Human test of AIDS vaccine approved.

Human Test of AIDS Vaccine Approved

Federal officials announced this week that they have granted approval for the testing of a potential AIDS vaccine using human volunteers. The preliminary experiments, scheduled to begin within a few months, will be the first testing of an AIDS-vaccine candidate in humans allowed in the United States.

According to the U.S. Food and Drug Administration and the National Institute of Allergy and Infections Diseases (NIAID), MicroGeneSys of West Haven, Conn., received approval to initiate human testing of its proposed vaccine this fall. Other U.S. companies are seeking similar approval for their own AIDS vaccines, and French scientists announced last March they had injected

a possible AIDS vaccine into humans, with promising results (SN: 3/28/87, p.198).

Testing of the MicroGeneSys vaccine will be coordinated by NIAID scientists, who plan to study its effects in 60 homosexual and 3 heterosexual male volunteers. The volunteers, who must be healthy and test negative for infection with the AIDS virus, will be examined for adverse side effects and any changes in their immune system, and will be compared with 18 controls given a placebo. Only when the vaccine's safety is ensured will studies be planned to determine whether it can actually prevent AIDS infection, NIAID Director Anthony S. Fauci said in this week's announcement.

To make the vaccine, researchers at the biotechnology company concentrated on a viral protein called gp 160, taken from the "envelope' structure surrounding a custom-made AIDS virus supplied by NIAID. They then inserted a gene coding for gp 160 into another type of virus called baculovirus, which infects moths and butterflies. In order to obtain large amounts of gp 160 material, the researchers are growing genetically engineered baculoviruses in cultures containing insect cells.

Human vaccine testing is complicated by the question of whether all AIDS vaccines should first be tested in chimpanzees, apparently the only nonhuman animals that can be infected by the human AIDS virus (SN: 4/4/87, p.213). Costly and time-consuming, tests in chimpanzees nonetheless may provide data essential to the vaccine search, as shown by a report in the Aug. 20 NATURE.

In that study, scientists at Oncogen in Seattle, the Yerkes Regional Primate Research Center in Atlanta and the Southwest Foundation for Biomedical Research in San Antonio, Tex., tested Oncogen's AIDS vaccine, made by inserting envelope proteins from the AIDS virus into vaccinia viruses. The procedure is similar to that used by the French researchers who injected their vaccine into humans, says Oncogen's Shiu-Lok Hu.

Chimps immunized with the recombinant vaccinia viruses developed general antibodies against the AIDS virus, as well as cells that attack the virus, say the authors. But unlike the French researchers who worked with humans, the U.S. group did not detect any so-called neutralizing antibodies--which prevent viruses from infecting cells--in the vaccinated chimps. As a consequence, the researchers found viruses inside the cells of both immunized and nonimmunized animals. They plan to follow the chimps for several years to detect any sign of disease.

Although two of the unvaccinated chimps developed a pre-AIDS condition, there are few examples of infected chimps going on to develop clinical symptoms of AIDS, says Hu. He told SCIENCE NEWS that the presence of the virus in vaccinated chimps may help solve the mystery of why, in humans as well as chimps, infection with the AIDS virus may not necessarily lead to development of the disease. It also could indicate differences in the response to AIDS between humans and chimps, he says.