Immunopathogenic Mechanisms of HIV Infection

The outcome of infection of CD4-bearing target cells with HIV is dependent on complex interactions between viral and cellular factors (Haseltine 1988). In addition to genes which code for the structural proteins of the virion and the enzymes which facilitate the transcription of viral RNA into DNA and the integration of the viral DNA into the host cell genome (Varmus 1988), the HIV genome contains at least six genes which act in distinct ways to regulate HIV replication. For several of these regulatory genes, the mechanism of action involves the long terminal repeat (LTR) sequences of the HIV genome. For example, the target for tat—mediated enhancement of viral replication is the trans-acting responsive (TAR) region of the LTR (Rosen et al 1985). The nef gene product has also been shown to regulate viral transcription by interacting with the negative regulatory element (NRE) of the LTR (Ahmad and Venkatesan 1988). In addition to TAR and NRE, the HIV LTR contains other regulatory sequences such as the TATAA promotor sequence, the NFkB core enhancer elements, and Sp-1 binding sites (Starcich et al 1985).