Antibodies to V3 loop peptides derived from chimpanzee lentiviruses and the divergent HIV-1 ANT-70 isolate in human sera from different geographic regions

OBJECTIVE: To study the spread of antibodies to V3 loop peptides of two chimpanzee lentiviruses and the divergent HIV-1ANT-70 isolate (group O) in human sera from different geographic regions, and to compare this with reactions to peptides from known North American (subtype B) and Zairean (subtype D) strains. METHODS: A total 2495 HIV-1-antibody-positive sera from nine countries were tested by enzyme-linked immunosorbent assay for antibodies to the V3 loop of 10 HIV/SIV isolates (including MN, SF2, HXB2, RF, MAL, ELI, Z6 and ANT-70 for HIV-1, and cpz-gab and cpz-ant for SIV). RESULTS: In each country, the highest prevalences were observed against the MN peptide (58.8-91.7%). Seroreactivity to other peptides from subtype B were generally lower. Prevalences of antibodies to V3 peptides derived from Zairean strains belonging to subtype D were generally lower than to subtype B. Relative high prevalences of sera reactive with the SIVcpz-gab V3 peptide were observed. The lowest rates were seen in Brazil (4.2%) and Belgium (25.7%). Among the African countries, the prevalence rates varied between 30.1 and 67.6%. Prevalence to the V3 loop derived from the SIVcpz-ant strains was much lower. Prevalence of sera reactive to the ANT-70 V3 loop peptide was very low, and the highest rates were observed in Cameroon (10.2%), Niger (6%) and Gabon (4.6%). Only the sera reactive to the ANT-70 V3 loop peptide from Cameroon and Gabon were confirmed on a specific HIVANT-70 Western blot (i.e., presence of antibodies to the envelope protein gp 120). CONCLUSIONS: The extent to which different V3 peptide reactivity patterns reflect the circulation of different HIV-1 strains in a particular population is not yet clear. However, V3 peptide serology using the very specific V3 peptide of the HIVANT-70 is a good indicator of the very aberrant group O in a particular population