title: Evaluation of protective immune response against fowl typhoid in chickens vaccinated with the attenuated strain Salmonella Gallinarum ΔcobSΔcbiA.
abstract: Salmonella enterica serovar Gallinarum biovar Gallinarum (SG) causes fowl typhoid in chickens, a septicemic infection which results in high mortality rates. This disease causes high economic impact to the poultry industry worldwide because of the mortality or elimination of positive flocks to control bacterial dissemination. Live vaccines are used in the fields, however the characterization of immune mechanisms important for protection are being studied to improve the efficacy of vaccination schemes. In this study, we evaluated the immune response in brown layer-hens, vaccinated or not, during the most critical period of infection. Cellular and humoral immunity were extensively evaluated until 7 days post-infection (DPI), by flow cytometry and ELISA, respectively. Furthermore, we evaluated the expression of important pro-inflammatory cytokines after infection of bone marrow derived macrophages (BMDMs) with the live attenuated SG vaccine and with the wild SG strain. The results showed an increasing production of IgG and IgM during the first week post-infection, in vaccinated layer-hens, which was absent in unvaccinated birds. The population of CD8(+)CD44(+) and CD4(+)CD44(+) T cells in spleen and cecal tonsils constantly decreased in unvaccinated birds in comparison with vaccinated layers. The expression of IFN-γ and TNF-α in BMDMs was induced by both SG strains (attenuated and wild) at similar levels (p>0.05). Vaccination with live SG vaccine reduced systemic infection by challenge strain of SG and prevented the mortality rate of 85% that occurred in unvaccinated layer-hens during 30 dpi. Furthermore, the immunization enhanced the proliferation of effector CD4(+) and CD8(+) T cells after challenge.
authors.affiliation: School of Agricultural and Veterinary Sciences, São Paulo State University (UNESP), Jaboticabal Campus, SP, Brazil, 14884-900; College of Veterinary Medicine, Cornell University, Ithaca, NY, USA. Electronic address: rafaelpenha12@yahoo.com.br.
authors.forename: Rafael Antonio Casarin
authors.initials: RAC
authors.lastname: Penha Filho
authors.affiliation: School of Agricultural and Veterinary Sciences, São Paulo State University (UNESP), Jaboticabal Campus, SP, Brazil, 14884-900.
authors.forename: Silvia Juliana Acelas
authors.initials: SJA
authors.lastname: Diaz
authors.affiliation: Ribeirão Preto Medical School, University of São Paulo (USP), Ribeirão Preto, SP, Brazil, 14049-900.
authors.forename: Tiago da Silva
authors.initials: TDS
authors.lastname: Medina
authors.affiliation: College of Veterinary Medicine, Cornell University, Ithaca, NY, USA.
authors.forename: Yung-Fu
authors.initials: YF
authors.lastname: Chang
authors.affiliation: Ribeirão Preto Medical School, University of São Paulo (USP), Ribeirão Preto, SP, Brazil, 14049-900.
authors.forename: João Santana
authors.initials: JS
authors.lastname: da Silva
authors.affiliation: School of Agricultural and Veterinary Sciences, São Paulo State University (UNESP), Jaboticabal Campus, SP, Brazil, 14884-900.
authors.forename: Angelo
authors.initials: A
authors.lastname: Berchieri
mesh_terms: D000818:Animals; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D002645:Chickens / Q000276:immunology; D005260:Female; D056724:Immunity, Humoral; D007114:Immunization; D011201:Poultry Diseases / Q000382:microbiology / Q000517:prevention & control*; D012481:Salmonella Infections, Animal / Q000382:microbiology / Q000517:prevention & control*; D022562:Salmonella Vaccines / Q000276:immunology*; D019779:Salmonella enterica / Q000276:immunology; D014409:Tumor Necrosis Factor-alpha; D014613:Vaccines, Attenuated / Q000276:immunology
chemical_list: D022562:Salmonella Vaccines; D014409:Tumor Necrosis Factor-alpha; D014613:Vaccines, Attenuated
keywords: BMDM; T cells; acquired immunity; flow cytometry; live vaccine