"The findings explain the results of a recent clinical trial showing that the anti-HIV drug tenofovir, when it is formulated as a vaginal gel, could reduce the risk of herpes simplex virus (HSV) infections -- as well as HIV infections -- in women.
Tenofovir taken orally had been demonstrated to inhibit reproduction of HIV, but had not been known to block the genital herpes virus.
"HIV infection is closely associated with herpes viral infection. When people with genital herpes are exposed to HIV, they are more likely to become infected than are people who do not carry the herpes virus," said Leonid Margolis, Ph.D., head of the Section on Intercellular Interactions at NICHD and one of the authors of the study. "Human tissues convert tenofovir to a form that suppresses HIV. We found that this form of tenofovir also suppresses HSV. This discovery may help to identify drugs to treat the two viruses even more effectively." Discoveries leading to new uses for previously approved drugs have the potential to save millions of dollars, Dr. Margolis said. New drugs typically undergo years of testing for safety and effectiveness before they are approved for patients. Finding new uses for an approved drug increases the value of the initial investment in testing, because most of the testing has previously been completed."