Apoptosis in AIDS

Infection with the human immunodeficiency virus type 1 (HIV-1) leads to progressive immunodeficiency and onset of opportunistic infections and neoplasms. The loss of immune competence is associated with declines in both the functionality and the number of CD4+ lymphocytes. Multiple mechanisms have been proposed to explain death and dysfunction of CD4+ T-cells. The mechanisms of HIV-1-mediated cell death which are relevant in vivo are unclear at present. However, in vitro explorations on the cytopathic effects of HIV-1 have yielded a wealth of potential triggering events, and signaling and effector pathways leading to apoptosis. The types of pro- and anti-apoptotic stimuli that have been associated with HIV-1 are multiple and often appear overlapping or even contradictory. This review focuses on the various molecular determinants from HIV-1 that play a role in induction of apoptosis in T-lymphocytes. Special attention is devoted to the viral genes, env, nef, tat and vpr, for which a significant body of literature on apotosis-related effects is available.