The New York Times - December 30, 1983
Lawrence K. Altman

Simian AIDS has been studied in primates at the California Primate Research Center at Davis, at the New England Primate Research Center in Southborough, Mass., and at other primate centers in this country.

Veterinarians and other scientists are studying simian AIDS extensively in hope that the research will yield clues to the cause of the human disorder. The researchers are also hoping that the primates may serve as a useful model for developing therapies and preventions for human AIDS.

However, because simian AIDS differs from human AIDS in several biological respects, experts are not certain the two diseases are the same or that they are caused by the same agent. Despite several attempts to transmit human AIDS to primates, no resulting experimental infection has yet been reported.

Disease Transmitted in Study

In the Jan. 6 issue of Science, being released today, the National Institutes of Health and the Davis researchers reported they had succeeded in transmitting simian AIDS from diseased rhesus monkeys to normal rhesus monkeys. They did it by injecting samples of whole blood or filtered plasma, a liquid portion of blood, into the monkeys.

But they said that, despite numerous attempts, they could not identify the agent that transmitted the disease. They said they believed the agent was a virus because it was contained in plasma that had been filtered and presumably would have screened out nearly everything but viruses.

The experiments were done independently at Davis and at the national institutes in Bethesda, Md., but the researchers shared the data.

There were two parts to the experiment. In total, all eight rhesus monkeys receiving whole blood or filtered plasma developed signs of simian AIDS two to four weeks after inoculation. Six of the eight monkeys died from 5 to 11 weeks after inoculation.

In the first part of the experiment, researchers injected less than one milliliter of whole blood into four young rhesus monkeys. Two were at the center at Davis and two were at the Bethesda center. Three of the four monkeys died from two to three months after the injections. The fourth is alive but has simian AIDS.

Search for Agent

The second part of the experiment was done to try to specify where in the blood the putative virus might be present. Such identification presumably would be helpful in further research in trying to identify the agent.

In this phase of the experiment, the researchers injected four other rhesus monkeys, two in each research center, with three milliliters of plasma. All four monkeys developed simian AIDS from two to four weeks after receiving the plasma. Three have died; the fourth is gravely ill.

The new research extends earlier studies in which the researchers transmitted the disease from two animals at the Davis center to four rhesus monkeys at the Bethesda center. In those studies, the researchers used samples derived from organs of monkeys with simian AIDS and sent them from Davis to Bethesda for injection there.

The new study also extends an experiment done earlier at the New England Primate Research Center in which macaques developed simian AIDS after inoculation with material derived from a lymphoma cancer in macaques. In the experiment, which was reported in the Sept. 10 issue of The Lancet, a British journal, a small number of macaques did not develop a lymphoma as had other macaques injected with similar material. The researchers said that they did not know why lymphomas developed in some animals and simian AIDS in others after inoculation with the material.

In the study, the monkeys did not have the changes in the numbers of lymphocyte cells called T-4 and T-3 that characterize most cases of human AIDS. It is because of such differences that some researchers debate whether simian and human AIDS are the same.

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