AEGiS-11IAC: Removal of V3-specific antibodies from the serum of infected patients has minimal effect on neutralization of primary isolates of clade E HIV-1.

11th International AIDS Conference

Vancouver, British Columbia — July 7-12, 1996

Removal of V3-specific antibodies from the serum of infected patients has minimal effect on neutralization of primary isolates of clade E HIV-1.

Int Conf AIDS 1996 Jul 7-12; 11:9 (abstract no. Mo.A.271)
Stamatos NM, VanCott TC, Mascola J, Loomis LD, Louder M, Birx DL; Walter Reed Army Institute of Research, Rockville, MD. Fax: 301-762-4177. E-mail: nstamatos@HIV.hjf.org.

OBJECTIVE: To determine the role of V3-specific antibodies in mediating neutralization of primary clade E viral isolates. To compare these results with previous reports demonstrating a minimal role for V3-specific antibodies in neutralizing primary clade B viruses.

METHODS: Sera from 3 HIV-infected patients from Thailand were selected based on a high level of V3-specific antibody and strong neutralizing activity in vitro against at least 2 clade E primary isolates of HIV-1. Sera were depleted of V3-specific antibodies by binding to a 34 amino acid clade E V3 peptide coupled to CNBr-activated Sepharose 4B; alternatively, for a negative control, sera were passed through a column prepared with a clade B V3 peptide. Affinity-purified clade E V3 antibody from one patient was eluted from the column and a portion was concentrated six-fold. The efficiency of depletion and determination of nonspecific losses of antibody were determined by biomolecular interaction analysis (BIAcore). Neutralization assays were performed with undepleted and V3-depleted sera from each patient by pretreating 100 TCID50 of 2 primary isolates of clade E HIV-1 with serial 5-fold dilutions of serum prior to incubation with PHA-stimulated PBMCs. Neutralization titers were determined after measuring levels of p24 antigen by ELISA.

RESULTS: Greater than 95% of detectable V3-specific antibodies were removed from each serum with minimal nonspecific loss of anti-gp160 antibody. There was minimal difference in the ability of V3-depleted and undepleted serum from all three patients to neutralize the two primary clade E viruses. Titers for 50 and 90% neutralization of undepleted and V3-depleted sera were within 20% of each other in most cases. Furthermore, affinity-purified, V3-specific antibody from the serum of one patient had no neutralizing activity, even when used at a concentration six-fold greater than in the undepleted serum.

CONCLUSIONS: These data suggest that V3-specific antibodies in the sera of patients infected with clade E HIV-1 contribute minimally to the neutralization of primary viral isolates, as has been shown for primary isolates of clade B HIV-1. The role of non-V3 epitopes of gp120/41 in generating neutralizing antibodies to clade E HIV-1 are currently being evaluated. These results should help influence vaccine design for individuals in Northern Thailand.

Keywords: AEGIS, HIV-1, HIV Antibodies, Epitopes, Antibodies, Antibodies, Monoclonal, Binding Sites, Antibody, Peptides, Enzyme-Linked Immunosorbent Assay, Thailand, In Vitro, Human, immunology, ICA11

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