Multiple-sequence alignment of flagellin amino acid sequences representing serogroups H1, H2 and H12 of E. coli using Clustal W. The amino acid sequence of H1a was obtained in this study [GenBank: KC753181]. The amino acid sequences of serogroups H1b, H12c,H2d and H2e were retrieved from NCBI protein database [GenBank: ADR27342, AAQ22679, AAD28525 and BAI30971, respectively]. Two very distinctive H2 flagellin sequences were included in the alignment (H2d: common H2 sequence; H2e: peculiar H2 sequence obtained from E74/68). A dash (‘-’) denotes a gap in the alignment. Amino acid sequence differences are indicated in bold letters. Numbers indicate the various amino acid sequence positions.