Role of flagella-related rPoN and fliA genes in Campylobacter jejuni

To investigate the role of the rpoN and fliA in the regulation of C.jejuni colonization, the rpoN fliA gene were inactivated by allelic exchange with a defective copy of the gene carrying a tetracycline-resistance cassette. Phenotypically, the C. jejuni rpoN mutant exhibited aflagellar filament on transmission electron microscopy and non motility on MH medium supplemented with 0.4% Bacto agar while the fliA mutant possessed a truncated flagellar filament in most cells and strongly diminished motility. Adhesion and invasion ability tests of the rpoN and fliA mutants were performed to assess the role of the these genes in regulating C. jejuni infection. The rpoN and fliA mutants showed significantly less (p<0.0005) adherence and invasion compared to the wild type C. jejuni. To determine the colonization capacity of C.jejuni rpoN and fliA mutants, 1 day old chicks were inoculated with the defined C.jejuni mutants. The C.jejuni rpoN and fliA mutants demonstrated a marked impairment in their ability to colonize chicks as none of 10 chickens inoculated with rpoN and fliA mutants were colonized. In conclusion control of flagellin expression in C.jejuni involves the alternative sigma factor genes rpoN and fliA. The results of this study are consistent with the previous results that bothfliA and rpoN genes regulate the process of binding and internalization of C.jejuni to epithelial cells in vitro and in vivo.