Study reveals mouth as primary source of COVID-19 infection, spread

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A unique study shows that the mouth is a robust place for infection and transmission of COVID-19. This is the result of new studies published on October 27th on the preprint server medRxiv.

A team of researchers led by the University of North Carolina at Chapel Hill and the National Institute of Dental and Craniofacial Research shows that coronavirus can invade the salivary glands, where it replicates, and in some cases lead to prolonged illness when infected saliva Swallowed is sucked into the gastrointestinal tract or lungs, where pneumonia can develop.

While most of the COVID-19 research has focused on the nose and lungs, this is the first study to identify the mouth as the primary site for coronavirus infection, underscoring the importance of wearing a face covering and physical distancing. The results were not reviewed by experts.

“Our results indicate that oral COVID-19 infection may be underestimated,” said lead study author Kevin M. Byrd, research professor at UNC-Chapel Hill Adams School of Dentistry and Anthony R. Volpe Research Scholar at the American Dental Association Science and research institute. “Like a nasal infection, oral infection could be the cause of the asymptomatic spread that makes it so difficult to contain the disease.”

Byrd, along with Blake Warner, director of salivary disorders at NIDCR, coordinated research at the National Institutes of Health, the Wellcome Sanger Institute, the UNC’s Marsico Lung Institute, and the J. Craig Venter Institute.

Researchers are just beginning to study the oral symptoms patients experience during COVID-19, such as loss of taste or smell and persistent dry mouth.

In the study, researchers report preliminary results from a clinical study of 40 subjects with COVID-19 that showed that detached epithelial cells lining the mouth were infected with SARS-CoV-2, the coronavirus that causes COVID-19 can be. According to the study, the amount of virus in the patient’s saliva correlated positively with changes in taste and smell.

Using oral cell identity cards, the researchers also examined where the virus infects in the mouth. They examined oral tissues with the highest levels of ACE2, the receptor that helps coronavirus capture and invade human cells.

Based on ACE2 expression and cadaver tissue analysis, the most likely sources of infection in the mouth are the salivary glands, tongue, and tonsils.

The results provide further evidence for the role of saliva in COVID-19. COVID-19 infection, especially in the mouth, can allow the virus to spread internally and to others if the infected person breathes, speaks, and coughs.

The research team began their investigation early in the pandemic and after six months of collaboration have gained new insights into how COVID-19 infects the mouth and throat.

Their work has resulted in the creation of the oral and craniofacial biological network as part of the human cell atlas. As members of the network work towards the goal of creating comprehensive maps of oral and craniofacial cells as a basis for understanding oral health and diseases, they will openly share research that may influence the COVID-19 response.

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More information:
Kevin M. Byrd, et al. Integrated single cell atlases reveal an oral SARS-CoV-2 axis of infection and transmission (2020). DOI: 10.1101 / 2020.10.26.20219089 Provided by the University of North Carolina at Chapel Hill

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