• 한국수산과학회지
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• 제48권5호
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• pp.719-724
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• 2015

In this study aiming at the cultured olive flounders in Jeju island of Korea, has performed a total of 216 cases of pathogen tests for the olive flounders which seemingly had the symptom of emaciation in 24 farms on the suspicion of its occurrence from June 2010 to December 2013 and intended to get the basic information about the pathogen. According to the survey results of the emaciation infection status of 24 farms in Jeju over the period of this survey, it was confirmed that 18 (75%) of 24 farms in Jeju are positive in the emaciation infection. Among them, as for the rate of infection per year, it was observed that they are 38% in 2010, 48% in 2011, 50% in 2012 and 60% in 2013, and over the period of this survey the infection rate in accordance with the temperature of water has observed a variety of incidence rates from the summer to the winter season. In addition, according to the results of emaciation infection status for each size, the equivalent showed a detection rate, 54% in 11-20 cm, 43.9% in 21-30 cm and 25.4% in over 31 cm. This result accounts for an important portion among the diseases of farmed olive flounders in Jeju, is considered to be one of the diseases which cause troubles in the farms for olive flounders on land and it is thought that it can be utilized as basic data in order to estimate emaciation which may occur in the similar size of the cultured olive flounders in Jeju island.

• 한국어병학회지
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• 제21권3호
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• pp.157-166
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• 2008

Streptococcal diseases are known as serious problems in fresh water and marine fish culture industry worldwide. Recently, the importance of the infection of Streptococcus parauberis has been increased among the streptococcicosis since severe outbreaks in cultured olive flounder (Paralichthys olivaceus) were recorded in Korea. The aims of the present study were to investigate immunomodulatory differences between S. parauberis and S. iniae. In this study, S. parauberis isolated from diseased olive flounder was investigated on the characteristics of morphological and immune responses. Immune response of the fish to the pathogen was characterized by bactericidal activity in the serum, phagocytic activity and reactive oxygen intermediaters (ROIs) production of olive flounder. The capsules of both bacteria, S. parauberis and S. iniae seem to be associated with the ability to resist killing activity of normal sera. Also, capsulated strains could survive in the phagocytes and induce to lower ROIs production.

• 한국어병학회지
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• 제30권1호
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• pp.41-49
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• 2017

생균제는 성장촉진, 면역증진 및 질병예방에서 넙치 Paralichthys olivaceus 치어의 양식에서 우수한 생산효과로 적용될 수 있다. 성장률, 선천성면역 및 항병력을 증강시킬 수 있는 생균제의 효과를 조사하기위해 Bacillus subtilis, Bacillus licheniformis 및 Lactobacillus plantarum (BSL-LAB)이 혼합되어있는 생균제와 NBS (nitrifying bacteria con- sortium) 분말을 사료에 첨가 또는 수조에 투입하여 시험을 수행하였다. 생균제 첨가사료는 7주간 투여하였고 3가지의 생균제 조합 시험군 모두에서 넙치의 성장과 항병력에서 대조군에 비해 높은 유효성을 발휘 하였다. 어병세균에 대한 항병력의 긍정적인 결과는 생균제에 대한 면역기능의 향상으로 나타난 효과이며 상기 시험결과로 볼 때, 넙치치어 양식에서 생균제의 혼합첨가는 성장 및 선천성면역 뿐만 아니라 질병저항성에 좋은 효과를 나타낼 수 있을 것으로 사료된다.

• Fisheries and Aquatic Sciences
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• 제9권3호
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• pp.123-128
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• 2006

An epizootic causing mortality among cultured marine finfishes occurred in 1999 in the province of Kyoungsang, Korea. The disease was characterized by the presence of enterocele, abdominal swelling, and gastroenteritis. The causative bacteria were isolated from olive flounder (Paralichthys olivaceus), black rockfish (Sebastes schlegeli), turbot (Scophthalmus maximus) and the rearing water. These bacteria showed swarming activity on agar plates and yellowish or greenish colonies on thiosulfate-citrate-bile salts-sucrose (TCBS) agar plates, but no luminescence. The pathogen was identified as Vibrio harveyi based on morphological and biochemical characteristics and the sequence of l6S rDNA. The lethal doses (LD$_{50}$) of olive flounder and black rockfish were estimated to be $1.24\times10^6-1.36\times10^8$ and $3.24\times10^5-5.8\times10^7$ CFU/fish respectively following intraperitoneal injection.

• 한국어병학회지
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• 제30권2호
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• pp.135-148
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• 2017

Pathogen introductions associated with aquatic invasive species threaten ecosystems and biodiversity worldwide. Bigheaded carps (BHC), including Silver Carp Hypophthalmichthys molitrix, Bighead Carp H. nobilis, and their hybrids, are prolific, invasive pests in central US rivers. However, little is known about pathogen effects on invading BHC or how BHC affect the disease risk profile for native fishes in receiving ecosystems. We therefore conducted, from May 2013-December 2014, a systematic pathogen survey for BHC and native fishes in the Wabash River watershed, Indiana, USA. We found Pseudomonas fluorescens, P. putida, and Salmonella enterica DNA in BHC as well as native fishes, although none of these bacteria were exclusively present in BHC. DNA from other bacterial taxa was detected only in native fishes and Common Carp Cyprinus carpio. No gastrointestinal helminths were detected in BHC, although they were common in most native fishes examined. We also conducted in vitro studies on BHC tissues (skin, gill, fin, and fry) and found high sensitivity to Largemouth Bass virus, viral hemorrhagic septicemia virus, and infectious pancreatic necrosis virus. We conclude that BHC are not heavily burdened by bacteria, viruses and parasites in the invaded study ecosystems, although they do harbor native bacteria and show potential for high sensitivity to endemic viruses.

