IDENTIFICATION OF A NEUTRALIZING DOMAIN IN THE EXTERNAL ENVELOPE GLYCOPROTEIN OF SIMIAN IMMUNODEFICIENCY VIRUS

Two murine monoclonal antibodies (MAbs), designated MATG2014 and MATG2033, were generated. They are reactive with the external envelope glycoprotein gp130 of the simian immunodeficiency virus of macaque monkey (SIV(mac251)), and display a cell-free virus neutralizing activity in vitro. In addition, MATG2014 cross-reacts with HIV-2(Rod) gp140. Epitope mapping of these MAbs was performed by screening an SIV(mac) peptide library expressed in yeast and confirmed using synthetic peptides. MATG2014 and MATG2033 recognize two overlapping epitopes localized in an 18 residue domain between amino acid 171 and 188 of the SIV(mac251) gp130. Sera from experimentally SIV-infected macaques are immunoreactive with this neutralizing domain. Sequence comparison with related SIV and HIV-2 viral strains indicates a low variability of this region, consistent with the cross-reactivity of MATG2014 with HIV-2(Rod) gp140. This domain should then be considered in designing experimental vaccines.