The virus that causes Covid-19 infects multiple cell types in several organs and multiplies there – which explains why some people have gastrointestinal symptoms.
With each passing day, we understand more about how the new coronavirus (Sars-CoV-2) behaves in the human body. Apparently, it affects much more than the respiratory system: there are reports that it can cause conjunctivitis, thrombosis, and even neurological damage.
According to a study published in the journal Science on May 1, the new coronavirus can also attack the intestine – which explains why a third of patients experience symptoms such as nausea and diarrhea.
To reach this conclusion, Dutch scientists used cell cultures that correspond to those found in the human intestine. They infected these cells with Sars-CoV-2 and monitored the cellular response to the microorganism.
The scientists noted that the cells became quickly infected, as well as the number of contaminated cell structures, indicating the virus’s replication in the intestine. Using RNA sequencing, the scientists evaluated the response of intestinal cells to the new coronavirus. They noticed the activation of a protein called interferon, produced by leukocytes and fibroblasts to prevent the replication of infectious agents (such as Sars-CoV-2).
Except that, as other studies have already demonstrated, the increase in the activity of interferon does not help much: the new coronavirus can infect our cells through ACE2, an enzyme produced in greater quantity when our body detects a threat. In this case, then, it ends up functioning as a gateway to the Sars-CoV-2. These enzymes can be found in organs such as the nose, lung and, according to the study published on Science, are present in large quantities in the intestine.
In addition to clarifying the gastrointestinal symptoms seen in some patients, these findings also explain why the virus can be detected in human feces even after the respiratory symptoms have disappeared.
But, according to Bart Haagmans, one of the study’s main authors, it is still unclear whether the presence of the virus in the intestine is in any way infectious. “Our findings indicate that we should look into this possibility more closely,” writes the virologist in a statement. The study authors propose, however, that in addition to tests on the nose and throat, rectal swabs or stool samples may also be needed.