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Researchers hoping to get OK for AIDS treatment experiment

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If ethics committees approve, researchers in Boston and Geneva will soon do the crucial AIDS experiment: Stop all antiviral drugs in a group of patients who began treatment soon after they became infected with HIV.

AIDS specialists attending the 12th World AIDS Conference here hope the experiment will show that HIV infection does not necessarily sentence individuals to a lifetime of costly and onerous triple-drug therapy.It's not that these early treated patients are cured. In fact, scientists know that about 1 million AIDS viruses still lurk in each patient's system, even though the most sensitive tests can detect none in their blood.

In terms of viral infection, that is a tiny amount. But it is more than enough to kindle a raging infection if either antiviral drugs or immune defenses cannot keep HIV suppressed to such low levels.

The aim is to see if these patients' immune systems have revived enough to keep the AIDS virus under permanent control, just as most people's do with the chickenpox, Herpes simplex, or Epstein-Barr virus.

"We will see if the virus rebounds without drug treatment and if the immune system can handle it," Dr. Bruce W. Walker of Massachusetts General Hospital said in an interview here Wednesday. "It's a question we're compelled to answer."

Walker and his colleagues have identified 19 patients who were treated soon after they acquired HIV infection, before the virus had time to damage their immune systems irreparably. They will be asked if they are willing to halt treatment while doctors monitor their blood for signs that HIV has returned in large numbers.

If it does, doctors will immediately resume triple-drug HIV treatments. Recent studies indicate that resumption of treatment should once again suppress HIV.

Dr. Bernard Hirschel of University Hospital in Geneva, chairman of this week's massive AIDS meeting, said a similar group of early-treated patients here will stop therapy if the hospital's ethics committee approves. "I think it will be accepted," Hirschel said.

"Unlike others, patients who started treatment during very early infection have undetectable levels of HIV in their blood even with tests capable of detecting as few as five copies of the virus per cubic millimeter," he said. "This suggests an essential difference between patients treated early and those treated later."

In a separate set of experiments that will get under way this summer in Boston and New York, Walker and New York AIDS researcher David Ho will give two different experimental vaccines to patients infected with HIV to see if they can "tweak" the immune system into generating cells capable of keeping the virus under control.