• 한국수산과학회지
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• 제54권5호
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• pp.652-659
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• 2021

Microorganism-derived compounds, such as peptidoglycan, lipoteichoic acid, and β-glucan were supplemented in the scuticociliate Miamiensis avidus (M. avidus) vaccine to verify the specify component contribution to the adjuvant effect. Vaccine was formulated with the inactivated M. avidus antigen (YS2, 4.44×10⁵ cells/fish) in combination with either peptidoglycan (10 ㎍ and 100 ㎍/fish), lipoteichoic acid (5 ㎍ and 50 ㎍/fish), or β-glucan (10 ㎍ and 100 ㎍/fish). Olive flounder injected with peptidoglycan supplemented vaccine (10 ㎍ and 100 ㎍/fish) exhibited significant protection, and the relative percent survival (RPS) was 55% and 65% at 4 weeks post vaccination (wpv), respectively, at the corresponding doses. The vaccine groups with added lipoteichoic acid (5 ㎍ and 50 ㎍/fish) exhibited RPS of 40% and 5%, respectively. Additionally, the group with added β-glucan (100 ㎍/fish) exhibited RPS of 35%, but no effect was observed in the group with added 10 ㎍/fish β-glucan. At 8 wpv, olive flounder injected with peptidoglycan and lipoteichoic acid supplemented vaccines exhibited protection with RPS range of 11/11% and 5/21%, respectively, at the respective doses. M. avidus vaccine containing 10 ㎍ and 100 ㎍/fish of β-glucan exhibited the RPS of 32% and 37%, respectively. Conclusively, peptidoglycan contributed in high protection of the M. avidus vaccine, and thus, it can be used as an effective adjuvant in the M. avidus vaccine.

• 한국어병학회지
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• 제28권1호
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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.

• 한국어병학회지
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• 제35권2호
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• pp.225-230
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• 2022

Viral hemorrhagic septicemia (VHS) is one of the most serious viral diseases affecting farmed olive flounder (Paralichthys olivaceus) in Asian countries. VHS, caused by viral hemorrhagic septicemia virus (VHSV), occurs in over 80 different cultured and wild fish species worldwide. Our previous study demonstrated that VHSV infection can be restricted by adjusting the water temperature to over 17℃ from the host optima. We confirmed that the effective VHSV immersion vaccine treatment was a tissue culture infection dose (TCID) of 10^5.5 TCID₅₀/mL at 17℃. However, the safety of live VHSV immersion vaccines remains unclear. The objectives of this study were to 1) demonstrate the safety of the live VHSV immersion vaccine under co-habitant conditions and 2) estimate the pathogenicity of VHSV in live VHSV-vaccinated flounder at 10℃. No mortality was observed in olive flounder treated with the live VHSV immersion vaccine, and the vaccinated flounder challenged with VHSV did not transfer VHSV to naïve fish at 10℃ through cohabitation. VHSV titration was below the detection limit (< 1.3 log TCID₅₀/mL) in live VHSV immersion vaccine-treated flounder challenged with VHSV at 10℃. This study demonstrated that flounder treated with the live VHSV immersion vaccine were resistant to VHSV infection, and the live vaccine was also safe for naïve fish even at a water temperature known to be VHS infectious.

• 한국어병학회지
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• 제37권1호
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• pp.17-23
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• 2024

Spring viremia of carp virus (SVCV) poses a significant threat to numerous cyprinid fish species, particularly the common carp (Cyprinus carpio), often resulting in substantial mortalities. This study explores the potential use of a chimeric recombinant snakehead rhabdovirus carrying the SVCV G gene (rSHRV-Gsvcv) as a live vaccine against SVCV infection. Through virulence testing in zebrafish at different temperatures (15 ℃ and 20 ℃), no mortality was observed in groups infected with either rSHRV-wild or chimeric rSHRV-Gsvcv at both temperatures, whereas 100% mortality occurred in fish infected with wild-type SVCV. Subsequently, as no mortality was observed by rSHRV-Gsvcv, three independent experiments were conducted to determine the possible usage of chimeric rSHRV-Gsvcv as a vaccine candidate against SVCV infection. Fish were immunized with either rSHRV-Gsvcv or rSHRV-wild, and their survival rates against the SVCV challenge were compared with a control group injected with buffer alone at four weeks post-immunization. The results showed that chimeric rSHRV-Gsvcv induced significantly higher fish survival rates compared to rSHRV-wild and the control groups. These findings suggest that genetically engineered chimeric rSHRV-Gsvcv holds the potential for a prophylactic measure to protect fish against SVCV infection.

