title: Long-term colonisation-inhibition studies to protect broilers against colonisation with Salmonella Enteritidis, using Salmonella Pathogenicity Island 1 and 2 mutants.
abstract: Mutants in the Salmonella Pathogenicity Island 1 (hilA and sipA) and 2 (ssrA) were tested for their potential to induce protection against infection by homologous virulent Salmonella Enteritidis challenge strain, administered 24h later, in chickens. Although they colonised the internal organs to a significantly lower degree compared to the wild type strain, both a sipA and a ssrA mutant persistently colonised the gut when inoculated to newly hatched chicks. After inoculation of 1-day-old chicks with a sipA or a ssrA mutant and subsequent challenge with a wild type Salmonella Enteritidis 24h later, a significant degree of resistance against caecal and internal organ colonisation by the challenge strain was found. The protection lasted for the full 6 weeks of study, but due to their persistence, the sipA and ssrA mutants are not useful to induce broiler protection. After inoculation of newly hatched chicks with a hilA mutant no positive cloacal swabs could be detected anymore at 4 weeks post-inoculation and the hilA mutant was almost completely cleared from the gut. When newly hatched chicks were inoculated with a hilA mutant and challenged 24h later, the excretion of the virulent challenge strain was significantly reduced and the intestinal colonisation of the challenge strain was inhibited to a high level until the age of 9 days. Moreover, the hilA mutant exerted a significant profound inhibition of internal organ colonisation by the virulent challenge strain throughout the study period. The approach of vaccination with a hilA mutant strain can be a valuable basis for development of vaccine strains for broilers protection.
authors.affiliation: Department of Pathology, Bacteriology and Avian Diseases, Research Group Veterinary Public Health and Zoonoses, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820 Merelbeke, Belgium. Lotte.Bohez@UGent.be
authors.forename: Lotte
authors.initials: L
authors.lastname: Bohez
authors.forename: Richard
authors.initials: R
authors.lastname: Ducatelle
authors.forename: Frank
authors.initials: F
authors.lastname: Pasmans
authors.forename: Freddy
authors.initials: F
authors.lastname: Haesebrouck
authors.forename: Filip
authors.initials: F
authors.lastname: Van Immerseel
mesh_terms: D000818:Animals; D001428:Bacterial Vaccines / Q000235:genetics / Q000276:immunology*; D002432:Cecum / Q000382:microbiology; D002645:Chickens; D004195:Disease Models, Animal; D044404:Genomic Islands / Q000235:genetics*; D008099:Liver / Q000382:microbiology; D011201:Poultry Diseases / Q000276:immunology / Q000517:prevention & control*; D012481:Salmonella Infections, Animal / Q000276:immunology / Q000517:prevention & control*; D012477:Salmonella enteritidis / Q000235:genetics / Q000276:immunology* / Q000472:pathogenicity; D013047:Specific Pathogen-Free Organisms; D013154:Spleen / Q000382:microbiology; D014613:Vaccines, Attenuated / Q000235:genetics / Q000276:immunology*
chemical_list: D001428:Bacterial Vaccines; D014613:Vaccines, Attenuated