Development and evaluation of a VP1-ELISA for detection of antibodies to duck hepatitis type 1 virus

The VP1-encoding gene of the duck hepatitis type 1 virus (DHV-1) HP-1 strain was cloned and expressed in Escherichia coli. The open reading frame (ORF) of VP1 comprised 714 bp and encoded 238 amino acids, with a predicated molecular mass of 26.5 kDa. The expressed VP1 fusion protein in E. coli was detected by Western blotting with duck anti-DHV-1 polyclonal serum. A VP1-ELISA using the expressed VP1 protein as a coating antigen for the detection of antibodies to DHV-1 in ducks was developed. In comparison with the virus neutralization test, the specificity and sensitivity of the VP1-ELISA was 92.5% and 96.7%. Comparative analysis between Western blots and the VP1-ELISA showed that the concordance between the two methods was 86%. The VP1-ELISA did not react with the anti-sera to other duck viral pathogens, implying that this protein is specific for the recognition of duck anti-DHV-1 antibodies. Taken together, the VP1-ELISA is a highly sensitive and specific test that could be used for screening for DHV-1 infection and monitoring antibody titres against DHV-1.