• Journal of Veterinary Clinics
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• v.19 no.1
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• pp.14-18
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• 2002

An epidemiological study was performed to evaluate the state of fish diseases between aquaculture fishes in the area of southern Kyeongnam, especially Tongyeong-si, Geoje-si, and Goseong-gun. Examination for a total of 91 cases was carried out for a variety of fishes, including Japanese flounder(Paralichthys olivaceus), rock fish (Sebastes schlegeli), sea bass (Lateolabrax japonicus), sea breams(Pagrus major), and red drum (Sciaenops ocellatus) from November, 1999 to October, 2001. The investigation resulted in exploring 155 infectious diseases, including 62 Vibriosis, 16 Edwasiella infection, 11 Streptococcosis, 7 Pseudotuberculosis, 15 Scuticociliatida infection, 20 Gill flukes, and 9 Trichodiniasis. When the infections were classified according to fish species, Japanese flounder was infected by 30 Vibrio spp., 16 Edwardsiella tarda, 6 Streptococcus spp., 12 Scuticociliatida infection. In case of sea bass, 10 Vibrio spp. was able to isolate out of 10 outbreaks, on the other hand, rock fish was dominantly infected by gill flukes since it was observed 12 out of a total of 20 cases. With reference to seasonal fluctuation, Vibrio spp. infection was continually observed through all seasons but Edwardsiella septicaemia, Streptococcosis and Pseudotuberculosis was mainly isolated in summer and autumn when the water temperature was raised high. Scuticociliatida infection was frequently occurred from late autumn to early spring but gill flukes were watched all the year regardless of temperature. As regards, multiple infection, 47 out of 91 cases was Identified to have involved in more than 2 pathogens, especially Vibrio spp. was highly mixed with other pathogens since 42 out of 47 cases was mixed with Vibrio spp.

• Journal of fish pathology
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• v.19 no.2
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• pp.173-181
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• 2006

Miamiensis avidus is a scuticociliate causing mortality in olive flounder Paralichthys olivaceus. To evaluate immune response of olive flounder against M. avidus, 2.6×106cells/fish of Formalin killed cell (FKC) was intraperitoneally (i.p.) injected, and 2.4 × 106cells/㎖ of sonicated FKC was immersion immunized to 14.9 cm (26.8g) fish. Fish were immunized 2 times with 2 weeks intervals. Antiserum from immunized fish caused agglutination and immobilization of the ciliate. In ELISA test, immunized group exhibited higher titers than control group. In addition, i.p. immunized fish showed higher phagocytic ratio, phahgocytic index and chemotaxic activity. To evaluate in vivo efficacy of FKC on fish, 1.43 × 105cells/fish was i.p.. injected, and 2.2 × 105 cells/㎖ of sonicated cell was immersed into 8.6cm (6.3g) fish. After 2 times immunization with 2 weeks intervals, fish were infected with 2.0 × 104 and 2.0 × 103 cells/ml of live ciliates by immersion. After 3 weeks, cumulative mortality was lower in the i.p. immunized group and mortality was delayed in immersion immunized group. In conclusion, specific immune response of oliver flounder against M. avidus was elevated after immunization and these immune response may prevent and/or delay for the M. avidus infection to olive flounder.

• Journal of fish pathology
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• v.22 no.2
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• pp.97-105
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• 2009

