Intestinal colonisation-inhibition and virulence of Salmonella phoP, rpoS and ompC deletion mutants in chickens.
Administration of live Salmonella strains to day-old chicks provides profound protection against superinfection with a related strain within a matter of hours by a colonisation-inhibition mechanism, which is primarily a bacterial physiological process. Although currently available, commercial, live attenuated Salmonella vaccines induce protection by adaptive immunity, none of them is able to induce protection against Salmonella organisms by colonisation-inhibition and, therefore, they are unable to protect newly-hatched birds immediately after oral vaccination. In this study, mutants of Salmonella Typhimurium and Enteritidis with deletions in phoP and rpoS, either alone or in combination with ompC, were characterised and tested for their level of attenuation and their ability to inhibit the intestinal colonisation of the isogenic parent strains in chickens. Mutants with deletions only in rpoS demonstrated an unaffected potential to inhibit the intestinal colonisation of the challenge strain but were still fully virulent for the chickens. Mutants with deletions in phoP, either alone or in combination with rpoS, resulted in a high level of attenuation, unimpaired ability to colonise the gut and a nearly unaffected potential to inhibit the challenge strain from caecal colonisation. Mutants with an additional deletion in ompC revealed a reduced capacity of intestinal colonisation-inhibition when compared to the control strains and both the single rpoS and the phoP deletion mutants. Mutations in phoP- or phoP-regulated genes may therefore be used for the development of live attenuated Salmonella vaccines possessing these novel characteristics.
Methner
U
U
Federal Research Centre for Virus Diseases of Animals, Bundesforschungsanstalt für Viruskrankheiten der Tiere (BFAV) Institute for Bacterial Infections and Zoonoses, Naumburger Str. 96a, D-07743 Jena, Germany. u.methner@jena.bfav.de
Barrow
P A
PA
Gregorova
D
D
Rychlik
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I
D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000276:immunology; D002432:Cecum / Q000382:microbiology; D002645:Chickens; D015169:Colony Count, Microbial / Q000662:veterinary; D008099:Liver / Q000382:microbiology; D016254:Mutagenesis, Insertional; D018272:Porins / Q000235:genetics / Q000276:immunology; D011201:Poultry Diseases / Q000276:immunology / Q000382:microbiology* / Q000517:prevention & control; D012481:Salmonella Infections, Animal / Q000276:immunology* / Q000382:microbiology / Q000517:prevention & control; D022562:Salmonella Vaccines / Q000235:genetics* / Q000276:immunology; D012477:Salmonella enteritidis / Q000235:genetics* / Q000254:growth & development / Q000276:immunology; D012486:Salmonella typhimurium / Q000235:genetics* / Q000254:growth & development / Q000276:immunology; D012808:Sigma Factor / Q000235:genetics / Q000276:immunology; D014613:Vaccines, Attenuated / Q000235:genetics / Q000276:immunology; D014774:Virulence
D001426:Bacterial Proteins; C113724:OmpC protein; D018272:Porins; D022562:Salmonella Vaccines; D012808:Sigma Factor; D014613:Vaccines, Attenuated; C069567:sigma factor KatF protein, Bacteria; C061064:PhoP protein, Bacteria