SARS-CoV-2 infects neurons, astrocytes, choroid plexus epithelial cells and pericytes of the human central nervous system

Abstract

SARS-CoV-2, the coronavirus responsible for the COVID-19 pandemic, is associated with a range of neurological manifestations including haemorrhage, thrombosis and ischaemic necrosis and encephalitits. However, the mechanism by which this occurs is unclear. Neurological disease associated with SARS-CoV-2 infection has been proposed to occur following direct infection of the central nervous system and/or indirect sequelae as a result of peripheral inflammation. We profiled ACE2 and TMPRSS2 in brain tissue from five healthy human donors, and observed expression of these proteins in astrocytes, neurons and choroid plexus epithelium within frontal cortex and medulla. Primary human astrocytes, neurons and choroid plexus epithelial cells supported productive SARS-CoV-2 infection in an ACE2- dependent manner. Infected cells supported the full viral lifecycle, releasing infectious virus particles. In contrast, primary brain microvascular endothelial cells, pericytes and microglia were refractory to SARS-CoV-2 infection. These data support a model whereby SARS-CoV-2 is neurotropic, and this may in part explain the neurological sequelae of infection. ImportanceA subset of patients with COVID-19 develop neurological symptoms, but the underlying cause is poorly understood. We observed that cells within normal human brain express the SARS-CoV-2 entry factors ACE-2 and TMPRRS2, with expression mainly observed within astrocytes, neurons and choroid plexus epithelium. Primary human astrocytes, neurons and choroid plexus epithelial cells cultured in vitro supported the full SARS-CoV-2 life cycle with a range of SARS-CoV-2 variants. This study demonstrates that cells of the human central nervous system express SARS-CoV-2 entry factors in vivo and support viral infection in vitro, thus supporting a model where neurological symptoms seen in some COVID-19 patients may be as a result of direct viral infection of the central nervous system. Furthermore, these data highlight the importance of investigating the ability of therapeutics to clear virus from this potential reservoir of infection.