HIV-1 Tat and Vpr proteins (Tat, Vpr)

HIV-1 Tat and Vpr are distinct accessory proteins produced by human immunodeficiency virus type 1 (HIV-1) that play critical roles in the viral replication cycle. Tat, an 86–101 amino acid protein, functions as a trans-activator by binding the TAR RNA element to strongly enhance viral transcription from the HIV-1 long terminal repeat (LTR), enabling efficient proviral gene expression. Vpr, a 14–15 kDa, 96-amino acid virion-associated protein highly conserved across HIV-1, HIV-2, and simian immunodeficiency viruses, promotes nuclear import of the preintegration complex (PIC) in nondividing cells like macrophages, facilitating infection of these targets. Vpr also arrests the cell cycle at G2/M in infected proliferating cells, optimizing LTR-directed gene expression and viral production while inducing apoptosis and defects in mitosis, cytokinesis, nuclear envelope integrity, and centrosome function. These activities provide HIV-1 with a replication advantage by manipulating host cell processes, though Tat and Vpr are not unitary "receptors" or typical therapeutic targets like enzymes or GPCRs; current HIV therapies target other viral elements such as reverse transcriptase and protease. No approved drugs directly interact with Tat or Vpr, and their roles highlight challenges in HIV persistence due to cell cycle modulation and nuclear effects.

Other names

HIV-1 trans-activator of transcriptionHIV-1 viral protein RHIV-1 accessory proteins