Evaluation of protective immunity in chickens vaccinated with combined IB H۱۲۰/D۲۷۴ and IB H۱۲۰ against IS/۱۴۹۴/۰۶ in Iran

Infectious bronchitis virus (IBV) has a variety of serotypes that cause many problems in the poultry industry. Two H۱۲۰ and H۱۲۰-D۲۷۴ live vaccines were evaluated against strain IS/۱۴۹۴/۰۶ (variant ۲) infectious bronchitis virus challenge. The study aimed to determine whether it is 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 the Poultry Infectious Bronchitis Virus. After random selection of ۱۰۰ SPF chickens, four ۲۵ chicks/group experimental groups were arranged in the H۱۲۰ (IB-H۱۲۰, Intervet®; Serial No: **** at ۱st day + Booster ۱۴th day + Challenged with IS/۱۴۹۴/۰۶- ۱۴ DPV), H۱۲۰-D۲۷۴ (Poulvac® IB Primer at ۱st day + Booster ۱۴th day + Challenged with IS/۱۴۹۴/۰۶- ۱۴ DPV), Control (No vaccine and No Challenge), and Challenged (No vaccine + Challenge). After euthanasia of the animals on the ۴۲nd day of the research, serum neutralization (days ۱۴, ۲۸, and ۴۲), ELISA (۱۴ days after the booster vaccine and before challenged), Ciliostasis (۷ days after the booster vaccine and seven days after challenged) and pathological lesion scores were evaluated on day ۱۴ after being infected with IS/۱۴۹۴/۰۶ type ۲ strain (day ۴۲). Also, the virus shedding was monitored by real-time RT-PCR. Infection with the IS/۱۴۹۴/۰۶ variant۲ strain showed high to moderate ciliostasis and pathologic scores. All groups that received the IB-H۱۲۰-D۲۷۴ vaccine had fewer lesions relatively. The IB-H۱۲۰-D۲۷۴ vaccinated groups showed the highest protection rates and high protection scores (۷۰.۳) compared to the IB-H۱۲۰ vaccine groups (۲۴.۴). The virus shedding was significantly reduced in groups that received the H۱۲۰-D۲۷۴ vaccine compared to those that received the IB-H۱۲۰ vaccine. In conclusion, the homologous IB-H۱۲۰-D۲۷۴ vaccine showed superior results compared to the IB-H۱۲۰ vaccine.

کلیدواژه ها:

IBV ، combined vaccine ، Serum neutralization test ، ELISA ، Real-time PCR