Molecular characterization of the 9.36 kb C-terminal region of canine coronavirus 1-71 strain

A total of 9.36 kb nucleotides of the C-terminal one-third genome of the canine Coronavirus (CCV) 1-71 strain, including all the structural protein genes and some non-structural protein (nsp) genes were cloned and sequenced. Nucleotide and amino acid sequence alignment as well as phylogenetic analysis of all the structural ORFs with reference coronavirus strains showed that CCV 1-71 was highly related to Chinese CCV isolates. This indicates that these CCV stains may have the same ancestor. Two large deletions were found in ORF3 and led to an elongated nsp3a and a truncated nsp3b. A single “A” insertion in a 6A stretch resulted in the truncation of nsp7b. The great variation in nsp3b and nsp7b indicates that these proteins are not essential for the viral replication.