• Journal of fish pathology
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• v.11 no.2
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• pp.97-104
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• 1998

Since 1989, mass mortality has repeatly occurred in cage-cultured sevenband grouper, Epinephelus septemfasciatus along the southern coast of Korea in the summer season and usually reached over 80% within a few months. Diseased fish showed the clinical signs of anorexia, dark coloration, loss of eqilibrium, spinal swimming behaviour, vertebral deformity and inflation of swim bladder. Histopathologically, necrosis and/or vacuolation of the nerve cells in the brain and retina were observed. We previously reported that the causative agent was filtrable. The causative agent was not culturable in various fish cells; RTG-2, CHSE-214, BF-2, EPC and FHM. However, electron microscopic observation revealed unenveloped icosahedral viral particles with about 30 nm in diameter in the cytoplasm of nerve cells of the brain. The characteristics of the virus was tested by an artificial infection with the filtrate of the homogenate of diseased fish. The pathogenicity of the virus was retained after treatment with ether or heat ($50^{\circ}C$, 30 min) but partly lost by pH 3 or 11 treatment. These results suggest that the causative agent are similar to the fish nodavirus. In order to compare the causative agent with a fish nodavirus, Striped Jack Nervous Necrosis Virus (SJNNV), a polymerase chain reaction (PCR) was performed with primers specific to SJNNV. As a result, about 430 by PCR products were detected from the brain and the eye of both naturally and artificially infected sevenband grouper. All these results represent that the mass mortality in the cultured sevenband grouper is caused by the infection of a nodavirus similar to SJNNV and this is the first report of a fish nodavirus from the cultured sevenband grouper in Korea.

• Journal of fish pathology
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• v.4 no.2
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• pp.87-94
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• 1991

In the late summer of 1990 and 1991, mass mortality occured among cage-cultured grouper, Epinephelus septemfasciatus in south cost of Korea. The moribund fish didn't feed and became pale or dark chestnut colour and irregularly swimmed due to the loss of equilibrium, finally the diseased fish fell down side away on the bottom or the surface of cage showing the bent of body and died. The diseased fish showed the extensive hemorrahge in brain, the swelling of spleen and bile duct as the specific syptoms of internal organs. So the gill, skin and other organs of the diseased fish were examined for the presence of pathogenic parasites and bacteria. The parasitic Trichodina sp. were detected only from the gill lamella of the diseased fish, but these parasites seemed to be not a direct causative agents that induced the gross mortality of the cultured grouper. because these parasites were also observed in normal grouper, yellowtail, red seabream and rock bream co-cultured with the diseased grouper in same or near cages. In the viral examination, although isolation of the causative agent by the use of estabilshed cell Lines, RTG-2 and CHSE-214, was not succeed, the normal grouper inoculated intramuscularly with the filtered homogenate of the organs of the diseased fish showed the same external and internal signs with the naturally infected grouper. They died within a week. By using the naturally and the artificially infected fishes, electron microscopic observation revealed numerous hexagonal or polygonal particles in the cytoplasm of liver cells. Based on the these results, we suggest that the mass mortality of the cultured grouper would be occurred by the infection of a viral agent.

• Journal of Food Hygiene and Safety
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• v.20 no.4
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• pp.205-210
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• 2005

The content of the trace metals in the cultured and wild fishes were determined. The tested fishes were genuin porgy (Pagrus major) and black porgy (Acanthopogrus schlegeli). The samples of the cultured and wild fishes were collected from slices of raw fish in shops, during 2003 to 2004. The samples were digested with acids, then analyzed by ICP (inductively Coupled plasma Spectrometer) and AAS (Automic Absorption Spectrometer) for the content of lead (Pb), cadmium (Cd), arsenic (As), copper (Cu), manganese (Mn) and zinc (Zn). The content of mercury (Hg) was determined using mercury analyzer. The mean contents of trace metals in cultured and wild fish was 0.031,0.047mg/kg far total-mercury,0.321,0.407 for Pb, 0.048,0.063 for Cd, 1.006, 1.132 for As, 0.467,0.806 for Cu, 0.233, 0.293 for Cr, 9.69, 12.20 for Zn,0.798, 0.624 mg/kg far Mn, respectively. The content of all the trace metals except manganese in wild fish was more than that in cultured fish. The highest level of total-mercury, lead, cadmium, zinc, chromium and arsenic in the samples analyzed were all below the quarantine limit of Korean regulation and guideline established by the U.S. Food and Drug Administration f3r human consumption. The level of the trace metals in the samples was negligible, which could be endogenous. Our data obtained in this study showed that the average weekly intakes of lead, cadmium and mercury from cultured and wild fishes takes about $6\∼13\%$ of Un(Provisional Tolerance Weekley Intakes) that FAO/WHO Joint Food Additive and Contaminants Committee has set to evaluate their safeties.

