July 26, 2010
By: David Gutierrez
A kind of protein naturally occurring in bananas may hamper the spread of HIV, according to a study conducted by researchers from the University of Michigan and published in the Journal of Biological Chemistry.
The protein, known as BanLec, is in the family known as lectins. Lectins are able to identify and attach to foreign sugars, including those found in the outer coating of the virus that causes AIDS. The researchers found that HIV viruses in the presence of BanLec were blocked as effectively as viruses in the presence of two different modern HIV drugs.
Multiple applications of lectins’ newfound property suggest themselves. For example, the proteins could be incorporated into topically applied vaginal microbicides to reduce women’s risk of HIV infection.
“The explosion of AIDS in poorer countries continues to be a bad problem because of tremendous human suffering and the cost of treating it,” senior author David Markovitz, said. “That’s particularly true in developing countries where women have little control over sexual encounters, so development of a long-lasting, self-applied microbicide is very attractive.”
Researchers also hope to find a way to use lectins to prevent the HIV virus from integrating into host cells even if it does gain entry into the body.
“The problem with some HIV drugs is that the virus can mutate and become resistant, but that’s much harder to do in the presence of lectins,” co-author Michael D. Swanson said. “Lectins can bind to the sugars found on different spots of the HIV-1 envelope, and presumably it will take multiple mutations for the virus to get around them.”
Although AIDS is especially a problem in Third World countries, it also remains a serious health problem in the United States. An estimated 57,000 women in the United States are infected with HIV, along with three times as many men. AIDS is the single biggest killer of African American women between the ages of 35 and 34.
December 16, 2009
Los Angeles Times
By Thomas H. Maugh II
A microbicide gel designed to block the transmission of the AIDS virus to women has failed the largest clinical trial to date, a bitterly disappointing finding for researchers that likely spells the end of research on this form of such products. The findings announced Monday by England’s Medical Research Council represent a major letdown because results from a smaller study presented in February at a major AIDS conference suggested that the microbicide could block transmission of HIV by 30%, although the results were not statistically significant. Researchers are now turning their attention to microbicides containing anti-HIV drugs.
Short of a vaccine, vaginal microbicides are considered one of the most promising ways to prevent transmission of the virus to women. Such an approach would give women a great deal of control over their health when marital or other sexual partners refuse to use condoms. The idea is that the microbicide will tie up or kill the virus in the vagina before it can penetrate the tissues and infect the woman. Such a product must not be unpleasantly messy or sticky and should be able to block the virus without impeding the much larger sperm.
The trial involved a microbicide called PRO 2000 manufactured by Endo Pharmaceuticals of Chadds Ford, Penn. Its active ingredient is a polymer of naphthalene sulfonate designed to bind to receptors on the surface of HIV, preventing it from penetrating vaginal tissue. Tests in the laboratory showed that it binds strongly to the virus, suggesting that it would be effective in actual use.
The trial, sponsored by the London-based Microbicides Development Programme–a coalition of 16 European and African research institutions–involved 9,385 African women in four countries. The women were given either a placebo gel, a gel containing 0.5% of PRO 2000 or a gel containing 2% PRO 2000. The gels were to be used before and after sex. The women were also counseled to use condoms whenever possible and on other ways to minimize the risk of infection. The women reported that they liked the gel and many were disappointed when they had to stop using it.
The arm of the trial using the higher concentration was halted in February 2008 when it became clear that the microbicide would not work at that concentration.
There were 130 HIV infections in the 3,156 women who received the 0.5% gel and 123 in the 3,112 women receiving the placebo gel during the 12 to 24 months of follow-up. That works out to a rate of 4.5 infections per 100 women-years in the group receiving PRO 2000 and 4.3 in the placebo group.
“This result is disheartening, particularly in light of the results of a smaller trial sponsored by the U.S. National Institutes of Health,” the study’s chief investigator, Dr. Sheena McCormack of the Medical Research Council, said in a statement. “Nevertheless, we know that this is an important result and it clearly shows the need to undertake trials which are large enough to provide definitive evidence for whether a product works.