AIDS Vaccine Research: Promising Protein

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AIDS vaccine research: Promising protein

A viral antigen that "does the right stuff" has brightened hopes for the development of an AIDS vaccine, government scientists said at a press briefing last week.

The antigen, a protein from the outer coat, or "envelope," of the AIDS retrovirus, triggered an immune response when injected into animals, report researchers at Duke University in Durham, N.C., and the National Cancer Institute (NCI) in Bethesda, Md. That finding was encouraging in itself. Beyond that, however, what one researcher calls "the right stuff" made itself apparent when the antibodies made by the animals neutralized AIDS virus in the test tube.

Thus far, researchers have induced antibody formation in goats, rabbits, mice and guinea pigs. They have begun tests on rhesus monkeys to see if the protein, called gp120, will similarly prod a primate immune system into making the neutralizing antibodies. But since none of these animals is susceptible to human AIDS, the real test of the antigen's potential as a vaccine will come with chimpanzees, who are vulnerable to the virus. The researchers hope that exposure to the antigen alone will have the chimpanzees' immune systems revved up and ready with antibodies, able to neutralize the virus before it can invade the animals' cells.

Antibodies with at least a slight ability to neutralize the AIDS virus in the test tube have been found in the blood of some AIDS and "pre-AIDS" patients (SN: 7/20/85, p. 40). Clearly, the antibodies found in AIDS patients have been ineffective against the virus. But, says Donald Francis of the Berkeley, Calif., office of the Centers for Disease Control, the situation in AIDS patients is "very different from pre-exposure presentation [of the antigen] to an individual who has not seen the virus, and whose system has not been deranged by the virus."

Antibodies formed in the body are a response to the living, whole virus. But researchers can't use the whole virus as a vaccine, even if it is killed, because of a double risk: The virus might revitalize itself, and the incorporation of viral genes into cellular DNA might at some point trigger cancer. …