Pathogenesis of two strains of infectious bronchitis virus for the oviduct of unvaccinated laying hens

The pathogenesis of Infectious Bronchitis Virus (IBV) for different parts of the oviduct was studied in unvaccinated Isa Brown laying hens exposed to T and N1/88 strains of IBV. Two hens from T and one hen from N1/88 infected groups went out of lay. Ultrastructural findings revealed that the infundibulum and magnum were more negatively affected than the isthmus, tubular shell gland and shell gland pouch. However, all parts of the oviduct of hens out of lay showed severe cytopathology. Overall, T strain was more pathogenic for the fully functional oviduct than N1/88. Virus particles were recorded on the 10th day p.i. and severe cytopathology was observed between 10 and 12 days p.i.