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7th International AIDS ConferenceFlorence, Italy — June 16-21, 1991 |
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Int Conf AIDS 1991 Jun 16-21; 7:40 (abstract no. M.A.73)
Kliks SC, Wu WW, Levy JA; University of California, School of Medicine, San Francisco, CA, USA
OBJECTIVE: To investigate the mechanism of strain-specific antibody neutralization and enhancement of infection by HIV-1 strains. The studies were undertaken because sera from humans and primates immunized with HIV-1 envelope glycoproteins have been found to have dual properties.
METHODS: Human anti V3 monoclonal antibodies (MAb) were tested for their neutralizing and/or enhancing activity against three HIV-1 strains: the North American predominant SF2 strain, and two brain derived isolates, SF162 and SF128A. Neutralization was defined as 67% reduction in virus replication; enhancement was defined by a two-fold or greater increase in virus progeny production in culture. Interviral envelope recombinant viruses using SF2 and SF128A were also tested for sensitivity to neutralization and enhancement with specific monoclonal antibodies.
RESULTS: None of the MAbs showed any effect on the SF162 strain. Some human MAbs neutralized SF2 and some showed enhancement with SF128A. A noteworthy observation was the neutralization (with SF2) and enhancement (with 128A) with the same human MAb. The sequences at the corresponding linear epitopes of V3 in these three HIV-1 strains are different by only 1 or 2 amino acids. Other MAb studies with the recombinant viruses suggested the involvement of regions outside the V3 epitope in determining the viral sensitivities to serum antibodies.
CONCLUSIONS: These results are the first demonstrating that human MAb to the V3 loop of HIV-1 gp120 can be involved in both viral neutralization and enhancement. The difference in the biologic effect depends on the primary sequence within an epitope and perhaps other regions outside this reactive site.
Copyright © 1991 - International AIDS Society (IAS). Reproduction of this abstract (other than one copy for personal reference) must be cleared through the IAS.
