Characterization of neutralizing sites in the second variable and fourth variable region in gp125 and a conserved region in gp36 of human immunodeficiency virus type 2

Several determinants of human immunodeficiency virus (HIV) have been sugges ted to harbor sites important for neutralization. The third variable region (V3) of the envelope glycoprotein (gp) is an important neutralizing determ inant for both serotypes of HIV, The localization of additional neutralizin g regions is an urgent task because the virus appears to mutate to phenotyp es that escape neutralizing antibodies. Therefore, we have focused on the p ossibility of finding other immunodominant regions in the envelope glycopro teins of human immunodeficiency virus type 2 (HIV-2), By immunization of gu inea pigs with peptides corresponding to different selected regions of gp12 5 and gp36, we have found three antigenic determinants located in the V2 an d V4 regions of the envelope protein gp125, and one region in the glycoprot ein gp36, which are important for human antibody binding and also as target s for neutralization, The peptide representing the V2 region had the most p ronounced capacity to induce neutralizing anti-HIV-2 antibodies in guinea p igs, Neutralizing activity was also detected in an antipeptide guinea pig s era representing a linear site in gp36, amino acids 644-658, A substitution set of peptides representing the conserved antigenic site in the central p art of gp36 was used to identify the role of individual amino acids importa nt for human antibody binding.