Research with female monkeys at the Tulane National Primate Research Center has for the first time shown that three different anti-viral agents in a vaginal gel protect the animals against an HIV-like virus. The research suggests that a microbicide using compounds that inhibit the processes by which HIV attaches to and enters target cells could potentially provide a safe, effective and practical way to prevent HIV transmission in women, according to study investigators. The study, published online October 30 in the journal Nature was funded principally by the National Institute of Allergy and Infectious Diseases (NIAID) of the National Institutes of Health.
To test the microbicides, the Tulane team first gave the monkeys a long-acting hormonal form of birth control (Depo-Provera) to synchronize their menstrual cycles and thin the vaginal membrane, which increases susceptibility to virus infection, Veazey says. During testing, researchers placed the experimental gels in the animals' vaginas. Thirty minutes later, the animals were exposed to high-dose SHIV.
The three inhibitors were each effective when used alone and also when tested in combination. Of 20 monkeys given the BMS and Merck microbicides in combination, 16 were protected from infection. All three monkeys given the triple combination of microbicides remained virus-free. None of the monkeys experienced vaginal irritation or inflammation from the experimental gels.
"We felt these inhibitors were likely to be pretty safe. Compounds similar to them have a good safety record in humans, at least so far," Veazey says.
"This study demonstrates that combination microbicides are feasible," says NIAID Director Anthony Fauci. "We need to build on these promising animal studies and move toward establishing the safety and effectiveness of combination microbicides in women."