title: Immunity to infectious bronchitis virus from spray vaccination with derivatives of a Holland strain.
abstract: Study was made of the protection of chickens from spray vaccination with different modifications of a Holland (H) strain of infectious bronchitis virus (IBV). Noted in each trial were the virus-serum-neutralizing antibody titers induced and the virulence of the vaccine virus at different passage levels. Protection against respiratory signs was good from challenge with a homologous virus serotype as well as with 5 heterologous IBV isolates. This occurred from vaccinating day-old chicks possessing homologous IBV antibodies as well as vaccinating susceptible 4-week-old chickens. The tracheal virus shed-rate following challenge was considered low (20% or less) with 4 of the challenge viruses. The challenge virus shed-rate was somewhat higher from vaccination at one day old than from vaccination at 4 weeks; the virus-serum-neutralization titers were lower, or even insignificant, with early-age vaccination. The immunogenicity and virulence of the vaccine virus was apparently reduced in the higher embryo passages employed. None of the vaccine derivatives was considered virulent under these conditions.
mesh_terms: D000336:Aerosols; D000818:Animals; D000914:Antibodies, Viral / Q000032:analysis; D002645:Chickens; D003332:Coronaviridae / Q000276:immunology*; D001351:Infectious bronchitis virus / Q000254:growth & development / Q000276:immunology*; D011201:Poultry Diseases / Q000276:immunology*; D014611:Vaccination / Q000662:veterinary*; D014765:Viral Vaccines / Q000008:administration & dosage*; D014777:Virus Diseases / Q000276:immunology / Q000662:veterinary
chemical_list: D000336:Aerosols; D000914:Antibodies, Viral; D014765:Viral Vaccines