Human herpesvirus DNA polymerase (Pol)

Human herpesvirus DNA polymerase is a fundamental enzyme required for the replication of the double-stranded DNA genomes of all human herpesviruses, including Herpes Simplex Virus (HSV-1 and HSV-2), Varicella-Zoster Virus (VZV), and Cytomegalovirus (CMV) [UniProt, NIH]. As a DNA-directed DNA polymerase, it catalyzes the addition of deoxyribonucleotides to the 3'-end of a growing DNA chain using a viral DNA template [UniProt]. The enzyme typically functions as part of a larger replication complex and often exhibits 3'-5' exonuclease activity, which provides a proofreading mechanism to ensure high-fidelity replication [NIH]. Because of its central role in the viral life cycle and its distinct structural features compared to human DNA polymerases, it is a major target for antiviral chemotherapy [DrugBank, StatPearls]. Most therapeutic agents, such as acyclovir and ganciclovir, are prodrugs that are phosphorylated to active triphosphate forms which then compete with natural substrates to inhibit the enzyme and cause chain termination [DrugBank, StatPearls]. Other inhibitors like foscarnet target the pyrophosphate binding site directly without requiring metabolic activation [StatPearls]. Clinical challenges associated with targeting this enzyme include the development of drug resistance through point mutations and potential toxicities such as nephrotoxicity or bone marrow suppression depending on the specific drug used [StatPearls].

Other names

Human herpesvirus viral DNA polymeraseDNA-directed DNA polymeraseUL30UL54BALF5ORF28U38ORF54Herpesvirus DNA polymerase

Nucleoside and nucleotide analogs act as competitive inhibitors of deoxyribonucleotide triphosphates (dNTPs) and function as DNA chain terminators upon incorporation into the nascent viral DNA strand [DrugBank, StatPearls]. Pyrophosphate analogs like foscarnet non-competitively inhibit the enzyme by binding to the pyrophosphate exchange site, preventing the cleavage of pyrophosphate from deoxynucleoside triphosphates and thus blocking DNA chain elongation [StatPearls].