RNA binding assays for the regulatory proteins Tat and Rev

Abstract The replication of the human immunodeficiency virus (HIV) is controlled by two viral proteins, Tat, the trans-activator protein and Rev, the regulator of virion expression. The two proteins play complementary roles in the HIV life cycle. In permissive cells, transcription of the integrated proviral genome is initiated by host cell transcription factors (1-3). Initially, only small, multiply spliced mRNAs including the mRNAs for Tat and Rev are produced (4). Tat synthesized during this primary round of transcription then establishes a ‘positive feedback loop’ which boosts mRNA production 200- to 1000-fold (5- 7). Once a critical Rev threshold is surpassed, HIV gene expression switches away from the production of the mRNAs for the regulatory proteins towards the production of the unspliced or partially spliced mRNAs encoding the virion proteins (8-10).