Mouth mucosal cells are one of the main targets of the SarsCoV2 virus.
This extends the list of organs that the virus is capable of affecting and which until now included the lungs, upper respiratory tract, stomach, intestines, blood vessels, heart and kidneys.
This is indicated by the study published in the journal Nature Medicine by researchers from the National Institute of Health and the University of North Carolina at Chapel Hill.
That the saliva contained high levels of the coronavirus was known, but it was not yet clear where it came from.
The researchers, led by Blake M. Warner, hypothesized that at least some of the virus in saliva could have come from infected tissues in the mouth itself.
To verify this, they first checked the oral tissues of healthy people in order to identify areas of the mouth susceptible to infection.
In the body, cells vulnerable to SarsCov2 contain the RNA with the instructions for making the proteins the virus needs to enter cells, namely the Ace2 receptor and the TMPRSS2 enzyme.
Researchers also found the RNA for these two proteins in salivary gland cells and tissues lining the oral cavity.
Once the susceptibility of the mouth to the coronavirus was confirmed, the researchers looked for traces of the infection in oral tissue samples from Covid-19 patients, detecting the RNA of the virus in more than half of the salivary glands examined, as well as specific sequences. viral RNA.
Finally, to clarify the relationship between oral symptoms and the presence of the virus in saliva, the researchers collected salivary samples from 35 asymptomatic or mildly infected volunteers.
Of the 27 who had had symptoms, those with the virus in their saliva had experienced loss of taste and smell more often, thus suggesting that oral infection may underlie the oral symptoms of Covid.
The mouth therefore plays a more important role in infection than previously thought.