• Journal of fish pathology
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• v.4 no.1
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• pp.41-46
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• 1991

• Journal of fish pathology
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• v.28 no.1
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• pp.9-15
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• 2015

The potential of Streptococcus iniae glyceraldehyde-3-phosphate dehydrogenase (GAPDH) as an antigen for a subunit vaccine was investigated using a zebrafish model. The recombinant S. iniae GAPDH was purified using His-tag column chromatography, and antisera against the recombinant GAPDH (rGAPDH) were produced by intraperitoneal immunization of rats. By immunization with S. iniae rGAPDH, the survival rates of zebrafish against an S. iniae challenge increased, suggesting that GAPDH would be an antigen capable of inducing protective immune responses in fish. Furthermore, we demonstrated using Western blotting, that the antisera against rGAPDH of S. iniae had cross-reactivity with GAPDH from Streptococcus parauberis and Lactococcus garviae, which are also culprits of streptococcosis in cultured fish in Korea. These results suggest that S. iniae GAPDH may be used as an antigen for the development of a subunit vaccine against streptococcosis caused by diverse cocci in cultured fish.

• Journal of fish pathology
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• v.19 no.3
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• pp.215-225
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• 2006

Viral and bacterial pathogens of the wild marine fishes were monitored in 176 wild fish and 15 wild shrimp from 13 and 1 species, respectively, which were captured by a trawl net in the southern sea of Korea during June 2006. Viral pathogens that are common etiologically agents to cultured fish in Korea were not isolated. One and 5 bacterial strains were affiliated to the genus Proteus and Pseudomonas, respectively, but these bacteria do not seem to be associated with mortality of aquacultural fish. An extended monitoring on wild marine fishes were necessary for identification of agents responsible for the cultured fish infections.

• Journal of fish pathology
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• v.30 no.1
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• pp.11-24
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• 2017

The current investigation dealing with the causative agent of mass mortalities in cultured Oreochromis niloticus. The diseased fish showed external hemorrhage, unilateral and bilateral eye opacity, ended by blindness and fish death. The postmortem lesions revealed congested friable kidney and spleen, and liver has yellow nodules. Obtained isolates were identified as Aeromonas hydrophila (the causative agent of Motile Aeromonas Septicemia) and found to be highly pathogenic as they contained hemolysin virulence gene causing mortality reached to 100 and 70% in intraperitoneal and intramuscular infection. The prevalence of MAS was 80% among the surveyed O. niloticus. Blood and serum were collected from naturally diseased, intraperitoneal and intramuscular injected O. niloticus for hematological and biochemical examination. Similarly, gills, musculature, kidney, liver and spleen were collected for histopathological evaluation, and micropathomorphological analysis of spleen was done. Macrocytic hypochromic anemia was recorded in the intraperitoneal infection. Serum protein, albumin and globulin were decrease only in naturally diseased fish. Leucocytosis with heterophilia and lymphocytosis were observed in naturally diseased and intraperitoneal infected fish. There were severe degenerative changes and hemorrhagic necrosis in the examined tissues which were more obvious in intraperitoneal than intramuscular infection. Activation and proliferation of melanocytes macrophages centers with severe hemosiderosis were recorded in spleen of naturally diseased and experimentally infected fish.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.5
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• pp.596-616
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• 2021

A global increase in fish consumption has led to a rapid expansion of aquaculture production, which has been linked to enhancing the spread of infectious diseases. Viral diseases can cause high mortality in many cultured fish species, posing a serious threat to the aquaculture industry. Infectious hematopoietic necrosis virus (IHNV) is one of the primary threats to aquacultured salmonid species, causing huge economic losses. Since the first report in cultured sockeye salmon Oncorhynchus nerka during the 1950s in North America, IHNV has spread to other regions, including Europe, Asia, South America, and Africa by transportation of infected fish and eggs, causing disease and increasing mortality in a wide variety of salmonid species. Here, we review existing information relevant to IHNV: its phylogenetic characteristics, origin, infection history, virulence determinants, susceptible hosts, vectors, and vaccine development. This review also addresses a possible cross-species transmission of IHNV to a new host, olive flounder Paralichthys olivaceus, a cultured fish of economic importance in East Asian countries.

• Food Science and Biotechnology
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• v.17 no.3
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• pp.508-513
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• 2008

Erythromycin has been used to treat Streptococosis, Edwardsiel1osis, Vibriosis, Bacterial enteritis in the cultured fish. In this study, a rapid and effective erythromycin analysis method with new sample treatment protocol and liquid chromatography/tandem mass spectrometry (LC/MS/MS) system for fish products was developed. For the erythromycin extraction from fish muscle, the solvent mixture composed of 0.2% meta-phosphoric acid and methanol (6:4) showed good recovery rate, and the optimum extraction solvent volume was 20 mL. Erythromycin detection using LC/MS/MS were carried out under electro spray ionization (ESI) positive condition and erythromycin mass value 576.2 and 157.9. And the detection limit of the established method was 0.005 mg/kg in fish products. The recovery rate of the developed method applied to the fish species were as following, olive flounder, $87.6{\pm}5.0%$; black rockfish, $87.2{\pm}6.4%$; eel, $85.2{\pm}4.8%$; and rainbow trout, $86.0{\pm}6.2%$. In the established method in this study, the correlation of coefficient values ($R^2$) of erythromycin calibration curve (n=11) was 0.9998.

• Journal of fish pathology
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• v.12 no.1
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• pp.49-55
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• 1999

To detect birnavirus from cultured marine fish, RT-PCR assay was developed. This method was specific for aquatic birnaviruses that include IPNV Sp., IPNV Ab, IPNV VR-299 and MBV Y6. The birnavirus gene was detected (birnavirus positive samples detected 46/50) from clinical samples signed with abdominal distension and overall darkening even though the samples gave negative results in virus isolation (birnavirus isolate with CHSE-214 cell showed 12/50).