The Human Immunodeficiency Virus Type 1 Rev Protein: A Pivotal Protein in the Viral Life Cycle
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The human immunodeficiency virus type 1 (HIV-1) and related lentiviruses have more complex genomes than typical retroviruses (Cullen 1991). HIV-1 expresses at least nine different genes in a temporally regulated manner (Kim et al. 1989). In addition to the gag, pol, and env genes common to all retroviruses, HIV-1 also encodes genes for tat, rev, nef, vif, vpu, and vpr (Rosenblat et al., this volume). To encode nine different genes in a small, approximately 9-kb genome, the virus employs alternative reading frames and complex patterns of RNA splicing (Gallo et al. 1988; Schwartz et al. 1990a). The HIV-1 protein Rev (regulator of expression of the virion) plays an essential role in the temporal regulation of virus gene expression during a replication cycle (Kim et al. 1989; Pomerantz et al. 1990). The genes expressed by HIV-1 can be separated into two distinct groups based on whether their expression is Rev-dependent or not (Schwartz et al. 1990b; Hammerskjöld et al. 1989; Malim et al. 1989; Garrett et al. 1991). The Rev-inde-pendent or early genes encode Tat, Rev, and Nef. The Rev-dependent or late genes are important for virion production and encode the structural proteins Gag, Pol, and Env and the accessory products Vif, Vpu, and Vpr. Rev is absolutely required for HIV-1 replication. Proviruses that lack Rev function remain transcriptionally active, but fail to generate new viral particles.
KeywordsHuman Immunodeficiency Virus Acquire Immune Deficiency Syndrome Viral mRNA Ciency Virus Type
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