Detection of Israel variant 2 (IS/1494/06) genotype of Infectious Bronchitis Virus in a layer chicken flock

The aim of this study was to determine an infectious bronchitis (IB) infection, caused by Israel variant 2 (IS/1494/06)-like IBV, in a layer chicken flock regularly vaccinated with vaccines containing IBV H120 and 4/91 strains. Mild respiratory symptoms, drop egg production soft-shelled eggs eventually death were observed flock. Clinical samples from four diseased chickens examined for the detection genotyping virus isolation, commercial real time reverse transcription polymerase chain reaction (rRT-PCR) nucleotide sequencing. Both (IS-Var2) 793/B serotypes detected rRT-PCR, but sequencing results 345 bp part S1 gene revealed that our isolate, HFT-IBV, IS/1494/06 (IS-Var2)-like 97.7% genetic similarity. These suggested immunity against vaccination combination different genotypes (H120 4/91) could not be protective IS-Var2 field infection. In addition, identification clinical samples, such as swabs organ rRT-PCR assays failed find correct genotype responsible IB whereas analysis gold standard test undoubtedly causative Also, findings indicated there is urgent need consider genotype- or protectotype-match strategies prevent vaccine- IB-dependent economic losses poultry sector logically protect