title: Salmonella Typhimurium SPI-1 genes promote intestinal but not tonsillar colonization in pigs.
abstract: Salmonella Pathogenicity Island 1 (SPI-1) genes are indispensable for virulence of Salmonella Typhimurium in several animal species. The role of SPI-1 in the pathogenesis of Salmonella Typhimurium infections of pigs, however, is not well described. The interactions of a porcine Salmonella Typhimurium field strain and its isogenic mutants with disruptions in the SPI-1 genes hilA, sipA and sipB with porcine intestinal epithelial cells were characterized in vitro and in a ligated intestinal loop model in pigs. HilA and SipB were essential in the invasion of porcine intestinal epithelial cells in vitro. A sipA mutant was impaired for invasion using a polarized cell line, but fully invasive in a non-polarized cell line. All SPI-1 mutants induced a significant decrease in influx of neutrophils in the porcine intestinal loop model compared with the wild type strain. Pigs were orally inoculated with 10(8) colony forming units of both the wild type Salmonella Typhimurium strain and its isogenic sipB::kan mutant strain. The sipB mutant strain was significantly impaired to invade the intestinal, but not the tonsillar tissue, one day after inoculation and was unable to efficiently colonize the intestines and the GALT, but not the tonsils, 3 days after inoculation. This study shows that SPI-1 plays a crucial role in the invasion and colonization of the porcine gut and in the induction of influx of neutrophils towards the intestinal lumen, but not in the colonization of the tonsils.
authors.affiliation: Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium. filip.boyen@ugent.be
authors.forename: Filip
authors.initials: F
authors.lastname: Boyen
authors.forename: Frank
authors.initials: F
authors.lastname: Pasmans
authors.forename: Filip
authors.initials: F
authors.lastname: Van Immerseel
authors.forename: Eirwen
authors.initials: E
authors.lastname: Morgan
authors.forename: Connie
authors.initials: C
authors.lastname: Adriaensen
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Hernalsteens
authors.forename: Annemie
authors.initials: A
authors.lastname: Decostere
authors.forename: Richard
authors.initials: R
authors.lastname: Ducatelle
authors.forename: Freddy
authors.initials: F
authors.lastname: Haesebrouck
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000502:physiology; D002460:Cell Line; D004847:Epithelial Cells / Q000382:microbiology*; D044404:Genomic Islands / Q000502:physiology*; D007082:Ileum / Q000276:immunology / Q000382:microbiology; D007958:Leukocyte Count; D008198:Lymph Nodes / Q000382:microbiology; D008297:Male; D008565:Membrane Proteins / Q000502:physiology; D008840:Microfilament Proteins / Q000502:physiology; D009154:Mutation; D009504:Neutrophils / Q000276:immunology; D009924:Organ Culture Techniques; D014066:Palatine Tonsil / Q000382:microbiology*; D012480:Salmonella Infections / Q000382:microbiology*; D012486:Salmonella typhimurium; D013552:Swine; D015534:Trans-Activators / Q000502:physiology
chemical_list: D001426:Bacterial Proteins; C102236:HilA protein, Salmonella; D008565:Membrane Proteins; D008840:Microfilament Proteins; C118287:SipA protein, Salmonella; D015534:Trans-Activators; C094579:invasion protein B, Salmonella typhimurium