Monoclonal antibodies to an HIV-1 group O envelope recombinant.

: Monoclonal antibodies were developed to a recombinant HIV-I group O envelope protein derived from the isolate HAM112. These monoclonal antibodies were characterized for reactivity to a series of overlapping synthetic peptides (29-30 mers) covering gp120 C-terminal and gp41 ectodomain regions of the HIV-1 group O envelope protein. Most of these monoclonal antibodies reacted with peptides spanning sequences analogous to HIV-1 group M epitopes identified from studies in mice and humans. However, several of the antibodies that were nonreactive to individual peptides did react to a mixture of longer peptides from the N-terminal and C-terminal helical regions of the gp41 ectodomain. The monoclonal antibodies described in this study are valuable tools for characterization of antigenic differences between HIV-1 group O and group M viruses.