Experimental Microbicide Might Help Prevent Transmission of HIV, Herpes, Study Says
Lexington, Mass.-based Indevus Pharmaceuticals' experimental microbicide PRO 2000 might help protect against transmission of HIV and the herpes simplex virus, according to a report published in the Jan. 1 issue of the Journal of Infectious Diseases, Reuters Health reports (Reuters Health, 1/24). Microbicides include a range of products -- such as gels, films, sponges and other products -- that could help prevent the sexual transmission of HIV and other sexually transmitted diseases (Kaiser Daily HIV/AIDS Report, 1/10). Betsy Herold and colleagues from Mount Sinai School of Medicine collected cell samples from the vaginas and cervixes of 20 HIV-positive women before and one hour after vaginal application of either two milliliters of PRO 2000 -- which is formulated to prevent HIV from attaching to human cells -- or a placebo gel. The researchers found that women treated with PRO 2000 showed significantly reduced HIV viral loads in their cell samples compared with women treated with the placebo. The researchers then conducted a similar experiment that used proteins cloned from a type of HIV that often exists "after sexual transmission and may be more readily transmitted via mucosal routs," according to the report. Researchers found that more than 99% of cervical and vaginal cells that were exposed to PRO 2000 did not contract the cloned HIV proteins. The report also finds that the gel produced anti-HSV activity compared with the placebo, according to Reuters Health. The researchers said, "This trial demonstrates ... that a candidate microbicide is sufficiently bioavailable and retains substantial anti-HIV and anti-HSV activity after intra vaginal application."
In a related Journal of Infectious Diseases perspective, Darpun Dhawan and Kenneth Mayer, researchers at Brown Medical School, said there are many challenges to making safe and effective microbicides, including: developing ways for preclinical tests to determine safety and possible microbicidal resistance in the genital tract; recruiting thousands of HIV-negative, high-risk people to participate in clinical trials that will last several years; and developing microbicides to prevent HIV transmission during anal intercourse (Reuters Health, 1/24). Dhawan and Mayer wrote, "Safe and effective topical microbicides are biologically plausible," adding, "Several trials that are under way may demonstrate the ability of microbicides to protect against transmission of HIV, but multiple challenges remain" (Dhawan/Mayer, Journal of Infectious Diseases, 1/1).