Scuticociliates Miamiensis avidus (syn. Philasterides dicentrarchi) causes high mortality and bad growth in olive flounder Paralichthys olivaceus. Temperature is an important factor not only for growth of pathogens but also for host immune system in poikilothermal animal. In this study, temperature affecting ciliate growth and pathogenicity against olive flounder were examined. Doubling time for the ciliate growth was 61.82 hours at $5{^{\circ}C}$, 26.32 hours at $10{^{\circ}C}$, 21.14 hours at $15{^{\circ}C}$, 16.86 hours $20{^{\circ}C}$ and 16.21 hours at $25{^{\circ}C}$. Maximum ciliate numbers were similar at $10-20{^{\circ}C}$ at the range of $1.54-1.75{\times}10^{5}$/ ml. Duplicated intraperitoneal injections were conducted with the ciliates by the concentrations of $1{\times}10^{2}$, $1{\times}10^{6}$, $1{\times}10^{4}$and $1{\times}10^{5}$/ fish (average 8.34 cm, 4.33 g) then kept at $10{^{\circ}C}$, $15{^{\circ}C}$ and $20{^{\circ}C}$. Cumulative mortality was low at $10{^{\circ}C}$ and the mortality was increasing at higher water temperatures. In addition, cumulative mortality was higher at higher dose of infections. In conclusion, Scuticocilite M. avidus grew well at higher temperature (at $5{^{\circ}C}$, $10{^{\circ}C}$, $15{^{\circ}C}$ and $25{^{\circ}C}$) in vitro, and olive flounder mortality due to M. avidus was highly water temperature and dose dependent. The results of this study suggest that water temperature control may one of the essential factor to reduce mortality due to M. avidus infection.

• Journal of fish pathology
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• v.36 no.2
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• pp.311-321
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• 2023

The efficacy of the alginate microsphere (Alginate MS) oral vaccine against Miamiensis avidus in olive flounder (Paralichthys olivaceus) was confirmed through challenge infections by both immersion and injection routes. In trial 1, the formalin-inactivated M. avidus coated with alginate, designated as 'IMa+Alginate MS' group, and the IMa group were administered with vaccines mixed with feed, with a total antigen dose of 3.75 × 10⁶ cells/fish. When challenged with immersion infection at five weeks post vaccination, the relative percent survival (RPS) in the IMa+Alginate MS group was 50% (immersed in 50% seawater) and 37.5% (immersed in 100% seawater). The group that received only IMa showed a low survival rate. In trial 2, the antigen was fed mixed with feed at a total dose of 2.38 × 10⁶ cells/fish for 5 days. Two weeks after oral vaccination, fish were intraperitoneally injected for infection. The RPS in the IMa+Alginate MS group was 30.8%, while the IMa-only group showed no vaccine efficacy. At five weeks post vaccination, when subjected to challenge infection by immersion in 50% seawater, the IMa+Alginate MS group recorded a RPS of 42.9%, whereas the IMa group had a RPS of 14.3%. The results of this study indicate that coating M. avidus antigen with alginate can provide higher protection in olive flounder compared to administering the antigen alone.

• Journal of fish pathology
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• v.6 no.2
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• pp.191-195
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• 1993

With the rapid progress in seed production techniques, aquaculture production of economically important species of marine fish has been accelerated in Japan. Howecer, mass mortalities due to viral infections as well as other microbial infections have often occurred during the seed production and grow-out stages. Among these diseases, four viral diseases have been known in cultured Japanese flounder (Paralichthys olivaceus) since around 1980. In this paper, viral diseases of cultured flounder in Japan are briefly reviewed, with special attention to two viral diseases. viral epidermal hyperplasia and rhabdovirus infection which are relatively important because of their frequent occurrence. Viral epidermal hyperplasia is characterized by fin opacity and associated with high mortality in larval flounder Electron microscopy of affected epidermal cells and transmission experiments with tissue filtrates demonstrated that the disease was caused by a herpesvirus but the agent has not been isolated in fish cell lines. On the other hand, rhabdovires infection occurrs in juvenile and production size fish with hemorrhage in the skeltal muscle and fins, congestion of the gonads, and ascites. A rhabdovirys was isolated in RTG-2 cells from the diseased flounder as a causative agent, which was designated hirame rhabdovirus (HRV) or Rahbdovirus olivaceus. HRV is serologically distinguishable from other known fish rhabdoviruses. Intensive researches on these viral diseases started in 1980th. but properties of the causative agents and infection mechanisms have not been fully investigated. This results in difficulty in controlling these diseases.

