Detection of herpesviral hematopoietic necrosis virus (Cyprinid herpesvirus 2, CyHV-2) from goldfish, Carassius auratus (L.) in Korea

In April and June 2014, mortalities of goldfish occurred at Korea. The principal signs included pale gills, severely enlarged and softened spleen and kidney and red liver. Moreover, the histopathological characteristics observed mainly in hematopoietic tissues of kidney, gill lamellae and intestine. The predominant histopathological changes were severe necrosis of hematopoietic tissue. In addition, nucleus exhibiting peripherally displaced chromatin were particularly abundant in the kidney of affected fish. The histological examination led to hypothesize the implication of a virus in the mortality. The hematopoietic necrosis herpesvirus (Cyprinid herpesvirus 2, CyHV-2) DNA polymerase gene successfully detected in DNA extracted from kidney and spleen of affected fish using PCR assay and showed 100% identity with already deposited CyHV-2 DNA polymerase gene in NCBI. Artificial infection trials using affected tissues filtrates gave cumulative mortalities of 30% for virus injected goldfish. In the present study, CyHV-2 was detected and identified as the causative pathogen of the epizootic in goldfish in Korea.