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Old Strategy for Tackling HIV Makes a Comeback

Jon Cohen

ScienceNOW 2009 (304), (04 Mar 2009)

For 20 years, AIDS researchers have searched for a vaginal microbicide that can block HIV, butthey have made little progress. One gel has shown hints of working in a large-scale human study (ScienceNOW, 9 February), but the rest have failed or even caused harm. Now a new monkey study suggeststhat a microbicide containing a compound that many investigators would consider old-fashioned may have the power to thwart the AIDS virus. The failure of first-generation microbicides has led thefield to largely abandon the strategy behind them: that HIV could be stopped by compounds, such as soaps, that disable the virus without specifically attacking it. Today, most microbicides in humanstudies or on the drawing board contain anti-HIV drugs that cripple a critical viral enzyme. Yet as a team led by Ashley Haase of the University of Minnesota, Minneapolis, found, a nonspecificmicrobicide that targets the vaginal immune responses works remarkably well in monkeys. Haase and co-workers first detailed how SIV, the monkey version of the AIDS virus, establishes a vaginal infection. Byexamining blood and vaginal tissues, the researchers found that SIV causes an inflammatory immune response, which recruits mobs of CD4 white blood cells--the virus's favorite target--to the site. IfHaase and colleagues could prevent this from happening, they reasoned, they might be able to stomp out SIV's spark before it started a fire. The researchers decided to test a microbicide that containsglycerol monolaurate (GML), a fatty acid that has proven safe in many products: It's used as a fiber finish in tampons and also as an emulsifier in many foods and cosmetics. Unlike soap-basedmicrobicides, GML is not a so-called surfactant that aims to disrupt the viral membrane, says Haase. Rather, he was intrigued by its documented ability to dampen the immune responses triggered by vaginal...