Schematic representation of the outcomes of HIV-1 and HCV infection. Persistent viruses such as HIV-1 and HCV achieve high levels of chronic viral replication. The ultimate outcomes of HIV-1 and HCV infection depend on host-viral interactions. (A) After initial HIV-1 infection, the viral set point can vary considerably and is related to the ultimate speed of progression to AIDS. About 5%–15% of individuals experience slow progression, while a very small subset of individuals are termed “elite controllers” of HIV-1. (B) After HCV infection, a subset is able to control the virus over a sustained period, termed “spontaneous clearance” or “spontaneous control,” but the majority (~50%– 80%) progress to chronic viremia.