In Africa the highest HIV infection rate has been reported among female commercial sex workers (CSWs) who are at increasing risk of acquiring and transmitting HIV infection. In October 1995, 176 CSWs were studied in Bamako, the capital city of Mali. The ages of the CSWs ranged from 15 to 50 years old (mean, 28.8 years). Only 20.45% of the 176 CSWs were Malian; the majority were from Nigeria (32.9%) and Ghana (31.8%), and the remaining were from other African countries. Forty-one percent were active for less than 1 year as a commercial sex worker, and the length of prostitution for the remaining women ranged from 1 to 15 years (mean, 2.76). A total of 81 (46.02%) of the 176 CSWs were positive for HIV antibodies; 63 (35.8%) were HIV-1 positive, (3.9%) were HIV-2 positive, 11 (6.2%) had antibodies to HIV-1 and HIV-2, and none of them had antibodies to group O viruses. For all HIV antibody-positive samples, PBMCs were separated and genetic subtypes of HIV-1 were determined using the heteroduplex mobility assay (HMA), with ED5-ED12 as outer and ES7-ES8 as inner primers. Among the 66 HIV-1 strains characterized, 53 (80.3%) were subtype A, 2 (3.1%) belonged to subtype C, 1 (1.5%) belonged to subtype D, and 10 (15.1%) were identified as subtype G. Among the 10 subtype G strains, 8 were obtained from women who were very recent CSWs, with an activity of 1 year or less, assuming that there is a high probability that these infections occurred recently. Genetic subtypes of five HIV-2 viruses were determined by sequencing of the env and/or gag genes followed by phylogenetic analysis, and all of them belonged to subtype A. Comparison of HIV-1 and HIV-2 seroprevalence data from our study with previous data from Mali shows a significant rise in HIV-1 prevalence and a significant decrease in HIV-2 prevalence and confirms similar trends observed in neighboring countries. We have found four different genetic subtypes of HIV-1; however, subtype A is predominant and accounts for 80% of the cases and 15% of the HIV-1 infections were subtype G. It is important to continue the surveillance of subtypes on a systematic basis in order to see to what extent the proportions of the different subtypes will change over time.
PIP: The genetic variability of HIV-1 was investigated in a 1995 study of 176 commercial sex workers (CSWs) recruited in different areas in Bamako, Mali. 36 CSWs (20.45%) were born in Mali; 58 (32.9%) were from Nigeria and 56 (31.8%) were from Ghana. They ranged in age from 15-50 years (mean, 28.8 years). 41% of sex workers had been active for less than 12 months; the remaining women had been CSWs for 1-15 years (mean, 2.76 years). Of the 81 CSWs (46.02%) who were HIV-positive, 63 (35.8%) were infected with HIV-1, 7 (3.9%) with HIV-2, and the remaining 11 (6.2%) had antibodies to both HIV-1 and HIV-2. In contrast to other studies conducted among CSWs in Africa, none of these sex workers had antibodies to group O viruses. HIV-1 prevalence increased with age and length of time in prostitution and was higher among women with a history of sexually transmitted diseases. Among the 66 HIV-1 strains characterized, 53 (80.3%) were subtype A, 2 (3.1%) belonged to subtype C, 1 (1.5%) belonged to subtype D, and 10 (15.1%) were identified as subtype G. These results indicate a significant rise in HIV-1 prevalence and significant decreases in HIV-2 and combined HIV-1 and HIV-2 prevalence (10%, 15%, and 13%, respectively, in 1985). Ongoing surveillance of HIV-1 subtypes in Africa is important to identify shifts in the proportions of different subtypes over time. The genetic diversity of HIV has important implications for vaccine development.