Experimental infection with epizootic haematopoietic necrosis virus (EHNV) of rainbow trout (Oncorhynchus mykiss Walbaum) and European perch (Perca fluviatilis L.)

The aim of this study was the determination of the susceptibility of Polish farmed redfin perch (Perca fluviatilis L.) and rainbow trout (Oncorhynchus mykiss Walbaum) to experimental infection with haematopoietic necrosis virus (EHNV). A bath challenge model was tested at two temperature ranges: 13-15°C and 20-22°C. After 7 d, the first clinical signs and mortality were observed in fish kept at these temperatures. Significantly more mortality cases were reported in the redfin perch population, reaching a maximum of 24% compared with 12% in the rainbow trout group at 20-22°C. EHNV was reisolated from redfin perch and rainbow trout tissue in cell culture and the infection was confirmed by a molecular method and histopathology during the duration of the experiment. This study revealed that fish from Polish farms can be susceptible to EHNV even at lower temperatures.