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Juvenile turbot Scophthalmus maximus that became sick during an outbreak of disease at mariculture facilities at Go-Chang, Korea, in 2003, were examined to identify the cause of the disease. The fish had pale body color, an enlarged abdomen, protruding eyes, an enlarged spleen and kidney, and pale gills and/or liver. Histopathogical examination revealed basophilic enlarged cells in the kidney, spleen, gills, heart, stomach, intestine, liver, pancreas and skin. Hexagonal viral particles with a diameter of 136 to 159 nm were observed in the enlarged cells. A specific 1299 bp fragment of the major capsid protein (MCP) gene of the turbot iridovirus (TBIV) was amplified by PCR. Sequence homology was greater than 93.76% between the MCP gene in TBIV and the same gene in 5 viruses in the tentatively proposed genus Tropivirus (family Iridoviridae): red sea bream iridovirus, sea bass iridovirus, grouper sleepy disease iridovirus, African lampeye iridovirus and dwarf gourami iridovirus. These results suggest that the virus detected from turbot is similar to the proposed genus Tropivirus. KEY WORDS: Turbot · Scophthalmus maximus · Iridovirus · RSIV · MCP · Tropivirus Resale or republication not permitted without written consent of the publisherDis Aquat Org 64: [175][176][177][178][179][180] 2005 Korea. Juvenile turbot (mean weight 9.0 ± 1.9 g, mean length 7.9 ± 0.5 cm) began to show signs of disease in June 2003. Affected fish were lethargic and had a reduced appetite, pale body color, enlarged abdomen and protruding eyes. The key internal characteristics of the diseased fish were an extremely enlarged spleen and kidney, and pale gills and/or liver (Fig. 1).The fish farmers misdiagnosed the disease as hirame rhabdovirus (HRV) disease or viral hemorrhagic septicemia (VHS) disease, and increased the water temperature from 17-18°C to 20-23°C in an attempt to control the disease. The mortality increased rapidly when the water temperature was increased. Total mortality was about 50 to 70%. After sampling some of the diseased turbot, the remaining fish were killed, and all facilities were disinfected with sodium hypochlorite.Histology. The kidney, spleen, gills, heart, stomach, intestine, liver, pancreas, skin, eye and brain were removed from diseased fish and immediately fixed in 10% neutral buffered formalin (NBF). After fixation, standard histological procedures were used for tissue dehydration and paraffin embedding. Tissue sections were stained with haematoxylin and eosin (H&E).Electron microscopy. The spleens were fixed in 2.5% glutaraldehyde in 0.1 M phosphate buffer (pH 7.2) at 4°C. After several rinses with 0.1 M phosphate buffer, each sample was post-fixed with 1% OsO 4 for 1 h. Subsequently, the tissue was dehydrated in an ethanol series and embedded in Epon 812. Ultra thin sections were prepared using an RMC-MTX ultramicrotome (SIMS). Sections were stained with lead citrate and uranyl acetate. Stained grids were observed under a Hitachi-7000 electron microscope. DNA extraction. In preliminary investigati...

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Megalocytivirus was detected from paradise fish Macropodus opercularis imported from Indonesia. Four of 11 fish (36%) in 2006 and 40 of 117 fish (34%) in 2008 were found to be PCRpositive for megalocytivirus. Phylogenetic analysis based on partial major capsid protein (MCP) gene nucleotide sequences revealed that the sequences detected in paradise fish were classified as Genotype II, which includes freshwater fish isolates from Southeast Asian countries, closely related to infectious spleen and kidney necrosis virus (ISKNV), Murray cod iridovirus (MCIV), and dwarf gourami iridovirus (DGIV-2004). Paradise fish was added as a new host for megalocytivirus based on this study. KEY WORDS: Megalocytivirus · Paradise fish · Macropodus opercularis · Major capsid protein gene · MCP gene Resale or republication not permitted without written consent of the publisherDis Aquat Org 90: [235][236][237][238][239] 2010 sia, and Malaysia, and marine fishes caught in the South China Sea. Genotype III is mainly composed of isolates from flatfish species in Korea and China.In Korea, the first outbreak due to megalocytivirus infection was reported from cultured striped beakperch Oplegnathus fasciatus, red seabream Pagrus major, and black rockfish Sebastes schlegeli in southern coastal areas (Oh et al. 1999, Jung & Oh 2000. Since then, megalocytivirus has been detected not only from turbot Scophthalmus maximus in aquaculture (Kim et al. 2005), but also from wild marine fishes from the southern coast of Korea and the East China Sea (Lee et al. 2007). Moreover, recent outbreaks extended the host ranges to imported ornamental fishes (Lyu et al. 2006, Jeong et al. 2008b).Here we report the detection of megalocytivirus in paradise fish Macropodus opercularis, a freshwater ornamental species imported from Indonesia. One hundred percent cumulative mortalities of paradise fish occurred during acclimatization after importation. During the routine examination of these mortalities, megalocytivirus was detected and genetic analysis conducted. MATERIALS AND METHODSExperimental fish. In total, 128 paradise fish (body weight 1.2 to 3.3 g) were used for detection of megalocytivirus (Table 1). Fish were imported from Indonesia to Korea in 2006 and 2008, and immediately transported to the laboratory for acclimatization. They were placed into 30 l glass tanks with freshwater and maintained at 23°C. Mortality started on the first day after transportation and continued until 100% cumulative mortality was recorded by Day 3. Freshly dead or moribund fish observed during acclimatization were submitted for examination.DNA extraction. Internal organs including stomach, intestine, kidney, and spleen were removed from each fish. Each sample was homogenized with tissue culture medium (minimum essential medium, Sigma) in a tube with Precellys 24 (Bertin) at 6000 rpm for 30 s. A 50 µl aliquot of Proteinase K (1 mg ml -1 , TaKaRa) was added to 500 µl of the supernatant and incubated for 2 h at 55°C. Total DNA was extracted from the supernatant with phe...