Figure 1.

Phylogenetic relationship of CoVs. The phylogenetic tree illustrates the relationship among some HCoVs (red) and animal CoVs (blue) as a reference used in the tree, on the basis of complete genome nucleotide sequences. The viruses are grouped and subgrouped as (prototype shown): Alpha-CoV (pink, subgroup;1a,1b), Beta-CoV (light brown, subgroup; 1a,1b,1 c,1d), Gamma-CoV (light blue), and Delta-CoV (green). This tree is reconstructed with RNA-dependent RNA polymerase-coding region complete sequences of CoVs (with MEGA 7.2 software for maximum likelihood method).²⁴ Porcine enteric diarrhea virus (PEDV); infectious bronchitis virus (IBV); SARS- CoV; transmissible gastroenteritis virus (TGEV) MERS- CoV; Porcine respiratory CoV ISU-1 (PRCV ISU-1); and Wuhan seafood market pneumonia (Wuhan-Hu-1)