HIV-1 Trans-activator of transcription (Tat) (Tat)

HIV-1 Trans-activator of transcription (Tat) is a critical regulatory protein produced early in the HIV-1 life cycle, primarily responsible for the explosive amplification of viral gene expression (NIH, 2021). It functions by binding to the Trans-activation Response (TAR) element at the 5' end of nascent viral RNA transcripts, where it recruits the host positive transcription elongation factor b (P-TEFb) complex, consisting of CDK9 and Cyclin T1 (Wikipedia, 2023). This recruitment facilitates the phosphorylation of the RNA polymerase II C-terminal domain, significantly increasing the efficiency of transcriptional elongation (NIH, 2021). Beyond its role in the nucleus, Tat is actively secreted by infected cells and can be taken up by neighboring uninfected cells, leading to bystander effects such as immune dysregulation, neurotoxicity, and the promotion of Kaposi's sarcoma (MDPI, 2022). In vaccine development, such as those utilizing the Modified Vaccinia Ankara (MVA) vector, Tat is included as an antigen to stimulate the production of neutralizing antibodies and cytotoxic T-cell responses (NIH, 2011). These immune responses aim to block the extracellular activity of Tat and eliminate cells harboring the virus, potentially reducing the viral reservoir and slowing disease progression (MDPI, 2022).

Other names

p14Trans-activating proteinHIV-1 Tat proteinTat protein

Induction of humoral and cellular immune responses against the Tat protein to neutralize its extracellular activity and eliminate infected cells; inhibition of viral transcription by blocking Tat-TAR interaction.