Characterization of Spike Gene of Infectious Bronchitis Coronavirus CK/CH/ LDL97Ⅰ/97 Isolated in China
Abstract: The spike gene (S) of Infectious bronchitis virus (IBV) CK/CH/LDL97Ⅰ/97 isolate was amplified，cloned, sequenced and analyzed. Results showed that the S gene was 3501 bp encoding a polypeptide of 1167 amino acids. The precursor of the S protein was cleaved into S1 and S2 fragments, which comprised 541 and 626 amino acid residues, respectively. The cleavage site sequence was RRTGR. The homologies of nucleotide and amino acid sequences of S1 gene between CK/CH/LDL97Ⅰ/97 and 27 reference IBV strains ranged from 60.6% to 99.6%, and 50.5% to 99.1%, respectively. The CK/CH/LDL97Ⅰ/97 S1 was most similar to that of three proventriculus IBV isolates, Q1(99.1%), J2(98.9%), T3 (98.9%), which were isolated in China. Phylogenetic analysis of S1 proteins indicated that CK/CH/LDL97Ⅰ/97, Q1, J2 and T3 formed a separated cluster, which might belong to a novel genotype of IBV.