Role of SPI-1 in the interactions of Salmonella Typhimurium with porcine macrophages.
Salmonella Pathogenicity Island 1 (SPI-1) genes are indispensable for virulence of Salmonella Typhimurium in mice after oral challenge. These genes mediate invasion in intestinal epithelial cells and induce cell death in murine macrophages. The role of SPI-1 in the pathogenesis of Salmonella Typhimurium infections in food producing animals is not known. It was the aim of the present study to characterize the interactions of a porcine Salmonella Typhimurium field strain and its isogenic mutants in the SPI-1 genes hilA, sipA and sipB with porcine macrophages. SPI-1 was found to be important in the invasion of porcine pulmonary alveolar macrophages (PAM) and the induction of the formation of spacious phagosomes. Both early and delayed cytotoxicity were seen in PAM, but only the early cytotoxicity was SPI-1 dependent. Exposure of PAM to Salmonella Typhimurium induced the production of reactive oxygen species (ROS) and interleukin-8, but no differences were noticed between the induction mediated by the wild type strain and its SPI-1 mutant strains. In conclusion, invasion of porcine macrophages and the induction of early, but not delayed, cytotoxicity by Salmonella Typhimurium is SPI-1 dependent. SPI-1 dependent invasion, however, is not a prerequisite to induce a pro-inflammatory response.
Boyen
F
F
Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820 Merelbeke, Belgium. filip.boyen@UGent.be
Pasmans
F
F
Donné
E
E
Van Immerseel
F
F
Adriaensen
C
C
Hernalsteens
J-P
JP
Ducatelle
R
R
Haesebrouck
F
F
D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology*; D003601:Cytotoxicity Tests, Immunologic; D017931:DNA Primers / Q000737:chemistry; D016209:Interleukin-8 / Q000096:biosynthesis; D016676:Macrophages, Alveolar / Q000166:cytology / Q000382:microbiology*; D008565:Membrane Proteins / Q000502:physiology; D008840:Microfilament Proteins / Q000502:physiology; D009154:Mutation / Q000502:physiology; D010588:Phagosomes / Q000382:microbiology; D017382:Reactive Oxygen Species / Q000378:metabolism; D012481:Salmonella Infections, Animal / Q000382:microbiology* / Q000503:physiopathology*; D012486:Salmonella typhimurium / Q000235:genetics / Q000472:pathogenicity*; D013552:Swine; D013997:Time Factors; D015534:Trans-Activators / Q000235:genetics / Q000502:physiology
D001426:Bacterial Proteins; D017931:DNA Primers; C102236:HilA protein, Salmonella; D016209:Interleukin-8; D008565:Membrane Proteins; D008840:Microfilament Proteins; D017382:Reactive Oxygen Species; C118287:SipA protein, Salmonella; C419942:Spi1 protein, Salmonella; D015534:Trans-Activators; C094579:invasion protein B, Salmonella typhimurium