Neurological Components in Coronavirus Induced Disease: A Review of the Literature Related to SARS, MERS, and COVID-19

Table 1

Comparison chart of MERS with SARS and COVID-19.

Disease			MERS: Middle East respiratory syndrome coronavirus	SARS: severe acute respiratory syndrome coronavirus	COVID-19: corona virus disease 2019
Virus type [31, 35–37]			MERS-CoV	SARS-CoV	SARS-CoV2
Biological characteristics	Order		Nidovirales
	Family		Coronaviridae
	Subfamily		Orthocoronavirinae
	Genus		Betacoronavirus
			Subgenre C	Subgenre B
	Nucleotide identity (genomic) [25, 38]		(i) ∼85% to bat (MERSr-CoV); (ii) >99% to camel (MERSr-CoV); (iii) 45–65% the S protein between bat (MERSr-CoV), human, and camel (MERSr-CoV)	(i) 78.2–97% in the S protein with bat (SARSr-CoV); (ii) Almost identical with civets (SARSr-CoV)	(i) 88–96% to bat-SL-CoVZC45 and bat-SL-CoVZXC21 (SARSr-CoV); (ii) 79.0% to SARS‐CoV; (iii) 51.8% to MERS‐CoV
	Shape		Rounded or elliptical, often pleomorphic
	Size		65–125 nm in diameter
	Structure [5, 39, 40]	RNA [38]	Positive-sense RNA genome ranging from 26 to 32 kilobase in length
		Glycoprotein envelope (E) (∼8–12 kDa)	Interfered with host immune response or unknown function
		Glycoprotein nucleocapsid (N)
		Spike protein (S) [5, 38]	1270 aminoacids	1255 aminoacids	1273 aminoacids
		Glycoproteins membrane (M) (∼25–30 kDa)	Responsible for the transmembrane transport of nutrients, the bud release, and the formation of envelope
		Lipid membrane	Yes	Yes	Yes
		Cellular receptor [41]	DPP4 or CD26 (dipeptidyl peptidase 4)	ACE2	ACE2
	Host-pathogen interaction [15]		Bat ⟶ camel ⟶ human	Bat ⟶ civet cat ⟶ human	Bat ⟶ snake or pangolin ⟶ human
	Transmission [42]		Animal-human, human-human, zoonotic disease
	Incubation period [14]		2–10 days	2–14 days
	Organ affected [35, 43]		Unciliated bronchial epithelial cells and type II pneumocytes, epithelial cells in the kidney, small intestine, liver, prostate, and neurological system	Lymphocytes, monocytes and lymphoid tissues, ciliated bronchial epithelial cells and type II pneumocytes, intestinal mucosa, epithelium of renal distal tubules, tissue‐resident macrophages, and neurons in the brain	Lung alveolar epithelial cells and enterocytes of small intestine remarkably, the kidneys and liver
Immunological response [44]	Speed of spread [45]		Low	Moderate	High
	Recruitment of immune cells [46]		Dendritic cells, macrophages, and T cells	Monocyte/macrophages, dendritic cells	Monocyte/macrophages, neutrophils
	Production of proinflammatory cytokines and chemokines [43]		TNF‐α, IL‐6, CXCL‐10, CCL‐2, CCL‐3, CCL‐5, and IL‐8	IL‐1, IL‐6, IL‐12, interferon γ (IFN‐γ), transforming growth factor‐β, CCL2, CXCL9, CXCL10, and IL‐8	IL‐1β, IL‐1Rα, IL-6, IL‐7, IL‐8, IL‐9, IL‐10, basic FGF, GCSF, GMCSF, IFNγ, IP10, MCP1, MIP1A, MIP1B, PDGF, TNF‐α, and vascular endothelial growth factor
	Evades the response immune		Delayed development of the innate and adaptive immune response and prolonged virus clearance		Delayed innate immune response

°Images adapted from Cui et al. 2018 [47]. The genome comprises the 5′-untranslated region (5′-UTR), open reading frame (ORF), 1a/b encoding nonstructural proteins (NSPs) for replication, and structural proteins including S, E, M, and N and accessory proteins (studies have indicated notable variations in SARS-CoV and SARS-CoV2 such as the absence of 8a protein and fluctuation in the number of amino acids in 8b and 3c protein in SARS-CoV2). Envelope spike protein (S) is functionally divided into the S1 domain, responsible for receptor binding, and the S2 domain, responsible for cell membrane fusion. ACE2: human angiotensin-converting enzyme 2. SARS-CoV2 has 14 binding residues that interact with the ACE2 receptor and is 10- to 20-folds higher than that of SARS-CoV.