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New Insights Into Elusiveness of AIDS Virus

Cells change shape to evade immune system

WEDNESDAY, Dec. 11, 2002 (HealthDayNews) -- New research is giving scientists more insight into the amazing powers of AIDS to hoodwink the immune system.

It appears that HIV cells turn into shape shifters, tricking the body into thinking they're harmless when they are anything but that.

"We're figuring out nearly all the molecular tricks that the virus uses to avoid being killed. They are very complicated and extremely sophisticated," says Peter D. Kwong, a researcher at the National Institutes of Health's Vaccine Research Center. He is also the lead author of new study into the virus' ability to stay alive inside the human body. The findings appear in tomorrow's issue of Nature.

While it's unclear if the research will immediately help scientists trying to prevent and cure AIDS, Kwong says it does answer several questions about how the virus works.

At issue is the virus' ability to escape the clutches of the body's disease fighters known as antibodies, Kwong says: "There are tons of antibodies and yet none or very few properly neutralize the virus."

On the other hand, the virus is still able to link up with warriors of the immune system that are known as T-cells. The virus cripples the immune system by killing off the T-cells, a process that leads to the development of AIDS itself, Kwong says.

While powerful drugs are letting doctors postpone the development of AIDS in patients infected with the HIV virus, the full-fledged form of the disease remains incurable once it takes hold in the body.

Kwong found the virus changes shape and creates a kind of force field to keep antibodies away when they are near. This process, however, doesn't prevent the virus from changing shape again to let it hook up with the immune cells.

The findings probably won't help scientists develop treatments for the disease, Kwong says, but they may help researchers who are trying to make an AIDS vaccine. They need to find a way to prime the immune system so antibodies will be ready to attack the virus when it arrives, he says.

Theodore Jardetzky, an associate professor of structural biology at Northwestern University, says researchers will try to find antibodies that aren't susceptible to the tricks of the AIDS virus.

"You could imagine trying to engineer vaccines which take this idea into account," says Jardetzky, who wrote a commentary on Kwong's findings for Nature.

Several AIDS vaccines are in development, and some are now being tested in humans. However, the virus has a remarkable ability to change itself into different forms, Jardetzky says. Some of those forms may be able to evade the powerful AIDS-ready antibodies created by vaccines.

"Even within one person there's a lot of variation," Jardetzky says.

What To Do

To learn more about HIV and AIDS and treatments, visit the U.S. Centers for Disease Control and Prevention or the National Institute of Allergy and Infectious Diseases.

SOURCES: Peter D. Kwong, Ph.D., chief, structural biology center section, National Institute of Health's Vaccine Research Center, Bethesda, Md.; Theodore Jardetzky, Ph.D., associate professor, structural biology, Northwestern University, Evanston, Ill., Dec. 12, 2002, Nature
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