HIV vaccine regimen shows promise in non-human primates

A vaccine regimen which first primes the immune system and then boosts it to increase the response could protect against human immunodeficiency virus (HIV-1) infection, scientists have found.
The findings come from a preclinical study of an HIV "heterologous prime-boost" vaccine regimen used in non-human primates by scientists at Beth Israel Deaconess Medical Center (BIDMC), Crucell Holland BV, one of the Janssen Pharmaceutical Companies of Johnson & Johnson (Janssen), and several other collaborators.
"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," said Paul Stoffels, Chief Scientific Officer and Worldwide Chairman, Pharmaceuticals, Johnson & Johnson.

"Our ultimate goal is to develop a vaccine that prevents HIV in the first place," Stoffels said.
The pre-clinical study evaluated the protective efficacy of a "prime-boost" vaccine approach, which leverages AdVac Technology from Janssen and a trimeric envelope protein boost.
Non-human primates 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.
The study results showed that the investigational prime-boost vaccine regimen provided complete protection from becoming infected with simian immunodeficiency virus (SIV), a virus similar to HIV that infects non-human primates in half of the vaccinated non-human primates against a series of six repeated challenges.

This work also demonstrated that there is a strong link between the protective ability of the vaccine regimen and the number of antibody functions to fight the virus, so called polyfunctionality, which supports the continued development of the vaccine regimen for human use.
"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 H Barouch, Director of the Center for Virology and Vaccine Research at BIDMC and Professor of Medicine at Harvard Medical School.
Scientists are now enrolling 400 volunteers in the US and Rwanda to evaluate heterologous prime-boost regimens, with sites in South Africa, Uganda and Thailand opening soon.

Ongoing phase 1 clinical studies have been evaluating the safety and immunogenicity of different components which are included in the regimens to be used in this study.