Survivors of AIDS Virus Inspire Research : Medicine: About one-third of those who contract HIV are still healthy after 14 years. Scientists theorize on possible reasons.
Rob Anderson remembers how angry he felt back in 1985 when he read experts’ predictions about AIDS. Everyone who catches the virus would surely die from it, they said. By then, Rob Anderson had been infected for six years.
“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. 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 each day.
Clearly, the longer people are infected with HIV, the more likely they are to fall ill with full-blown AIDS and die. But the course of this decline is unpredictable.
Scientists wonder why, for instance, that 12% 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?
The study of long-term HIV survivors has become a hot area of study in AIDS; researchers would very much like to figure out what makes these lucky few different.
“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% to 17% still will be alive and free of disease 20 years after they catch HIV. Perhaps some will live out full lives with their infections.
Like so much in AIDS, there are few clear answers to the “why” questions.
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.”
Others credit their diets, their vitamins, their medicines, their exercise, their meditation. But 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.
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 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 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% of all infected people, has not continued to lose helper cells. Instead, his levels are close to 800.
“It will be imperative to follow these people for long periods of time to see what happens,” Schrager said. “Some may suddenly start losing CD4 cells. Some may never, which would be fascinating. There is clearly a hope that at least some of these people will represent a unique group, not just the tail of a normal distribution.”
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.
“It tells us that CD8 cells play a very important role in the response to this infection,” Phair said.
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.
“The question is: What’s different with these people?” asked Dr. Susan Buchbinder of the University of California, San Francisco.
She thinks genes may play a role, especially the human leukocyte antigens, or HLA, genes. These genes vary from person to person and play an integral role in regulating the immune system.
Buchbinder has found a particular pattern of HLA genes that appears to be more common among longtime HIV survivors.
Other evidence suggests, however, 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.
A strange tragedy in Australia adds more evidence of the importance of viral strains.
Between nine and 13 years ago, six people got HIV from blood transfusions donated by one infected man. They ranged in age from 35 to 77 and got blood for different medical reasons.
The only thing they have in common is the outcome of their infections: All of them, as well as the donor, remain healthy.
Differences in immune system responses may account for some people’s longevity with HIV, said Dr. Jennifer Learmont of the Red Cross Blood Bank in Sydney. But “in this case,” she said, “we think it’s the bug.”
While long-term HIV survivors may find such theories interesting, many seem to view the virus as a personal foe, one that may eventually catch up with them. Even Anderson admits to apprehension when he catches the flu or a cold.
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.”
