Genetic engineering of avian pathogenic E. coli to study the functions of FimH adhesin.

Adhesion of pathogen to host cells is an important prerequisite for successful colonization and establishment of the pathogenesis. The aim of this study is to examine the function of FimH adhesin in the adherence of avian pathogenic E. coli to porcine intestinal epithelial cell lines (IPEC-J2) and human lung epithelial cell line (A549) in an in vitro infection model. Three strains of avian pathogenic Escherichia coli (APEC) and one strain of non-pathogenic E coli were used. The isogenic FimH mutants were constructed by lambda Red-mediated recombination system. The wild types and mutants strains were adhered to the host cells with different adherence patterns in certain incubation time. The results demonstrated that the adherence of the isogenic FimH mutants to the porcine intestinal epithelial cells (IPEC-J2) were similar to those of wild types. However, the adherences of isogenic FimH mutants to human lung epithelial cells (A549) were significantly different from the wild types. A549 cell can be used as a type of cell model for colonization of the chicken extraintestinal. FimH offers a unique opportunity to investigate the role of the strength of adhesion independently from the many other factors that may affect surface colonization.