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Certain human leukocyte antigens, by presenting conserved immunogenic epitopes for T cell recognition, may, in part, account for the observed differences in human immunodeficiency virus type 1 (HIV-1) susceptibility. To determine whether HLA polymorphism influences HIV-1 susceptibility, a longitudinal cohort of highly HIV-1-exposed female sex workers based in Nairobi, Kenya, was prospectively analyzed. Decreased HIV-1 infection risk was strongly associated with possession of a cluster of closely related HLA alleles (A2/6802 supertype; incidence rate ratio [IRR], 0.45; 95% confidence interval [CI], 0.27-0.72; P=.0003). The alleles in this supertype are known in some cases to present the same peptide epitopes for T cell recognition. In addition, resistance to HIV-1 infection was independently associated with HLA DRB1*01 (IRR, 0.22; 95% CI, 0.06-0.60; P=.0003), which suggests that anti-HIV-1 class II restricted CD4 effector mechanisms may play an important role in protecting against viral challenge. These data provide further evidence that resistance to HIV-1 infection in this cohort of sex workers is immunologically mediated.

EXUALLY TRANSMITTED INFECtions (STIs) are important cofactors in the human immunodeficiency virus type 1 (HIV-1)/AIDS pandemic. In HIV-infected individuals, not only may symptomatic and asymptomatic STIs enhance sexual transmission of HIV-1 by increasing virus shedding from the genital tract, 1-3 but at the same time HIV-1 infection itself increases susceptibility to STIs. 4 There is also considerable evidence that STIs may increase HIV-1 susceptibility in uninfected individuals, 5,6 although differentiating cause from effect is more difficult in this situation. 7 Prevention or control of STIs as a strategy for preventing HIV-1 transmission has met with mixed success. Improved syndromic management of STIs reduced HIV-1 incidence in com-munities in Mwanza, Tanzania, 8 but in Uganda neither a similar strategy nor antibiotic mass-treatment of whole communities had an impact on HIV-1 Author Affiliations and Members of the Kibera HIV Study Group are listed at the end of this article.

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This study assessed individual-level effects of adding micro-enterprise services to a peer-mediated HIV/AIDS intervention among 227 female sex workers (FSWs) in Kenya. Survey data were collected in May-July 2003 and July-August 2005. Two-thirds of participants had operational businesses by end-line survey. Nearly half reported to have stopped sex work. Self-reported weekly mean number of all sexual partners changed from 3.26 (SD 2.45) at baseline to 1.84 (SD 2.15) at end-line survey (P < 0.001). Weekly mean number of casual partners did not change significantly. Weekly mean number of regular partners changed from 1.96 (SD 1.86) to 0.73 (SD 0.98) over the follow-up period (P < 0.001). Consistent condom use with regular partners increased by 18.5% and remained above 90% with casual partners. Micro-enterprise services may empower FSWs by giving them an alternative livelihood when they wish to exit or reduce reliance on sex work. Determinants of successful business operation by FSWs deserve further research.

HIV-1-specific IgA is present in the genital tract of most HIV-1-resistant Kenyan sex workers, and of a minority of lower risk uninfected women, where it is associated with risk-taking behaviour. These data suggest a role for mucosal HIV-1-specific IgA responses in HIV-1 resistance, independent of host cellular responses.

Despite significant HIV inhibitory activity, cervicovaginal levels of alpha-defensins and LL-37 were associated with increased HIV acquisition, perhaps due to their association with bacterial sexually transmitted infections.