ABSTRACT
Avian infectious bronchitis(IB)is an acute and highly contagious disease caused by infectious bronchitis virus(IBV).In the study, according to IBV gene sequences published in Gen Bank, specific primers were designed to clone N gene by RT-PCR, and this gene was inserted into p ET-30a(+)vector resulting in a prokaryotic expression plasma p ET-30a-N. The results of SDS-PAGE and Western Blot analysis showed that the recombinant protein was expressed successfully and had good reactivity with IBV positive serum. Using purified recombinant N protein as a coating antigen, the indirect ELISA protocol was established and optimized, in which N protein was 2.5mug.m Lsup-1/sup of concentration, sample serum of 1:40 dilution. For clinical specimen, the IBV antibodies could be detected by this method efficiently and got nearly the same results as those of IBV-mediated ELISA. It would provide a good tool for rapid diagnosis and epidemiological study of avian infectious bronchitis.