title: The role of fimbriae and flagella in the adherence of avian strains of Escherichia coli O78:K80 to tissue culture cells and tracheal and gut explants.
abstract: To investigate the role of fimbriae and flagella in the pathogenesis of avian colibacillosis, isogenic insertionally inactivated mutant strains of Escherichia coli O78:K80 strain EC34195 defective in the elaboration of type-1 and curli fimbriae and flagella were constructed by allelic exchange. Single and multiple non-fimbriate and non-flagellate mutant strains were compared to the wild-type in vitro in adherence assays with a HEp-2 cell line, a mucus-secreting cell line HT2916E, a non-mucus-secreting cell line HT2919A, tracheal explant and proximal gut explant. Mutant strains defective in the elaboration of type-1 fimbriae were significantly less adherent--in the order of 90% reduction--than the wild-type strain in all assays. Mutant strains defective in the elaboration of flagella were generally as adherent as the wild-type strain except when assayed with the mucus-secreting cell line HT2916E, for which a significant reduction of adherence--of the order of 90%--compared with the wild-type strain was observed. Mutant strains defective for the elaboration of curli fimbriae adhered as well as the wild-type strain in all assays, except when assayed in tests with gut explant tissue for which a significant reduction of adherence--of the order of 80%--compared with the wild-type strain was observed. Adherence to explants was to epithelial, not serous, surfaces and was 10-fold greater to tracheal than to gut explants. Together, these data support the hypothesis that type-1 fimbriae are significant factors in adherence, aided by flagella for penetration of mucus and curli fimbriae for adherence to the gut.
authors.affiliation: Bacteriology Department, Veterinary Laboratories Agency (Weybridge), New Haw, Addlestone, Surrey KT15 3NB.
authors.forename: R M
authors.initials: RM
authors.lastname: LA Ragione
authors.affiliation: Bacteriology Department, Veterinary Laboratories Agency (Weybridge), New Haw, Addlestone, Surrey KT15 3NB.
authors.forename: W A
authors.initials: WA
authors.lastname: Cooley
authors.affiliation: Bacteriology Department, Veterinary Laboratories Agency (Weybridge), New Haw, Addlestone, Surrey KT15 3NB.
authors.forename: M J
authors.initials: MJ
authors.lastname: Woodward
mesh_terms: D000818:Animals; D001422:Bacterial Adhesion; D001717:Birds; D015139:Blotting, Southern; D002460:Cell Line; D002645:Chickens; D046508:Culture Techniques; D004386:Duodenum / Q000382:microbiology* / Q000648:ultrastructure; D004926:Escherichia coli / Q000472:pathogenicity / Q000502:physiology* / Q000648:ultrastructure; D004927:Escherichia coli Infections / Q000382:microbiology / Q000473:pathology; D010861:Fimbriae, Bacterial / Q000502:physiology*; D005407:Flagella / Q000502:physiology*; D008855:Microscopy, Electron, Scanning; D009154:Mutation; D016133:Polymerase Chain Reaction; D011897:Random Allocation; D013047:Specific Pathogen-Free Organisms; D014132:Trachea / Q000382:microbiology* / Q000648:ultrastructure