While much research on the coronavirus has been focused on its impacts on the lungs, clinical and scientific data has shown that the virus can damage a range of different organs throughout the body.
The study, titled "A Single-Cell RNA Expression Map of Human Coronavirus Entry Factors,” mapped the expression of 28 human genes named "SCARFS" or SARS-CoV-2 and Coronavirus-Associated Receptors and Factors, according to the Cornell Chronicle.
Examining the single-cell RNA expression of these 28 genes can help scientists predict which tissues and cell types are most vulnerable to infection.
“You can learn which cells and organs are most likely to be infected – at least at the onset of an infection,” said Cedric Feschotte, professor in the Department of Molecular Biology and Genetics, in the College of Agriculture and Life Sciences. “This is very important to emphasize, because once the virus infects a particular tissue, the [genetic] landscape might shift.”
The coronavirus can turn off an entire branch of the immune system, meaning that naturally occurring restriction factors that are present in tissues serve as the body's main defense against SARS-CoV-2, as the immune system is unable to respond quickly.
Mapping the entry points for the virus is also necessary for trying to predict where the virus will go once it enters the body and may help researchers use those areas as targets for developing drugs against the virus, according to the Cornell Chronicle.
The study found alternate entry paths for the virus into the lungs, central nervous system and heart and supports emerging data that shows that the virus can infect the intestines, kidney and placenta. Specific groups of cell within the prostate and testes may be permissive to the coronavirus and may explain male-specific vulnerabilities.Since the pandemic began, medical professionals have begun reporting patients with symptoms throughout the body, not just in the respiratory system, including a loss of taste and smell, gastroenterological issues, strokes and epidemiological issues.
The research team also found that tissue on the roof of the nose canal, called the nasal epithelium, may serve as a main battleground for the virus as the tissue has high expressions of genes that both facilitate and restrict infection. The outcome of this battle could be critical in determining the course of infection, according to the study.
The study also found a statistical difference in the expression level of the genes in the nasal tissue of people under the age of 30 compared to those over the age of 50.
While the sample size of the study was too small to draw a firm conclusion, if it's demonstrated in larger sample sizes, then “it could, in part, explain why old people are getting more sick than young people,” explained Manvendra Singh, a postdoctoral associate in the Feschotte Lab, according to the Cornell Chronicle.
The study also found that cells called trophoblasts in the placenta seem to be vulnerable to the virus as well, raising concerns that the virus may infect other fetal tissues possibly harming the fetus.
The placenta may prevent newborns from getting infected and current studies indicate that transmission between infected mothers and their babies during the third trimester is very rare. It's still too early to say, however, whether there may be a higher risk in earlier stages of pregnancy.
The single-cell RNA expression of SCARFs are available on an open-access, user-friendly web interface to allow scientists easy access to the data.
“This is a useful resource for COVID-19 but perhaps also for the next coronavirus pandemic – not that I wish one. But we have to be realistic and better prepared. Part of being prepared is having the data out there," said Feschotte.