Potential of Ocular Transmission of SARS-CoV-2: A Review.

Brad P Barnett,Natalie Afshari,Derek Welsbie,Karl Wahlin,Michal Krawczyk,Daniel Chao,Doran Spencer

doi:10.3390/vision4030040

Abstract

Purpose of review: to provide a prospective on the current mechanisms by which SARS-CoV-2 enters cells and replicates, and its implications for ocular transmission. The literature was analyzed to understand ocular transmission as well as molecular mechanisms by which SARS-CoV-2 enters cells and replicates. Analysis of gene expression profiles from available datasets, published immunohistochemistry, as well as current literature was reviewed, to assess the likelihood that ocular inoculation of SARS-CoV-2 results in systemic infection. Recent findings: The ocular surface and retina have the necessary proteins, Transmembrane Serine Protease 2 (TMPRSS2), CD147, Angiotensin-Converting Enzyme 2 (ACE2) and Cathepsin L (CTSL) necessary to be infected with SARS-CoV-2. In addition to direct ocular infection, virus carried by tears through the nasolacrimal duct to nasal epithelium represent a means of ocular inoculation. Summary: There is evidence that SARS-CoV-2 may either directly infect cells on the ocular surface, or virus can be carried by tears through the nasolacrimal duct to infect the nasal or gastrointestinal epithelium.

Highlights

Due to the widespread impact of the COVID-19 pandemic, an in depth understanding of the mechanisms of SARS-CoV-2 infection on both the macro and molecular scale is needed
We identified a total of 60 articles that are relevant to ocular transmission of SARS-CoV-2
Four key proteins implicated in SARS-CoV-2 infection were identified: Transmembrane Serine Protease 2 (TMPRSS2), CD147, Angiotensin-Converting Enzyme 2 (ACE2) and Cathepsin L (CTSL), and datasets were utilized to analyze the expression of these proteins in ocular and non-ocular tissue

Summary

Introduction

Due to the widespread impact of the COVID-19 pandemic, an in depth understanding of the mechanisms of SARS-CoV-2 infection on both the macro and molecular scale is needed. Due to the ever-shifting landscape of our understanding of the virus, any consensus statement must be taken with a grain of salt Conceding this shortcoming, for the ophthalmological community we have attempted to summarize, as well as reinterpret the literature to date as it relates to this virus. Dipeptidyl peptidase 4 (DPP4) is an entry receptor for MERS-CoV, but is thought to be uninvolved in SARS-CoV-2 infection [1] Despite these distinctions, fortuitously, the mechanism of transmission of SARS-CoV-2 in multiple respects parallels that of SARS-CoV-1 and MERS-CoV. The mechanism of transmission of SARS-CoV-2 in multiple respects parallels that of SARS-CoV-1 and MERS-CoV This paper highlights these parallels to guide the ophthalmological community in making educated inferences on SARS-CoV-2 and how it relates, thereby, providing a roadmap to guide preventative and therapeutic interventions

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Conclusion