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NSC-based Investigation of the Role of Glia in SARS-CoV2 Neurovirulence

William Lynch, Ph.D., Anatomy and Neurobiology, NEOMED

Severe acute respiratory syndrome (SARS) mediated by the Coronavirus-2 (CoV-2) is reported to be associated with neurological signs in a large portion of hospitalized COVID-19 patients. These include headache, impaired consciousness, confusion, dizziness, ataxia, myoclonus, hypogeusia, hyposmia, fatigue, agitation, seizures, and encephalopathy, which correlate with poor disease prognosis.  Prior studies on closely related human coronaviruses including SARS-CoV and MERS-CoV have documented their CNS neurotropism and neuroinvasion in humans and in engineered mouse models, predicting similar neurotropism and neurovirulence for CoV-2.  Because the neurovirulence of other enveloped viruses is associated with viral glycoprotein expression in neuroglia, the primary goal of this pilot award is to investigate whether neural glial expression of SARS-CoV2 spike (S) glycoprotein affects CNS function/integrity in mouse brain chimera models.  Toward this end we proposed to generate engraftable human and mouse neural stem cells (NSCs) that expressed S for a) expression and differentiation analysis in vitro, and b) transplantation and physiologic assessment in post-natal developing mouse brains.  These glial brain chimeras will allow examination of whether 1) S affects NSC differentiation/glial function, and 2) S adversely affects brainstem neuronal activity that could account for the neurological and respiratory manifestations of COVID-19.  Our preliminary results indicated that murine NSCs can indeed express S protein, however, expression was low and transient. Because many coronavirus S proteins are particularly prone to induce endoplasmic reticulum (ER) stress, and thus, may be directly cytotoxic or become suppressed, we will undertake viral protein complementation experiments and employ tightly-regulated gene expression tools to circumvent the limitations to brain chimera analysis, that should facilitate investigation of NSC/glial S expression in vivo.