reduced egg production, and egg quality is also observed [2], [3].
The causative agent of IB is infectious bronchitis virus (IBV), a non-segmented, positive-sense, single-stranded RNA virus, which belongs to the genus Gammacoronavirus, family Coronaviridae, in the order Nidovirales [4]. The full length RNA genome of IBV is 27.6 kb in length and encodes non-