GEOGRAPHICAL-DISTRIBUTION OF HIV-1 GROUP-O VIRUSES IN AFRICA

Objective: To determine to what extent HIV-1 group O strains are prese nt in different African countries. Materials and methods: A total of 1 4 682 samples of sera from a range of patients from 12 different Afric an countries were tested. All the sera were tested with an enzyme-link ed immunosorbent assay (ELISA) using a combination of V3 peptides from ANT-70 and MVP-5180. Samples reactive in ELISA were retested in a lin e immunoassay (LIA-O). Samples reactive in ELISA were also retested wi th an inhouse Western blot to determine the presence of antibodies to gp120 of HIV-1 ANT-70. Polymerase chain reaction was performed on HIV- 1 group O and group O indeterminate sera. Results: Of all the sera sam ples tested, only 19 sera had antibodies to group O V3 peptides exclus ively and 46 were indeterminate for group O infection in LIA-O. The hi ghest prevalence of HIV-1 group O infection among HIV-positive sera wa s observed in Cameroon (2.1%) and neighbouring countries, 1.1% in Nige ria and 0.9% in Gabon. The lowest rates were seen in west Africa: 0.07 % in Senegal, 0.14% in Togo, 0.16% in Chad and 0.3% in Niger. Group O sera were observed in almost all the population categories tested. The ANT-70 V3 peptide in LIA-O was reactive with ail of the sera consider ed to be HIV-1 group O antibody positive by LIA, versus 78.9% for the MVP-5180 peptide. Thirteen out of 19 group O samples of sera were test ed in PCR. Eight samples were identified as group O by specific group O pol and/or V3 primers; in the remaining five samples no HIV RNA coul d be detected. Of the indeterminate sera samples, two were identified as group O. Conclusion: In eight of the 12 countries tested, antibodie s to group O viruses were identified. Numbers of HIV-1 group O viruses are low. Their presence is not restricted to Cameroon and neighbourin g countries but can also be found in west and south-east Africa.