Antigenic and immunogenic properties of the canine distemper virus nucleocapsid protein expressed in Escherichia coli employing codon optimized synthetic gene

Despite common occurrence and importance of canine distemper disease the majority of tests currently available for diagnosis are hampered by either low sensitivity or specificity. In this study it was evaluated antigenic and immunogenic characteristics of a conserved region of nucleocapsid protein of canine distemper virus (rCDV NP) expressed in Escherichia coli employing a codon optimized synthetic gene. The expression of rCDVNP in Star strain (mean 300 mu g/mL, purified) was confirmed by SDS-PAGE and Western blot analysis by using His-Tag monoclonal antibodies. Western blot and ELISA, employing positive and negative control dog sera, demonstrated the rCDVNP antigenicity. The rCDVNP was inoculated in hens and immunoglobulin Y (IgY) was purified from the egg yolk. The mean yield of IgY was 28.55mg/mL. IgY reacted with the recombinant protein as demonstrated by Western blot and ELISA assays. In summary, our findings demonstrated that rCDVNP is antigenic since CDV positive dog sera recognized the protein in vitro. Additionally, the rCDVNP proved to be immunogenic in hens being possible to isolate a high concentration of specific IgY antibodies from the egg yolk. Taken together, these results indicate that the rCDVNP along with the specific IgY could be useful tools for development of the canine distemper immunodiagnostic assays.