Human immunodeficiency virus 1 reverse transcriptase and Hepatitis B virus polymerase (HIV/HBV RT)

HIV/HBV Reverse Transcriptase refers to the essential viral enzymes from Human Immunodeficiency Virus (HIV) and Hepatitis B Virus (HBV) that catalyze the conversion of viral RNA into DNA, a process known as reverse transcription. In HIV-1, this function is performed by the reverse transcriptase (RT) heterodimer (p66/p51), while in HBV, it is a domain within the multifunctional HBV polymerase (P protein) [1.1.1, 1.1.4]. These enzymes are critical for the replication cycles of both viruses, making them primary targets for antiviral therapy. Drugs targeting these enzymes, primarily nucleoside and nucleotide reverse transcriptase inhibitors (NRTIs) such as tenofovir, lamivudine, and emtricitabine, act as chain terminators that halt DNA synthesis [1.3.1, 1.4.1]. Because HIV and HBV share similar replication strategies involving reverse transcription, certain NRTIs are effective against both viruses, which is particularly important for managing co-infected patients [1.3.1]. These drugs are typically administered as prodrugs that require intracellular activation to their triphosphate forms before they can compete with natural nucleotides for incorporation into the viral DNA [1.3.3]. However, the use of these drugs is challenged by the emergence of resistance mutations, such as M184V in HIV and M204V in HBV, which can lead to treatment failure [1.2.1, 1.2.2]. Additionally, therapeutic management must account for potential side effects including hepatotoxicity, renal impairment, and the risk of HBV reactivation if treatment is discontinued [1.2.1, 1.2.4].

Other names

HIV-1 RTHBV PolHBV PolymeraseReverse transcriptaseP proteinRNA-directed DNA polymerase

Nucleoside and nucleotide reverse transcriptase inhibitors (NRTIs) are prodrugs that require intracellular phosphorylation to their active triphosphate forms. These active metabolites compete with natural deoxynucleotide triphosphates (dNTPs) for incorporation into the nascent viral DNA strand by the reverse transcriptase enzyme. Once incorporated, they act as chain terminators because they lack the 3'-hydroxyl group necessary for the formation of the next phosphodiester bond, thereby halting viral DNA synthesis and replication [1.3.3, 1.3.4].