title: Avian pathogenic Escherichia coli MT78 invades chicken fibroblasts.
abstract: Avian pathogenic Escherichia coli (APEC) are responsible for extraintestinal diseases, called colibacillosis, in avian species. The most severe manifestation of the disease is colisepticemia that usually starts at the respiratory tract and may result in bird death. However, it is not yet clear how APEC cross the respiratory epithelium and get into the bloodstream. In this work, we studied the interaction between 8 APEC strains (UEL31, UEL17, UEL13, UEL29, MT78, IMT5155, IMT2470, A2363) and a chicken non-phagocytic cell, the fibroblast CEC-32 cell line. We investigated the association profile, the invasion capability, the cytotoxicity effect and the induction of caspase-3/7 activation in an attempt to understand the way the pathogen gains access to the host bloodstream. Association to cells was determined after 1 h of infection, while cell invasion was determined after 4 and 24 h of infection. The cytotoxic effect of bacterial infection was measured by lactate dehydrogenase (LDH) release and the activation of the apoptotic program was verified by caspase-3/7 activation. Also, the presence of genes for adhesins, invasins and other related virulence-associated factors was verified by PCR. All bacterial strains showed similarity in relation to adhesion, LDH release and caspase-3/7 activation. However, one APEC strain, MT78, showed high invasion capability, comparable to the invasive Salmonella typhimurium strain SL1344. Since an APEC strain was capable of invading non-phagocytic cells in vitro, the same may be happening with the epithelial cells of the avian respiratory tract in vivo. CEC-32 monolayers can also provide a useful experimental model to study the molecular mechanisms used by APEC to invade non-phagocytic cells.
authors.affiliation: Departamento de Biofísica, Universidade Federal do Rio Grande do Sul, PO Box 15005, 9500 Av. Bento Gonçalves, 91501-970 Porto Alegre, RS, Brazil.
authors.forename: Letícia Beatriz
authors.initials: LB
authors.lastname: Matter
authors.forename: Nicolle Lima
authors.initials: NL
authors.lastname: Barbieri
authors.forename: Marcel
authors.initials: M
authors.lastname: Nordhoff
authors.forename: Christa
authors.initials: C
authors.lastname: Ewers
authors.forename: Fabiana
authors.initials: F
authors.lastname: Horn
mesh_terms: D018829:Adhesins, Bacterial / Q000235:genetics; D000818:Animals; D001422:Bacterial Adhesion; D053148:Caspase 3 / Q000378:metabolism; D053179:Caspase 7 / Q000378:metabolism; D002460:Cell Line; D002645:Chickens / Q000382:microbiology*; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development / Q000472:pathogenicity*; D004927:Escherichia coli Infections / Q000382:microbiology / Q000662:veterinary*; D029968:Escherichia coli Proteins / Q000235:genetics; D005347:Fibroblasts / Q000378:metabolism / Q000382:microbiology*; D005838:Genotype; D011201:Poultry Diseases / Q000382:microbiology*; D012137:Respiratory System / Q000378:metabolism / Q000382:microbiology; D037521:Virulence Factors / Q000235:genetics
chemical_list: D018829:Adhesins, Bacterial; D029968:Escherichia coli Proteins; D037521:Virulence Factors; D053148:Caspase 3; D053179:Caspase 7