Human immunodeficiency virus 1 tat-vpr overlapping mRNA region

The HIV-1 tat-vpr overlapping mRNA region is a segment of the human immunodeficiency virus type 1 (HIV-1) genome where the open reading frames for the Tat (transactivator of transcription) and Vpr (viral protein R) proteins overlap. This region is critical for the viral life cycle as it encodes essential components of two regulatory proteins: Tat, which is indispensable for efficient transcription of the viral genome, and Vpr, which facilitates the nuclear import of the pre-integration complex and induces cell cycle arrest in host cells. Because this sequence is highly conserved and dual-coding, it represents an attractive target for RNA-based therapeutic interventions designed to disrupt multiple viral functions simultaneously. The most prominent drug candidate targeting this region is the hammerhead ribozyme OZ-1 (also known as Rz2), which was developed to bind and cleave the viral mRNA at a specific site within the overlap. By cleaving the mRNA, OZ-1 prevents the translation of both Tat and Vpr, thereby significantly inhibiting viral replication and spread. Clinical trials have investigated the transplantation of autologous hematopoietic stem cells or T cells modified to express this ribozyme as a potential strategy for achieving a functional cure for HIV-1 infection. Despite showing safety and some evidence of increased CD4+ T cell counts, challenges remain regarding the low frequency of gene-modified cells in patients and the potential for viral escape through mutations. Overall, this target represents a pioneering approach in the field of HIV gene therapy, focusing on the direct destruction of viral transcripts to achieve long-term viral suppression.

Other names

Tat-Vpr overlapHIV-1 tat/vpr RNARz2 target siteOZ-1 target siteHIV-1 tat-vpr overlapping reading frameHIV-1 tat/vpr overlap

Ribozyme-mediated cleavage of viral mRNA at a specific site within the overlapping reading frames of tat and vpr, preventing the translation of both proteins.