Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: SUNDAY, January 30, 1994 TAG: 9401300023
SECTION: NATIONAL/INTERNATIONAL PAGE: A5 EDITION: METRO
SOURCE: Associated Press
DATELINE: LENGTH: Long
"I decided, `I'll show them,' " he said.
And he did.
Anderson has had HIV, the AIDS virus, for about 15 years. He still is healthy. And this raises a question that has begun to fascinate scientists: Why does the AIDS virus kill some people much more slowly than others?
Early in the brief history of this disease, death seemed to be the only certainty. More than 200,000 Americans have been lost so far; about 100 more die daily.
Clearly, the longer people are infected with HIV, the more likely they are to fall ill with full-blown AIDS and die. Yet the course of this decline is unpredictable.
Scientists wonder why, for instance, that 12 percent of those infected with HIV go on to develop AIDS within five years of catching the virus. Why do half stay healthy for 10 years? Why are a third still going strong after 14 years?
"It's a question of following clues," said Dr. Lewis Schrager of the National Institute of Allergy and Infectious Diseases. "We hope the clues will give us new ideas and directions for vaccine development and therapeutic strategies."
The disease is so new that no one really knows how long people can live with the infection. The latest projections, however, suggest that 10 percent to 17 percent still will be alive and free of disease 20 years after they catch HIV. Perhaps some will live out full lives with their infections.
Long-term HIV survivors like Anderson, a 40-year-old San Francisco artist, have their own theories.
"I feel it all goes back to my attitude," he said. "I won't let this make me ill. I've watched quite a number of friends go from being relatively healthy to sick and dead in very short periods of time. In every case, they all bought into the idea that you have to die from AIDS if you have HIV. I just simply don't agree with that."
As far as scientists can tell, long-term survival has little to do with how people get infected, their sex habits, the food they eat or anything else they do. Instead, they are looking at three main theories of why some people survive longer with HIV:
They are genetically different.
Their immune systems work better.
They are infected with less rapacious strains of the virus.
Indeed, all three possibilities could be true.
Most information about long-term survivors comes from studies of gay men that began in the early 1980s, shortly after the AIDS epidemic started.
The largest of these is the Multicenter AIDS Cohort Study conducted by the National Institutes of Health. Of 4,954 men enrolled in the study, 1,809 already were infected at the outset in 1984. Two Scientists wonder why 12 percent of those infected with HIV go on to develop AIDS within five years of catching the virus; why half stay healthy for 10 years, and why a third still are going strong after 14 years? similar studies in San Francisco are following a total of 2,700 men.
The men in these studies give blood samples regularly so doctors can track the course of their infections. The AIDS virus attacks a crucial variety of white blood cells called helper T-cells or CD4 cells.
Healthy people have about 1,000 of these cells per cubic millimeter of blood. Most people experience an initial drop in helper cells immediately after they get infected. Then, the loss almost - but not quite - levels off. For years, the totals drop very slowly. Eventually, they fall below 200, and this puts people at risk of overwhelming infections, the hallmark of AIDS.
The researchers are especially fascinated by Anderson and others who escape this inexorable damage. He, like perhaps about 5 percent of all infected people, has not continued to lose helper cells. Instead, his levels are close to 800.
If a difference in immune responses explains long-term survival, some experts believe another type of virus-suppressing blood cells called CD8 cells could be the key.
Dr. John Phair of Northwestern University and others have noticed that long-term survivors have abnormally high levels of these white cells in their bloodstreams.
Just why is unclear. But scientists are especially intrigued by the possible role of a variety of CD8 cells known as cytotoxic lymphocytes, which recognize HIV-infected CD4 cells and destroy them.
Researchers theorize that long-term survivors might have more of these cells, or that the ones they have might do a better job of hunting down infected CD4 cells before they release more copies of the virus into the blood.
Other evidence suggests that differences in the strains of virus people catch could be just as important as variations between people.
Dr. David Vlahov of Johns Hopkins University studies genetic diversity in the virus. He found that some long-term survivors carry forms that stay genetically stable. Those who fall sick have HIV that mutates rapidly.
LeBaron Moseby of Boston, who has been infected for at least nine of his 49 years, simply feels lucky to be alive.
"A lot of people want to be long-term survivors," he said. "But I'd rather be newly infected any day, knowing what I do about this virus."
by CNB