Evolutionary relationship between CCoV-HuPn-2018 and other alphacoronaviruses. The phylogenetic tree was constructed based on amino acid sequences of S proteins using the neighbor-joining method implemented in MEGA7.0.26 software. The scale bar indicates amino acid substitutions per site. The percentage of replicate trees in which the associated taxa clustered together in the bootstrap test (1,000 replicates) is shown next to the branches. The newly emerged CCoV-HuPn-2018 and Haitian strain HuCCoV_Z19 are highlighted in red like other HCoVs. BatCoV, bat coronavirus; PRCV, porcine respiratory coronavirus; SADS-CoV, swine acute diarrhea syndrome coronavirus; SeCoV, swine enteric coronavirus.