In 2009 outbreaks of an emerging disease in shrimp farms were first reported in China. The disease was known as early mortality syndrome (EMS), or acute hepatopancreatic necrosis disease (AHPND). Since 2009, the disease has been spread to Vietnam, Malaysia, Thailand and Mexico. The causative agent of the disease was identified as Vibrio parahaemolyticus. It is a common seawater inhabitant bacterium, and the pathogen can sometimes contaminate seafood. The disease has caused mass mortality of cultivated shrimp, and huge economic losses in the countries named above. In order to prevent the introduction and establishment of AHPND, emergency measures, such as strengthening of import conditions and even import bans, were put in place by many other countries. In Korea, on the other hand, there are large quantities of shrimp imports from countries, such as Thailand and Vietnam. Transportation of live and fresh dead shrimp is highly likely, and could be a transmission pathway if the shrimp are sourced from populations in AHPND endemic areas. It is important to recognize that importing countries may provisionally adopt sanitary or phytosanitary measures on the basis of available pertinent information, including that from the relevant international organizations, as well as from sanitary or phytosanitary measures applied by other countries based on "Agreement on Application of Sanitary and Phytosanitary Measures". It is pertinent that Korea also takes proper emergent measures to keep out diseases and provide safe seafood.

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.

The purpose of this study is to explore the possibility of essential oils and flavonoids improving the performance of antibiotics, proving a higher efficacy in the presence of natural substances against Edwardsiella tarda and Streptococcus iniae. Increased efficacy was observed in several cases: both essential oils and flavonoids increased antibacterial efficacy of oxytetracycline and flumequine against E. tarda by 2-fold; essential oils and flavonoids increased antibacterial efficacy of nalidixic acid against E. tarda by 4-fold; flavonoids increased antibacterial efficacy of josamycin against S. iniae by 4-fold. The results obtained in this study suggest that essential oils and flavonoids might be especially useful in increasing the antimicrobial activity of nalidixic acid and josamycin against E. tarda and S. iniae in fish. Natural compounds examined in this study could also be useful to help decrease the overuse of antibiotics in fish.

Viral hemorrhagic septicemia virus (VHSV)는 세계적으로 담수와 해산어에 심각한 경제적 손실을 야기시키는 주요바이러스이다. 이매패류는 감염어로부터 해수로 방출된 바이러스를 여과섭식작용을 통해 축적하는 것으로 알려져 있어 carrier로써의 가능성이 보고된 바 있으므로. 본 연구에서는 이를 확인하기 위해 국내 어류 양식장 주변에 서식하는 참굴(Crassotrea gigas)과 담치(Mytilus edulis)를 샘플링하였고, RT-PCR법을 통해 바이러스를 검출하여 패류 내 VHSV존재를 확인하였다. 기존 병성감정기관에서 사용하는 primer로는 IVa genotype만을 검출할 수가 있었기 때문에 Glycoprotein(G) gene의 conserved region에 대한 primer를 제작하여 VHSV의 4가지 타입 모두 검출할 수 있게 하였고 이를 본 연구에 사용하였다. 총 84개 중 22개의 시료가 nested PCR을 통해 양성으로 확인되었고, 이 중 6개의 양성시료를 시퀀싱하여 유전학적 분석을 실시하였다. 그 결과 국내 여러 지역의 패류에서 검출된 VHSV는 모두 IVa genotype으로 아주 제한적인 결과를 보여주었으며, 이는 국내 어류에게 질병을 일으키는 VHSV의 타입은 IVa genotype이라는 이전의 보고와 상응하는 결과를 나타냈다고 할 수 있다. 결론적으로 본 연구에서는 양식장 주변에 서식하는 이매패류의 여과섭식작용으로 인한 축적되는 바이러스로 인한 전염가능성과 패류 내 존재하는 바이러스와 어류에서 질병을 발생시키는 바이러스와의 상호관계를 조사하였으며, 향후 다른 genotype의 유입 및 검출을 위한 연구는 계속적으로 필요하다고 생각된다.

