Enterohaemorrhagic Escherichia coli serogroup O111 inhibits NF-(kappa)B-dependent innate responses in a manner independent of a type III secreted OspG orthologue.
Enterohaemorrhagic and enteropathogenic Escherichia coli (EHEC and EPEC) inject a repertoire of effector proteins into host cells via a type III secretion system (T3SS) encoded by the locus of enterocyte effacement (LEE). OspG is an effector protein initially identified in Shigella that was shown to inhibit the host innate immune response. In this study, we found ospG homologues in EHEC (mainly of serogroup O111) and in Yersinia enterocolitica. The T3SS encoded by the LEE was able to inject these different OspG homologues into host cells. Infection of HeLa cells with EHEC O111 inhibited the NF-kappaB-dependent innate immune response via a T3SS-dependent mechanism. However, an EHEC O111 ospG mutant was still able to inhibit NF-kappaB p65 transfer to the nucleus in infected cells stimulated by tumour necrosis factor alpha (TNF-alpha). In addition, no difference in the inflammatory response was observed between wild-type EHEC O111 and the isogenic ospG mutant in the rabbit ligated intestinal loop model. These results suggest that OspG is not the sole effector protein involved in the inactivation of the host innate immune system during EHEC O111 infection.
Nobe
Rika
R
Université de Toulouse, ENVT, UMR1225, F-31076 Toulouse, France.|INRA, UMR1225, ENVT, F-31076 Toulouse, France.
Nougayrède
Jean-Philippe
JP
Université de Toulouse, ENVT, UMR1225, F-31076 Toulouse, France.|INRA, UMR1225, ENVT, F-31076 Toulouse, France.
Taieb
Frédéric
F
Université de Toulouse, ENVT, UMR1225, F-31076 Toulouse, France.|INRA, UMR1225, ENVT, F-31076 Toulouse, France.
Bardiau
Marjorie
M
Department of Infectious Diseases, Bacteriology, Faculty of Veterinary Medicine, University of Liège, Sart Tilman, Liège B4000, Belgium.
Cassart
Dominique
D
Department of Morphology and Pathology, Faculty of Veterinary Medicine, University of Liège, Sart Tilman, Liège B4000, Belgium.
Navarro-Garcia
Fernando
F
Department of Cell Biology, Centro de Investigación y de Estudios Avanzados (CINVESTAV-IPN), Ap. Postal 14-740, 07000 Mexico DF, Mexico.
Mainil
Jacques
J
Department of Infectious Diseases, Bacteriology, Faculty of Veterinary Medicine, University of Liège, Sart Tilman, Liège B4000, Belgium.
Hayashi
Tetsuya
T
Division of Bioenvironmental Science, Frontier Science Research Center, University of Miyazaki, 5200 Kiyotake, Miyazaki 889-1692, Japan.
Oswald
Eric
E
Université de Toulouse, ENVT, UMR1225, F-31076 Toulouse, France.|INRA, UMR1225, ENVT, F-31076 Toulouse, France.
D000595:Amino Acid Sequence; D000818:Animals; D054324:Enterohemorrhagic Escherichia coli / Q000276:immunology* / Q000472:pathogenicity*; D054308:Enteropathogenic Escherichia coli / Q000276:immunology / Q000472:pathogenicity; D004927:Escherichia coli Infections / Q000276:immunology* / Q000382:microbiology* / Q000473:pathology; D029968:Escherichia coli Proteins / Q000502:physiology*; D023061:Gene Order; D006367:HeLa Cells; D006801:Humans; D007113:Immunity, Innate; D007422:Intestines / Q000382:microbiology / Q000473:pathology; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000037:antagonists & inhibitors*; D011817:Rabbits; D016415:Sequence Alignment; D012703:Serotyping; D037521:Virulence Factors / Q000502:physiology*
D029968:Escherichia coli Proteins; D016328:NF-kappa B; C545437:OspG protein, E coli; D037521:Virulence Factors