Genetic Subtypes of HIV Type 1 and HIV Type 2 Strains in Commercial Sex Workers from Bamako, Mali

Abstract

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.

Molecular epidemiology of HIV in Ghana: Dominance of CRF02_AG

“…Serology does not differentiate between cross-reactivity of antibody from an HIV-1 infected subject with HIV-2 antigens (or the reverse) and antibody response both to HIV-1 and HIV-2 (double infection). In addition, poorly sensitive PCR, might not be able to amplify HIV-1 or HIV-2 in double reactive samples [Peeters et al, 1998;Sagoe et al, 1999;Esteves et al, 2000]. In the present study, gag primers were designed to amplify both HIV-1 and HIV-2, env primers to amplify HIV-1 only and LTR primers HIV-2 only ].…”

“…As soon as it was fully analysed its mosaic structure became clear, with alternating A and G segments [Carr et al, 1998]. Mostly on the basis of partial genome sequencing, subtypes A, D, and G have been reported frequently as the most prevalent subtypes in West Africa [Ishikawa et al, 1996;Peeters et al, 1998;Davies et al, 1999;Sarr et al, 2000]. With the characterisation of CRF02_AG, phylogenetic analysis allowed to differentiate pure A and G subtypes from IbNg-related strains, leading to the conclusion that CRF02_AG and its recombinants represented the most prevalent HIV-1 strains in West Africa at present.…”

Behaviour change and competitive exclusion can explain the diverging HIV-1 and HIV-2 prevalence trends in Guinea–Bissau

“…Guinea-Bissau has the highest HIV-2 prevalence worldwide (8 %-10 % in the general adult population) [2][3][4]. In recent years a decline in the prevalence of HIV-2 has been observed in most populations in West Africa including some communities in Guinea-Bissau [5][6][7]. HIV-2 prevalence decreased in men but not in women in a community study from urban Guinea-Bissau between 1987 and 1996 [8].…”

Human immunodeficiency virus type 2 (HIV-2) in Portugal: Clinical spectrum, circulating subtypes, virus isolation, and plasma viral load

“…Among the pathogenetic mechanisms contributing to the lower virulence of HIV-2, a reduced functionality of its nef regulatory gene [Switzer et al, 1998] and a low infectious virus level in infected individuals, have been suggested [Simon et al, 1993]. Six different genetic subtypes of HIV-2 (A-F) have been recognized so far, HIV-2 subtype A being the most predominant [Gao et al, 1994;Chen et al, 1997;Takehisa et al, 1997;Peeters et al, 1998]. Lower or even lack of pathogenicity have been suggested for non-A subtypes [Gao et al, 1994].…”