Satish’s analysis strongly supported the idea that during antiretroviral therapy, HIV is not actively replicating and infecting new cells. Instead, the virus seems to be shut down, dormant within latently infected cells. This finding has important implications for future research. Says Satish, “If there is a little bit of residual replication during drug therapy, it implies that the drugs are not as good as they could be and that we might be able to design better drugs. On the other hand, this result suggests that we won’t get much bang for our research buck in tinkering with the drugs to make them more effective. They are already very good.”

In fact, many researchers are now focusing on the idea of actually curing HIV — a lofty goal that now seems more attainable based on the case of the so-called Berlin patient, Timothy Ray Brown. In this unusual case, Brown, an HIV-positive man with leukemia, received a bone marrow transplant from a person with genetic resistance to HIV. The procedure was performed in 2007 and involved wiping out Brown’s own immune system and replacing it with cells generated by the donated bone marrow. He has been off medication and HIV-free ever since. New research from Satish and his colleagues shows that recent media reports that Brown still carries HIV are spurious and probably due to laboratory contamination.

Of course, Brown’s case is unusual and could not be scaled up to treat most infected individuals, but it suggests that a cure is possible. Currently, the road to a cure is blocked by latently infected cells — the source of rebounding infections once drug therapy is stopped. Some researchers envision a cure in which latently infected cells are stimulated to reactivate and purge their virus, allowing the resulting active infection to be wiped out entirely with antiretrovirals. But such a cure would depend upon finding the latently infected cells and turning them on…