Unlike the above four human CoVs, SARS-CoV, MERS-CoV, and 2019-nCoV have caused severe pneumonia and/or failure of other organs, even death, among infected populations (Nicholls et al., 2003; Zhong et al., 2003; Zaki et al., 2012; Zhu et al., 2020). The epidemic outbreak of SARS-CoV began in the Guangdong Province of China in November 2002, and spread through human-to-human transmission to other parts of the world within a few months (Ksiazek et al., 2003). From November 2002 to August 2003, SARS-CoV infected more than 8,098 people in 29 counties, resulting in over 774 deaths with ∼10% fatality rate (Du et al., 2009a). Palm civets serving as a potential intermediate host of this virus were traced immediately (Tu et al., 2004). Chinese horseshoe bats (Rhinolophus sinicus) are the natural reservoir of SARS-CoV (Li et al., 2005b). Various bat SARS-related CoVs (SARSr-CoV) have been identified in Yunnan, China, several of which can infect human cells, and have been further characterized (Ge et al., 2013; Hu et al., 2017). These discoveries indicate the threat of re-emergence of SARS-CoV or SARSr-CoV.