• 한국어병학회지
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• 제22권1호
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• pp.45-52
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• 2009

Zebrafish was firstly applied to an experimental model for scuticociliatosis caused by Philasterides dicentrarchi, a facultative parasitic ciliate in cultured marine fish. The susceptibility of zebrafish to infection of P. dicentrarchi was assessed by intraperitoneal injection of the ciliates, which produced typical symptoms of scuticociliatosis and significant mortality. The potential use of zebrafish as a model to evaluate the vaccine efficacy against scuticociliatosis was analyzed by immunization of zebrafish with the ciliates lysate. Furthermore, the effect of different adjuvants, such as Quillaja saponin (QS), Montanide, and Freund’s incomplete adjuvant (FIA) on the protective efficacy of the vaccine was investigated. Groups of zebrafish injected with QS or Montanide alone showed higher survival of fish against challenge test compared to control fish. The results suggest that adjuvant-mediated enhancement of innate immune responses play important roles in protection of fish against scuticociliatosis. The considerably high survival in the fish immunized with the antigen alone indicates that the ciliate lysate itself is highly immunogenic to zebrafish, which can elicit protective immune responses. The protective potential of the antigen, ciliate lysate, was enforced through combined administration with adjuvants including QS, Montinide and FIA. No or low mortalities in the groups of fish immunized with the antigen plus adjuvants suggests that the adaptive immune responses of zebrafish might be accelerated by the adjuvants or the protective potential of the antigen and adjuvants might synergistically interact. In spite of several shortcomings such as difficulties in sampling of serum and leucocytes enough to routine immunological analyses, zebrafsih might be the most convenient experimental animal for scuticociliatosis.

• Fisheries and Aquatic Sciences
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• 제26권3호
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• pp.188-203
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• 2023

Lysozymes are well-known antibacterial enzymes that mainly target the peptidoglycan layer of the bacterial cell wall. Animal lysozymes are mainly categorized as g-type, c-type, and i-type based on protein sequence and structural differences. In this study, c-type (AcLysC) and g-like-type (AcLysG-like) lysozymes from Amphiprion clarkii were characterized in silico via expressional and functional approaches. According to in silico analysis, open reading frames of AcLysC and AcLysG-like were 429 bp and 570 bp, respectively, encoding the corresponding polypeptide chains with 142 and 189 amino acids. Elevated expression levels of AcLysC and AcLysG-like were observed in the liver and the heart tissues, respectively, as evidenced by quantitative real-time polymerase chain reaction assays. AcLysC and AcLysG-like transcript levels were upregulated in gills, head kidney, and blood cells following experimental immune stimulation. Recombinant AcLysC exhibited potent lytic activity against Vibrio anguillarum, whereas recombinant AcLysG-like showed remarkable antibacterial activity against Vibrio harveyi and Streptococcus parauberis, which was further evidenced by scanning electron microscopic imaging of destructed bacterial cell walls. The findings of this study collectively suggest the potential roles of AcLysC and AcLysG-like in host immune defense.

• 한국임상수의학회지
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• 제26권3호
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• pp.226-230
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• 2009

We evaluated the efficacy of $\beta$-hemolytic Streptococcus(S.) iniae vaccine on cultured olive flounder. Three hundred flounders(weight $50{\pm}5$ g) were obtained from two farm at Wando and Taean in the southern and western coast of Korea at May and June 2007, respectively. Twenty of flounders moved in 0.5 tons aquaria in land-marine tank system of National Veterinary Research and Quarantine Service. Seawater was transported from the sea of Inchon in western Korea, and water temperature maintained to $22^{\circ}C$ and $25^{\circ}C$ during the vaccination and challenge test, respectively. We used the formalin-inactivated $\beta$-hemolytic S. iniae vaccine produced by domestic manufacturers. The vaccine was intraperitoneally administered to fish. The vaccinated and control group were challenged with intraperitoneal injection by virulent S. iniae SI-36 isolates with $5.0{\times}10^8$ CFU/fish at 3 weeks after vaccination. We evaluated the vaccine efficacy by calculating numbers of dead fish, and observing of clinical signs, exterior and gross lesions, and examining bacteria isolation and identification. Thirty-four(25.2%) of 135 control and vaccinated group fish were dead with serious anemia, abdominal extension, and hernia of intestine during 3 weeks post vaccination. We isolated Neoheterobothrium hirame from the buccal cavity and Edwardsiella tarda from kidney of dead and diseased fish. When infected fish with these agents were challenged with S. iniae SI-36 isolates, the cumulative mortality of control and vaccinated group were 86.7, and 46.7%, respectively. However, significant differences(p<0.05) were observed on cumulative mortality between control(20.0%) and vaccinated group(95.0%) at second trials with 40 healthy, and relative percent survival(RPS) was 78.0%. We confirmed that the efficacy of $\beta$-hemolytic S. iniae vaccine on olive flounder were impacted by health condition such as bacterial and parasitic diseases.

