• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.5
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• pp.668-675
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• 2021

The infection status of domestic farmed eels Anguilla japonica, Anguilla bicolor and Anguilla marmorata with Japanese eel endothelial cell-infecting virus (JEECV) and anguillid herpesvirus 1 (AnHV) was examined at the major eel farming areas in Korea. These viruses were detected in all areas examined, regardless of the eel species or age. Any farm with a history of viral infection in adult fish confirmed the infection to be transmitted to stocked fry within 3 to 5 months. It is proposed that both viruses are horizontally transmitted within a given farm. The primary symptoms and histopathological lesions produced by the two viral infections are similar, making it difficult to distinguish the two diseases through clinical symptoms. Both viruses displayed 100% detection in the gills, suggesting that the gills are an optimal tissue for JEECV and AnHV monitoring. This study concluded that JEECV and AnHV were prevalent on eel farms across the country and caused very high mortality when the two viruses co-infected fry. Additional studies, including experimental infections, are needed to clearly understand the pathogenicity of each virus and the risk of co-infection.

• Journal of fish pathology
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• v.25 no.3
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• pp.151-158
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• 2012

Diseased eel (Anguilla bicolor) displayed severe hemorrhages in the gills, and congestion and swelling in the liver. During the epizootic, the water temperature was $28^{\circ}C$ and the morality rates were about 5%. No parasites were found on the gills and skin. Bacteria were not cultured from any internal organs using TSA or SS agar at $28^{\circ}C$ for 48 hrs. Histopathologically, the gills showed epithelial hyperplasia in the base of secondary gill lamellae and hemorrhages in the capillaries. Some cells in the proliferated interlamellar epithelia exhibited marginal hyperchromatosis. And severe vacuolated changes in the parenchymal cells and congestion in the central veins were observed in the liver. The specific amplicon (396 bp) was detected from gills and opercula of affected eel PCR using Anguillid herpesvirus-1 (AngHV-1) -specific primer sets HVAPOLVPSD (5-'GTG TCG GGC TTT GTG GTG C-3') and HVAPOLOOSN (5'-CAT GCC GGG AGT CTT TTT GAT-3'). Sequencing analysis of the amplicon demonstrated that this gene was 99% homologous to the AngHV-1 sequence deposited in GenBank. This is the first report of AngHV-1 outbreak in the farmed shortfin eels (A. bicolor) in Korea. When diseased fish were maintained for 10 days at water temperatures of $32^{\circ}C$ and $35^{\circ}C$, the cumulative mortalities were 100% and 10%, respectively. Even though the AngHV-1 genome in the gills from the eel kept at $35^{\circ}C$ was detected using PCR, the structure of gill filaments was similar with that of normal fish. Increasing the water temperature to $35^{\circ}C$ was an effective way to diminish the mortality of AngHV-1 affected eel.