Characterization of monoclonal antibodies against the human immunodeficiency virus (HIV) gag products and their use in monitoring HIV isolate variation.

Monoclonal antibodies were raised against the gag proteins of a British isolate of the human immunodeficiency virus (HIV), CBL-1. Seven of the monoclonal antibodies recognized HIV gag-coded proteins of 55,000 mol. wt. (p55) and 24,000 mol. wt. (p24), three recognized p55/p18 and three p18 alone. Cross-competition assays suggested that at least two independent epitopes exist on the p24 cleaved from the p55 precursor, whereas a cluster of closely related epitopes was recognized by the p55/p18 and p18 antibodies. The panel of monoclonal antibodies was then used to compare by immunofluorescence the expression of gag-encoded antigenic determinants on HIV isolates from different geographical locations. Minor changes in epitope expression were observed in isolates from the U.S.A. and Haiti with the most notable changes being detected in isolates from Zaire, Tanzania and Uganda.