Scientists at the Harvard Medical School may have made a significant step forward in treating HIV.

In a comprehensive study led by HMS professor Dan H. Barouch ’93, scientists were able to use specific antibodies taken from human HIV victims to suppress viral activity in monkeys infected with simian-human immunodeficiency virus. The study was published in the scientific journal Nature on Oct. 30.

The success of Barouch’s study—which was largely funded by the Ragon Institute, a philanthropic institution that promotes HIV research at Massachusetts General Hospital, MIT, and Harvard—surpassed the expected result.

“After a single infusion of antibodies, we saw virus levels plummet to undetectable levels in a majority of cases, typically within seven days,” Barouch said. “The virus then rebounded in most animals in a period of one to three months, and that corresponded to when antibodies had a decline in the animal.”

According to Barouch, the most significant discovery was that, for a small portion of the monkeys, the suppression of viral levels was permanent.

“Perhaps most remarkably, in a subset of animals that started off with lowest levels of virus in the bloodstream, those animals had the virus go to undetectable levels, and those actually did not rebound at all,” Barouch said.

Barouch’s discovery differs from the standard approach to combatting HIV through antiretroviral drugs.

“Current antiretroviral therapy is extraordinarily potent and lifesaving,” Barouch said. “But also it has major limitations.”

Barouch, who conducts his research at Beth Israel Deaconess Medical Center, added that antiretroviral therapy is limited because its mechanism of action only includes actively targeting the replicating virus inside cells. Antibodies, on the other hand, have a different mechanism of action; they can directly target and eliminate free virus, as well as virally infected cells.

Barouch said that his next step will be to apply the results to humans in hopes of curing HIV.

“The caveat is that the study only involved animals, and so those observations will have to be reproduced in humans,” Barouch said.