Figure 2

Amino acid variations of 45 S proteins. The amino acid sequence of CUHK-SU10 strain isolated from 03-late epidemic group was used as the reference sequence. The shadows represent the sites or residues under positive selection with posterior probability ≥ 0.9. The red sashes highlight three special sites where amino acids were replaced and fixed in all 03 human strains, suggesting selective sweep acting on the S gene.