Herpes simplex virus type 2 DNA polymerase (HSV-2 UL30 or HSV-2 Pol)

Herpes simplex virus type 2 DNA polymerase (UL30) is a multifunctional viral enzyme essential for HSV-2 genome replication, forming a 190 kDa heterodimeric complex with the UL42 processivity factor. The enzyme catalyzes leading and lagging strand DNA synthesis and possesses intrinsic 3'-5' exonuclease proofreading activity, allowing it to correct replication errors. As a therapeutic target, HSV-2 DNA polymerase is the primary focus of antiviral drug development, with the majority of FDA-approved treatments being nucleoside analogs that competitively inhibit the enzyme's active site after viral activation. The emergence of drug-resistant mutations in immunocompromised patients represents a significant clinical challenge, driving interest in developing novel inhibitors with alternative mechanisms of action. Understanding the detailed structural dynamics of the polymerase, including its three catalytic states and interactions with DNA and the processivity factor, provides a foundation for rational design of next-generation antivirals with improved efficacy and reduced toxicity.

Other names

UL30UL30 protein

Nucleoside analogs (Acyclovir, Famciclovir, Penciclovir, Valaciclovir) require tri-phosphorylation (typically by viral thymidine kinase) before binding to and competitively inhibiting the polymerase at its active site. Once incorporated into the growing DNA strand, these analogs act as chain terminators, preventing further DNA elongation. Non-nucleoside inhibitor Foscarnet reversibly binds to the viral DNA polymerase at the pyrophosphate binding site without requiring viral enzyme activation, thereby preventing nucleotide binding and incorporation.