Could a 5-part vaccine be the key to preventing HIV?

The long and largely unsuccessful effort to develop a vaccine against HIV, the virus that causes AIDS, suffered a major setback in 2009, when the experimental shot RV144 was shown in a trial to be just 31% effective. Now scientists led by Duke University are taking insights from that trial, which was conducted in Thailand, and using them to design a more comprehensive vaccination approach.

In a study in monkeys, the Duke team achieved 55% protection from an HIV-like virus with a vaccine that builds on RV144, the university announced in a press release. They increased the level of protection by using a “pentavalent,” or five-part vaccine.

Working with colleagues at Los Alamos National Laboratory, the scientists added three targets to the “viral envelope,” which includes glycoproteins that allow the virus to bind to and enter host cells. Rather than zeroing in on two glycoproteins, as RV144 does, the experimental vaccine adds three targets that prompt antibody responses to other regions of the viral envelope, according to the release. They published their research in the journal Nature Communications.

"This is a proof-of-concept that provides a strategy to improve upon the first HIV vaccine regimen that provided limited protection in people," said lead author Todd Bradley of the Duke Human Vaccine Institute.

The HIV vaccine development effort has experienced a renaissance of sorts over the last couple of years. In May 2016, the NIH announced plans to start a large-scale HIV vaccine trial in South Africa testing the HVTN 100 regimen, which consists of one experimental vaccine each from Sanofi and GlaxoSmithKline. In late 2015, the European Commission poured $25 million into a collaboration between 22 companies and organizations working to advance HIV vaccine research.

In April 2015, Duke received $20 million in funding from the NIH for its HIV vaccine research. Part of Duke’s work has involved tracking an individual in Africa with HIV who is providing blood samples periodically. They are studying the evolution of the virus and the patient’s immune response and using the knowledge gained to improve vaccine development.

The next step for the developers of the pentavalent vaccine is to try to determine if the boosted protection against HIV came from all or just some of the three targets that were added to the viral envelope.