Experimental HIV Vaccine Could Be Tested on Humans Next Year

Scientists have created an experimental HIV vaccine that is able to neutralize HIV in animal models. Although the study was conducted on animals, human trials could begin as early as next year.

The study, published Monday in Nature Medicine, describes a major step forward in ongoing efforts by the National Institutes of Health to create an HIV vaccine. The vaccine works by teaching the body how to fend itself against HIV through the production of antibodies specifically designed to target and destroy the virus. In the recent trial, the experimental vaccine caused the immune systems of test animals to elicit antibodies that could neutralize up to 31 percent of 208 different strains of HIV-1.

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An Indian nurse carries out a test for HIV/AIDS during an event to mark International Condom Day in New Delhi on February 13, 2018. The vaccine works by teaching the body how to fend itself against HIV. Sajjad Hussain/AFP/Getty Images

"In this context, the vaccine regime 'worked'," lead study researcher Dr. Peter Kwong, chief of the Structural Biology Section at the National Institute of Allergy and Infectious Diseases Vaccine Research Center, told Newsweek. "However, we have not yet challenged the animals to see if they would be protected from HIV, as we are still the process of optimizing the immune response."

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The vaccine prompted the test animals' bodies to release broadly neutralizing antibodies. They naturally occur in about 10-25 percent of individuals who have had a long-term HIV infection and many scientists hope to harness the potential of these antibodies and use them in patients who are not already infected with HIV in order to provide them with protection against the virus.

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The new vaccine is based off an epitope on the HIV virus called the HIV fusion peptide, a press release on the study reported. An epitope, a site on the virus where antibodies can attach, was first identified by scientists from the National Institute of Allergy and Infectious Diseases in 2016 and plays a role in HIV's ability to enter human cells.

When a protein known as an immunogen fits into an epitope, it stimulates an immune response—the release of antibodies—that destroy the virus. However, not all immunogens fit into every epitope. The researchers had to create immunogens that fit into the structure of the HIV fusion peptide.

The team then injected the immunogens into mice, and then guinea pigs and monkeys, and analyzed the antibodies that were generated as a result.

"Prior to this study, no vaccine regime could reproducibly elicit antibodies capable of neutralizing more than a small fraction of the diverse strains of HIV-1 that typify natural infection," Kwong said. "So it was surprising that we could induce immune responses that neutralized up to 30 percent of HIV-1 strains in mice, guinea pigs and rhesus macaques."

More work is needed to further develop this vaccine and improve its effectiveness, but human trials are expected to begin as early as the second half of 2019. The hope is that this vaccine will allow the bodies of HIV negative individuals to create the antibodies needed to protect them against the virus. Kwong suggested that if the vaccine is proven to be effective and safe, he sees no reason why it should not be used a public health measure and provided to all that would benefit.

"Because we were able to elicit broad fusion peptide-directed responses in mice, guinea pigs and rhesus macaques, we believe similar broad responses could be elicited in humans," Kwong said.