Histopathology of two serotypes (T & N1/88) of avian infectious bronchitis virus (IBV) in vaccinated and unvaccinated birds

The histopathology of Harderian gland, trachea, kidney and oviduct was studied in vaccinated and unvaccinated birds exposed to T and NI/88 strain of Infectious Bronchitis Virus (IBV). The trachea and kidney of vaccinated birds were protected to a moderate extent but the oviduct to only a small extent. The sequential histopathological changes revealed that IBV multiplies initially in the Harderian gland, then in the tracheal mucosa and simultaneously in the kidney and oviduct. The severity and persistence of lesions were greater in the shell gland and kidney of T infected birds whereas in trachea and Harderian gland the effects of the two IBV strains were similar. The NI/88 strain seemed to be more pathogenic for magnum of vaccinated and unvaccinated birds.