GENETIC SUBTYPES OF HIV TYPE-1 AND HIV TYPE-2 STRAINS IN COMMERCIAL SEX WORKERS FROM BAMAKO, MALI

In Africa the highest HIV infection rate has been reported among femal e commercial sex workers (CSWs) who are at increasing risk of acquirin g and transmitting HIV infection. In October 1995, 176 CSWs were studi ed in Bamako, the capital city of Mall. The ages of the CSWs ranged fr om 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 percen t mere 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 ye ars (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 the m had antibodies to group O viruses. For all HIV antibody-positive sam ples, PBMCs were separated and genetic subtypes of HIV-1 were determin ed using the heteroduplex mobility assay (HMA), with ED5-ED12 as outer and ES7-ES8 as inner primers. Among the 66 HIV-1 strains characterize d, 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. A mong the 10 subtype G strains, 8 were obtained from women who mere ver y recent CSWs, with an activity of 1 year or less, assuming that there is a high probability that these infections occurred recently. Geneti c subtypes of five HIV-2 viruses were determined by sequencing of the env and/or gag genes followed by phylogenetic analysis, and all of the m belonged to subtype A. Comparison of HIV-1 and HIV-2 seroprevalence data from our study with previous data from Mall shows a significant r ise in HIV-1 prevalence and a significant decrease in HIV-2 prevalence and confirms similar trends observed in neighboring countries. We hav e found four different genetic subtypes of HIV-1; however, subtype A i s predominant and accounts for 80% of the cases and 15% of the HIV-1 i nfections were subtype G. It is important to continue the surveillance of subtypes on a systematic basis ill order to see to what extent the proportions of the different subtypes mill change over time.