The V3-directed immune response in natural human immunodeficiency virus type 1 infection is predominantly directed against a variable, discontinuous epitope presented by the gp120 V3 domain.

Important note: Information in this article was accurate in 1998. The state of the art may have changed since the publication date.

The V3-directed immune response in natural human immunodeficiency virus type 1 infection is predominantly directed against a variable, discontinuous epitope presented by the gp120 V3 domain.

J Virol. 1997 Dec;71(12):9198-205. Unique Identifier : AIDSLINE MED/98037629
Schreiber M; Wachsmuth C; Muller H; Odemuyiwa S; Schmitz H; Meyer S; Meyer B; Schneider-Mergener J; Medical Microbiology Section, Bernhard Nocht Institute for Tropical; Medicine, Hamburg, Germany. mschreib@sgi1.chemie.uni-hamburg.de

Abstract: The specific binding of antibodies to the V3 loop in sera from human immunodeficiency type 1 (HIV-1)-infected individuals was investigated. Different V3 structures were analyzed as full-length loops or by pepscan. Our data show that on full-length V3 loops, both variable regions on either side of the tip of the loop (GPGRAF) contribute to a common epitope for type-specific antibodies. Type-specific antibodies bound strongly and at high titers to native V3 loops but negligibly once the loop was denatured. In contrast to the type-specific, discontinuous epitope, the linear, conserved epitopes presented by the full-length V3 loop, the tip, the amino-terminal base, and the carboxy-terminal base were not accessible to serum antibody. When the V3 sequences were analyzed with linear peptides, antibodies bound preferentially to peptides containing the conserved GPGRAF sequence. Thus, two different specificities of V3-directed antibodies were detected in patient sera. Unlike group-specific antibodies directed against GPGRAF peptides, lack of type-specific antibodies directed against the discontinuous epitope was correlated with viral escape from autologous neutralization. Our data suggest that the full-length conformation of the V3 loop is accessible predominantly to highly type-specific antibodies present in sera from HIV-1-infected individuals. These antibodies are directed against discontinuous V3 epitopes, not against conserved linear V3 targets. The implications of these findings for viral escape and blockade of infection with V3-based vaccines are discussed.

Keywords: *Epitopes, B-Lymphocyte/IMMUNOLOGY *HIV Antibodies/IMMUNOLOGY *HIV Antigens/IMMUNOLOGY *HIV Envelope Protein gp120/IMMUNOLOGY *HIV Infections/IMMUNOLOGY *HIV-1/IMMUNOLOGY *Peptide Fragments/IMMUNOLOGY
980330
M9831185

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