Yet as powerful as the current drug treatments are, they need to be taken daily to keep the virus suppressed, and they can’t actually rid the body of infected cells. For self-preservation, some HIV does not actively pump out more copies of itself, but instead lies dormant inside certain immune cells. “The drugs are remarkably good at stopping the virus from replicating,” says Dr. Robert Siliciano, professor of medicine at Johns Hopkins University School of Medicine, who first identified these sleeping virus reservoirs. “The problem is that there is also a form of HIV that is not replicating and is latent, that is not affected by the drugs and not seen by the immune system.” These are the viruses that come roaring back when people stop taking their medications, or take them erratically.

But in the latest report presented this month at the Conference on Retroviruses and Opportunistic Infections in Boston, researchers revealed the strongest evidence yet that these latent viruses can be activated and eliminated, at least in animals. In a study involving a form of HIV that infects monkeys, Dr. Dan Barouch and his colleagues at Beth Israel Deaconess Medical Center and Harvard Medical School showed that a drug that stimulates the immune system and activates the dormant HIV, combined with a powerful antibody that can neutralize the HIV-infected cells, prevented HIV from surging back in five of 11 animals, six months after they stopped taking ARVs. In the monkeys whose HIV did return, the virus levels were 100 times lower than they were in animals that were not treated at all.