Miami Herald - Friday, June 9, 1989
Rosemary Goudreau, Herald Staff Writer

Salk, a Nobel laureate, said during the Fifth International Conference on AIDS that it's too early to tell whether the vaccine will be effective in humans, but he believes "we're on the right path."

"We haven't gotten to the end of it, you might say. We're intending to move as rapidly as possible to a point at which clinical trials can be carried out as well as further studies in animals."

It will take several years to know whether the vaccine works in people, Salk said.

One thing is also clear, he added: "A diagnosis of HIV infection need not be regarded as a death sentence."

Salk and colleagues from the National Institutes of Health and the University of Southern California reported preliminary results from 19 people suffering the symptoms of AIDS-related complex who were given the vaccine in a Phase I trial and followed for 68 weeks. The only point of a Phase I trial is to determine whether a new drug or vaccine can be tolerated and at what dose.

"We're finding no evidence of toxicity immediately, or in the one year of follow-up," said Dr. Alexandra Levine, of the USC School of Medicine.

Although statements about efficacy cannot be made at this time, the people taking the vaccine "have remained stable, clinically, for the most part," she said.

One patient developed pneumocystis carinii pneumonia 18 weeks after the trial began, and another developed the skin cancer Kaposi's sarcoma 56 weeks into the study, but "all of the individuals remain well and alive," Levine said.

While six people have lost weight, an equal number have gained weight. Twelve are now skin-test positive to HIV. As with a TB test, that means there is a good immune response to the virus, she said.

The vaccine Salk and researchers are talking about is not a vaccine in its truest form. Although the researchers hope it might one day be universally given to prevent infection, right now it appears to hold more promise in preventing disease in people already infected, similar to the way a rabies vaccine works to prevent disease in people bitten by an infected animal.

Unlike most research attempts at a vaccine, which use pieces of the virus, the Salk vaccine uses the whole virus, minus its outer coat. The virus is killed by exposing it to chemicals and gamma radiation, "each of which would effectively destroy particles, but to be certain, we killed it twice."

In his experiments with chimpanzees, the vaccine appeared to counter a variety of AIDS virus strains, Salk said.

Dr. C.J. Gibbs, of the NIH Neurological Institute, said the vaccine was given to three chimpanzees: two that were infected with HIV and one that was not.

Three months later, the three chimps were infected with HIV. A fourth unvaccinated chimp was also infected for the sake of comparison. All four got infected, meaning the vaccine didn't prevent infection in the one healthy vaccinated chimp.

However, the vaccinated chimp's viral infection rapidly declined and "we have been unable to isolate virus from this chimp for the last six months. So we have somehow ameliorated the course of infection in this animal," Gibbs said.

In the two chimps that had already been infected before receiving the vaccine, all measurable signs of the virus disappeared.

The fourth unvaccinated chimp, meanwhile, is showing "a continuous buildup in the concentration" of virus, he said.

Salk compared the AIDS vaccine research to his work on the polio vaccine in the early 1950s. As with polio, it might be easier to prevent the AIDS virus from causing disease, rather than prevent the virus from infecting the body.

"I believe the same condition applies. So long as we prevent disease, it wouldn't matter if infection occurs, although I do believe it would be possible to prevent infection as well as disease," Salk said.

"We're quite satisfied that this shows substantial block of the viral infection for at least 12 months. That's a fairly substantial time."

Dr. Robert Gallo of the National Cancer Institute, a co-discoverer of the AIDS virus, said: "For infected people, if this holds up . . . it could be of substantial importance."

However, Gallo said that making a vaccine "from killed whole virus is not the approach we would like to go.

"Most of us use pieces of the virus, not the whole thing. It's impossible to guarantee that there's not a live virus left. In fact, that happened in polio" where a batch was not properly treated and live virus was injected into people.

Dr. Dani Bolognesi of Duke University Medical Center, one of the nation's top researchers in the search for an AIDS vaccine, said the fact that previously infected chimpanzees have gone 12 months without virus showing up is "in itself, a remarkable finding because the consensus of everyone in the field is that once you are infected with HIV, you are infected for life.

"Something happened in these animals and we need to find out what it is," he said. "I'm encouraged . . . but all these experiments must be validated with proper controls."

Bolognesi, who presented a summary of several promising vaccine projects under way, said, "Some significant progress has been made in vaccine design in 1989.

"There are beginnings of progress that we did not have a year ago. My sense is that it's not impossible to stop these viruses," he said.

CAPTION: PHOTO Jonas SALK

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