A novel corneal epithelial cell culture assay for assessing topical antivirals against herpes simplex virus keratitis

Various in vitro models have been used to study HSV infection, but corneal epithelial-based assay systems for evaluating antiviral activity remain limited. In this study, we established a in vitro assay of HSV keratitis using the CRL-11516, an immortalized human corneal epithelial (HCE) cell line. HSV readily infected HCE cells and exerted cytopathic effects. These effects were quantified via formazan-based colorimetric assay, which indicated the suitability of our system for antiviral evaluation. Most clinically available antivirals exhibited sufficient activity in our model. Specifically, acyclovir and its prodrug, valaciclovir, exerted comparable effects after direct application to HCE cells. In contrast, vidarabine showed little antiviral activity. Notably, 2′-deoxycoformycin, an adenosine deaminase inhibitor, only partially restored its activity, indicating that factors other than adenosine deaminase contribute to the limited efficacy of vidarabine. These results support the widely recognized superior clinical performance of acyclovir. Our system also supported assays with thymidine kinase-deficient HSV-1, showing high application potential. Overall, the developed immortalized HCE cell-based model provides a practical platform for topical antiviral evaluation that can reduce the reliance on animal experiments for preclinical drug development.