Invisible condom protects monkeys from AIDS virus
Date: 13-Feb-03
Country: USA
Author: Maggie Fox, Health and Science Correspondent
The study, published in the journal Nature Medicine, helps boost claims by advocates that an "invisible condom" could be a useful way to help stop the spread of AIDS, which now infects 36 million people worldwide.
AIDS has no cure and is always fatal, although expensive and toxic drugs can extend a patient's life for years. Condoms are the best known method for stopping its transmission.
Half of all new cases of HIV infection are in women, and many who live in societies where a woman is not always free to demand that her partner use a condom. In addition many men refuse to use one - whether having sex with another man or with a woman.
Thus many experts advocate the development of a gel or cream, akin to spermicides used for birth control, that men and women alike could use quietly to prevent infection.
John Moore of Cornell University in New York, Ronald Veazey of Tulane University in Louisiana and colleagues in the United States and Britain made a gel using one of the antibodies the human body naturally makes to the HIV virus.
To test it they used monkeys, which do not get AIDS, Researchers have concocted a substitute virus called SHIV, which is a combination of human immunodeficiency virus and the monkey version, called SIV.
They put the gel, or a saline solution carrying the antibodies, into the vaginas of the 12 female monkeys, then put the virus in up to two hours later. This simulated sexual transmission of the virus.
"Only three of 12 animals ... became infected," they wrote in their report. In contrast, 12 of 13 animals given a sham treatment became infected with SHIV.
The antibody Moore's team used does not protect against all strains of HIV, but it is an important proof of the idea, they said. "These observations support the concept that viral entry inhibitors can help prevent the sexual transmission of HIV to humans," they wrote.
Rebekah Webb, policy development officer for the National AIDS Trust in Britain, welcomed the results.
"It is definitely a step in the right direction but just one of many promising results from the lab confirming that microbicide is possible," she said in a telephone interview.
"One of the huge problems in the microbicide field is funding because no big pharmaceutical company is interested in microbicide research," Webb said.
Drug companies have suggested the market is not big enough - a view that activists have tried hard to dispel. "We think there is a market. We think there are many emerging markets around the world and companies should be interested in that," Webb said.
Many studies have been done on potential microbicides, and some are designed to prevent infection not only with HIV but with a range or sexually transmitted diseases, such as syphilis and gonorrhea.
