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As far as I know the route of SARS-Cov-2 spreading in the human body isn't known beyond the change in locality of symptomatic expression with progression of Covid-19 (upper respiratory tract to lower respiratory tract.) Research has shown (1) the distribution of ACE2 protein, the functional receptor for SARS-Cov and SARS-Cov-2 (2), to include various human organs (oral and nasal mucosa, nasopharynx, lung, stomach, small intestine, colon, skin, lymph nodes, thymus, bone marrow, spleen, liver, kidney, and brain) along with arterial and venous endothelial cells and arterial smooth muscle cells in all organs studied. And ACE2 mRNA has been found in virtually all organs. So there is definitely the potential for cells in the circulatory system binding viruses. What may be significant here is the concentration of ACE2 protein in cell membranes. One Chinese analysis of a group of 170 Covid-19 fatalities(3) found half of the cases suffered from hypertension. ACE inhibitors are a class of medication prescribed for lowering blood pressure and according to models they increase the concentration of ACE2 protein in lower respiratory tract cells. Given that fatality results from respiratory distress originating in the lower respiratory tract and that not all cases progress to the lower respiratory tract it seems possible that the spread of the virus within the body may be related to concentration of ACE2 protein in cells. The disease progression would also support mucosal transport of the virus within individuals the same as between them. (1) Tissue distribution of ACE2 protein, the functional receptor for SARS coronavirus. A first step in understanding SARS pathogenesis. https://www.ncbi.nlm.nih.gov/pubmed/15141377
(2) Structure, Function, and Antigenicity of the SARS-CoV-2 Spike Glycoprotein https://www.sciencedirect.com/science/article/pii/S009286742...
(3) Controversial Study Links COVID-19 Severity to ACEIs and ARBs (Newsweek, March 24, 2020) |