title: Humoral and cell-mediated immune responses to different doses of attenuated vaccine against avian infectious bronchitis virus.
abstract: The antibody and cellular immune responses against infectious bronchitis virus (IBV) were evaluated at mucosal sites of chickens after immunization with various doses of an attenuated vaccine at 1 day of age. The correlation of these immune responses with protection of tracheal tissues was evaluated after experimental infection of these birds. Significantly reduced tracheal pathologic effects, measured according to ciliostasis and histology lesions, and reduced viral load were observed only in the full-dose vaccinated group at 5 days post-infection (dpi), while incomplete protection was observed for the subdose vaccinated groups. Moreover, birds of vaccinated groups, especially with full dose, developed higher levels of lachrymal IBV-specific IgG and IgA and increased the expression of cell-mediated immunity (CMI) genes, such as gamma interferon (IFNγ), CD8+ T cell marker, and granzyme homolog A more rapidly. In addition, these humoral and cellular immune responses evaluated at mucosal sites correlated significantly with tracheal protection against homologous IBV challenge in a vaccine dose-dependent manner. The results indicate that IgG, IgA and CD8+ T cell responses developed at mucosal sites after IBV vaccination of day-old chicks, could be taken as good correlates of protection against this virus.
authors.affiliation: Laboratory of Immunology and Virology, Department of Veterinary Pathology, Universidade Estadual Paulista, Jaboticabal, SP, Brazil. c_okino@yahoo.com.br
authors.forename: Cintia Hiromi
authors.initials: CH
authors.lastname: Okino
authors.forename: Antônio Carlos
authors.initials: AC
authors.lastname: Alessi
authors.forename: Maria de Fátima Silva
authors.initials: Mde F
authors.lastname: Montassier
authors.forename: Artur Jordão de Magalhães
authors.initials: AJ
authors.lastname: Rosa
authors.forename: Xiuqing
authors.initials: X
authors.lastname: Wang
authors.forename: Hélio José
authors.initials: HJ
authors.lastname: Montassier
mesh_terms: D000818:Animals; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D002645:Chickens / Q000276:immunology / Q000821:virology; D018352:Coronavirus Infections / Q000276:immunology* / Q000517:prevention & control / Q000662:veterinary*; D053804:Granzymes / Q000096:biosynthesis; D007070:Immunoglobulin A / Q000097:blood; D007074:Immunoglobulin G / Q000097:blood; D001351:Infectious bronchitis virus / Q000276:immunology*; D007371:Interferon-gamma / Q000096:biosynthesis; D009092:Mucous Membrane / Q000276:immunology; D011201:Poultry Diseases / Q000276:immunology* / Q000821:virology; D014132:Trachea / Q000276:immunology / Q000473:pathology / Q000821:virology; D014613:Vaccines, Attenuated / Q000008:administration & dosage / Q000276:immunology*; D019562:Viral Load / Q000276:immunology / Q000662:veterinary; D014765:Viral Vaccines / Q000008:administration & dosage / Q000276:immunology
chemical_list: D007070:Immunoglobulin A; D007074:Immunoglobulin G; D014613:Vaccines, Attenuated; D014765:Viral Vaccines; D007371:Interferon-gamma; D053804:Granzymes