COVID-19 Infection of Cells in the Mouth
According to information released on March 25, 2021, they had announced that they had found evidence that SARS-CoV-2, the virus that causes COVID-19, infects cells in the mouth.
It is known that the primary sites of SARS-CoV-2 infection are the "respiratory tract" and "lungs," but this does not mean that other sites are not infected.
New research has focused on the oral cavity.
The research focused on the oral cavity.
The fact that the virus can infect multiple areas of the body may help explain the wide range of symptoms caused by COVID-19 infection.
According to the findings, the mouth may transmit SARS-CoV-2 to the lungs, or digestive system, via virus-laden saliva from infected oral cells.
The study was conducted by researchers from the National Institutes of Health and the University of North Carolina at Chapel Hill.
The researchers found that
We already know that saliva from COVID-19 patients may contain high levels of SARS-CoV-2, and studies have shown that saliva testing is a reliable way to diagnose COVID-19.
However, they still do not know where the SARS-CoV-2 in saliva comes from.
In COVID-19-infected people with respiratory symptoms, some of the virus in saliva may come from nasal secretions or sputum from the lungs, and researchers have studied oral tissues of healthy people to identify areas of the mouth that are susceptible to SARS-CoV-2 infection.
Vulnerable cells contain RNA instructions to create the "entry proteins" needed for the virus to enter the cell.
RNA for two major entry proteins, known as the ACE2 receptor and the TMPRSS2 enzyme, was found in certain cells of the salivary glands and tissues of the oral cavity, and in a small percentage of salivary gland and gingival cells, RNA for both ACE2 and TMPRSS2 was expressed in the same cells.
This indicates an increase in vulnerability as the virus is thought to require both entry proteins to enter the cell.
The expression levels of entry factors are similar to those in areas known to be susceptible to SARS-CoV-2 infection, such as the tissue lining the nasal cavity of the upper airway," Warner said.
Warner said.
The researchers found that
After confirming that parts of the oral cavity were susceptible to SARS-CoV-2 infection, they examined oral tissue samples from people with COVID-19 for evidence of infection.
In samples collected at the NIH from deceased COVID-19 patients, SARS-CoV-2 RNA was found to be present in just over half of the salivary glands tested.
In salivary gland tissue from one person who died, and from a living person with acute COVID-19, scientists detected a specific sequence of viral RNA that indicates the cells are actively creating new copies of the virus.
After the team found evidence of infection in oral tissues, the researchers wondered if those tissues could be the source of the virus in saliva.
This seemed to be the case, and in people with mild or asymptomatic COVID-19, the cells released from the mouth into saliva were found to contain SARS-CoV-2 RNA and RNA for invasion proteins.
To determine whether the virus in saliva was infectious, the researchers exposed the saliva of eight people with asymptomatic COVID-19 to healthy cells that had been kept in petri dishes.They found that the saliva of two volunteers caused infection of the healthy cells, and that even people without symptoms could transmit infectious SARS-CoV-2 to others through their saliva.
Finally, to investigate the relationship between oral symptoms and the virus in saliva, the team collected saliva from another group of 35 NIH volunteers with mild or asymptomatic COVID-19.
Of the 27 people who experienced symptoms, those whose saliva contained the virus were more likely to report loss of taste and smell, suggesting that oral infections may underlie the oral symptoms of COVID-19.
To sum up.
The researchers.
said the results of this study suggest that the mouth, via infected oral cells, plays a larger role in SARS-CoV-2 transmission than previously thought.
We believe that SARS-CoV-2 can infect the throat, lungs, and even the intestines when infected saliva is swallowed or its tiny particles are inhaled," Bird said.
Bird said.
More studies will be needed to confirm the findings in more people and to determine the exact nature of the mouth's involvement in SARS-CoV-2 transmission and transmission out of the body.
Huang N, Perez P, et al. SARS-CoV-2 infection of the oral cavity and saliva. Nature Medicine. 25 March 2021. doi: 10.1038 / s41591-021-01296-8
