Characterization of Neutralizing Monoclonal Antibodies to Linear and Conformation-Dependent Epitopes within the First and Second Variable Domains of Human Immunodeficiency Virus Type 1 gpl20

A number of linear and conformation-dependent neutralizing monoclonal antibodies (MAbs) have been mapped to the first and second variable (Vi and V2) domains of human immunodeficiency virus type 1 (HIV-1) gp120. The majority of these MAbs are as effective at neutralizing HIV-i infectivity as MAbs to the V3 domain and the CD4 binding site. The linear MAbs bind to amino acid residues 162 to 171, and changes at residues 183/184 (PI/SG) and 191/192/193 (YSVGSS) within the V2 domain abrogate the binding of the two conformation-dependent MAbs, 11/68b and CRA-4, respectively. Surprisingly, a change at residue 435 (Y/