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

Due to the high homology among coronaviruses in the same subgroup, antisera from HCoV-NL63 (Alphacoronavirus, subgroup 1b), HCoV-OC43 (Betacoronavirus, subgroup 2a), SARS-CoV (Betacoronavirus, subgroup 2b) and MERS-CoV (Betacoronavirus, subgroup 2c)-infected humans recognize the N proteins of a particular subgroup but do not react with N proteins from other subgroups, as previously reported (Sudhakar et al., 2014) . However, cross-reactivities have been found previously among different genera. Anti-CCoV sera reacted with the N protein of SARS-CoV, a Betacoronavirus (Sun and Meng, 2004; Vlasova et al., 2007) . Furthermore, polyclonal antibodies from Alphacoronaviruses, including HCoV-229E, feline infectious peritonitis virus (FIPV), and TGEV, reacted with SARS-CoV infected Vero cells (Shi et al., 2003) , demonstrating conserved antigenic sites of N protein might exist among different genera. However, there is no data on the reactivity between CCoV or CRCoV N proteins and antisera derived from other human coronaviruses (such as HCoV-OC43, -NL63, -HKU1 and MERS-CoV).