One of the salient clinical features of human immunodeficiency virus type 1 (HIV-1) infection is the relatively long period of latency which is characterized by a low to undetectable expression of the virus, following an early acute phase of infection with viremia. However, the mechanisms responsible for the maintenance of this clinical latency have been as yet poorly understood. During the extended latency or asymptomatic period, only a few infected cells are detected in peripheral blood. This may be due to an efficient removal of HIV-1-expressing cells by the host's immune defense mechanisms at early stages of infection. However, yet unidentified mechanism(s) to suppress the expression of the virus may also be operative in infected individuals at the early stages of infection.