Coronaviruses,members of the family Coronaviridae and subfamily Coronavirinae,are enveloped positive-strand RNA viruses which have spikes of glycoproteins projecting from their viral envelopes,thus exhibit a corona or halo-like appearance (Masters and Perlman,2013;Cui et al.,2019).Coronaviruses are the causal pathogens for a wide spectrum of respiratory and gastrointestinal diseases in both wild and domestic animals,including birds,pigs,rodents,etc (Dhama et al.,2014).Previous studies have found that six strains of coronaviruses are capable to infect humans,including four strains circulating yearly to cause common cold,and other two strains which are the source for severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS-CoV),respectively (Dhama et al.,2014;Cui et al.,2019).