• Fisheries and Aquatic Sciences
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• v.5 no.4
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• pp.311-313
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• 2002

Proteolytic activity of live Uronema manum was analyzed by fluorescence polarization (FP) technique. Protease activity was measured by a decrease in FP value using fluorescein isothiocynate (FITC)-casein as a protein substrate. The results demonstrated an inverse linear relationship between fluorescence polarization (FP) values and live ciliate concentration over the range $1\times10^4\;to\;2\times10^5$ cells/well. However, the FP values of $10-10^3$ live parasites were not different significantly from that of control. Time-dependent decrease in FP value was shown in the wells containing live U. marinum. In the present study, FP assay had the benefit to provide measurements of substrate hydrolysis by live parasites in real-time, and did not require separations, precipitations, or transfers of reaction mixture.

• Fisheries and Aquatic Sciences
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• v.5 no.3
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• pp.145-149
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• 2002

The effects of pH, temperature and various inhibitors on the proteolytic activity of the cell lysate of Uronema marium were investigated using colorimetric and substrate gel electro­phoretic methods. The cell lysate of U. marinum showed proteolytic activity over a wide range of pH, and pH optima ranged from pH 5 to 7. The proteolytic activity was increased according to a rise of temperature but decreased at $40^{\circ}$. The proteolytic activity of the parasite lysate was significantly inhibited by protease inhibitors including trans-epoxysuccinyl -L-leucylamido-(4-guanidino) butane (E-64), pepstatin A, phenyl-methanesulfonyl fluoride(PMSF), and ethylenediamine-tetraacetic acid (EDTA). Preincubation of the lysate with E-64 showed the maximum inhibition of the caseionolytic activity. Four protease bands (152, 97, 67 and 40 kDa) were detected by gelatin SDS-PAGE. Significant inhibition of caseinolytic activity and complete abolition of a 152 kDa band in gelatin SDS-PAGE by EDTA indicated that the cell lysate of U. marinum had a metalloprotease Another three proteolytic bands were inhibited by E64, a cysteine protease inhibitor. Preincubation of the cell lysate with pepstatin or PMSF had no effects on the protease bands.

• The Journal of the Korea Contents Association
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• v.21 no.12
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• pp.322-330
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• 2021

In modern aquaculture, mass mortality is a very important issue that determines the success of aquaculture business. If a fish disease is not detected at an early stage in the farm, the disease spreads quickly because the farm is a closed environment. Therefore, early detection of diseases is crucial to prevent mass mortality of fish raised in farms. Recently deep learning-based automatic identification of fish diseases has been widely used, but there are many difficulties in identifying objects due to insufficient images of fish diseases. Therefore, this paper suggests a method to generate a large number of fish disease images by synthesizing normal images and disease images using SinGAN deep learning model in order to to solve the lack of fish disease images. We generate images from the three most frequently occurring Paralichthys Olivaceus diseases such as Scuticociliatida, Vibriosis, and Lymphocytosis and compare them with the original image. In this study, a total of 330 sheets of scutica disease, 110 sheets of vibrioemia, and 110 sheets of limphosis were made by synthesizing 10 disease patterns with 11 normal halibut images, and 1,320 images were produced by quadrupling the images.

• Journal of fish pathology
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• v.18 no.1
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• pp.29-37
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• 2005

This study investigated external symptoms, behavior characteristics and the distribution pattern of the scuticociliates in the skin, gill and blood vessel of the tiger puffer, Takifugu rubripes, infected with scuticociliates among tiger puffer cultured. The fish infected with scuticociliates did not show any external symptoms, such as change in body color or swimming behavior, in the early infection stage. However, they showed congestion, erosion, and ulcer on the skin and fin at advanced stages. They showed a turning movement, mainly stayed on the bottom, and swam with their mouths open at the surface of water. Some fish showed a sudden swimming movement of zigzag type. The scuticociliates were ovoid in shape and $20\times40{\mu}m$ in size. The scuticociliates had a contractile vesicle and a caudal cilium that ranged 10-12 ${\mu}m$, and reproduced by binary fission. Therefore the scuticociliates were identified as ciliated, belonging to class Hymenostomatia, order Scuticociliatida in morphogenetic character. The gills infiltrated with scuticociliates showed clubbed gill filament due to hypertrophy of gill lamella. Within the blood vessels, scuticociliates were observed one to ten individuals, depending on diameter of the blood vessels. Some of the scuticociliates were observed to have ingested erythrocytes.