• 한국임상수의학회지
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• 제27권1호
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• pp.62-65
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• 2010

Arowana (Scleropages formosus) is the most valuable group of ornamental fishes and very much in demand in the ornamental fish trade and commands high price ranging from hundreds to thousands of dollars per fish. In this paper, we described a case of mortality of arowana from a private aquarium in Korea. A bacterial pathogen from fish organs (brain, kidney, liver) was cultured, identified and confirmed using Vitek System 2, API 20E test, multiplex PCR and 16S rRNA gene sequencing. The morphological and biochemical properties of the bacterium isolated from the brain, kidney and liver of the fish were similar to Aeromonas sobria. Positive amplification products using the multiplex PCR assay for detection of A. sobria were obtained from these organs. The 16S rRNA gene of the isolates from fish was identical and exhibited 100% sequence similarity with A. sobria (AY987762.1) strain available from GenBank. This bacterium contained hemolysin gene, a virulence factor that plays an important role in outbreaks of disease and is pathogenic to humans as well as in fish. Although this opportunistic bacterium was isolated from a fish without any external symptoms, this pathogen may act as a reservoir and enhance chances of zoonosis to human such as during handling.

• 한국어병학회지
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• 제26권3호
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• pp.207-217
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• 2013

최근 울산광역시 소재의 넙치 양식장에서 체색 흑화, 간 위축, 장관 백탁 등의 증상을 보이며 넙치의 대량 폐사가 빈번히 발생하여, 병원체를 분리하고 감염 특성에 관하여 연구하였다. 2012년 5월 병어로부터 분리한 원인균은 생화학 시험과 16S rRNA, dnaJ gene을 이용한 염기서열 분석을 통해 V. scophthalmi로 동정하였다. 병원성 시험 결과, 본 시험 균주가 $10^6$ CFU/fish에서 75%의 누적 폐사율을 보여 강한 병원성이 확인되었다. V. scophthalmi 감염어는 조직병리학적 병변으로서 간 위축, 장 상피 탈락, 장내 세포 물질 유출 및 장관백탁증 등이 확인되었다.

• Fisheries and Aquatic Sciences
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• 제25권6호
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• pp.320-326
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• 2022

Most of the emerging diseases that threaten humans are caused by RNA viruses which are extremely mutable during evolution. The fish RNA virus, viral hemorrhagic septicemia virus (VHSV) can infect a broad range of aquatic animal hosts, but the transmissibility of VHSV to mammals has not been thoroughly investigated. Therefore, our study aimed to investigate the potential adverse effects of VHSV in mammals. Briefly, the survival of VHSV was determined using only minimum essential media (MEM-2) and mammalian SNU-1411 and hepa-1c1c7s cells at 15℃ and 37℃. Mice (Mus musculus, 27.3 ± 1.9 g) were intravenously injected with VHSV (2.37E+05 TCID₅₀·mice^-1) in triplicate. Clinical signs and survival rates were examined at 14 days post-challenge, and infection was confirmed in the surviving mice. The 50% tissue culture infective dose (TCID₅₀) and polymerase chain reaction analysis were used to determine viral titers and the infection rate, respectively. The titer of VHSV suspended in MEM-2 at 15℃ was reduced by only one log after 8 days, whereas the virus maintained at 37℃ was inactivated 8 days post-inoculation (dpi). There were no recognizable cytopathic effects in either SNU-1411 or hepa-1c1c7s cells inoculated with VHSV at 15℃ and 37℃. VHSV in those cell lines at 37℃ was rapidly decreased and eventually inactivated at 12 dpi, whereas virus at 15℃ remained at low concentrations without replication. In vivo experiment showed that there were no signs of disease, mortality, or infection in VHSV-infected mice. The results of this study indicate that it is highly unlikely that VHSV can infect mammals including humans.

• Fisheries and Aquatic Sciences
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• 제5권3호
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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.

• 대한수의학회지
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• 제49권1호
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• pp.35-38
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• 2009

The zebra shark Stegostoma fasciatum which had been reared in the commercial aquaria was found dead and submitted for postmortem examination. A pure bacterial culture was isolated from pale and enlarged liver. The analysis of ureC and 16S rRNA genes confirmed the isolate as Photobacterium (P.) damselae subsp. damselae and this pathogen was sensitive to gentamicin. Although, no mortality in mouse was observed in the experimental infection study, the isolation of this pathogen in aquarium fish is significant because it can act as a reservoir to other aquatic animals and can also be zoonotic potential to human during aquarium management. This paper describes the first isolation of P. damselae subsp. damselae from zebra shark.