Commercial human 3D corneal epithelial equivalents for modeling epithelial infection in herpes keratitis

Herpes stromal keratitis (HSK) is a leading cause of infectious blindness in the western world that is a consequence of corneal epithelial infections by HSV-1. However, both VZV and CMV can also infect the cornea resulting in HSK. There are several animal models of HSV corneal infection, however study of corneal infection by VZV and hCMV using animals has been considerably more limited because of their human specificity. Although infection by all three herpesviruses has been studied in corneal epithelium-derived cell cultures or donated human corneas, these models suffer from absence of tissue organization in the former, and access to and consistency of the later. We here explored the use of commercially available 3D human corneal epithelial equivalents (HCE) cultured at an air-liquid interface to study corneal epithelial infection by all three human herpesviruses causing HSK. Infection of HCE by recombinant HSV-1 and hCMV expressing fluorescent proteins did not require scarification of the tissue and resulted in an expanding infection. HSV-1 spread was, while hCMV was much slower. In contrast, infections with cell-free fluorescent VZV required scarification and did not spread after initial infection. Acyclovir introduced topically effectively reduced replication of HSV-1 in the HCE model. We conclude that quality-controlled, readily available HCE may be a useful model for studying herpesvirus infection of the human corneal epithelium, as well for testing the effects of antiviral drugs.