Researchers have identified a new potential treatment target: Ssu72, a human protein that spurs dormant HIV-infected cells into an actively replicating state by interacting with a virus-generated protein known as Tat, without which HIV cannot live. Ssu72 is a phosphatase, an enzyme that binds to Tat to help to begin viral transcription; Ssu72 also creates a kind of feedback loop that accelerates this process. Another protein, CycT1, interacts with Tat similarly but is needed for normal human cell function, making it a less-than-ideal drug target. Ssu72, on the other hand, isn’t needed for developing RNA for most human cell genes. Researchers are hoping to target Ssu72 in order to prevent viral replication. They are also studying whether low levels of the protein result in HIV-infected CD4 cells entering a resting state.