INHIBITION OF ANTI-V3 DOMAIN ANTIBODY-BINDING TO HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1-INFECTED CELLS BY SULFATED POLYSACCHARIDES

The third variable domain (V3 domain) of the human immunodeficiency vi rus type 1 (HIV-1) envelope glycoprotein gp120 is an immunodominant re gion. Anti-V3 domain antibodies neutralize both HTV-1 infection and sy ncytium formation. The V3 domain has a high density of positive charge which is a potential binding site for anti-HTV-1 sulfated polysacchar ides. To investigate the inhibitory effect of sulfated polysaccharides on the binding of anti-V3 domain anibody, fluorescence-activating cel l sorting analysis was performed using two kinds of antibodies, NEA928 4 (purified, 0.25 mu g/ml) and 0.5 beta (ascite, 2.0 mg/ml), and HN-1- infected CEM cells. When the binding assay with a 1:100 dilution of ea ch antibody was performed in the presence of dextran sulfate, heparin, and inositol hexasulfate at concentrations which are antiviral, the c ompounds did not inhibit the binding of either antibodiy. As the antib ody concentration was decreased with higher dilution, dextran sulfate was able to reduce antibody binding by 50-60%. Thus, antagonism of ant i-V3 domain antibody binding by sulfated polysaccharides is not as ext ensive as reported previously by several groups. (C) 1995 Academic Pre ss, Inc.