V3 serological subtyping of human immunodeficiency virus type 2 infection is not relevant

V3 enzyme immunoassays have been shown to discriminate effectively between human immunodeficiency virus type I (HIV-1) subtypes. The aim of this study was to investigate the feasibility of V3 serotyping for HIV-2 infection. W e serotyped 29 sera with three peptides, corresponding to the V3 loop of su btypes A, B, and D of HIV-2. Sera were collected from HIV-2-infected patien ts, whose infecting strains were sequenced and subjected to phylogenetic an alysis. Our results indicate that HIV-2 serotyping using V3 peptides is not relevant. V3 serotyping data were not consistent with genotyping results. The V3-A and V3-D peptides displayed poor discrimination, and the V3-B pept ide was not representative of circulating viruses. Comparison of amino acid sequences and serotype reactivities demonstrated the importance of positio ns 309 and 314, located on either side of the tip of the V3 loop, in antibo dy binding.