( immunodeficiency virus (SHIV) a hybri...)Vaginal gel may provide a new approach to HIV prevention

The Tulane team tested gels containing two small molecules and a peptide -- alone and in combination --designed to block SHIV from fusing with its target cells at or near the tissue lining of the vagina, to see whether this would prevent the virus from entering the monkeys' bodies. The test compounds were provided by Bristol-Myers Squibb Inc., Merck Research Laboratories and Weill Medical College of Cornell University.

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."