본 연구에서는 넙치 (평균체장 및 무게: $20{\pm}2.0cm$, $70{\pm}5.0g$)에 옥시테트라사이클린(oxytetracycline, OTC)-네오마이신(neomycin, N) 복합제를 25-10 ppm 및 50-20 ppm으로 용해하여 2일 동안, 3시간씩 약욕을 실시하였고, 약물투여 중지 후 1일, 5일, 14일, 40일째에 시험군별로 각각 5마리씩 넙치의 근육을 채취하여 항생제 잔류농도를 조사하였다. OTC와 N 표준용액을 농도별로 희석하여 표준곡선을 작성한 결과 각각 $R^2=0.9999$, $R^2=0.9952$로 양호한 직선성을 나타내었고, OTC와 N 회수율은 각각 90~93%, 88~95%가 관찰되었다. 잔류농도에 대한 측정결과, OTC와 N 복합제를 25-10 ppm 투여한 시험군에서 1일째 OTC는 $0.97{\pm}0.084{\mu}g/ml$이 검출되었고, N은 $0.118{\pm}0.079{\mu}g/ml$이 검출되었으나 5일째 이후부터 검출이 되지 않았다. OTC와 N 복합제를 50-20 ppm 투여한 시험군에서 1일째 OTC는 $1.324{\pm}0.062{\mu}g/ml$이 검출되었고 N은 $0.788{\pm}0.05{\mu}g/ml$이 검출되었으나 5일째 이후부터 검출이 되지 않았다.

아목시실린(AMOX)의 수온에 따른 약동학적 특성과 잔류량을 알아보기 위해 넙치(평균 100 g)를 $(17{\pm}2)^{\circ}C$ 및 $(22{\pm}2)^{\circ}C$에 수용하여 1회 근육투여한 후 시간에 따른 혈장, 간, 신장의 잔류농도를 HPLC-UVD로 분석하였다. 이 측정결과를 바탕으로 2-compartmental model로 PKSolver program을 이용하여 AMOX의 반감기, AUC 등의 pharmacokinetic parameter를 조사하였다. 혈장, 간, 신장의 최고농도 및 도달시간의 범위가 각각 $27.23-257.36{\mu}g/m{\ell}$ (0.05-0.91 h), $5.49-41.65{\mu}g/g$ (1.36-3.28 h), $16.75-129.31{\mu}g/g$ (1.95-4.49 h)으로 나타났다. 수온에 따른 잔류기간을 시험하기 위해 어체중 kg 당 40 및 400 mg을 투여한 후 LC-MS/MS로 분석하였다. 40 mg/kg은 5일 후, 400 mg/kg은 7일 후에 각각 최대잔류허용량인 0.05 mg/kg 이하로 검출되었다.

Here, we report the physiological changes and growth in disk abalone, Haliotis discus discus, in relation to dietary supplementation with citrus pomace (CP) 6%, Ecklonia cava residue (ECR) 6%, and CP + ECR (3% + 3%). The composition and nutrient content, survival rate and growth rate were measured 0, 4, 8 and 12 weeks after feeding the supplemented diets of CP and/or ECR. Moreover, the experiment of low salinity stress (25psu) for environmental resistance was examined for a period of 48 hours after feeding the supplemented diets for 12 weeks. The activities of superoxide dismutase (SOD), catalase (CAT), lysozymes, respiratory burst, and phenoloxidase were measured. The moisture content and crude protein condition of the body were increased with the addition of ECR only (P<0.05). We observed higher levels of survival in the experimental group compared with the control group. Moreover, the growth disk abalone that were fed a diet containing ECR was higher compared with the control group. However, the growth of abalone fed a diet containing CP was similar to the control group. With a rearing condition of low salinity stress, survival rate and lysozyme activity were increased in the ECR group compared with the control group. Dietary ECR reduced the level of CAT activity to approximately 30% of the control, however the level of CAT activity in the ECR group was similar to the start level of the previous stress. These results suggest that dietary ECR gives rise to an enhanced immunity in disk abalone, as a result of the decrease in CAT and lysozyme activity in particular. Accordingly, the growth and survival rate were increased by feeding an ECR-supplemented diet in the rearing of disk abalone, Haliotis discus discus.