Does coronaviruses induce neurodegenerative diseases? A systematic review on the neurotropism and neuroinvasion of SARS-CoV-2.

The novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was identified in 2019 in Wuhan, China. Clinically, respiratory tract symptoms as well as other organs disorders are observed in patients positively diagnosed coronavirus disease 2019 (COVID-19). In addition, neurological symptoms, mainly anosmia, ageusia and headache were observed in many patients. Once in the central nervous system (CNS), the SARS-CoV-2 can reside either in a quiescent latent state, or eventually in actively state leading to severe acute encephalitis, characterized by neuroinflammation and prolonged neuroimmune activation. SRAS-CoV-2 requires angiotensin-converting enzyme 2 (ACE2) as a cell entry receptor. The expression of this receptor in endothelial cells of blood-brain barrier (BBB) shows that SRAS-CoV-2 may have higher neuroinvasive potential compared to known coronaviruses. This review summarizes available information regarding the impact of SRAS-CoV-2 in the brain and tended to identify its potential pathways of neuroinvasion. We offer also an understanding of the long-term impact of latently form of SARS-CoV-2 on the development of neurodegenerative disorders. As a conclusion, the persistent infection of SRAS-CoV-2 in the brain could be involved on human neurodegenerative diseases that evolve a gradual process, perhapes, over several decades.