SARS-CoV-2 Infects Mouth Cells: Study
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Researchers recently found evidence that SARS-CoV-2 infects cells in the mouth, specifically in the salivary glands and tissues lining the oral cavity, suggesting that it is a site for potential infection and transmission. It is known that the upper airways and lungs are sites of infection with the virus that causes COVID-19, but these most recent findings may explain the wide-ranging symptoms associated with the disease.

To explore the possibility that the virus could be coming from infected tissues in the mouth, researchers studied oral tissues from healthy people. They identified RNA for two entry proteins that allow the virus to enter cells — the ACE2 receptor and the TMPRSS2 enzyme — located in the salivary glands and, to a lesser degree, the mucosa.

The team looked for evidence of infection in oral tissue samples taken from patients with COVID-19.SARS-CoV-2 RNA was present in just over half of tissue samples taken from patients with the disease who had died. In salivary gland tissue samples from one person who died and another living patient with COVID-19, cells were actively making new copies of the virus.

The researchers said they discovered that cells shed from the mouth into saliva in patients with mild or asymptomatic disease were found to contain SARS-CoV-2 RNA, in addition to RNA for the entry proteins, indicating that oral tissues were a source of the virus in saliva. Then, the researchers exposed saliva from eight people with asymptomatic COVID-19 to healthy cells grown in a dish, according to the press release.

The saliva from two of the volunteers infected healthy cells, suggesting that even those who do not have COVID-19 symptoms might pass infectious virus to others through their saliva. They also gathered saliva from a separate group of 35 people with asymptomatic or mild COVID-19. Of the 27 who experienced symptoms, those who were found to have the virus in their saliva were more likely to report the loss of taste and smell, possibly explaining the oral symptoms of COVID-19.

"Not only do our results illustrate a connection between reported symptoms ... and the presence of virus in the saliva, but they also demonstrate the possibility that SARS?CoV?2 in saliva may be the source of spread within the body," the Researcher says.