Anti-AIDS gel might help men too, study finds

WASHINGTON (Reuters) - A gel designed to protect women from the AIDS virus made using Gilead Sciences' drug Viread could protect men from infection during anal sex, British researchers reported on Tuesday.

Tests on monkeys showed that a gel made using the drug, known generically as tenofovir, may prevent AIDS transmission when applied rectally.

The macaques pre-treated with rectal tenofovir gel up to two hours before being given a monkey version of HIV were partly or totally protected from infection, also rectally, Dr. Martin Cranage of St. George's University of London and colleagues reported.

Untreated animals and most of those treated with a placebo gel, or treated with tenofovir gel after getting inoculated with virus, became infected with the virus, called simian immunodeficiency virus or SIV.

The study also added to evidence that the drug can protect in various ways from infection with HIV if taken before exposure -- some of the protected macaques developed T-cell immune responses to the virus, they reported in the Public Library of Science journal PLoS Medicine.

Many experts are pressing for the development of a microbicide -- a gel or cream that could be applied vaginally or rectally to protect against sexual transmission of the human immunodeficiency virus that causes AIDS.

None are on the market now, although several are being tested. Two versions use HIV drugs such as tenofovir, which is usually taken as a pill to suppress the virus.

Last month mathematical experts published a study showing that development of a microbicide would protect male sex partners of such HIV-infected women.

Condoms prevent infection but many men refuse to use them. Experts say women, and some men, need a private way to protect themselves.

Florian Hladik of the Fred Hutchinson Cancer Research Center and the University of Washington and Charlene Dezzutti of the University of Pittsburgh, who were not involved with the research, said tests in monkeys might not reflect real-life use in human beings.

"High-risk behavior in humans is marked by repeated exposures to the virus, which potentially will require reapplication of the microbicide gel numerous times, possibly over extended time periods," they wrote in a commentary.

This might damage the delicate mucous membranes in the vagina or rectum, making transmission more, not less, likely, they said.

An estimated 33 million people have HIV, mostly in Africa. More than 60 percent of Africans with HIV are women who were infected by their husbands or other male sexual partners.

Most of the 2 million people who get HIV every year globally are women although men who have sex with other men have, on average, 19 times the risk of most people of being infected, according to research published this week at the International AIDS Society meeting in Mexico City.

(Reporting by Maggie Fox; Editing by Julie Steenhuysen)