Monkeys protected from HIV-like virus by microbicide gel

Researchers found that glycerol monolaurate, an ingredient in some foods and cosmetics, is the basis for a microbicide that can protect female monkeys from an HIV-like virus.

It is thought that the compound has the effect to suppress an immune response that helps the virus instead of combating it. During the earlies stages of an infection, the immune system summons CD4+ cells, a type of immune cell, to the site of the infection. The virus doesn't mind this, on the contrary, this response actually helps it spread even further. Nature reports that immunologist Ashley Haase of the University of Minnesota in Minneapolis and his colleagues found how this is done. The researchers think that the microbicide they use may be acting by suppressing this response. Preliminary results from a clinical trial of the candidate microbicide, Pro 2000, suggest that the gel does reduce HIV infection in women who used it. However, the results were not statistically significant, and because of that, researchers are awaiting the results of a larger trial, expected later this year. Because the time of initial HIV infection is not often known in humans, it is hard to study the initial stages of the infection. This is why Haase and his colleagues are studying SIV (Simian Immunodeficiency Virus) in female rhesus macaques (Macaca mulatta) The researchers watched how a small population of CD4+ cells was initially infected in the cervix and the vagina, and how the infection spread when more of these cells arrived at the infection site. They also discovered that the immune system produces several proteins during the first days of infection. This reminded Haase of work by Patrick Schlievert, a colleague immunologist of the university of Minnesota who had discovered that glycerol monolaurate inhibits the production of certain deadly bacterial toxins, and that it also inhibits certain immune responses to a toxic shock syndrome toxin. Haase then mixed glycerol monolaurate with a gel and found out that, after two weeks of testing on the macaques, four of the five monkeys that were treated with the gel only, were infected by the virus, whereas none of the monkeys that were treated with glycerol monolaurate were infected, although one of them did develop an infection later on. Promising results, but reluctant anyway These results are very promising, but many researchers are very reluctant to go in this direction. The trouble is that glycerol monolaurate is a surfactant. Trials with the spermicide nonoxynol-9, another surfactant, turned to disaster. Not only did it fail to protect women from HIV, but it actually increased their risk. It is still possible that glycerol monolaurate is actually directly destroying the virus, something most surfactants are thought to do. Because of that, Haase will have a very hard time to convince his colleagues that his results look promising. Sharon Hillier, another investigator in the Microbicide Trials Network, says that the results are provocative and that more attention is needed before they will know whether or not glycerol monolaurate has promise as a microbicide.