The Human Immunodeficiency Virus Type-1 Long Terminal Repeat and Its Role in Gene Expression

It is nearly a decade since the isolation of the first molecular clones of the human immunodeficiency virus, type 1 (HIV-1) (1-3). Since then, an intense effort has been made by investigators worldwide to try to understand in detail how HIV-1 gene expression is regulated. The first step in the life cycle of HIV-1 involves an initial burst of viral gene expression upon cellular infection. Until recently, this was thought to be followed by a variable latency period almost inevitably leading to resuming an active stage of the infectious process, resulting in deterioration of the patient's immune and often neurological status. However, recent studies indicate that HIV-1 gene expression may be active throughout infection in a subset of cells within the lymph nodes of infected individuals. At the same time, most infected cells may retain HIV-1 in a dormant stage (4, 5).