title: Experimental infection of chickens by a flagellated motile strain of Salmonella enterica serovar Gallinarum biovar Gallinarum.
abstract: Salmonella enterica subsp. enterica serovar Gallinarum biovar Gallinarum (SG) causes fowl typhoid (FT), a septicaemic disease which can result in high mortality in poultry flocks. The absence of flagella in SG is thought to favour systemic invasion, since bacterial recognition via Toll-like receptor (TLR)-5 does not take place during the early stages of FT. In the present study, chicks susceptible to FT were inoculated with a wild type SG (SG) or its flagellated motile derivative (SG Fla(+)). In experiment 1, mortality and clinical signs were assessed, whereas in experiment 2, gross pathology, histopathology, systemic invasion and immune responses were evaluated. SG Fla(+) infection resulted in later development of clinical signs, lower mortality, lower bacterial numbers in the liver and spleen, and less severe pathological changes compared to SG. The CD8(+) T lymphocyte population was higher in the livers of chicks infected with SG at 4 days post-inoculation (dpi). Chicks infected with SG had increased expression of interleukin (IL)-6 mRNA in the caecal tonsil at 1 dpi and increased expression of IL-18 mRNA in the spleen at 4 dpi. In contrast, the CD4(+) T lymphocyte population was higher at 6 dpi in the livers of birds infected with SG Fla(+). Therefore, flagella appeared to modulate the chicken immune response towards a CD4(+) T profile, resulting in more efficient bacterial clearance from systemic sites and milder infection.
authors.affiliation: School of Agricultural and Veterinary Sciences, Universidade Estadual Paulista, Jaboticabal, São Paulo 14884900, Brazil.
authors.forename: P D
authors.initials: PD
authors.lastname: Lopes
authors.affiliation: School of Agricultural and Veterinary Sciences, Universidade Estadual Paulista, Jaboticabal, São Paulo 14884900, Brazil. Electronic address: oliveirocaetano@yahoo.com.br.
authors.forename: O C
authors.initials: OC
authors.lastname: Freitas Neto
authors.affiliation: School of Agricultural and Veterinary Sciences, Universidade Estadual Paulista, Jaboticabal, São Paulo 14884900, Brazil.
authors.forename: D F A
authors.initials: DF
authors.lastname: Batista
authors.affiliation: School of Agricultural and Veterinary Sciences, Universidade Estadual Paulista, Jaboticabal, São Paulo 14884900, Brazil.
authors.forename: J
authors.initials: J
authors.lastname: Denadai
authors.affiliation: School of Agricultural and Veterinary Sciences, Universidade Estadual Paulista, Jaboticabal, São Paulo 14884900, Brazil.
authors.forename: M F F
authors.initials: MF
authors.lastname: Alarcon
authors.affiliation: School of Agricultural and Veterinary Sciences, Universidade Estadual Paulista, Jaboticabal, São Paulo 14884900, Brazil.
authors.forename: A M
authors.initials: AM
authors.lastname: Almeida
authors.affiliation: School of Agricultural and Veterinary Sciences, Universidade Estadual Paulista, Jaboticabal, São Paulo 14884900, Brazil.
authors.forename: R O
authors.initials: RO
authors.lastname: Vasconcelos
authors.affiliation: Department of Poultry Diseases, Faculty of Veterinary Medicine, Cairo University, Giza Square 12211, Egypt.
authors.forename: A
authors.initials: A
authors.lastname: Setta
authors.affiliation: School of Veterinary Medicine and Science, University of Nottingham, Sutton Bonington, Leicestershire LE12 5RD, United Kingdom.
authors.forename: P A
authors.initials: PA
authors.lastname: Barrow
authors.affiliation: School of Agricultural and Veterinary Sciences, Universidade Estadual Paulista, Jaboticabal, São Paulo 14884900, Brazil.
authors.forename: A
authors.initials: A
authors.lastname: Berchieri
mesh_terms: D000818:Animals; D002645:Chickens; D005407:Flagella / Q000502:physiology; D007113:Immunity, Innate; D011201:Poultry Diseases / Q000276:immunology* / Q000382:microbiology; D011897:Random Allocation; D012481:Salmonella Infections, Animal / Q000276:immunology* / Q000382:microbiology; D019779:Salmonella enterica / Q000235:genetics / Q000472:pathogenicity*; D065288:Serogroup; D014774:Virulence
keywords: Domestic fowl; Fowl typhoid; Immune response; Pathogenicity; Salmonella enterica biovar Gallinarum