Competitive enzyme-linked immunosorbent assay using baculovirus-expressed VP7 for detection of epizootic haemorrhagic disease virus (EHDV) antibodies.

Epizootic haemorrhagic disease (EHD) is a vector-borne infectious viral disease of domestic and wild ruminants. EHD could spread from infected northern African countries in free territories like the EU; therefore, the availability of diagnostic assays would represent key components for adequate surveillance and control programs. In this study, the gene encoding the VP7 protein of EHD virus (EHDV) was expressed into a baculovirus-infected insect cell system. With this unpurified protein we developed a home-made competitive ELISA (cELISA) and a total number of 275 serum samples, originating from domestic and wild ruminants, were tested. 74/275 were previously shown to be positive for EHDV antibodies by a commercially available ELISA kit. A "very good" agreement was demonstrated when compared to a commercial ELISA kit (Cohen's kappa value=0.832). Samples which caused disagreement between the two assays originated from wildlife which highlights the need for further validation by using serum samples from wild animals.