The present invention relates i.a. to a 4/91 IBV (infectious bronchitis virus) encoding for a heterologous S (spike) protein or fragment thereof. Further, the present invention relates to an immunogenic composition comprising said 4/91 IBV encoding for a heterologous S (spike) protein or fragment thereof. Furthermore, the present invention relates to methods for immunizing a subject comprising administering to such subject the immunogenic composition of the present invention. Moreover, the present invention relates to methods of treating or preventing clinical signs caused by IBV in a subject of need, the method comprising administering to the subject a therapeutically effective amount of an immunogenic composition according to the present invention.
