Sequence analysis of the turkey coronavirus nucleocapsid protein gene and 3′ untranslated region identifies the virus as a close relative of infectious bronchitis virus

The 3′ end of the turkey coronavirus (TCV) genome (1740 bases) including the nucleocapsid (N) gene and 3′ untranslated region (UTR) were sequenced and compared with published sequences of other avian and mammalian coronaviruses. The deduced sequence of the TCV N protein was determined to be 409 amino acids with a molecular mass of approximately 45 kDa. The TCV N protein was identical in size and had greater than 90% amino acid identity with published N protein sequences of infectious bronchitis virus (IBV); less than 21% identity was observed with N proteins of bovine coronavirus and transmissible gastroenteritis virus. The 3′ UTR showed some variation among the three TCV strains examined, with two TCV strains, Minnesota and Indiana, containing 153 base segments which are not present in the NC95 strain. Nucleotide sequence identity between the 3′ UTRs of TCV and IBV was greater than 78%. Similarities in both size and sequence of TCV and IBV N proteins and 3′ UTRs provide additional evidence that these avian coronaviruses are closely related.