Mapping Reactivities of Murine Monoclonal Antibodies to the External Envelope Glycoprotein (gp120) of Human Immunodeficiency Virus Type 1 (HIV-1)

Abstract

A group of monoclonal antibodies generated from the envelope glycoprotein (gp120) of human immunodeficiency virus type 1B (HIV-1B) or type 1RF (HIV-1RF) were selected for characterization and epitope mapping studies. The reactivity of the clones to media enriched gp120 from three isolates of HIV-1; B, RF, and MN was determined using various immunological assays. The assays included western blotting, enzyme linked immunosorbent assays (ELISA), and radioimmunoprecipitations (RIPs). The reactivity of the clones to bacterially expressed fragments and synthetic peptides analogous to regions of gp120 were also defined to aid in characterization and epitope determination. Subsequently, attempts were made to define the reactive epitopes of the monoclonal antibodies on HIV-1B media enriched gp120. Gp120 from HIV-1B was cleaved using proteolytic and glycolytic enzymes to generate reproducible patterns. The reactivity of the clones for digested and chemically modified preparations of B gp120 was analyzed and used in defining epitope location. A nitrocellulose slot immunoassay was developed to rapidly screen digested and chemically modified preparations of B gp120 to determine reactivity of the monoclonal antibodies. Further analysis for defining the location of the reactive epitopes on HIV-1B gp120 was attempted with the technique protein "footprinting" (Sheshberadaran et al., 1988). With the available techniques and reagents, the monoclonal antibodies were characterized and their epitopes mapped on native gp120 of HIV-1B.