Supplementary Material for: Activation of Checkpoint Kinase 2 Is Critical for Herpes Simplex Virus Type 1 Replication in Corneal Epithelium

Background/Aims: Herpes simplex virus (HSV) type I keratitis remains a leading cause of corneal morbidity, despite the availability of effective antiviral drugs. Improved understanding of virus-host interactions at the level of the host DNA damage response (DDR), a known factor in the development of HSV-1 keratitis, may shed light on potential new therapeutic targets. This report examines the role of checkpoint kinase 2 (Chk2), a DDR mediator protein, in corneal epithelial HSV-1 infection. Methods: A small-molecule inhibitor of Chk2 (Chk2 inhibitor II) was applied to HSV-1-infected cultured human corneal epithelial cells (hTCEpi and HCE) as well as to explanted and organotypically cultured human and rabbit corneas. Infection levels were assessed by plaque assay and real-time PCR. RNAi-mediated depletion of Chk2 was performed to confirm the effect of the inhibitor. Results: Inhibition of the Chk2 kinase activity greatly suppresses the cytopathic effect, genome replication and infectious progeny production in vitro and ex vivo. Conclusion: This report demonstrates the critical role of Chk2 kinase in the establishment of HSV-1 corneal epithelial infection. These data contribute to our understanding of herpesvirus-host interactions and underscore the significance of DDR activation in HSV-1 keratitis.