MOLECULAR ANALYSIS OF AVIAN INFECTIOUS BRONCHITIS VIRUS IN QALYOUBIA GOVERNORATE DURING 2017-2018

The regular updates of molecular studies of Avian Infectious Bronchitis Virus in Egypt become imperative specially with the ongoing emergence of new strains of infectious bronchitis virus (IBV) that worsen the situation in poultry farms and causing extensive economic losses.In our study, we collect samples from twenty broiler flocks range from 18 to 36 days of age and manifested severe respiratory signs with mortality up to 30%.The collected flocks located in Qalyoubia governorate during period between January 2017 to December 2018.IBV Screening in collected samples was conducted by real time rRT-PCR targeting the nucleoprotein (N) gene.A total of 12 out of 20 examined farms were positive for IBV with percentage of (60%).Five positive IBV isolates were selected for amplification and sequencing of 400 -bp targeting the hypervariable region-3 (HVR 3) of S1 protein.Phylogenetic analysis confirmed that these viruses were closely related to each other (90-98% identity) and were clustered to variant II (GI 23) viruses within the Egy/Var-Ⅱ subgroup.The amino acids homology showed (75% to 80% identity) between our Egyptian/Qal variants and the common vaccine used for IBV infection in Egyptian poultry farms.