Fig. 2

SARS-CoV-2 infects the brain via the haematogenous route. a SARS-CoV-2 is a respiratory virus that spreads primarily through airborne droplets, causing infection of the lungs. Left panel: SARS-CoV-2 infection of the lungs may lead to endothelial damage and increased capillary permeability, which allow the transfer of SARS-CoV-2 from the lungs to the pulmonary microcirculation. Right panel: SARS-CoV-2 in the blood can enter the cerebral circulation, where the slow blood flow may allow the virus to damage the BBB. b Viruses in the cerebral circulation may infect and destroy microvascular endothelial cells, resulting in increased BBB permeability and facilitating viral entry into brain tissues. c SARS-CoV-2 infects brain cells via the interaction of S protein with ACE2, NRP1 and other potential receptors on microvascular endothelial cells after the S protein is primed by TMPRSS2. Once SARS-CoV-2 enters the cell, the viral life cycle begins, including genome replication, protein synthesis, virus assembly, maturation and release, ultimately leading to brain parenchyma infection and tissue damage