Experimental microbicide containing natural compound provides protection in monkeys against simian version of HIV

Mar 5 2009

An experimental microbicide containing a naturally occurring compound provides protection in monkeys against the simian version of HIV by diminishing immune responses to the virus, according to a study published Wednesday in the journal Nature, the Los Angeles Times reports.

HIV typically spreads in the body by entering CD4+ T cells, which the immune system sends out to attack the virus after exposure. The compound -- called glycerol monolaurate, or GML -- works by inhibiting immune signals that dispatch the T cells to attack the infection. It is those T cells that HIV infects and uses to proliferate throughout the body (Engel, Los Angeles Times, 3/5). GML occurs naturally in the human body and already is approved for use as an antimicrobial and anti-inflammatory ingredient in cosmetics and toiletries, as well as an emulsifier in foods. In addition, each dose of GML used in the study costs less than one cent. According to the researchers, the study's findings have promising implications for the development of effective microbicides to prevent HIV (AFP/Google.com, 3/4).

For the study -- led by Ashley Haase, head of the microbiology department at the University of Minnesota Medical School, and microbiologist Patrick Schlievert -- researchers administered the GML gel vaginally to five rhesus monkeys and then repeatedly exposed them to the simian version of HIV, or SIV. After two weeks, all of the five monkeys tested negative for the virus. However, four out of five monkeys that did not receive the GML gel contracted SIV. According to the researchers, five months after the experiment, they learned that one of the monkeys treated with GML tested positive for the virus. The researchers said they are unsure how this monkey contracted SIV, but they suggested that a small amount of the virus might have spread in the body undetected or the monkey might have been exposed to SIV after the study ended (Lerner, Minneapolis Star Tribune , 3/4).

Haase said the current research is "a relatively preliminary study but worth sharing because it establishes a novel approach." The researchers added that a mathematical model suggests that even if the microbicide were 60% effective and used 20% of the time, it still could prevent about 2.3 million HIV cases over a three-year period. According to the study authors, researchers will need to conduct further animal studies to determine whether the microbicide should be administered over a longer period of time to provide long-term protection against the virus (Los Angeles Times, 3/5). Further study also will be needed to demonstrate whether GML prevents HIV transmission among humans, they added. The researchers said they plan to undertake a larger study with monkeys, followed by a study with female volunteers. In addition, the University of Minnesota has applied for patents for the new compound combining GML with a personal lubricant, which currently is not available commercially. According to Schlievert, the ultimate goal will be to develop a gel that can be used for both men and women (Minneapolis Star Tribune, 3/4).

According to the study authors, the research "represents a highly encouraging new lead in the search for an effective microbicide to prevent HIV transmission that meets the criteria of safety, affordability and efficacy" (Fox, Reuters, 3/4). Haase said that although the research "sounds counter-intuitive, halting the body's natural defense system might actually prevent transmission and rapid spread of the infection" (AFP/Google.com, 3/4). Charlene Dezzutti, laboratory network director of the Microbicides Trial Network at the University of Pittsburgh, said the research illustrates "a new approach to thinking about microbicides." She added that she believes scientists "definitely" could develop an effective microbicide before developing an HIV/AIDS vaccine. "It's just a matter of getting all the right pieces together," she said (Lauerman, Bloomberg, 3/4). Rowena Johnston, vice president of research for the Foundation for AIDS Research, said that if further studies confirm these results, "then this is really a fabulous new finding." She said that although future microbicide research could encounter setbacks, the study is "absolutely a great beginning to a research project."

According to Schlievert, women could apply the GML microbicide "an hour or so before they had sex" to protect against HIV transmission. In addition, the gel might provide protection against other sexually transmitted infections, such as chlamydia, he said (Minneapolis Star Tribune, 3/4). According to AFP/Google.com, Schlievert first identified the microbicidal properties of GML when studying the use of the compound in preventing toxic shock syndrome associated with tampons. He said research repeatedly has found that the compound is safe and has no effect on beneficial vaginal bacteria (AFP/Google.com, 3/4). Lorraine Teel, executive director of the Minnesota AIDS Project, said the gel could provide women with a way to prevent disease transmission in areas of the world where many people do not use condoms because of cultural or other pressures. The research has "absolutely enormous implications" for women worldwide, she said (Minneapolis Star Tribune, 3/4). Anthony Fauci, director of NIH's National Institute of Allergy and Infectious Diseases, said an effective microbicide would "empower women to protect themselves in a sexual situation in which they may not have complete control" (Los Angeles Times, 3/5).

An abstract of the study is available online.