HSV-2 Suppression for HIV Prevention
What is HSV-2 Suppression for HIV Prevention?
Why is HSV-2 suppressive treatment or HSV-2 prevention a possible HIV risk reduction strategy? Genital herpes is caused by the sexually transmitted virus herpes simplex virus type 2 (HSV-2). There is a possibility that prevention of HSV-2 or suppressive use of antivirals—acyclovir and valcyclovir—can reduce the recurrence of HSV-2 lesions. There is also the possibility that HSV-2 infection can be prevented by a vaccine. This may have the added benefit of reducing the risk of HSV-2 infected/HIV-uninfected people acquiring HIV, and of HSV-2/HIV dually-infected people transmitting HIV to their sexual partners. HSV-2 is found in 20 to 30 percent of HIV-uninfected people in industrialized world compared to 40 to 70 percent of HIV-uninfected people in resource-limited settings. HSV-2 prevalence is highest (>80%) in HIV-infected people. Therefore, preventing HSV-2 or treating HSV-2 in both HIV negative and positive people could potentially have an impact on the HIV epidemic.
HSV-2 Suppression Investment
In 2012, a total of US$2.3 million was provided for HSV-2 vaccine research, most from the US NIH; the Australian ARC and NHMRC also provided funding. As in previous years, commercial investors were often subsidized by public-sector institutions, such as the US NIH. Pharmaceutical and biotechnology companies investing in HSV-2 vaccine R&D include GSK, Genocea Biosciences, Juvaris BioTherapeutics and Vical.
In mid-2012 results of GSK’s NIH-funded Phase III trial assessing the company’s HSV vaccine, Simplirix, were published, shedding light on GSK’s decision in 2010 to halt the trial due to lack of efficacy. GSK and NIH investigators are conducting further analysis of the results from that study to gain better understanding of the vaccine.