Herpes virus shedding increases HIV infectivity too

The genital shedding of herpes simplex virus (HSV) and HIV is closely correlated, meaning that a person shedding HSV is more infectious for HIV, according to a study published in the December 6 edition of the journal AIDS.

Investigators screened women for HIV who were receiving hormonal contraceptives at the Coast Provincial General Hospital in Mombassa, Kenya between May 1996 and September 1999. In total 210 women tested HIV-positive and were eligible for the study, which involved baseline tests including taking blood samples, plasma viral load, and CD4 cell counts, and the taking of cervical swabs to detect the shedding of HSV and HIV. Follow-up was one and two months later. Women who had or had recently had gonorrhoea, chlamydia or genital ulcers were excluded as these have been shown to increase the amount of HIV-infected cells in the genitals.

The lower limit of detection for the plasma HIV viral load tests was 50 cells/mL and 125 cells m/L for the cervical swabs. Detectable cervical HIV was present in 66.7% of women (28/42) with detectable cervical HSV and in 65.8% of women (98/149) without, leading the investigators to comment that “the detection of cervical HSV DNA was not significantly associated with HIV-1 levels greater than 125 copies/swab or with the detection of HIV-1 infected cells.”

However, the investigators add that although there was no relationship between detection of the two viruses, there was a significant relationship between the quantities of HSV and HIV found in cervical secretions of HSV shedding women. A 10-fold (one log) increase in the amount of cervical HSV was associated with 1.36 increase in cervical levels of HIV. This relationship remained unchanged when differences in CD4 count and plasma viral load were adjusted for. No significant relationship was found between the shedding of cervical HSV and plasma HIV viral load.

The investigators speculate that “local interactions between HSV and HIV-1 may provide a plausible explanation for the association between the genital shedding of the two viruses”. They conclude that “HSV suppression could be an important means of deceasing” the spread of HIV, and given the high levels of HSV infection in their study population call for “additional prospective studies of the relationship between HSV and HIV-shedding.”

The relationship between HSV and HIV infectivity and disease progression is the subject of intensive investigation. A study conducted in the US before the introduction of HAART found that treatment for HSV resulted in a modest reduction in HIV viral load, and a recent South African study found that recent HSV infection was associated with HIV seroconversion.

Click here for NAM’s Factsheets on herpes and sexual health.