A decade later, another highly pathogenic human CoV, MERS-CoV, emerged, and the first patient with MERS-CoV infection was reported in Saudi Arabia in June 2012 (Zaki et al., 2012). By December 26, 2019, a total of 2,494 laboratory-confirmed cases of MERS, including 858 associated deaths in 27 countries (fatality rate 34.4%), were reported to the WHO1. Globally, the majority (about 80%) of human cases have been reported in Saudi Arabia, where people get infected through direct contact with infected dromedary camels or persons2 (Zaki et al., 2012). Isolation of MERS-CoV and detection of neutralizing antibodies from dromedary camels suggest that these camels are potentially an important intermediate host (Reusken et al., 2013; Azhar et al., 2014). Similar to SARS-CoV, MERS-CoV is also an emerging zoonotic virus (Li and Du, 2019). Bats habituate several CoVs phylogenetically related to MERS-CoV, and some of them are identical to MERS-CoVs, suggesting that MERS-CoV may originate from bats (Annan et al., 2013; Lelli et al., 2013; Lau et al., 2018; Luo et al., 2018a). Different from SARS-CoV, which has not caused infections in humans since 2004 (Du et al., 2009a), the transmission of MERS-CoV has not been interrupted, and the infected human cases continue increasing1 (Mobaraki and Ahmadzadeh, 2019). Currently, human-to-human transmission of MERS-CoV is limited.