Phylogenetic relationships of 59 S gene sequences of SARS-CoVs from human and animals. The tree was generated with MrBayes 3.1.2 program. Posterior probabilities are shown on the nodes of the tree. Branch between BSL group and others was depicted with dotted line, because the branch was too long to be displayed at same scale. Bar, 0.001 nucleotide substitutions per site.