U. scientists work on HIV prevention
Gel could help women to protect themselves against spread of virus
While scientists continue to report the quick spread of HIV in Africa and other impoverished areas, University of Utah researchers are working on a unique vaginal gel that could stop it from infecting more people.
Human tests of the microbicide that bioengineering professor Patrick Kiser is calling a "molecular condom" could begin in the next few years, with the product going on the market years after that if proved successful. The idea, which is the first of its kind, involves a before-sex insertion of a vaginal gel that turns semisolid in the presence of semen, trapping AIDS virus particles in a microscopic mesh so they can't infect vaginal cells.
"We did it to develop technologies that can enable women to protect themselves against HIV without approval of their partner," Kiser said. "This is important — particularly in resource-poor areas of the world like sub-Sahara Africa and south Asia, where, in some age groups, as many as 60 percent of women already are infected with HIV. In these places, women often are not empowered to force their partners to wear a condom."
Cultural and socioeconomic factors keep women in certain areas from negotiating the use of protection with their partner, said Julie Jay, U. doctoral candidate of pharmaceutical chemistry and author of a study testing the behavior of the new gel, which is published online in the Journal of Advanced Functional Materials.
The new gel, she said, could be inserted a few hours before sex and would essentially detect the presence of semen and provide a protective barrier between the vaginal tissue and HIV. It leaves the body as vaginal tissues naturally re-acidify, and is either eliminated or absorbed.
"We wanted to build a gel that would stop HIV from interacting with vaginal tissue," Jay said. She and Kiser have been working on the project since 2007, with four other U. researchers and experts from Northwestern University's medical school in Chicago.
The newly devised product, applied as a gel, becomes more solid and impenetrable as changes in pH, by the introduction of semen in the vagina, alter the strength of the bond between the gel's two key polymer components — phenylboronic acid and salicylhydroxamic acid. Older versions of a similar process were inserted as a liquid, turned to gel to coat the cavity and then in the presence of semen, turned liquid again to release an anti-HIV drug. Such methods failed either because they carried antiviral drugs that weren't strong enough or didn't last long enough, or because patients failed to use them, Kiser said.
High temperatures in Africa also prevented the gel from turning back to liquid, which prevented an even coating of the vagina.
In the newer version, the polymers form a mesh that is smaller than microscopic, with a size of a mere 30 to 50 nanometers, or 30 to 50 billionths of a meter, blocking AIDS virus particles so they can't infect vaginal cells.
An HIV particle is about 100 nanometers wide, while sperm measure about 5 to 10 microns (5,000 to 10,000 nanometers) in cross section. Relatively, the width of human hair is roughly 100 microns (100,000 nanometers). Kiser said particles half the size of an HIV particle cannot breach the new polymer mesh. The process is explained in the study, which was funded by National Institutes of Health as part of their efforts to prevent the spread of AIDS in impoverished nations.
Kiser said there is nothing specific about the HIV particles that makes them susceptible to the polymer mesh and that ultimately the gel should block other viruses and sperm. It could work as a contraceptive and possibly prevent infection by herpes viruses and human papilloma virus (HPV), a major cause of cervical cancer, he said. As a product being researched for use in developing countries, Kiser said protocol has to follow FDA guidelines and at some point in the research, it is very likely that a pharmaceutical company will pick up the idea and market it for profit in the U.S. as well.
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