Influence of Deletions in N or C Terminus of HIV-1 Glycoprotein 120 on Binding of Infectivity-Enhancing Antibody

Human monoclonal antibody 2.3a was previously shown to enhance human immunodeficiency virus type 1 (HIV-1) infection in vitro. This enhancing antibody recognizes a conserved epitope of envelope glycoprotein gp120. We report here that binding of the 2.3a antibody to gp120 is significantly affected by deletions of certain N- or C-terminal residues of gp120. However, not all such deletions affect the epitope recognized by a broadly neutralizing human monoclonal antibody, 1.5e. These findings suggest the feasibility of designing a gp120 antigen that is free of 2.3a epitope while retaining the conformation of the 1.5e epitope.