Sequencing and comparative analysis of flagellin genes fliA and fliB in bovine Clostridium chauvoei isolates

BACKGROUND: Clostridium chauvoei is the etiological agentof blackleg as an endogenous infection in cattle. Flagella havebeen known to play a critical role in the protective immunityof animals to clostridial infections. C.chauvoei has two copiesof fliC gene, namely fliA and fliB. OBJECTIVES: The aim of thisstudy was the determination and nucleotide sequence analysisof both copies of fliC genes in vaccinal strain and Iranian C.chauvoei isolates. METHODS: Six specific primers for amplificationof fliA, fliB, and flagellin (fliC) genes were designedby Oligo software. Polymerase chain reaction was performedto amplify a fragment of 700 bp for both copies of flagellin(fliA and fliB) genes. The nucleotide percentage identity anddivergence among isolates were deduced using BlAST andMegAlign softwares. RESULTS: It was found that divergencein fliB was more than fliA by sequence alignment analysis. Sixhighly conserve regions, thirty-one SNPs and 13 amino acidpolymorphisms were found in fliC gene (between fliA and fliBsequences) of Iranian C. chauvoei isolates. In comparativeanalysis, genomic similarity of the fliA and fliB genes betweenthe vaccinal strain and examined field isolates was proved to beas high as 97.3 % and 98.2%, respectively. CONCLUSIONS: ThefliC copies were identified as excellent biomarkers to study themolecular epidemiology and strain diversity among C. chauvoeiisolates. The existence of genetic variation between twoalleles of fliC gene in C. chauvoei is reported for the first timein Iran. In spite of some genetic variations, the immunologiccross protection test showed a high protection power of the localvaccine (produced by Razi Institute) against homologousand heterologous challenge.