Nucleocapsid protein gene sequence analysis reveals close genomic relationship between turkey coronavirus and avian infectious bronchitis virus

Antibodies to infectious bronchitis virus (IBV) cross-react with turkey cor onavirus (TCV) in immunofluorescence assay (IFA) indicating that IBV and TC V may share an amino acid sequence similarity. To determine its extent, the gene encoding the nucleocapsid (N) protein of TCV was amplified by reverse transcription-PCR (RT-PCR) from RNA purified from intestines of embryos of turkeys infected with Various TCV isolates and from allantoic fluid of chi cken embryos infected with IBV M41 strain, the obtained N genes were cloned sequenced and compared with known sequences of N genes of five IBV strains . Tire primers for amplification were designed from the genome of IBV. PCR products were obtained only from two of eight TCV isolates tested. II was f ound that the two TCV isolates were identical with five IBV strains by 90.1 -94.1% at the N gene level. It was also observed that the N gene of eight T CV isolates originating from various regions of the USA could not be amplif ied by the primers designed from the N gene of bovine coronavirus (BCV).