Preventative HIV vaccines induce robust, comparable immune responses in humans and monkeys

More than three decades after the identification of the human immunodeficiency virus (HIV), scientists are still working to develop a preventative vaccine that could finally put an end to the epidemic for which there are nearly two million new infections each year.

In a new study, published July 6 in The Lancet, a team of researchers led by Beth Israel Deaconess Medical Center's Dan H. Barouch, MD, PhD, Director of the Center for Virology and Vaccine Research in collaboration with Janssen Vaccines & Prevention and other partners, evaluated a series of preventative HIV vaccine regimens in uninfected human volunteers in five countries. In a similarly designed study, Barouch and colleagues tested the same vaccine for its ability to protect rhesus monkeys challenged with an HIV-like virus from infection. The findings showed the vaccines induced robust and comparable immune responses in humans and monkeys and protected monkeys against acquisition of infection.

"This study demonstrates that the mosaic Ad26/Ad26 plus gp140 vaccine candidate induced robust and comparable immune responses in human and monkeys," said Barouch, who is also Professor of Medicine at Harvard Medical School. "Moreover, the vaccine provided 67 percent protection against viral challenge in monkeys."

Intended to provide broad protection from the many strains of HIV that are prevalent worldwide, the "mosaic" vaccine contains a patchwork of genetic sequences found among various HIV strains. Known as APPROACH, the phase 1/2a trial tested seven different Ad26/Env HIV vaccine regimens for their safety, tolerability and the ability to elicit immune responses in 393 healthy adult volunteers in Rwanda, South Africa, Thailand, Uganda and the United States. All vaccine regimens were well-tolerated and induced robust immune responses in the participants.

"Based on these data, the mosaic Ad26/Env HIV-1 vaccine has been advanced into a phase 2b clinical efficacy study to determine whether this vaccine will prevent HIV infection in humans in southern Africa," said Barouch. "We expect results in 2021. This is only the 5th HIV vaccine concept that will be tested for efficacy in humans in the 35+ year history of the global HIV epidemic."