Coronaviruses typically result in respiratory and enteric infections and affect both animals and humans. Six coronavirus species are known to cause human infection, two of which typically can cause severe respiratory illness and fatalities: SARS-CoV (severe acute respiratory syndrome coronavirus) which had an outbreak in Guangdong, China, between 2002 and 2003 and MERS-CoV (Middle East respiratory syndrome coronavirus) which had an outbreak in 2012 outbreaks in the Middle East [6, 7]. By January 7, 2020, Chinese scientists had isolated the novel coronavirus from patients in Wuhan [3]. It has been reported [8] that SARS-CoV-2 was more similar to two bat-derived coronavirus strains (bat-SL-CoVZC45 and bat-SL-CoVZXC21) than to known human-infecting coronaviruses, including the virus that caused the SARS outbreak of 2003. Molecular modeling has shown structural similarity between the receptor-binding domains of SARS-CoV and SARS-CoV-2, which suggests that SARS-CoV-2 may use angiotensin-converting enzyme 2 (ACE 2) as a receptor. The differences of the etiological characteristics among SARS-COV, MERS-COV, and SARS-CoV-2 are shown in Table 1.
Table 1 Etiological characteristics of SARS-COV, MERS-COV, and SARS-CoV-2
Virus Genus Intermediate host Reservoir host Receptor Origin
SARS-COV-2 β-coronavirus ? Bat ACE2 Wuhan, China
SARS-COV β-coronavirus Civet Bat ACE2 Guangzhou, China
MERS-COV β-coronavirus Dromedary Bat CD26/DPP4 Saudi Arabia