Increase of HIV-1 subtype A in Central African Republic

The concomitant presence of five distinct HIV-I subtypes and of unclassifie d HIV-I was reported in Bangui, Central African Republic (C.A.R.) between 1 990 and 1991. This previous study was conducted in individuals belonging to the C.A.R. Armed Forces (FACA) Cohort and in patients from the University Hospital of Baugui. To follow the HIV-I subtype distribution in Bangui over time, we conducted a cross-sectional surveillance of HIV-1 subtypes betwee n 1987 and 1997 in three groups of individuals in Bangui: 47 men belonging to the FACA Cohort, 38 patients from the CNHUB hospital, and 51 individuals consulting the sexually transmitted diseases (STD) clinic. One hundred and ten HIV-I were subtyped by heteroduplex mobility assay (HMA) and/or sequen cing of env regions encompassing the V3 domain. Ey comparing the HIV-1 dist ribution in two time periods (1987-1991 and 1991-1996) in the FACA cohort, we observed a significant increase of subtype A from 43.7% to 83.9%. This s ubtype distribution does not seem specific to the FACA cohort, in that subt ype A accounted for 46.7% of the HIV-I infections in CNHUB patients in the first time period studied and for 69.6% in the second time period. In STD p atients,subtype A infections were predominant in 1995 (72.7%) and 1997 (89. 7%). Subtype E viruses could be identified in the second time period, but r epresented only between 6.5% and 21.8% of the infections in the three group s of individuals studied. Other subtypes (B, C, H) and non-classified HIV-I in C2-V3 were detected with only a 3.2% to 9.1% frequency for each in the second time period. Phylogenetic analysis excluded infection by a single so urce for the individuals included in the study. Our data demonstrate an inc rease in die proportion of HN-I subtype A infections in Bangui that raises the question of a preferential transmissibility of specific HIV-1 variants.