Envelope (Env) proteins are the sole virally-encoded external proteins of HIV-1 and targets of neutralizing antibody activity. Unfortunately, Env sequences are not conserved among HIV-1 isolates and antibodies elicited toward one virus type will not necessarily neutralize another. For this reason, we have prepared a multi-Env HIV-1 vaccine. Vaccine production began with the construction of thirty distinct VV-recombinants (VVenv), each expressing a distinct Env (gp140) protein. VVenv were then tested individually and in combination in a chimpanzee model. Four chimpanzees were immunized subcutaneously with three injections of VVenv recombinants. Chimpanzees 1 and 2 received a single VVenv given repeatedly in each of the three injections. Chimpanzees 3 and 4 received ten distinct VVenv in each of the three injections yielding thirty VVenv in total. After the third injection, all four chimpanzees received one intramuscular injection with recombinant gp120/gp41 protei n in alum. Safety was demonstrated in all four animals, only two of which showed signs of ulceration at the injection site. Serum samples were monitored by numerous tests for HIV-1-binding and neutralization. The antibodies of chimpanzees 3 and 4 demonstrated the highest quality of antibody activity. In chimpanzee 4, neutralizing function was demonstrated both against a laboratory isolate and a primary isolate of HIV-1, neither of which was specifically represented in the multi-Env vaccine. The priming of lymphocytes with mixed Env proteins thus provides a promising method by which high-quality antibodies may be elicited against diverse HIV-1.
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