Development and assessment of an antigen capture ELISA for the detection of epizootic haematopoietic necrosis virus (EHNV) in redfin perch (Perca fluviatilis) and rainbow trout (Salmo gairdneri)

Epizootic haematopoietic necrosis virus (EHNV) was grown in BF-2 cells, purified from cell culture material, and tested for cellular contamination by SDS-PAGE, western transfer and immunostaining with anti-BF-2 serum. Purified virus was introduced to sheep and rabbits to raise antiserum against EHNV. These antibodies were used in the development of an antigen capture enzyme linked immunosorbent assay (ELISA) for the detection of EHNV in redfin perch and rainbow trout. The ELISA format chosen after many optimisation experiments has the ability to detect virus in cell culture to a titre of 10' TCIDst/ml. After screening 1,200 tissue homogenates by virus isolation and using the tissue homogenates and the culture supematants in an ELISA, positive/negative cutoffs of 0.95 and 0.75, respectively, were chosen. Although quite high these cutoffs did not affect the utility of the test. The sensitivity and specificity of the antigen capture ELISA appear more than adequate for diagnostic screening of test samples from fish populations.