ROLE OF FLAGELLA IN ADHERENCE, INTERNALIZATION, AND TRANSLOCATION OF CAMPYLOBACTER-JEJUNI IN NONPOLARIZED AND POLARIZED EPITHELIAL-CELL CULTURES

Previous studies of Campylobacter jejuni have suggested that flagellin is an adhesin for epithelial cells and that motility is a virulence f actor of this bacterium. The role of flagella in the interactions of C jejuni with nonpolarized and polarized epithelial cells was examined with flagellar mutants. Flagellated, nonmotile (flaA flaB+ Mot-) and n onflagellated, nonmotile (flaA flaB Mot-) mutants of C jejuni were con structed by in vivo homologous recombination and gene replacement tech niques. Both classes of mutants were found to adhere to cells of human epithelial origin (INT 407) equally well; however, on the basis of th e percentage of the inoculum internalized, internalization of the flaA flaB Mot- mutants was decreased by factors ranging from approximately 30 to 40 compared with the parent. The flaA flaB+ Mot- mutant was int ernalized by the INT 407 cells at levels six- to sevenfold higher than the flaA flaB Mot- mutants. Both classes of mutants, unlike the paren t, were unable to translocate across polarized Caco-2 monolayers. Thes e results indicate that flagella are not involved in C. jejuni adheren ce to epithelial cells but that they do play a role in internalization . Furthermore, the results suggest that either the motility of C. jeju ni or the product of flaA is essential for the bacterium to cross pola rized epithelial cell monolayers.