IMMUNITY RESPONSE FROM AN INACTIVATED INFECTIOUS BRONCHITIS VACCINE

Vaccination of chickens in two trials with a beta-propiolactone-inactivated infectious bronchitis virus (IBV) used in Great Britain failed to stimulate the formation of significant neutralizing antibodies against Massachusetts 41 and Beaudette IBV strains. Furthermore, upon challenge of immunity, all the chickens examined and tested were susceptible to infection and developed severe respiratory signs. No differences could be seen when the vaccinated chickens were compared with unvaccinated chickens using Massachusetts 41, Gray, and Holte IBV isolates from chickens in the United States as challenge.