Conjunctival epithelial cells resist productive SARS-CoV-2 infection

Conjunctival epithelial cells, which express viral-entry receptors angiotensin-converting enzyme 2 (ACE2) and transmembrane protease serine type 2 (TMPRSS2), constitute the largest exposed epithelium of the ocular surface tissue and may represent a relevant viral-entry route. To address this question, we generated an organotypic air-liquid-interface model of conjunctival epithelium, composed of basal, suprabasal, and superficial epithelial cells, and fibroblasts, which could be maintained successfully up to day 75 of differentiation. Using single-cell RNA sequencing (RNA-seq), with complementary imaging and virological assays, we observed that while all conjunctival cell types were permissive to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) genome expression, a productive infection did not ensue. The early innate immune response to SARS-CoV-2 infection in conjunctival cells was characterised by a robust autocrine and paracrine NF-KB activity, without activation of antiviral interferon signalling. Collectively, these data enrich our understanding of SARSCoV-2 infection at the human ocular surface, with potential implications for the design of preventive strategies and conjunctival transplantation.

Automated summary

Conjunctival epithelial cells, the largest exposed epithelium of the ocular surface tissue, may serve as a potential route for SARS-CoV-2 entry. Through the use of an organotypic model and molecular assays, it was found that although conjunctival cells are susceptible to SARS-CoV-2 infection, productive infection does not occur. Furthermore, the early innate immune response in conjunctival cells is characterized by robust NF-KB activity without activation of antiviral interferon signaling.