In general, the distribution of the host’s receptor cells determine viral tropisms [58–60]. Neurotropism appears to be a common feature of coronaviruses in general, as these viruses share similar viral structures and pathways [50]. Both SARS-CoV and SARS-CoV-2 enter the body via an ACE-2 receptor-facilitated manner; ACE-2 receptors are highly expressed in the epithelial structures of the airway and vessels, lung parenchyma, the kidney, and cells of the small intestine [61,62]. Unlike its predecessor, the SARS-CoV, however, the SARS-CoV-2 virus, enters human cells in a process involving dipeptidyl peptidase 4 (DPP4), which is most abundant in the lower respiratory tract, kidney, small intestine, liver, and immune system [63]. The SARS-CoV virus does not utilize the DPP4 system and is not associated with lower respiratory tract infections [4].