• 한국어병학회지
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• 제31권1호
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• pp.35-39
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• 2018

Atypical furnculosis caused by atypical Aeromonas salmonicida, is an emerging problem of farming of rockfish (Sebastes schlegeli) in Korea. In this study, protection against atypical furunculosis was compared in rockfish vaccinated with A. salmonicida formalin killed cell (FKC) and adjuvant containing FKC. The formalin inactivated A. salmonicida vaccine provided a low protection of 20% and 10% relative percent survival (RPS) at 44 and 58 days post vaccination. However, addition of adjuvant (squalene and aluminum hydroxide) into inactivated A. salmonicida vaccine clearly enhanced the level of protection showing 70% and 50% RPS at 44 and 58 days post vaccination.

• 한국해양생명과학회지
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• 제4권1호
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• pp.1-13
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• 2019

Fucoidan(후코이단)은 주로 갈조류에서 추출되는 fucose를 함유한 함황 다당류의 일종으로, 항균, 항바이러스 및 항종양 효과와 함께 다양한 경로로 면역력을 향상시키는 생리 기능성물질로 알려져 있다. 최근 연구에 따르면, 인체 백신 분야에서는 fucoidan의 백신 adjuvant(항원보조제)로서의 가능성이 제시되었다. 수산업 분야에서는, 보조사료로서의 fucoidan의 기능에 관한 연구는 보고되고 있으나, 수산용 백신 개발을 위한 adjuvant 연구는 전무한 실정이다. 동물세포에서 fucoidan의 adjuvant에 대한 긍정적인 검토와 함께 안전성을 증명한 연구는 많이 있지만, fucoidan을 어류 백신용 adjuvant로 사용하기 위해서는 어류에서도 이를 확인할 필요가 있다. 또한 fucoidan의 분자량에 따라 세포 내 흡수율이 각기 다르다는 점과 병원체의 인위감염에 따른 항체 생성을 포함한 어류의 특이면역 반응 시스템에 대한 연구가 많이 부족하다는 제약이 있다. 따라서 이러한 분야에 대한 적극적인 연구가 뒷받침 된다면 안전하고 효과적인 adjuvant로 사용할 수 있을 것이다. 본 연구에서는 fucoidan이 사람과 동물을 포함하여 어류의 면역자극 즉 체액성 및 세포성 면역에 미치는 영향에 대한 연구를 검토하고, 수산업 분야에서 fucoidan의 사용과 어류 백신용 adjuvant로서의 가능성을 고찰하였다.

• 한국어병학회지
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• 제24권3호
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• pp.189-195
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• 2011

Starry flounder, which are recently increasingly cultured in Korea, are known to highly vulnerable to Streptococcus parauberis infection. Five groups of starry flounder (n=30 for each group) were vaccinated with S. parauberis formalin-killed whole cells by intraperitoneal injection at a final concentration of 0, 0.01, 0.1, 1 and 10 mg $fish^{-1}$. Specific antibody production of 1 and 10 mg $fish^{-1}$ administered groups significantly increased at four weeks post immunization. All vaccinated groups showed higher survival rates than a control group when five groups of fish were challenged with S. parauberis at a dose of $1.14{\times}10^4$ cfu $fish^{-1}$ and $1.14{\times}10^2$ cfu $fish^{-1}$, respectively. In particular, 0.1 or higher concentrations of formalin killed bacterial cells are able to confer the fish high protection against S. parauberis infection.