Histological examinations revealed that although there were no differences in the severity of pathology following virus challenge among the rFPV-IBVS1, rFPV-IBVS1-ChIFNγ and the attenuated live IB vaccine groups, the time period of pathological changes persisted and the detection of IBV antigen in kidney was shortened by 3 days in the rFPV-IBVS1-ChIFNγ group. However, it is important to note that all chickens were susceptible to IBV challenge and local replication of viruses was not effectively suppressed in any of these vaccinated groups.