Fig. 3

SARS-CoV causes damage to the gastrointestinal system through direct viremia (attachment to ACE2) receptors and inflammation. (1) In the gut, the virus binds to ACE2 receptors in the gut epithelium and enters the cells causing inflammation and damage to the epithelial cells. This can result in function of the epithelial cells and cause diarrhea [94]. Furthermore, it can disrupt the normal population of gut flora which has some important functions in the body including maintaining a balance between different organisms in the gut. SARS infection can disrupt this balance leading to diarrhea. Since the gut flora also has impact on respiratory flora and vice-versa, referred to as the gut lung axis, this also affects the flora of respiratory tract and hence lead to respiratory symptoms [95, 97]. (2) In the liver, viral attachment to ACE2 receptors cause upregulation of ACE2 receptors in hepatocytes leading to hepatocyte proliferation and resulting tissue injury [92]. (Image created with Biorender.com)