THURSDAY, Oct. 14, 2004 (HealthDayNews) -- Researchers report that a new topical cream appears to stop female monkeys from getting an HIV-like virus.
The treatment, which aims to protect cells in the vagina from infection, is years away from being ready for testing in women. Other topical approaches, known generally as microbicides, are further along in the pipeline. But the latest discovery uncovers a potential bull's-eye, said study co-author Dr. Michael Lederman, director of the Case Western University/University Hospitals of Cleveland Center for AIDS Research. His report appears in the Oct. 15 issue of Science.
"We've identified a good target for topical strategies to prevent vaginal acquisition of HIV, and that's pretty good," Lederman said. "Having a nice target to point at is a good thing."
While efforts to develop an AIDS vaccine have often gotten more attention, researchers have spent years investigating topical treatments -- creams, lubricants, and jellies -- that could prevent HIV infection in the vagina.
Some approaches aim to kill or disable the AIDS virus, while others boost the vagina's natural defenses against invaders, explained Lori Heise, director of the Global Campaign for Microbicides. Other techniques prevent HIV from spreading by creating barriers. "It's a complicated process," she said. "You can interrupt [HIV infection] at any of a number of stages."
The goal is to give women a weapon against HIV besides abstinence or condoms, especially in cases where an old prevention standby -- monogamy -- may not necessarily provide protection.
"If you look at where women are most at risk or increasingly at risk, it's with sex in long-term partnerships," Heise pointed out. "That means that women are getting infected within their relationship because their partners are having outside relationships or IV drug-using habits."
Condoms aren't an answer in long-term relationships because "that's when the condom comes off," Heise said.
Five potential topical treatments are in or near the final stages of large-scale human testing. "If one of those proves successful, we could have a product available within the next four to five years," Heise said.
Lederman's approach is still in the early stages. He and his colleagues coated the vaginas of 25 rhesus monkeys with various levels of synthesized molecules dissolved into saline solution. Five other monkeys received a placebo -- saline solution only.
Researchers then exposed the monkeys to a virus that is, in essence, a blend of HIV and simian immunodeficiency virus, which affects monkeys. HIV alone wouldn't have fully infected the monkeys, Lederman explained.
"We found that this agent protected monkeys from getting infected by the vaginal route," Lederman said. "The more that was used, the greater the level of protection."
The treatment appears to work by blocking the ability of the AIDS virus to bind with "receptors" in cells in the vagina, Lederman said. In layman's terms, it's as if a jigsaw puzzle piece lost one of its rounded edges, preventing another piece from joining with it.
Lederman said researchers aren't sure which cells are gaining defensive abilities from the treatment. Nor do they know if humans will tolerate the treatment in a topical form, such as a sexual lubricant. The monkeys, however, seemed to do fine, he said.
The next steps are to figure out if lower doses will still protect animals against the virus, he said. Then, down the line, tests may begin in humans.
More information
To learn more about microbicides and other topical treatments to prevent AIDS transmission, try the Global Campaign for Microbicides.
