ABSTRACT
Various reported cases related to the COVID-19 pandemic since 2019 has shown that SARS-CoV-2 directly or indirectly affects the nervous system besides the upper respiratory tract (Whittaker et al. 2020). SARS-CoV-2 is a zoonotic strain of coronavirus with various structural proteins. It is reported that spike protein, which is one of its structural proteins, can bind to or interact with Neuropilin-1, CD147 (Basigin), KREMEN1, ASGR1 (Asialoglycoprotein Receptor), Furin, LRP1 (Lipoprotein Receptor-Related Protein 1) and Ephrin receptors as well as ACE-2 (Angiotensin Converting Enzyme-2) and TMPRSS2 (Transmembrane Serine Protease 2) receptors. The related studies suggest that these possible receptors in the target of SARS-CoV- 2 cooperate with ACE-2, hence make the central nervous system an open target for the virus (Zalpoor et al. 2022). The first possible route of SARS-CoV-2 is seen as the route from the olfactory epithelium to its bulb via the trigeminal nerve (CN V) and olfactory nerve (CN I) pathway. Additionally, the virus entering the bloodstream can reach the Blood Brain Barier, cross the barrier and spread to neurons through the oligodendrocyte in a process called “Trojen horse”. Lastly, another route considered focuses on the vagal nerves of the enteric system associated with the central nervous system (Guadarrama-Ortiz et al. 2020). This literature review focuses on possible entry routes of SARS-CoV-2 into the nervous system. In this context, a route has been established based on the receptors in the nervous system cells, which are reported to be the target of SARS-CoV-2, based on the studies.