THURSDAY, March 25, 2004 (HealthDayNews) -- New research suggests that once the AIDS virus takes hold in the body, it sends out weakened strains to infect other people during sex.
The findings could help scientists develop vaccines to stop the virus before it has time to gather strength and stick around permanently.
"It's important for understanding the biology of the virus," says Dennis R. Burton, a professor of immunology at The Scripps Research Institute. "The weakest point in the life cycle of HIV is when it moves from one person to another, and that's probably the best place to stop it."
AIDS treatment has grown by remarkable degrees over the last decade, and a group of powerful drugs often succeeds at preventing the AIDS virus, known as HIV, from replicating in the body after a person has been infected. But doctors still don't have any simple ways to stop infection before it begins, and researchers say a vaccine may not appear for five years or more.
To better understand the infection process, researchers examined eight HIV-positive couples in the African country of Zambia. The findings appear in the March 26 issue of Science.
The subjects were initially part of a research project on couples in which one person is HIV-negative and the other is HIV-positive. While counselors provide education about safer sex and condoms, a small number of infections occur "despite the fact that we do everything to prevent [it]," says study co-author Eric Hunter, director of the Center for AIDS Research at the University of Alabama at Birmingham.
The researchers found the newly infected partners harbored strains of HIV that lack a kind of armor developed to protect the virus against its host's immune system. This may sound like a bad move on the virus's part, but the immune system of the person being infected isn't yet primed to handle the invasion. "The virus can go and not worry too much," Hunter says.
Why does this happen? In a way, it's as if a soldier were to take off part of his unwieldy uniform to infiltrate an enemy base. The virus may need to do that to infiltrate the virgin territory of the person not yet infected, Hunter says. "We think in order to establish infection in a new host, the virus has to get rid of some of that armor, just to be able to bind to the receptors it needs."
Burton cautions that the meaning of the findings isn't entirely clear, and it could be the weakened strains actually develop in the newly infected people and aren't transmitted to them as part of the infection process.
"It's going to take more work to know if this will have any significance for vaccines," he says.
More information
To learn more about HIV/AIDS and treatments, visit the U.S. Centers for Disease Control and Prevention or the National Institute of Allergy and Infectious Diseases.
