title: Monophasic expression of FliC by Salmonella 4,[5],12:i:- DT193 does not alter its pathogenicity during infection of porcine intestinal epithelial cells.
abstract: Non-typhoidal serotypes of Salmonella enterica remain important food-borne pathogens worldwide and the frequent emergence of epidemic strains in food-producing animals is a risk to public health. In recent years, Salmonella 4,[5],12:i:- isolates, expressing only phase 1 (FliC) of the two flagellar antigens, have emerged and increased in prevalence worldwide. In Europe, the majority of 4,[5],12:i:- isolates belong to phage types DT193 and DT120 of Salmonella Typhimurium and pigs have been identified as the reservoir species. In this study we investigated the ability of pig-derived monophasic (4,[5],12:i:-) and biphasic DT193 isolates to invade a porcine intestinal epithelial cell line (IPEC-1) and activate TLR-5, IL-8 and caspases. We found that the 4,[5],12:i:- isolates exhibited comparable adhesion and invasion to that of the virulent S. Typhimurium isolate 4/74, suggesting that these strains could be capable of colonizing the small intestine of pigs in vivo. Infection with 4,[5],12:i:- and biphasic DT193 isolates resulted in approximately the same level of TLR-5 (a flagellin receptor) and IL-8 (a proinflammatory chemokine) mRNA upregulation. The monophasic variants also elicited similar levels of caspase activation and cytotoxicity to the phase-variable DT193 isolates. These findings suggest that failure of 4,[5],12:i:- DT193 isolates to express a second phase of flagellar antigen (FljB) is unlikely to hamper their pathogenicity during colonization of the porcine intestinal tract.
authors.affiliation: Department of Infection Biology, Institute of Infection & Global Health and School of Veterinary Science, University of Liverpool, Leahurst Campus, Cheshire, UK.
authors.forename: Georgina
authors.initials: G
authors.lastname: Crayford
authors.affiliation: Department of Infection Biology, Institute of Infection & Global Health and School of Veterinary Science, University of Liverpool, Leahurst Campus, Cheshire, UK.
authors.forename: Janine L
authors.initials: JL
authors.lastname: Coombes
authors.affiliation: College of Medicine, Swansea University, Singleton Park, Swansea, UK.
authors.forename: Tom J
authors.initials: TJ
authors.lastname: Humphrey
authors.affiliation: Department of Infection Biology, Institute of Infection & Global Health and School of Veterinary Science, University of Liverpool, Leahurst Campus, Cheshire, UK.
authors.forename: Paul
authors.initials: P
authors.lastname: Wigley
mesh_terms: D000818:Animals; D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001434:Bacteriophage Typing; D004847:Epithelial Cells / Q000382:microbiology*; D005408:Flagellin / Q000235:genetics / Q000378:metabolism*; D007422:Intestines / Q000382:microbiology*; D012481:Salmonella Infections, Animal / Q000382:microbiology*; D012486:Salmonella typhimurium / Q000145:classification / Q000302:isolation & purification / Q000472:pathogenicity* / Q000502:physiology; D013552:Swine; D013553:Swine Diseases / Q000382:microbiology*; D014774:Virulence
chemical_list: D001426:Bacterial Proteins; D005408:Flagellin