Salk Begins New Test Of Aids Vaccine -- Polio-Vaccine Pioneer In Seattle For Meeting

Researchers directed by Dr. Jonas Salk have just begun testing a new group of patients infected by the AIDS virus to see if a vaccine designed by the famous scientist can stave off the disease itself.

About 100 patients nationwide are being inoculated to determine if the vaccine does better than it did in an earlier successful test, Salk told a meeting in Seattle of the American Federation for Clinical Research yesterday.

"The prospect for prevention of infection and/or disease is quite good," said Salk. "Now it's a matter of fine tuning."

Salk, 76, who developed the first successful polio vaccine, is focusing for now on boosting the immune systems of already-infected patients rather than taking the approach of most vaccine researchers: preventing infection in those exposed to the virus.

He is convinced both approaches must be developed to prevent the disease.

He said he doesn't think infection can ever be completely prevented.

When tests of his vaccine are conducted on non-infected individuals, Salk said, he will take the vaccine himself.

Since 1981, AIDS has been reported in more than 175,000 people in the United States, including nearly 2,400 in Washington state. Nearly 60 percent of those have died.

In Salk's earlier vaccine study, the number of disease-fighting cells in 30 of 46 AIDS-infected patients remained stable after the patients were vaccinated. The number declined in the other one-third.

"It's a good sign that they stayed level. We're trying to determine if there is a cause-and-effect relationship," said Salk, director of the Salk Institute for Biological Sciences in San Diego.

Other studies have shown that in the first weeks after infection, the body naturally wages a furious battle against the invading AIDS virus. Then, over time, it inexplicably winds down the fight. The objective of Salk's vaccine is to keep the defenses up indefinitely.

In the new study, which is being conducted in nine medical centers, the vaccine is being given to patients early in their infection to see if that makes a difference.

"We think that if we can get to them earlier, we can increase the probability" of AIDS prevention, Salk said after speaking at the convention's "Frontiers of Science Symposium."

Unlike other AIDS-vaccine researchers, Salk is employing the same technique he used in developing the first successful polio vaccine: using a killed actual virus to stimulate the body's immune system.

Other scientists are using genetically engineered copies of the virus coating. About 10 vaccines are being studied.

Salk said yesterday he is confident live AIDS virus will not slip through in producing the vaccine. The live viruses are killed with a huge dose of gamma radiation, he said.

Some live polio virus did slip through in the 1950s, when more than 1 million children were inoculated with the Salk vaccine. Some 204 were infected, including about 150 who were paralyzed and 11 who died of the disease. It was later replaced by a vaccine developed by Dr. Albert Sabin.

Salk refused to speculate on when an effective AIDS vaccine may be widely available. A vaccine must be tested in large numbers of people before it can be approved.

Salk said scientists have discussed the possibility of conducting the tests on military recruits in Africa, who have about a 15 percent rate of infection. An estimated 6 million people in several African nations carry the virus.

Salk acknowledged that large pharmaceutical companies have been reluctant to support AIDS-vaccine research because of worries about product liability and the difficulty of tests. But he predicted that is a temporary problem.

"Wait until we get an effective preparation and see what happens," he said. "Then the floodgates will open."