Fig. 2

The secondary structures and properties analysis of the S, E and M protein. a Analysis of the S protein. It contains most α-helix and β-sheet, some Turn and Coli region, several discontinuous high flexibility fragments, fluctuant surface probability with a few of positive peak and several antigenicity regions with positive peak. The S protein showed concentrated high antigenicity peaks in 600–800 residues. b Analysis of the E protein. It contains most α-helix and β-sheet, some Turn and Coli region, three high flexibility fragments, few surface probability regions and two antigenicity regions with positive peak in the begin and the end of polypeptide chain, respectively. The E protein showed concentrated high antigenicity peaks in 60–70 residues. c Analysis of the M protein. It contains most α-helix and β-sheet, some Turn and Coli region, several high flexibility fragments, few surface probability regions, two antigenicity region with positive single peak in the begin and middle of peptide chain, respectively, and consecutive positive peaks in the end. The M protein showed concentrated high antigenicity peaks in 200–220 residues. Interestingly, the high antigenicity peaks of all three proteins were in the region where the α-helix is relatively sparse, which may be related to the fact that the α-helix structure of the helix prevents continuous residues from being located on the surface