This pathogen has proven to be particularly transmittable however, in large part because avenues of infection are not limited to the mechanisms listed above. Coronavirus fomites remain active on some surfaces for days at a time, its incubation requirements are relatively forgiving and a new study published in bioRxiv and affiliated with the Department of Pathology, Johns Hopkins University School of Medicine has revealed that the pathogen can even be transmitted through the eyes. Even worse, SARS-Cov-2, which causes the COVID-19 infection, is almost100 times more effective at infecting the eye as well as airways than SARS.
Similar to the immunogen breakthroughs that have begun appearing in the last few weeks, this latest find revolves around key proteins, namely an agent found in the lungs, respiratory tract cornea and eyelids called ACE-2 and an enzyme called TMPRSS2.
Viruses rely on proteins to inject their genetic material into host cells, which means they are currently the most determinative elements of transmission and supportive care. Viral spikes rely on enzymes to enable Rna reproduction. Both processes contribute considerably to the stability of a pathogen in any given community.
“Conjunctival signs and symptoms are observed in a subset of patients with COVID-19, and SARS-CoV-2 has been detected in tears, raising concerns regarding the eye both as a portal of entry and carrier of the virus. The purpose of this study was to determine whether ocular surface cells possess the key factors required for cellular susceptibility to SARS-CoV-2 entry/infection,” the authors wrote in the new paper. “Across all eye specimens, immunohistochemical analysis revealed expression of ACE2 in the conjunctiva, limbus, and cornea, with especially prominent staining in the superficial conjunctival and corneal epithelial surface. Surgical conjunctival specimens also showed expression of ACE2 in the conjunctival epithelium, especially prominent in the superficial epithelium, as well as the substantia propria.”
ACE2 and TMPRSS2 on the human ocular surface and SARS-CoV-2 susceptibility
The researchers began their analysis with a pool of non-fatal coronavirus patients.
The authors soon determined that expressions of the ACE2 protein and the TMPRSS2 enzyme were present in the ocular surfaces of every single one of recruitments.
The previously conducted research has compellingly identified ACE2 as a receptor for the SARS-CoV-2 virus. Just as early reports confirmed TMPRSS2, as the cell protease that facilitates viral entry following binding of SARS-CoV-2’s viral spike protein to ACE2.
Both of these agents were found in the corneas, eyelids, and in the scleras of the participants involved in the analysis.
This discovery not only explains the high transmission rates among otherwise protected healthcare workers, but it also explains the conjunctivitis symptoms reported by a sizable portion of carriers.
Moreover, western blot analysis of protein lysates conducted during refractive surgery further confirmed meaningful expressions of ACE2 and TMPRSS2.
In short, ocular surface cells are very clearly susceptible to coronavirus infection and therefore present an additional risk potential for person-to-person transmission of this virus
“Infection of ocular surface cells could lead to the eye as being an important carrier, with ocular virus shedding constituting a significant mechanism for infection of other individuals,“ the authors conclude.”Our study, therefore, highlights the importance of safety practices in the general community to prevent infection and spread (hygiene, face masks) and the need for extra caution among ophthalmologists.”
CW Headley is a reporter for the Ladders and can be reached at email@example.com