Fig. 2.

Neuronal pathways of SARS-CoC-2 entry into the CNS. (a) Through the transcribral route, the virus enters and ruptures the ACE2 and TRPMSS2-expressing olfactory epithelial cells. The viral particles are then released into the olfactory bulb through the cribriform plate, and then they are transported into the various regions within the CNS via the CSF. (b and c) Nasal respiratory epithelium, small intestine and colon epithelial cells, and epithelial cells of the oral mucosa express high levels of ACE2. The virus can travel back from the periphery into the nervous centers through the retrograde spread via trans-synaptic transfer