RNA glycosidase and other agents target Tat to inhibit HIV-1 transcription

The HIV-1 tat gene encodes a small 86–104 amino acid protein depending on the HIV-1 strain. Tat is essential for HIV-1 replication through interactions with numerous cellular transcription factors. The interaction between Tat and P-TEFb, which is a cellular protein complex composed of cyclin T1 and CDK9, delivers P-TEFb to the newly transcribed viral mRNAs where phosphorylation of RNA polymerase II by CDK9 leads to highly efficient mRNA transcription. It has long been recognized that Tat is a potential anti-HIV-1 target and possibly a viral Achilles' heel. However, specifically targeting Tat without affecting normal host cell functions has been challenging. Means to inactivate Tat have been reported that includes small compounds, transdominant negative Tat proteins, and by plant-derived antivirals. Investigations of these agents have reported encouraging outcomes that inform and may hopefully affect strategies for a functional HIV-1 cure.