Neurotropic Viruses, Astrocytes, and COVID-19

• Published in: Frontiers in cellular neuroscience Vol. 15; p. 662578
• Main Authors: Tavčar, Petra, Potokar, Maja, Kolenc, Marko, Korva, Miša, Avšič-Županc, Tatjana, Zorec, Robert, Jorgačevski, Jernej
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Research Foundation 09.04.2021; Frontiers Media S.A
• Subjects: Aging; astrocyte; Astrocytes; Brain stem; Central nervous system; Consciousness; Coronaviridae; Coronaviruses; COVID-19; Disease transmission; Encephalitis; Encephalopathy; Environmental factors; Epidemics; flavivirus; Guillain-Barre syndrome; Homeostasis; Hypoxemia; Infections; Inflammation; Metabolism; Nausea; Neurodegenerative diseases; neuroinfection; Neuropathology; Neuroscience; neurotropic virus; Olfaction; Pathogens; Pathophysiology; Respiratory diseases; SARS-CoV-2; Severe acute respiratory syndrome coronavirus 2; Tick-borne encephalitis; Viruses; West Nile virus; Zika virus; COVID-19; SARS-CoV-2; neurotropic virus; astrocyte; neuroinfection; flavivirus
• ISSN: 1662-5102; 1662-5102
• DOI: 10.3389/fncel.2021.662578

At the end of 2019, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was discovered in China, causing a new coronavirus disease, termed COVID-19 by the WHO on February 11, 2020. At the time of this paper (January 31, 2021), more than 100 million cases have been recorded, which have claimed over 2 million lives worldwide. The most important clinical presentation of COVID-19 is severe pneumonia; however, many patients present various neurological symptoms, ranging from loss of olfaction, nausea, dizziness, and headache to encephalopathy and stroke, with a high prevalence of inflammatory central nervous system (CNS) syndromes. SARS-CoV-2 may also target the respiratory center in the brainstem and cause silent hypoxemia. However, the neurotropic mechanism(s) by which SARS-CoV-2 affects the CNS remain(s) unclear. In this paper, we first address the involvement of astrocytes in COVID-19 and then elucidate the present knowledge on SARS-CoV-2 as a neurotropic virus as well as several other neurotropic flaviviruses (with a particular emphasis on the West Nile virus, tick-borne encephalitis virus, and Zika virus) to highlight the neurotropic mechanisms that target astroglial cells in the CNS. These key homeostasis-providing cells in the CNS exhibit many functions that act as a favorable milieu for virus replication and possibly a favorable environment for SARS-CoV-2 as well. The role of astrocytes in COVID-19 pathology, related to aging and neurodegenerative disorders, and environmental factors, is discussed. Understanding these mechanisms is key to better understanding the pathophysiology of COVID-19 and for developing new strategies to mitigate the neurotropic manifestations of COVID-19.