Abstract：
Neurological complications, both acute and chronic, are reported commonly in COVID-19 affected individuals. In this context, the understanding of pathogenesis of SARS-CoV-2 in specific cells of central nervous system (CNS) origin is relevant. The present study explores infection biology of a clinical isolate of SARS-CoV-2 in human cell lines of neural origin such as the glioblastoma (U87-MG), neuroblastoma (SHSY5Y) and microglia (C20). Despite showing clear evidence of infection by immunofluorescence with an anti-spike protein antibody, all the three neural cell lines were observed to be highly restrictive to the replication of the infecting virus. While the U87-MG glioblastoma cells demonstrated no cytopathic effects and a low viral titre with no signs of replication, the SHSY5Y neuroblastoma cells exhibited cytopathic effects with bleb formation but no evidence of viable virus. The C20 microglial cells showed neither signs of cytopathic effects nor viable virus. Ultrastructural studies demonstrated intracellular virions in infected neural cells. The presence of lipid droplets in infected SHSY5Y cells suggested an impact on host cell metabolism. The decrease in viral RNA levels over time in all the neural cell lines suggested restricted viral replication. In conclusion, this study highlights the limited susceptibility of neural cells to SARS-CoV-2 infection. This reduced permissibility of neural cell lines to SARS-CoV-2 may point to their inherent lower expression of receptors that support viral entry in addition to the intracellular factors that potently inhibit viral replication. The study findings prompt further investigation into the mechanisms of SARS-CoV-2 infection of neural cells.
摘要：
神经系统并发症,急性和慢性，在受COVID-19影响的个体中普遍报告。在这种情况下，对SARS-CoV-2在中枢神经系统（CNS）起源的特定细胞中的发病机理的理解是相关的。本研究探讨了SARS-CoV-2临床分离株在神经起源的人类细胞系中的感染生物学，例如胶质母细胞瘤（U87-MG）。神经母细胞瘤（SHSY5Y）和小胶质细胞（C20）。尽管通过抗刺突蛋白抗体的免疫荧光显示出明显的感染证据，观察到所有三种神经细胞系对感染病毒的复制具有高度限制性。虽然U87-MG胶质母细胞瘤细胞没有细胞病变效应和低病毒滴度，没有复制的迹象，SHSY5Y神经母细胞瘤细胞表现出细胞病变作用,并伴有气泡形成,但没有活病毒的证据.C20小胶质细胞既没有显示细胞病变作用的迹象，也没有活的病毒。超微结构研究表明，受感染的神经细胞中存在细胞内病毒体。在感染的SHSY5Y细胞中存在脂滴表明对宿主细胞代谢的影响。所有神经细胞系中病毒RNA水平随时间的降低表明病毒复制受限。总之,这项研究强调了神经细胞对SARS-CoV-2感染的有限易感性.神经细胞系对SARS-CoV-2的可容许性降低可能表明，除了有效抑制病毒复制的细胞内因子外，它们固有的支持病毒进入的受体表达较低。该研究结果促使进一步研究SARS-CoV-2感染神经细胞的机制。
