SEQUENCING AND COMPARATIVE ANALYSIS OF FLAGELLIN GENES FLIA AND FLIB IN BOVINE CLOSTRIDIUM CHAUVOEI ISOLATES

BACKGROUND: Clostridium chauvoei is the etiological agent of blackleg as an endogenous infection in cattle. Flagella have been known to play a critical role in the protective immunity of animals to clostridial infections. C. chauvoei has two copies offli C gene, namely fliA and fliB. OBJECTIVES: The aim of this study was the determination and nucleotide sequence analysis of both copies offli C genes in vaccinal strain and Iranian C. chauvoeiisolates. METHODS: Six specific primers for amplification offliA, fliB, and flagellin (fli C) genes were designed by Oligo software. Polymerase chain reaction was performed to amplify a fragment of 700 bp for both copies of flagellin (fliA and fliB) genes. The nucleotide percentage identity and divergence among isolates were deduced using BlAST and MegAlign softwares. RESULTS: It was found that divergence infliB was more than fliA by sequence alignment analysis. Six highly conserve regions, thirty-one SNPs and 13 amino acid polymorphisms were found infli C gene (between fliA and fliB sequences) of Iranian C. chauvoei isolates. In comparative analysis, genomic similarity of thefli A and fliB genes between the vaccinal strain and examined field isolates was proved to be as high as 97.3 % and 98.2%, respectively. CONCLUSIONS: The fliC copies were identified as excellent biomarkers to study the molecular epidemiology and strain diversity amongC. chauvoei isolates. The existence of genetic variation between two alleles offli C gene in C. chauvoei is reported for the first time in Iran. In spite of some genetic variations, the immunologic cross protection test showed a high protection power of the local vaccine (produced by Razi Institute) against homologous and heterologous challenge.