Despite the robust immune response that is mounted following primary infection, the virus is not cleared from the body. Instead, a chronic infection develops that persists for a median time of 10 years before the untreated pt becomes clinically ill. During this period of clinical latency, the number of CD4+ T cells gradually declines, but few, if any, clinical signs and symptoms may be evident. However, active viral replication can almost always be detected by as plasma viremia and the demonstration of virus replication in lymphoid tissue. The level of steady-state viremia (referred to as the viral set point) at ~6 months to 1 year postinfection has important prognostic implications for the progression of HIV disease; individuals with a low viral set point at 6 months to 1 year after infection progress to AIDS more slowly than do those whose set point is very high at this time (Fig. 226-22, p. 1231, in HPIM-19).