title: Age-dependent immune responses and immune protection after avian coronavirus vaccination.
abstract: Infectious bronchitis virus (IBV) is an endemic disease of chickens and a major contributor to economic losses for the poultry industry despite vaccination. Recent observations indicated that chicks may have an immature immune system immediately after hatching when vaccinated for IBV. Therefore we hypothesized that early IBV vaccination will generate an immature, poorly protective IBV-specific immune response contributing to immune escape and persistence of IBV. To test this hypothesis the IBV-specific immune response and immune protection were measured in chicks vaccinated at different ages. This demonstrated a delayed production of IgG and IgA plasma antibodies in the 1, 7 and 14-day-old vaccination groups and also lower IgA antibody levels were observed in plasma of the 1-day-old group. Similar observations were made for antibodies in tears. In addition, IgG antibodies from the 1-day-old group had lower avidity indices than day 28 vaccinated birds. The delayed and/or lower antibody response combined with lower IgG avidity indices coincided with increased tracheal inflammation and depletion of tracheal epithelia cells and goblet cells upon IBV field strain challenge. The lack of vaccine-mediated protection was most pronounced in the 1-day-old vaccination group and to a lesser extent the 7-day-old group, while the 14-day-old and older chickens were protected. These data strongly support IBV vaccination after day 7 post hatch.
authors.affiliation: Department of Pathobiology, College of Veterinary Medicine, Auburn University, 217 Scott Ritchey Research Center, Auburn, AL 36849, USA. Electronic address: vangifw@auburn.edu.
authors.forename: Frederik W
authors.initials: FW
authors.lastname: van Ginkel
authors.affiliation: Department of Pathobiology, College of Veterinary Medicine, Auburn University, 217 Scott Ritchey Research Center, Auburn, AL 36849, USA.
authors.forename: Justin
authors.initials: J
authors.lastname: Padgett
authors.affiliation: Department of Pathobiology, College of Veterinary Medicine, Auburn University, 217 Scott Ritchey Research Center, Auburn, AL 36849, USA.
authors.forename: Gisela
authors.initials: G
authors.lastname: Martinez-Romero
authors.affiliation: Department of Pathobiology, College of Veterinary Medicine, Auburn University, 217 Scott Ritchey Research Center, Auburn, AL 36849, USA.
authors.forename: Matthew S
authors.initials: MS
authors.lastname: Miller
authors.affiliation: Department of Pathobiology, College of Veterinary Medicine, Auburn University, 217 Scott Ritchey Research Center, Auburn, AL 36849, USA.
authors.forename: Kellye S
authors.initials: KS
authors.lastname: Joiner
authors.affiliation: Department of Pathobiology, College of Veterinary Medicine, Auburn University, 217 Scott Ritchey Research Center, Auburn, AL 36849, USA.
authors.forename: Stephen L
authors.initials: SL
authors.lastname: Gulley
mesh_terms: D000367:Age Factors; D000818:Animals; D000914:Antibodies, Viral / Q000097:blood*; D000915:Antibody Affinity; D002645:Chickens; D018352:Coronavirus Infections / Q000473:pathology / Q000517:prevention & control / Q000662:veterinary*; D007070:Immunoglobulin A / Q000097:blood; D007074:Immunoglobulin G / Q000097:blood; D001351:Infectious bronchitis virus / Q000276:immunology*; D011201:Poultry Diseases / Q000276:immunology / Q000473:pathology* / Q000517:prevention & control*; D014765:Viral Vaccines / Q000008:administration & dosage* / Q000276:immunology*
chemical_list: D000914:Antibodies, Viral; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D014765:Viral Vaccines
keywords: Age-dependent immunity; Antibody kinetics; Avian coronavirus; Avidity index; Infectious bronchitis virus; Mucosal immunity