Study: conjunctival infections by SARS-CoV-2 unlikely
A few weeks ago, experts from the United States pointed out that the SARS-CoV-2 coronavirus can also cause conjunctivitis. However, researchers from Germany are now reporting on a study that shows that conjunctivae infections from the new pathogen are unlikely.
A few weeks ago, the American Academy of Opthalmology (AAO) referred to reports suggesting that the novel SARS-CoV-2 coronavirus can also cause conjunctivitis. However, researchers at the Freiburg University Hospital are now reporting that conjunctival infections from the virus are unlikely.
Conjunctivitis in COVID-19 sufferers
As the University Medical Center Freiburg explains in a recent release, the SARS-CoV-2 coronavirus uses certain proteins on the surface of human cells as door openers to penetrate the cells and multiply.
There have also been isolated reports of patients with conjunctivitis in COVID-19 disease. So far, however, it has been unclear whether conjunctival cells are susceptible to the novel virus and could therefore be a potential point of entry for SARS-CoV-2 viruses.
Researchers at the University Medical Center Freiburg now show in a study that SARS-CoV-2 infections of the conjunctiva are unlikely. The results were recently published in the Journal of Medical Virology.
New pathogens can infect various organs
"According to our research, SARS-CoV-2 is unlikely to trigger conjunctivitis," said Prof. Dr. Günther Schlunck, research group leader at the Ophthalmology Clinic of the University Medical Center Freiburg.
Previous studies suggest that the coronavirus can affect several organs. Door opener proteins such as the ACE-2 receptor and the TMPRSS2 enzyme, via which the new pathogen can penetrate human cells, have already been detected in the liver, stomach and respiratory tract of infected people.
Prof. Schlunck, Prof. Clemens Lange and other scientists from the Ophthalmology Clinic at the University Medical Center Freiburg have now examined whether these proteins are present on conjunctival cells.
“At the moment there is still a lot of uncertainty as to how the novel corona virus infects people. We wanted to help clarify this, ”explains Prof. Lange, first author of the study.
Viruses could get into the tear film
To this end, the researchers analyzed conjunctival tissue samples from 46 patients who were not affected by COVID-19. Using RNA sequencing, the ophthalmologists checked whether precursor molecules (mRNA), which are used to produce the door release proteins, were present in the tissue samples.
In addition, proteins present in the samples were visualized using labeled antibodies using immunohistochemical stains.
No relevant amounts of ACE-2 or TMPRSS2 were found in any of the samples. This makes infection of the conjunctiva by SARS-CoV-2 via binding to ACE-2 very unlikely, according to the experts.
"However, it is possible that viruses get into the tear film and reach the upper respiratory tract via the draining tear ducts and the nasal mucosa, where they can trigger an infection," explains Prof. Schlunck.
Comprehensive hygiene and protective measures are also appropriate
Although conjunctivitis with SARS-CoV-2 viruses is unlikely, comprehensive hygiene and protective measures are still appropriate.
As Prof. Lange explains, doctors who are in close contact with COVID-19 sufferers “should still take care to effectively protect the mouth, nose and, if necessary, the eyes.” (Ad)
Author and source information
This text corresponds to the requirements of the medical literature, medical guidelines and current studies and has been checked by medical doctors.
- University Clinic Freiburg: conjunctivitis by SARS-CoV-2 is unlikely, (access: May 30, 2020), University Clinic Freiburg
- Clemens Lange MD, PhD, Julian Wolf MD, Claudia Auw ‐ Haedrich MD, Anja Schlecht PhD, Stefaniya Boneva MD, Thabo Lapp MD, Ralf Horres PhD, Hansjürgen Agostini MD, Gottfried Martin PhD, Thomas Reinhard MD, Günther Schlunck MD: Expression of the COVID ‐ 19 receptor ACE2 in the human conjunctiva; in: Journal of Medical Virology, (published: 06.05.2020), Journal of Medical Virology