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Oral Tenofovir Does Not Reduce Herpes Virus Shedding

HIV positive people who took tenofovir (Viread, also in the Truvada and Atripla combination pills) as part of their antiretroviral regimen were no less likely to shed herpes simplex virus 1 or 2 (HSV-1 or HSV-2) than individuals using non-tenofovir regimens, according to research described in the January 14, 2011, issue of AIDS. These findings are notable because a recent microbicide study found that a tenofovir gel reduced the likelihood of HSV-2 infection.

Data from the landmark CAPRISA 004 trial, presented at the 2010 International AIDS Conference last summer, showed that women who used a vaginal gel containing 1% tenofovir were not only 39% less likely to become infected with HIV, but were also half as likely to contract HSV-2.

Before that report, tenofovir had not been linked to control of HSV. Darrell Tan and colleagues from the University of Toronto therefore designed a study to determine whether oral tenofovir, taken as part of combination antiretroviral therapy (ART), would have an effect on asymptomatic HSV shedding, or release of infectious virus in the absence of herpes lesions (an indicator of ongoing HSV replication).

This small study included 40 people coinfected with HIV and HSV (32 with HSV-1, 30 with HSV-2, and 22 with both HSV types). HSV-1 is the usual cause of oral herpes, while HSV-2 typically causes genital herpes. Just over half were using ART regimens containing tenofovir (22 patients or 55% overall; 17 patients or 57% among those with HSV-2). Participants had well-controlled HIV, with viral loads below 50 copies/mL, and had not experienced herpes symptoms for the previous 4 months.

Study participants self-collected oral, genital, and anal swabs daily for 28 days. Specimens were tested for HSV-1 and HSV-2 using polymerase chain reaction (PCR) assays. The shedding rate was calculated as the proportion of days with detectable HSV in swab samples.

Results

• The likelihood of shedding HSV-2 in the mouth or anal-genital area was low overall, occurring on 7.1% of specimen collection days.
• The number of days of HSV-2 shedding did not differ significantly between people who used tenofovir and those who did not (P = 0.36).
• In addition, there was no significant difference in the number of participants with HSV-2 shedding in the tenofovir and non-tenofovir groups (59% vs 46%; P = 0.49).
• Rates of HSV-1 shedding were also similar in the 2 groups (P = 0.59).

Based on these findings, the study authors concluded, "[A]lthough topical tenofovir 1% gel was associated with a significant decrease in HSV-2 acquisition among high-risk women in the recent CAPRISA 004 trial, in these preliminary data we did not observe an impact of oral tenofovir on HSV-2 or HSV-1 shedding rates among HIV, HSV co-infected asymptomatic adults."

Investigator affiliations: University Health Network, Division of Infectious Diseases, Canada; University of Toronto, Ontario, Canada.

1/25/11

Reference
DH Tan, R Kaul, JM Raboud, and SL Walmsley. No impact of oral tenofovir disoproxil fumarate on herpes simplex virus shedding in HIV-infected adults. AIDS 25(2):207-210 (Abstract). January 14, 2010.