Aug. 11 (Bloomberg) -- Asunta Wagura was 22 years old and a medical student at the University of Nairobi when she contracted HIV after having unprotected sex.

``At that age, to propose a condom to a partner, it would have looked like I was promiscuous,'' says Wagura, who is now 41 and runs an organization in Kenya that provides assistance to women with HIV. ``A woman is not supposed to propose a condom.''

Cultural attitudes are spurring the search for ways to help women like Wagura protect themselves from being infected by HIV, the deadly virus that causes AIDS. Almost 60 percent of the people with HIV in the hardest-hit countries of Africa are women, and the rates of infection are increasing faster among females than males, according to the United Nations.

Short of a vaccine against HIV, researchers are testing diaphragms to block entry of the virus and vaginal gels called microbicides that can kill it on contact. As scientists open the 16th International AIDS Conference in Toronto Aug. 13, researchers say most products, and a vaccine, may be years away.

``There is nothing for a woman that she can initiate by herself,'' says Gita Ramjee, a doctor in Durban, South Africa, who is the principal investigator on four clinical trials of experimental vaginal gels.

``A microbicide would offer that,'' says Ramjee, who was interviewed by telephone.

To spur the studies of existing ointments, and research to discover new ones, the Seattle-based Bill & Melinda Gates Foundation has announced gifts totaling $124 million. The U.S. government, through the National Institutes of Health and other agencies, allocated $117 million for microbicide research in the 2006 fiscal year, according to the Alliance for Microbicide Development in Silver Spring, Maryland.

Blood and Semen

The idea of developing a microbicide has been around for at least 17 years, when scientists at the New York-based Population Council, a nonprofit contraceptive-research group, began testing to see whether available creams might destroy HIV in blood and semen.

Only in the last few years, as it became clear that an AIDS vaccine might still be even decades away, did scientists begin a more earnest search, says Renee Ridzon, a senior program officer at the Gates Foundation.

``The challenge in developing a vaccine is that the basic scientific questions that have yet to be answered are very deep,'' Ridzon says. ``The questions with microbicides are more about delivery and formulation, and the feeling is that those can be addressed more quickly.''

Prevention is the best hope for the epidemic, says Zeda Rosenberg, chief executive officer of the International Partnership for Microbicides. AIDS has already killed more than 25 million people worldwide, and 38.6 million are infected with the virus today, according to the United Nations' UNAIDS program.

Epidemic

``You can't treat your way out of an epidemic,'' says Rosenberg, whose Silver Spring, Maryland-based nonprofit group is involved in testing and developing protective gels.

Speeding microbicide development will be among the topics considered at the AIDS conference in Toronto. The six-day meeting will draw about 24,000 doctors, scientists and advocates to discuss treatment, care and prevention of the disease.

Wagura, in a phone interview, says she would have used a microbicide had one been available when she was 22. Her organization, called the Kenyan Network of Women With AIDS, provides HIV medicines to women who need them, infant formula to new mothers to prevent transmission of the disease to babies through breast milk, and food for children whose parents have died as a result of AIDS.

`Helpless'

When women who aren't infected ask her group for ways to prevent the virus, she has little advice to offer. Condoms and abstinence are urged by many organizations, though women say they are vulnerable to pressure from men in their lives, especially to those whom they rely on for financial support.

``We feel helpless,'' Wagura says.

Women are eight times more likely than men to become infected with HIV after a single act of unprotected sex, according to the Global Campaign for Microbicides, based in Brussels and Washington. During sex, a woman's cervix, vagina and uterus are exposed to semen, providing a wide swath of cells for the virus to use to invade her body.

The idea behind microbicides is simple: to kill HIV topically. The gels work in a variety of ways, including providing a physical barricade to keep the virus out. Another approach is to stop HIV from binding to molecular hooks the virus uses to latch onto and enter cells in the bloodstream.

Scientists worldwide are evaluating 14 gels in people, five of which are in the final phase of testing, says Jennifer Kates, director of HIV Policy for the Kaiser Family Foundation, a nonprofit health research group based in Menlo Park, California. Results of those studies are still years away, she says.

Virus Killer

Among the most advanced products is a gel called cellulose sulfate, a derivative of cotton developed by Toronto-based Polydex Pharmaceuticals Ltd. It's being tested by groups including the Contraceptive Research and Development Program, or Conrad, at Eastern Virginia Medical School in Norfolk, Virginia.

Test tube experiments show the compound is an effective virus killer, says Henry Gabelnick, a professor at Eastern Virginia and executive director of Conrad, a collaboration with the U.S. Agency for International Development.

``It's active against a multiplicity of agents, which we think is somewhat different than some of the others,'' he says.

Cellulose sulfate also works as a contraceptive, and lab experiments suggest that it might help prevent other sexually transmitted diseases. Researchers are enrolling almost 5,000 patients in two studies in five countries in Africa, including a site that Ramjee is overseeing in South Africa, and in India. The research is being funded by the Gates Foundation and USAID.

The Real World

Because a gel is unlikely to be 100 percent effective, studies will need to be carefully designed to provide clear evidence that a microbicide is offering increased protection, says John Moore, a professor at Cornell University's Joan and Sanford I. Weill Medical College in New York City.

``This is the real world, and you're talking about real people in a sexually complicated environment,'' says Moore, who researches the way HIV invades healthy cells.

Compliance is a major challenge, says the Gates Foundation's Ridzon. A woman who has sex several times in one evening may faithfully apply her microbicide once at the beginning of the night but fail to use it a second or third time, she says.

``If a woman is already in bed and has to get up and find the product, the following sex acts are likely to have less adherence,'' Ridzon says.

No One Answer

In the same way that no single drug works to fight HIV once a person is infected, it's unlikely that one form of prevention will hold all the answers, says Nancy Padian, executive director of the Women's Global Health Imperative at the University of California, San Francisco.

Padian is studying diaphragms, latex cups that cover a woman's cervix and have been used for centuries in various forms to prevent pregnancy.

Other research is assessing whether it's possible to lower infection rates by helping women develop economic independence so they don't have to rely on prostitution or other types of dependent sexual relationships, she says.

``I don't think there's one magic bullet,'' Padian says. ``It's going to be a mix of things.''

To contact the reporter on this story: Marni Leff Kottle in San Francisco at mkottle@bloomberg.net

Last Updated: August 11, 2006 00:08 EDT