Harvard-led study finds vaccines partially protect monkeys from HIV-like virus

By Carolyn Y. Johnson, Globe Staff

A team led by a Boston scientist announced today that a vaccine had for the first time partially protected rhesus monkeys against infection with an aggressive and virulent HIV-like virus.

The study, led by Dr. Dan Barouch, a professor of medicine at Harvard Medical School and Beth Israel Deaconess Medical Center, is paving the way for a trial to test a similar vaccine in people. The study also provides insight into how vaccines trigger different immune responses when they are preventing infection, or helping keep an infection under control.

“You always have to be a little bit careful of direct extrapolations from animal studies, but I think in this case, this is a level above the usual kind of a study,” said Dr. Anthony S. Fauci, director of the National Institute of Allergy and Infectious Diseases, which provided funding for the study. He noted that unlike in previous studies, the researchers exposed the monkeys to a virulent, tough-to-defeat strain of the virus and saw a protective effect -- a situation more analagous to the one that doctors will face when developing a vaccine that protects people from HIV.

In the past, Fauci said, researchers found such protective benefit only when exposing an animal to an easily neutralized virus.

“So far, the approaches published in this paper are among the most promising ones that we’ve generated to date, so we are enthusiastic about takng this knowledge and moving the scientific advances forward, as well as the specific vaccine” into a clinical trial in people, Barouch said.

In the study, published in the journal Nature, rhesus monkeys were immunized with different vaccine regimens, including a sham vaccine, and then were exposed repeatedly to a virus called simian immunodeficiency virus. After repeated exposures, the researchers found that two of the vaccination combinations caused an 80 percent reduction in the likelihood of infection per exposure.

The study also elucidated more about how the vaccines prime the immune system to react, including the different responses that take place when the immune system reduces the amount of virus in the blood, compared with when it prevents infection. The insights help explain the results seen in a 2009 clinical trial in Thailand, where a vaccine regimen had modest protective effects against HIV infection in humans.

The study was partially supported by traditional funding sources, such as the National Institutes of Health, and partially by private philanthropy, through the Ragon Institute at Massachusetts General Hospital, MIT, and Harvard, a multidisciplinary center that brings together researchers focused on developing an HIV vaccine and research into the immune system.

“It shows the power of synergy between philanthropy and traditional funding sources, which I think is particularly relevant in times of fiscal constraint,” Barouch said.