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HIV Attack Launches Cell Seige and Suicide

Gene research shows AIDS virus causes rapid devastation

WEDNESDAY, June 13, 2001 (HealthDayNews) -- Scientists are getting their best picture ever of how the AIDS virus launches devastating attacks against the immune system and causes so much havoc that some cells literally kill themselves to prevent further destruction.

Research at the University of California at San Diego reveals that HIV is an even tougher virus than previously thought. "This is not particularly great news," says Jacques Corbeil, a professor of medicine at the university and one of the researchers. "It's a pretty nasty virus."

Using sophisticated technology that tracks the activity of individual genes, the researchers explored how the virus spreads in the immediate hours after infection.

They were able to follow almost 7,000 of the estimated 30,000 genes that make up the blueprint for human beings, Corbeil says. According to him, no researchers have tracked that many genes before.

The results of the research are reported in the July 2001 issue of the journal Genome Research.

Even though it may take six months for a person to test positive for HIV using traditional tests, the virus goes on the attack immediately. In fact, within a few weeks after infection, between 60 percent and 70 percent of patients suffer from flu-like symptoms, which is a sign that the immune system has kicked in to fight the virus.

The San Diego researchers found that only a half hour after infection, immune cells known as CD4+ T are busy defending themselves.

Like switches on a control panel, about 200 genes flip on to make the cells begin defensive maneuvers. Among other things, the cells create interferon, a so-called "Paul Revere" chemical that warns other cells of trouble.

But a whopping 500 genes -- including some that help cells repair damage -- are overwhelmed by the virus and turn off.

The AIDS virus "really shuts down the cell," Corbeil says. "Some of the ones that turn off are genes involved in maintaining the integrity of the DNA."

The cells eventually reach a point where they kill themselves. "The cell knows that something is happening to it," Corbeil says, and it kicks in a suicide protocol.

While immune cells begin dying off within moments after infection, it may take months or years for a patient's immune system to collapse and full-blown AIDS to begin. At that point, cancers and infections begin to blitz the body, bypassing the weakened immune system.

There are some limits to the gene research, Corbeil says. Although scientists looked at human cells, the cells were not in a body, so it's not clear whether HIV has the exact same effect in people.

Although the research findings are grim, experts say further understanding of HIV will help scientists develop treatments or a vaccine.

The genetic studies of the AIDS virus are a "powerful tool," says Carl Dieffenbach, associate director of the National Institutes for Health unit that studies AIDS. "They're looking at thousands of genes instead of one or two, giving you a chance to find those that you would never ever consider [to be involved]."

Dr. Dan Barouch, a clinical fellow who studies AIDS at Harvard Medical School, agrees.

"This will lead to new knowledge about how HIV affects cells, and that is the basis of developing new therapies," Barouch says.

What To Do

If you'd like to see what clinical trials are going on for AIDS, take a look at Veritas Medicine.

Learn more about HIV and AIDS in this Q&A created by the Centers for Disease Control and Prevention.

Some AIDS infections are becoming drug-resistant. Go here to learn about research into this area by the American Foundation for AIDS Research.

You also might want to read previous HealthDay articles on AIDS.

SOURCES: Interviews with Jacques Corbeil, Ph.D., assistant professor of medicine, University of California at San Diego; Carl Dieffenbach, Ph.D., associate director, Basic Science Program, Division of AIDS, National Institute of Allergy and Infectious Diseases, Bethesda, Md.; Dan Barouch, M.D., Ph.D., clinical fellow, Harvard Medical School, Boston, Mass.; July 2001 issue Genome Research
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