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Science & Technology

First clinical trial of possible HIV vaccine shows promising results

Scientists at San Diego’s Scripps Research have identified antibodies that could stop the very complex virus that gives people AIDS. KPBS sci-tech reporter Thomas Fudge tells of the first clinical trial of a possible HIV vaccine.

The search for an HIV vaccine has been underway for more than 30 years. And now scientists at Scripps Research in San Diego have begun to identify antibodies that could stop the very complex virus that gives people AIDS.

“This was done in the clinic. In people. So we’re on our way but we’ve a long way to go yet,” said Dennis Burton, the chair of immunology and microbiology at Scripps Research.

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Scripps researchers and their collaborators said this was the first clinical trial of a possible AIDS vaccine.

Scripps professor of immunology Bill Schief is co-author of an article in Nature that spells out the results of the experiment. Schief said the HIV virus has a lot of working parts and that makes it a very hard target to hit with a vaccine.

“In some ways HIV is like the coronavirus,” he said. “But the spike protein of HIV is far more variable than the spike protein of the coronavirus.”

That means an effective vaccine needs to mobilize a very specific kind of antibody to actually stop the virus. Those are called broadly neutralizing antibodies.

“We think a vaccine has to elicit broadly neutralizing antibodies against HIV, to protect against the hundreds of thousands or millions of HIV variants that are in humans around the world right now,” Schief said.

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He said that the clinical trial and the research around it have proven the strategy for creating a vaccine is on the right path. Scripps’ antigen, the precursor to a vaccine, elicited the correct response in 97% of the human test subjects.

“They’re not enough to be broadly neutralizing antibodies yet. But they’re sort of baby broadly neutralizing antibodies. They need to learn more. They need to gain mutations,” Schief said.

Burton compares the search for an HIV vaccine to a baseball game, in which getting all the way to home base means a vaccine is ready.

“And what Bill’s elegant work has done is shown how to get to first base,” he said.

Today many people with HIV are able to live well by taking antiretroviral drugs every day. But Burton says in places like sub-Saharan Africa, where HIV cases are higher, those drugs are expensive and are often inaccessible.

Schief said if his research does hit a home run, and a vaccine is developed, groups like the World Health Organization and some charitable foundations would need to get it to the patients most at risk.

“I've spoken with epidemiologists in South Africa who deal with the people most at risk,” Schief said. “And I said to them, ‘If we do get this to work … could you deliver that to the people most at risk?’ And they said yes.”