AIDS RESEARCH ONCE AGAIN LOOKING TO CHIMPS.

Byline: David Berreby The New York Times

It was not easy for scientists to decide to use chimpanzees for AIDS research back in the 1980s. But as much as they hesitated to give the animals a fatal disease, researchers believed that they could console themselves with two thoughts: The chimpanzee would turn out to be a useful model for human AIDS, and the animals would come down with the disease soon after being infected and thus would not suffer long.

Both assumptions turned out to be wrong. Years passed, grants expired and still the HIV-infected chimps did not come down with AIDS. Researchers shifted to other animals.

Meanwhile, confined to windowless quarters and attended by caretakers in biocontainment ``spacesuits,'' the chimps spent year after year living under conditions that were only supposed to last two or three years. Just last year, for instance, the Yerkes Regional Primate Center in Atlanta installed windows in the building where it keeps its HIV-infected chimpanzees.

Now, nearly 13 years after the first infection of a chimp with HIV, one has died and a few others are sick, apparently from AIDS. Jerom, a 13-year-old male who was first infected in 1985, died early last year at Yerkes. Another chimp at Yerkes, a male named Nathan, received a transfusion of Jerom's blood before the first ape's death.

``We're certainly studying the effects on Nathan on a virological and immunological basis, and possibly looking at other chimps as well,'' said Dr. Frank Noviembre, a biologist who does AIDS research at Yerkes. ``It's going to be interesting to look at what happened to Jerom and what's happening in Nathan and what possibly is happening in other chimps and try to correlate that with humans.''

HIV isolated from Jerom's blood was introduced into two more chimpanzees three months ago, one by injection and the other by application to her cervix. They have shown a steady decline in CD-4 blood cells, the immune cells that are attacked by the AIDS virus, said Dr. Patricia Fultz, a professor of microbiology at the University of Alabama at Birmingham, who is conducting the study. Two more chimps will be infected anally within the month, Dr. Fultz said. The purpose of the experiment, she said, is to develop a model of how HIV is acquired through different mucous membranes, which will be used to test and evaluate the effectiveness of possible vaccines.

Some AIDS researchers are focusing on factors that make the virus more easily transmitted. For example, a recent paper by Dr. Preston Marx, based on work done in monkeys at a Westchester (N.Y.) County research laboratory owned by New York University Medical School, suggests that vaginal transmission of the virus is enhanced by progesterone, a hormone whose synthetic version is used in birth control pills. Such work on methods of transmission might be another area in which chimps could prove useful to researchers.

``I think we can use long-term infected animals,'' Dr. Fultz said.

Not all researchers are convinced that Jerom died of human AIDS, but ``there's a strong possibility that the consensus will shift,'' said Dr. Marx, who is director of the Aaron Diamond AIDS Research Center in New York. ``There is at least a variant of HIV-1 that is causing an AIDS-like disease in chimpanzees,'' Dr. Marx said. ``The question becomes, how different is that strain from the human strain?'' The chance that larger numbers of chimpanzees could once again be used in AIDS research ``has emerged,'' he said, ``where a year ago that possibility did not exist.''

The prospect that some or all of the country's 150 to 200 HIV-infected chimpanzees will come down with AIDS raises a host of ethical questions. How much care, for example, should an AIDS-inflicted chimp receive? Should the animal be given AZT or protease inhibitors? At what stage of suffering, if at all, is euthanasia appropriate? If chimps with AIDS live on for decades, who will support them?

``It's a problem of economics more than anything,'' explained Noviembre, who said that he had not made up his mind about the question of euthanasia.

``If you have these chimps that are not progressing to disease,'' and another strain of HIV is available that scientists want to test, Noviembre said, ``but you have no other building, well, should you not do that research because you won't euthanize the chimps you have?''

He said: ``When I first presented some of our results last year at a conference, I was talking to a guy from Bristol-Myers Squibb, and he said, `You realize you've opened a big can of worms because the NIH is about to say chimps aren't needed in AIDS research?' I said, I know, but what can we do, really? We're just reporting what we're finding.''