Fig 4.

Viral DNA replication is required for PARP activation. (A) NAD⁺ levels after treatment with 1 μM acyclovir (ACV), an inhibitor of HSV-1 DNA replication, or DMSO. Serum-starved fibroblasts were infected (3 IU/cell) or mock infected, and drug was applied at 1 hpi. Metabolites were extracted at 18 hpi, and NAD⁺ levels were normalized to packed cell volume. Values are averages of duplicate experiments (±1 SD). (B) Production of infectious HSV-1 virions in cells treated with 1 μM acyclovir as described above. Values are representative of virus yield at 18 hpi and are expressed relative to DMSO-treated cells (±1 SD). (C) Analysis of poly(ADP-ribosyl)ation after inhibition of HSV-1 DNA replication. Serum-starved fibroblasts were infected with HSV-1 (3 IU/cell) or mock infected. At 1 hpi, 1 μM acyclovir was applied, and cells were harvested at 18 hpi. H₂O₂-treated cells were pretreated with 1 μM acyclovir for 1 h before H₂O₂ application. Whole-cell lysates were analyzed by Western blotting.