Short peptide designing, expression and purification. (A) Schematic diagram of the relative location of the truncated prM/M protein fragments and overlapping short peptides, M1-M20, spanning the prM/M protein. The numbers in parentheses indicate the amino acids located at the beginning or the end of each fragment. M1 to M20 are a set of partially overlapping short peptides covering the whole prM/M protein of JEV. (B) Expression and purification of recombinant peptide fusion proteins. For each peptide a fusion expression recombinant plasmid was constructed and transformed into host cell E. coli BL21 (DE3). After the cells were induced with IPTG, the supernatants of the sonicates were purified by affinity chromatography. The purified proteins were analyzed by 12% SDS-PAGE and stained with Coomassie brilliant blue. M stands for the protein molecular standards as labeled on the left.