Human immunodeficiency virus 1 reverse transcriptase and Hepatitis B virus reverse transcriptase (HIV-1 RT (for HIV-1 reverse transcriptase), HBV RT (for hepatitis B virus reverse transcriptase))

**Reverse transcriptase** is a viral enzyme found in both HIV-1 (a retrovirus) and hepatitis B virus (a hepadnavirus) that catalyzes the transcription of viral RNA into DNA, a critical step in the viral life cycle[1][3][4][5]. HIV-1 reverse transcriptase is a heterodimeric protein with DNA polymerase and RNase H activities, enabling conversion of viral RNA into double-stranded DNA, which is then integrated into the host genome[1][3][5]. HBV reverse transcriptase, encoded within the HBV polymerase, also possesses reverse transcriptase and RNase H activities, and is responsible for converting pregenomic RNA into partially double-stranded DNA within nucleocapsids[4][5][8]. Both enzymes are essential for viral replication and are major therapeutic targets: multiple classes of antiretroviral drugs (notably NRTIs and NNRTIs) inhibit these enzymes, and resistance often arises due to mutations in the viral RT gene[2][4][6][7]. The two enzymes share a common mechanism but are distinct proteins with unique resistance and drug interaction profiles. The widespread use of reverse transcriptase inhibitors for HIV/AIDS and chronic hepatitis B underlines the clinical importance of these enzymes as therapeutic targets[6][4].

Other names

HIV reverse transcriptaseHBV reverse transcriptaseHIV-1 RTHBV RTHIV-1 polymeraseHepatitis B polymeraseViral reverse transcriptase

Inhibition of DNA polymerase activity (NRTIs/NNRTIs inhibit the ability of reverse transcriptase to synthesize DNA from RNA); Termination of DNA chain elongation (many NRTIs act as chain terminators when incorporated); Direct allosteric inhibition (NNRTIs bind to non-catalytic sites and inhibit conformational changes necessary for enzymatic function); Competitive inhibition with natural substrates (NRTIs compete with natural nucleotides)