Resistance to HIV-1 infection among persistently seronegative prostitutes in Nairobi, Kenya

Women and HIV. Epidemiology and global overview

The global HIV-1 epidemic in women continues to expand at an alarming rate. More than 11 million women are currently estimated to be HIV-infected, with the majority living in sub-Saharan Africa. The primary risk factor for HIV infection in women is unprotected heterosexual intercourse. Several cofactors may influence a woman's risk for HIV acquisition. These include the presence of other STDs, the prevalence of HIV in the population, engagement in high-risk sexual behaviors at a young age, an increased number of sexual partners, HIV illness severity in an infected partner, host immunogenetic responses, hormonal and other local effects in the female genital tract, and viral characteristics. The general clinical findings in women with HIV disease are similar to those in HIV-infected men. Some studies have noted higher rates of esophageal candidiasis and decreased rates of Kaposi's sarcoma in women when compared with men. Overall disease progression and survival in women and men are similar once an adjustment is made for other important risk factors such as the time of seroconversion, the receipt of antiretrovirals, and baseline CD4 cell counts. Women with HIV have a high frequency of a number of diseases of the reproductive tract, including low-grade cervical dysplasia and vulvovaginal candidiasis. Despite progress in understanding the risk factors for HIV transmission to women and the variables related to disease progression, major research questions remain. These include the role of hormonal contraceptives in the risk for HIV acquisition, the primary mechanism of infection, and host systemic as well as local hormonal and immune responses in the female reproductive tract that may alter the risk of HIV infection. Over the next decade, it is anticipated that the quality of life and length of survival will improve dramatically for both HIV-infected women and men in settings in which new highly active combination antiretroviral therapy is available and affordable. Unfortunately, in most of the world, these antiretroviral drugs are not available for the treatment of the vast numbers of individuals infected by HIV. Therefore, development of successful strategies for primary prevention of HIV infection in women must be a top public health priority.

HIV-specific mucosal and cellular immunity in HIV-seronegative partners of HIV-seropositive individuals

HIV-specific mucosal and cellular immunity was analyzed in heterosexual couples discordant for HIV status in serum and in HIV-unexposed controls. HIV-specific IgA but not IgG was present in urine and vaginal wash samples from HIV-exposed seronegative individuals (ESN), whereas both IgA and IgG were observed in their HIV-seropositive partners; antibodies were not detected in low-risk controls. Envelope protein (Env) peptide-stimulated interleukin-2 (IL-2) production by peripheral blood mononuclear cells (PBMCs) was detected in 9 out of 16 ESNs, 5 out of 16 HIV-infected patients and 1 out of 50 controls. Env peptide-stimulated PBMCs of ESNs produced more IL-2 and less IL-10 compared with those of HIV-infected individuals; no differences were observed in chemokine production or in CCR5 expression. These data demonstrate that a compartmentalized immune response to pathogens is possible in humans and raise the possibility of protective roles for cell-mediated immunity and mucosal IgA in HIV-seronegative individuals exposed to HIV.

Reduction of concentration of HIV-1 in semen after treatment of urethritis: implications for prevention of sexual transmission of HIV-1. AIDSCAP Malawi Research Group

BACKGROUND

Transmission of HIV-1 is predominantly by heterosexual contact in sub-Saharan Africa, where sexually transmitted diseases (STDs) are also common. Epidemiological studies suggest that STDs facilitate transmission of HIV-1, but the biological mechanism remains unclear. We investigated the hypothesis that STDs increase the likelihood of transmission of HIV-1 through increased concentration of the virus in semen.

METHODS

HIV-1 RNA concentrations were measured in seminal and blood plasma from 135 HIV-1-seropositive men in Malawi; 86 had urethritis and 49 controls did not have urethritis. Men with urethritis received antibiotic treatment according to the guidelines of the Malawian STD Advisory Committee. Samples were analysed at baseline and at week 1 and week 2 after antibiotic therapy in urethritis patients, and at baseline and week 2 in the control group.

FINDINGS

HIV-1-seropositive men with urethritis had HIV-1 RNA concentrations in seminal plasma eight times higher than those in seropositive men without urethritis (12.4 vs 1.51 x 10(4) copies/mL, p = 0.035), despite similar CD4 counts and concentrations of blood plasma viral RNA. Gonorrhoea was associated with the greatest concentration of HIV-1 in semen (15.8 x 10(4) copies/mL). After the urethritis patients received antimicrobial therapy directed against STDs, the concentration of HIV-1 RNA in semen decreased significantly (from 12.4 x 10(4) copies/mL to 8.91 x 10(4) copies/mL at 1 week [p = 0.03] and 4.12 x 10(4) copies/mL at 2 weeks [p = 0.0001]). Blood plasma viral RNA concentrations did not change. There was no significant change in seminal plasma HIV-1 RNA concentrations during the 2-week period in the control group (p = 0.421).

INTERPRETATION

These results suggest that urethritis increases the infectiousness of men with HIV-1 infection. HIV-1-control programmes, which include detection and treatment of STDs in patients already infected with HIV-1, may help to curb the epidemic. Targeting of gonococcal urethritis may be a particularly effective strategy.

Host genes and HIV: the role of the chemokine receptor gene CCR5 and its allele

Since the late 1970s, 8.4 million people worldwide, including 1.7 million children, have died of AIDS, and an estimated 22 million people are infected with human immunodeficiency virus (HIV)(1). During 1995 and 1996, major clinical and laboratory discoveries regarding HIV pathogenesis provided new hope for the prevention and treatment of HIV infection. One major discovery was that members of the chemokine receptor family serve as cofactors for HIV entry into cells. We describe the role of allelic polymorphism in the gene coding for the CCR5 chemokine receptor with regard to susceptibility to and disease course of HIV infection. We also examine the effect of this discovery on medical and public health practices.