Herpes simplex virus DNA polymerase catalytic subunit (UL30) (UL30)

The Herpes simplex virus DNA polymerase catalytic subunit, encoded by the UL30 gene, is an essential enzyme for the replication of the viral double-stranded DNA genome [1, 4]. As a member of the B family of DNA polymerases, it possesses both 5'-3' polymerase activity and 3'-5' proofreading exonuclease activity, which are vital for maintaining the fidelity of the 152 kb viral genome [4, 6]. The enzyme functions as a heterodimer with the UL42 processivity factor, which anchors the polymerase to the DNA template to allow for the synthesis of long DNA strands [6, 8]. UL30 is the primary target for most clinically used anti-herpetic drugs, such as acyclovir, ganciclovir, and foscarnet [4, 7]. These agents inhibit viral replication by acting as chain terminators or by directly blocking the enzyme's catalytic activity [1, 4]. However, the clinical utility of these drugs can be limited by the development of resistance mutations within the UL30 gene, particularly in immunocompromised patients who require long-term antiviral therapy [1, 9].

Other names

UL30pUL30HSV-1 DNA polymeraseDNA polymerase catalytic subunitPolDNA-directed DNA polymerase catalytic subunit

Nucleoside analogs (e.g., acyclovir, ganciclovir) are converted to their triphosphate forms by viral and cellular kinases; these triphosphates then compete with natural deoxynucleotides for incorporation into the viral DNA by the UL30 polymerase, leading to DNA chain termination [1, 4]. Pyrophosphate analogs (e.g., foscarnet) non-competitively inhibit the enzyme by binding to its pyrophosphate-binding site, preventing the release of pyrophosphate from deoxynucleotide triphosphates and thus blocking DNA chain elongation [1, 6].