Figure 1. Cumulatively identified cases of COVID-19 worldwide,
as of 26 April, 2020 (WHO, 2020).
Virological characteristics of SARS-CoV-2
As previously mentioned, SARS-CoV-2, belonging to the coronaviridae
family, is the causative pathogen of COVID-19. Closely resembled other
β-CoVs, the SARS-CoV-2 virion with a genome size of ~3
kb has a nucleocapsid consisted of genomic RNA and phosphorylated
nucleocapsid (N) protein (Jin et al., 2020). Of note, the nucleocapsid
is embedded in a phospholipid bilayer and is encased by two disparate
types of spike proteins: spike glycoprotein trimmer present in all
coronaviruses and the hemagglutinin-esterase shared merely in some CoVs.
The spike (S) protein plays a pivotal role in binding to receptors and
is the key to determine host tropism and transmission capacity (Figure
2). The matrix protein (M) along with the viral envelop (E) are also
located in the viral envelope (Wu et al., 2020b). Genome analysis showed
that the SARS-CoV-2 possesses 5’ and 3’ terminal sequences, with a gene
order 5’ -replicase open reading frame (ORF)
1ab-S-envelope(E)-membrane(M)-N-3’ (Lu et al., 2020). The virus particle
is 60~100 nm in diameter and are round or oval (Xia et
al., 2020a). It can be inactivated by ultraviolet light or heated at 56
°C for 30 min and is sensitive to most disinfectants (i.e., ether, 75%
ethanol, peracetic acid, chlorine, as well as chloroform) (Kratzel et
al., 2020).