the "COMPANY").

                  WHEREAS,  the  non-preferred  holders of the  Company  who are
listed on the  signature  pages of the  Non-Preferred  Holder  Rights  Agreement
(collectively, the "NON-PREFERRED HOLDERS") and the Company, are parties to that
certain  Non-Preferred  Holder  Rights  Agreement  dated  March  29,  2000  (the
"NON-PREFERRED AGREEMENT");

                  WHEREAS, pursuant to a Stock Purchase Agreement dated June 23,
2000 by and  between  the New  Non-Preferred  Holder  and the  Company,  the New
Non-Preferred  Holders acquired shares of non-voting common stock of the Company
(the "STOCK PURCHASE Agreement"); and

                  WHEREAS,  a condition to the  obligations of the parties under
the  Stock  Purchase  Agreement  is that the New  Non-Preferred  Holders  become
parties to the  Non-Preferred  Agreement  concurrently  with the  execution  and
delivery of the Stock Purchase Agreement.

                  NOW,  THEREFORE,  in consideration of the premises,  and other
good and valuable consideration,  the receipt and sufficiency of which is hereby
acknowledged, each of the New Non-Preferred Holders and the Company hereby agree
as follows:

                  1. Each of the New  Non-Preferred  Holders  is  hereby  made a
party to the Non-Preferred  Agreement as a "Non-Preferred  Holder" in accordance
with Section 4.11 thereunder,  and each of the New Non-Preferred  Holders hereby
agrees  severally but not jointly to be bound by all the terms and conditions of
the Non-Preferred  Agreement as a "Non-Preferred  Holder" thereunder.  The terms
and  conditions  of the  Non-Preferred  Agreement  shall  apply to the shares of
common stock acquired pursuant to the Stock Purchase Agreement.

                  2.  Each  of the  New  Non-Preferred  Holders  represents  and
warrants  individually to the Company and the other  Non-Preferred  Holders that
the New Non-Preferred Holder: (a) has reviewed the Joinder and the Non-Preferred
Agreement (as attached hereto) in their  entireties,  and fully  understands all
provisions of the Joinder and the Non-Preferred Agreement, and (b) in accordance
with the terms of the Non-Preferred  Agreement the New Non-Preferred  Holder has
become a Non-Preferred Holder under the Non-Preferred  Agreement and is bound by
all the terms and conditions of the Non-Preferred Agreement with the same effect
as  though  the  New  Non-Preferred  Holder  was  a  subscribing  party  to  the
Non-Preferred Agreement.

                  3.  All   references   in  the   Non-Preferred   Agreement  to
"Non-Preferred Holder" or "Non-Preferred Holders" shall be deemed to include the
New Non-Preferred Holders.

                  4.  All of  the  terms  and  conditions  of the  Non-Preferred
Agreement are  unmodified  and shall continue in full force and effect and shall
be binding upon the parties  hereto and their  respective  assigns in accordance
with the terms thereof.
<PAGE>

                  5. This Joinder may be executed  (including  by  facsimile) in
one or more  counterparts,  each of which shall be deemed an original but all of
which together will constitute one and the same instrument.

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<PAGE>



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

                                     COMPANY

                                     INFORMAX, INC.

                                     By: /s/ ALEX TITOMIROV
                                         -------------------------------------
                                         Name:  Alex Titomirov
                                         Title: Chairman/CEO

                                     NEW NONPREFERRED HOLDERS

                                     GENE FUND, LP

                                     By: /s/ WILLIAM F. SNIDER
                                         -------------------------------------
                                         Name:  William F. Snider
                                         Title: General Partner

                                     KENSON VENTURE, LLC

                                     By:  /s/   Kenneth Fong
                                         ------------------------------------
                                         Name:  Kenneth Fong
                                         Title: Chairman

                                     VITALBIO HOLDINGS, INC.

                                     By: /s/ ROBERT P. CARTER
                                         -------------------------------------
                                         Name:  Robert P. Carter
                                         Title: V.P.

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