To seek a new delivery system of vaccine for infectious bronchitis virus (IBV), transgenic potato expressing full-length spike (S) protein of IBV was produced and its immunogenicity in chickens was investigated. One to three copies of S gene of IBV were randomly and stably inserted into potato (Solanum tuberrosum cv. Dongnong 303) genome by Agrobacterium tumefaciens-mediated transformation. Transcription and translation of S gene for IBV were confirmed by Northern blot and Western blot analyses in transgenic plantlets. Chickens immunized orally and intramuscularly with transgenic potato tubers expressing S protein generated the detectable levels of serum neutralizing antibodies and were protected against the challenge with the virulent IBV. In vitro secretion of interleukin 2 and T lymphocyte proliferation of spleen cells from the immunized chickens varied with the dose and the manner of vaccination with S protein derived from transgenic plants. The results indicated that S protein expressed in transgenic plants might be a new source for the production of Coronaviridae IBV vaccine.