Evaluation of Monoclonal Antibodies to Human Immunodeficiency Virus Type 1 Primary Isolates by Neutralization Assays: Performance Criteria for Selecting Candidate Antibodies for Clinical Trials

A collaborative study was organized to identify monoclonal antibodies (MAbs) that may be broadly and potently neutralizing for a panel of human immunodeficiency virus type 1 (HIV-1) low-passaged adult and pediatric primary isolates in peripheral blood mononuclear cells. Five laboratories evaluated a coded panel of seven human MAbs to HIV-1 subtype B envelope V3, CD4 binding region, gp41, and other conformationally sensitive determinants. Each laboratory measured neutralizing activity of the MAbs against the laboratory isolate HIV MN and a panel of 9 subtype B primary isolates. Antibodies were classified as suitable candidates for future clinical studies if they could neutralize at least half of the 9 primary isolates at a concentration of <25 μg/mL for 90% viral inhibition. The study identified three MAbs that met stated performance criteria: IgG1b12, 2G12, and 2F5. These results may provide a rationale for examining the clinical efficacy, either singly or in combination, of the three MAbs.