Identification of a novel canine distemper virus B-cell epitope using a monoclonal antibody against nucleocapsid protein

• LNFGRSYFDPA is a linear B-cell epitope of the CDV N protein.
• The alignment and comparison of the 1N8-defined epitope with other Morbillivirus sequences showed that the epitope is conserved among the Morbillivirus including Measles virus, Phocine distemper virus, Peste-des-petits-ruminants virus, and Rinderpest virus.
• The identified epitope can be recognized by CDV positive serum, it may be useful for clinical applications.

Canine distemper virus (CDV) is a member of the genus Morbillivirus within the family Paramyxoviridae and has caused severe economic losses in China. Nucleocapsid protein (N) is the major structural viral protein and can be used to diagnose CDV and other morbilliviruses. In this study, a specific monoclonal antibody, 1N8, was produced against the CDV N protein (amino acids 277–471). A linear N protein epitope was identified by subjecting a series of partially overlapping synthesized peptides to enzyme-linked immunosorbent assay (ELISA) analysis. The results indicated that 350LNFGRSYFDPA360 was the minimal linear epitope that could be recognized by mAb 1N8. ELISA assays revealed that mouse anti-CDV sera could also recognize the minimal linear epitope. Alignment analysis of the amino acid sequences indicated that the epitope was highly conserved among CDV strains. Furthermore, the epitope was conserved among other morbilliviruses, which was confirmed with PRRV using western blotting. Taken together, the results of this study may have potential applications in the development of suitable diagnostic techniques for CDV or other morbilliviruses.