Evaluation of protective immunity in chickens vaccinated with combined IB H120/D274 and IB H120 against IS/1494/06 in Iran.

Infectious bronchitis virus (IBV) has a variety of serotypes that cause many problems in the poultry industry. Two H120 and H120-D274 live vaccines were evaluated against strain IS/1494/06 (variant 2) IBV challenge. The study aimed to determine whether it was possible to achieve success in controlling disease symptoms and pathological lesions and reducing virus shedding by combining two types of vaccines against different severities of poultry IBV.