The effect of progesterone levels and pregnancy on HIV-1 coreceptor expression

High HIV incidence and sexual behavior change among pregnant women in Lilongwe, Malawi: implications for the risk of HIV acquisition

Background

HIV incidence is higher among pregnant women than their non-pregnant counterparts in some sub-Saharan African settings. Our aims were (1) to estimate HIV incidence during pregnancy and (2) to compare sexual activity between pregnant, postpartum, and non-pregnant women.

Methods

We examined a retrospective cohort of 1087 women to identify seroconverters using antenatal and labor ward HIV test results. We also conducted a cross-sectional survey, including a quantitative questionnaire (n = 200) and in-depth interviews (n = 20) among women in early pregnancy, late pregnancy, postpartum, and non-pregnancy. Outcomes included measures of sexual activity, reported spouse’s risky behavior, and beliefs about abstinence.

Results

11 of 1087 women seroconverted during pregnancy yielding a 1% seroconversion risk and an incidence rate of 4.0/100 person years (95% CI 2.2–7.2). The reported sexual activity of the early pregnancy and non-pregnancy groups was similar, but significantly higher than the late pregnancy and postpartum groups (p<0.001). During pregnancy, sex acts decreased as gestation increased (p = 0.001). There was no reported difference in the spouse’s risky behavior. Most women believed that sex should cease between the 6^th and 8^th month of pregnancy and should not resume until 6 months postpartum. Some talked about conflict between their cultural obligation to abstain and fear of HIV infection if their spouses find other partners.

Conclusions

HIV incidence is high among pregnant women in Malawi, and sexual activity decreases during pregnancy and postpartum. Pregnant women need to be informed of their increased risk for HIV and the importance of using condoms throughout pregnancy and the postpartum period.

High susceptibility to repeated, low-dose, vaginal SHIV exposure late in the luteal phase of the menstrual cycle of pigtail macaques

Fluctuations in susceptibility to HIV or SHIV during the menstrual cycle are currently not fully documented. To address this, the time point of infection was determined in 19 adult female pigtail macaques vaginally challenged during their undisturbed menstrual cycles with repeated, low-dose SHIV(SF162P3) exposures. Eighteen macaques (95%) first displayed viremia in the follicular phase, as compared with 1 macaque (5%) in the luteal phase (P < 0.0001). Due to a viral eclipse phase, we estimated a window of most frequent virus transmission between days 24 and 31 of the menstrual cycle, in the late luteal phase. Thus, susceptibility to vaginal SHIV infection is significantly elevated in the second half of the menstrual cycle when progesterone levels are high and when local immunity may be low. Such susceptibility windows have been postulated before but not definitively documented. Our data support the findings of higher susceptibility to HIV in women during progesterone-dominated periods including pregnancy and contraceptive use.

Increased risk of HIV-1 transmission in pregnancy: a prospective study among African HIV-1-serodiscordant couples

BACKGROUND

Physiologic and behavioral changes during pregnancy may alter HIV-1 susceptibility and infectiousness. Prospective studies exploring pregnancy and HIV-1 acquisition risk in women have found inconsistent results. No study has explored the effect of pregnancy on HIV-1 transmission risk from HIV-1-infected women to male partners.

METHODS

In a prospective study of African HIV-1-serodiscordant couples, we evaluated the relationship between pregnancy and the risk of HIV-1 acquisition among women and HIV-1 transmission from women to men.

RESULTS

Three thousand three hundred and twenty-one HIV-1-serodiscordant couples were enrolled, 1085 (32.7%) with HIV-1 susceptible female partners and 2236 (67.3%) with susceptible male partners. HIV-1 incidence in women was 7.35 versus 3.01 per 100 person-years during pregnant and nonpregnant periods [hazard ratio 2.34, 95% confidence interval (CI) 1.33-4.09]. This effect was attenuated and not statistically significant after adjusting for sexual behavior and other confounding factors (adjusted hazard ratio 1.71, 95% CI 0.93-3.12). HIV-1 incidence in male partners of infected women was 3.46 versus 1.58 per 100 person-years when their partners were pregnant versus not pregnant (hazard ratio 2.31, 95% CI 1.22-4.39). This effect was not attenuated in adjusted analysis (adjusted hazard ratio 2.47, 95% CI 1.26-4.85).

CONCLUSION

HIV-1 risk increased two-fold during pregnancy. Elevated risk of HIV-1 acquisition in pregnant women appeared in part to be explained by behavioral and other factors. This is the first study to show that pregnancy increased the risk of female-to-male HIV-1 transmission, which may reflect biological changes of pregnancy that could increase HIV-1 infectiousness.

Cofactors for HIV-1 incidence during pregnancy and postpartum period

OBJECTIVES

to estimate HIV-1 incidence and cofactors for HIV-1 incidence during pregnancy and postpartum.

DESIGN

retrospective study among women who were HIV seronegative during pregnancy.

METHODS

mothers accompanying their infants for routine 6-week immunizations at 6 maternal child health clinics in Nairobi and Western Kenya were tested for HIV-1 after completing a questionnaire that included assessment of sociodemographics, obstetric history and HIV-1 risk perception.

RESULTS

of 2,135 mothers who had tested HIV-1 seronegative antenatally, 2,035 (95.3%) accepted HIV-1 re-testing at 6 weeks postpartum. Of these, 53 (2.6%) were HIV-1 seropositive yielding an estimated HIV-1 incidence of 6.8 (95% CI: 5.1-8.8) per 100 woman-years). Mothers who seroconverted were more likely to be employed (45.3% vs 29.0%, p=0.01), married (96.2 vs 86.6%, p=0.04) and from a higher HIV-1 prevalence region (60.4% in Western Kenya vs 28.8% in Nairobi, p<0.001). Among married women, those in polygamous relationship were significantly more likely to seroconvert (19.6% vs 6.7%, p<0.001). In multivariate analysis, region and employment independently predicted seroconversion.

CONCLUSIONS

repeat HIV-1 testing in early postpartum was highly acceptable and resulted in detection of substantial HIV-1 incidence during pregnancy and postpartum period. Within prevention of mother-to-child HIV-1 transmission programs strategic approaches to prevent maternal HIV-1 acquisition during pregnancy are urgently needed.

Sex steroid hormones, hormonal contraception, and the immunobiology of human immunodeficiency virus-1 infection

Worldwide, an increasing number of women use oral or injectable hormonal contraceptives. However, inadequate information is available to aid women and health care professionals in weighing the potential risks of hormonal contraceptive use in individuals living with HIV-1 or at high risk of infection. Numerous epidemiological studies and challenge studies in a rhesus macaque model suggest that progesterone-based contraceptives increase the risk of HIV-1 infection in humans and simian immunodeficiency virus (SIV) infection in macaques, accelerate disease progression, and increase viral shedding in the genital tract. However, because several other studies in humans have not observed any effect of exogenously administered progesterone on HIV-1 acquisition and disease progression, the issue continues to be a topic of intense research and ongoing discussion. In contrast to progesterone, systemic or intravaginal treatment with estrogen efficiently protects female rhesus macaques against the transmission of SIV, likely by enhancing the natural protective properties of the lower genital tract mucosal tissue. Although the molecular and cellular mechanisms underlying the effect of sex steroid hormones on HIV-1 and SIV acquisition and disease progression are not well understood, progesterone and estrogen are known to regulate a number of immune mechanisms that may exert an effect on retroviral infection. This review summarizes current knowledge of the effects of various types of sex steroid hormones on immune processes involved in the biology of HIV-1 infection.