New York: A vaccine regimen that first primes the immune system and then boosts it to increase the response could ultimately prove to be the strategy for protecting against the global human immunodeficiency virus (HIV-1) infection, new research suggests.

The study showed that the investigational “prime-boost” vaccine regimen provided complete protection to non-human primates from becoming infected with simian immunodeficiency virus (SIV), a virus similar to HIV that infects the primates.

These results have now encouraged scientists to study the efficacy of the vaccine on a human study that is currently enrolling 400 volunteers in the US and Rwanda, with sites in South Africa, Uganda and Thailand opening soon.

“We are very encouraged by the results of this preclinical HIV vaccine study, and the findings lead to a clear path forward for evaluating this HIV vaccine candidate in humans,” said lead author Dan Barouch, professor of medicine at the Harvard Medical School.

For the study, non-human primates (NHP) were first given an adenovirus serotype 26 (Ad26) vectored vaccine to prime the immune system, and then a boost of a purified HIV envelope protein intended to enhance the immune system over time.

This approach is intended to increase both the magnitude of the immune response and the overall protection against subsequent viral challenge.

“Despite great progress in HIV treatments, HIV remains one of the greatest global health threats of our time with millions continuing to be infected each year. Our ultimate goal is to develop a vaccine that prevents HIV in the first place,” said Paul Stoffels from the Johnson & Johnson, which collaborated on the research.

The study was published in the online edition of the journal Science.