Three unique Sendai virus antigenic peptides screened from nucleocapsid protein by overlapping peptide array

Sendai virus (SeV) is strictly monitored in laboratory rodents. Currently, complete virions have been used as antigens in SeV serological tests. However, the complexity of SeV virion antigen limits the accuracy of the diagnostic method. In the current study, complete SeV virion antigen was separated on SDS-PAGE and analyzed, with nucleocapsid protein (NP) showing predominant antigenicity. A peptide array containing overlapping 14-mer peptides covering the entire NP was developed. The array used SeV positive serum and resulted in four antigenic linear peptides being identified, which were located in the carboxyl-terminus of NP. The four peptides were coated on ELISA plates and tested with SeV positive and SeV negative sera, and the antigenicity of three peptides, NP413-428, NP473-490 and NP507-524, was confirmed. Mixture of the three peptides showed comparable sensitivity and better specificity in clinical rat sera ELISA tests compared with complete SeV virion antigen. In conclusion, the three peptides, NP413-428, NP473-490 and NP507-524, would be good candidates as linear antigens for SeV detection.