Genetic and antigenic characterization of recombinant nucleocapsid proteins derived from canine coronavirus and canine respiratory coronavirus in China

Lu, Shuai; Chen, Yingzhu; Qin, Kun; Zhou, Jianfang; Lou, Yongliang; Tan, Wenjie

The genes encoding the N proteins of CCoV and CRCoV were amplified and sequenced with the gene lengths being 1,149 bp for CCoV-BJ70 and 1,347 bp for CRCoV-BJ202. Phylogenetic analysis showed that the CCoV N gene obtained in this study had the closest relationship with CCoV-NTU336, an Alphacoronavirus strain isolated in Taiwan ( Figure 1 ). Amino acid sequence alignment revealed the N gene of CCoV-BJ70 had a relatively high identity of 98.2% compared to CCoV-NTU336. In addition, the N gene of CCoV-BJ70 was also 91.4% to 97.7% identical to other strains of canine coronaviruses, including CCoV-TN449, CCoV-1-71, CCoV-fc00-089, CCoV-GPV, CCoV-A76, CCoV-K378, CCoV-BGF10, and CCoV-INSAVC. Compared with the closely related coronavirus strains from pig (TGEV-Purdue) and cat (FCoV-Black), the identity of amino acid sequence was 93.5% and 78.6% respectively (data not shown), showing the higher genetic relatedness between CCoV and TGEV. In order to determine the genotype of CCoV-BJ70, we amplified a partial sequence of the S gene and found that the genotype of CCoV-BJ70 belonged to CCoV-II (data unpublished). Comparison of the CRCoV-BJ202 N gene sequence to related CRCoV strains revealed that it was most similar to sequence data from BCoV-ENT, CRCoV-K37 and HCoV-OC43, which all belong to Betacoronavirus genus. The identity of the analyzed amino acid sequence was 98.4% to CRCoV-4182 and 97.6% to CRCoV-K37 respectively (data not shown), followed with the identity of 97.3% to BCoV-ENT and 96.7% to HCoV-OC43, while it was only 24.7% to CCoV-BJ70 (Table 1) .