THE BODY WINS ROUND 1

By Christine Gorman

For the past decade, AIDS researchers have focused on the last phase of the infection. Their main question: Why do people with the AIDS virus, or HIV, succumb to cancers, opportunistic infections and nerve disorders? During the past two years, however, a small number of immunologists and virologists have started asking a different, and potentially more useful, question: Why do so many people with the virus live in such good health for so long - in some cases for more than 12 years?

Two groups of scientists from the University of California, Los Angeles, and the University of Alabama believe they have found the beginning of an answer. In independent studies published in the New England Journal of Medicine, they demonstrated for the first time that the body launches a massive, effective coun­terattack on the virus soon after infection begins. If doctors can figure out how to reproduce that early, powerful immune response, they might be able to develop better treatments that would postpone - or prevent - the later, debilitating stages of the disease.

The researchers required tenacity - and more than a bit of luck. After all, to study someone at the beginning of a relatively silent phase of the HIV infection, they had to find people who did not yet realize they had contracted the virus. It turns out that at least a third of HIV-infected people develop a fever or a severe sore throat within in a few weeks to months after first exposure. Such signs, which usually clear up on their own, can easily be misdiagnosed as a bad flu or mononucleosis. Researchers realized the tip-off would come when they tested the patients and found HIV instead of influenza viruses or other disease-causing agents. By hanging out in hospital emergency rooms and talking to colleagues, the researchers identified seven young homosexual men - three in Alabama, four in California - suffering from a primary HIV infection.

Using advanced laboratory tests that had been developed only in the past few years, both sets of scientists discovered an explosive growth of virus in the men's bloodstreams. (Half of the men were able to pinpoint exactly when they became infected, and in each case it was during unprotected sex).Each liter of the men's blood contained as many as 10 million infectious viruses. "This is the first time anyone has reported such high levels of infectious virus early on", says Dr.Eric Daar, a specialist in infectious disease and one of the leaders of the UCLA study. "We've never seen these levels before except in people with severe AIDS".

Within days after the viral burst, the researchers measured a rapid increase in the bloodstream of the number of anti-HIV antibodies. These Y-shaped bits of protein sought out the virus and targeted it for destruction. Once the antibody attack reached full scale in the seven test subjects, the level of HIV in the blood­stream dropped precipitously. In the majority of cases, the researchers could de­tect little or no virus two to three weeks later. "In other words, the normal im­mune system can shut down the AIDS virus", says Dr.Stephen Clark, who organ­ized the study at the University of Alabama. Now researchers must figure out exactly how the body puts together this early effective defense - and how the virus manages, years later, to circumvent it.

Date: 2015-12-24; view: 1342