Genital Immune Correlates of Seroprevalent and Seroincident Herpes Simplex Type 2 Infection Among Women Who Sell Sex in Nairobi, Kenya.

PROBLEM: Most Herpes simplex virus type 2 (HSV-2) infection is asymptomatic but increases the risk of HIV acquisition, possibly due to alterations in genital immunology. We examine associations of HSV-2 prevalence and incidence with epithelial barrier disruption.

METHOD OF STUDY: The study was nested within the longitudinal Maisha Fiti cohort of women who sell sex in Nairobi, Kenya. HSV-2 serostatus was assessed by Kalon HSV-2 IgG assay. Socio-behavioural characteristics were assessed by questionnaire and analysed by logistic regression. Immune factors (including soluble E-cadherin (sE-cad)) were assayed in cervicovaginal secretions by multiplex immunoassay, log-transformed and analysed through linear regression.

RESULTS

Among 731 HIV-negative participants, 414 (57%) were HSV-2 seropositive. These women were older (median age 35 vs 28 years; p < 0.001) and reported increased intravaginal washing (64 vs 56%; p = 0.027) than those who were HSV-2 seronegative. Genital sE-cad levels were similar, and IL-6 levels were lower in seropositive participants (1.15 vs 1.28 pg/mL, p < 0.01). Seroincidence was 10.7/100 person (95% CI: 7.3, 15.2) years among the 317 initially seronegative participants. Incident infection was associated with older age (31 vs 28 years, p = 0.001), increased number of clients (6 vs 4 clients/week, p = 0.005), and bacterial vaginosis (BV) (32 vs 15%, p = 0.009). Although women who acquired HSV-2 had higher sE-cad and lower MIP-3α levels, there was no association after controlling for Nugent score.

CONCLUSIONS

Subclinical epithelial barrier disruption is unlikely to be underpinning HIV acquisition in asymptomatic HSV-2 infection. There was no evidence of genital immune predictors of HSV-2 acquisition, whereas the vaginal microbiome is important.