SARS-CoV-2 Particles Found in Retina

By Marilynn Larkin

August 06, 2021

NEW YORK (Reuters Health) - SARS-CoV-2 particles were found in the retinas of three deceased patients and may be associated with the infection's ocular manifestations, a post-mortem analysis in Brazil suggests.

"The study was prompted by our previous report in The Lancet showing COVID-related lesions in the retina," Dr. Alléxya A. A. Marcos of Federal University of São Paulo-UNIFESP told Reuters Health by email. "This was later confirmed by many reports. We decided, therefore, to study post-mortem eyes and look for the presence of viral particles in the retina."

"We believe the retina should be investigated as a sanctuary of virus particles, (with) a potential role in the development of vascular changes, as well as possible long-term involvement. The role of the virus itself in the pathogenesis of vascular lesions should be investigated."

"The retina is an essential biomarker of many vascular and central nervous system events and may also be necessary for COVID," she added. "Multimodal retinal clinical exams can potentially bring new important information in acute and long-term COVID."

As reported in JAMA Ophthalmology, Dr. Marcos and colleagues studied retinas from enucleated eyes of three patients (two men, one woman) who died from COVID-19. Their ages at death ranged from 69-78; all had severe pulmonary involvement requiring mechanical ventilation.

Presumed S and N COVID-19 proteins were seen under immunofluorescence microscopy within endothelial cells close to the capillary flame and in cells of the inner and the outer nuclear layers. At the perinuclear region of these cells, the team observed on transmission electron microscopy double-membrane vacuoles consistent with the virus, presumably containing COVID-19 viral particles.

The authors note, "It is now clear that after the initial infection in the respiratory system, the virus can spread throughout the whole body, reaching different tissues and organs. Current literature shows the eye may be involved in COVID-19 infection, and many retinal changes have been reported."

Dr. Marcos said the team is investigating the correlation between the clinical and molecular findings.

Dr. Nasreen Syed of the University of Iowa in Iowa City, coauthor of a related editorial, told Reuters Health by email, "In my opinion, the most important message for clinicians is that this study provides convincing evidence of the SARS CoV-2 virus in the retina in patients ill from the viral infection. The findings are important because they suggest that the virus can become disseminated throughout the body in various tissues/organs such as the retina, which is part of the central nervous system."

"Further research is needed to determine why the virus is there and how it enters retinal cells," he said. "In addition, we need more study to find out whether the virus is actually causing disease in the retina and how, if so, it could affect vision. Those things are not clearly understood at this point."

SOURCE: https://bit.ly/3fB3S8i and https://bit.ly/3lEYAfN JAMA Ophthalmology, online July 29, 2021.

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