We know that COVID-19 enters your body through your respiratory system but now scientists have pinpointed exactly how the virus infects us by attaching itself to hairlike structures protruding from epithelial cells lining our airway. Understanding the COVID-19 nasal infection at the molecular level could lead to an effective prophylactic or "'morning after' nasal spray that could knock out respiratory viruses' ability to colonize your nose and throat," according to the researchers.
From Stanford Medicine News:
A May 2020 Nature Communications study, co-authored by [Stanford Medicine pathologist and microbiologist Peter] Jackson, showed that ACE2 — the classic SARS-CoV-2-binding cell-surface molecule, or receptor — concentrates on the cilia of nasal epithelial cells. The new Cell study showed that SARS-CoV-2 bound to epithelial cilia via this receptor.
From there, Jackson said, the virus might slip past the mucus-mucin barrier in one of two ways: either by skipping down the side of cilia, hopscotch-style, from one ACE2 molecule to the next until it reaches the cell's main body, fusing with the cell membrane there and climbing in; or by wedging its way into the cilium and riding an internal freight elevator down to the cell body.
"Once the virus gets through that barrier," he said, "it can replicate freely in underlying cells." […]
The findings identify new targets for a nasally applied drug that, by impeding ciliary motion or microvilli gigantism, could prevent even unknown respiratory viruses — the kind you meet, say, at a pandemic — from making themselves at home in your nose or throat.
Jackson said substances used in these experiments could perhaps be optimized for use in, say, nasal sprays soon after a respiratory viral exposure, or as prophylactics.
"Delaying viral entry, exit or spread with a locally applied, short-duration drug would help our immune systems catch up and arrive in time to stop full-blown infection and hopefully limit future pandemics," he said.
Image: "To infect nasal epithelial cells, SARS-CoV-2 particles must slip past those cells' protective mucin-mucus mesh (green) by attaching themselves to cell-surface structures called cilia (gray)." (Chien-Ting Wu)