2023 Fiscal Year Final Research Report
Development of a toxoid for scuticociliatosis in fish
| Project/Area Number |
19K22336
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| Research Category |
Grant-in-Aid for Challenging Research (Exploratory)
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| Allocation Type | Multi-year Fund |
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| Review Section |
Medium-sized Section 40:Forestry and forest products science, applied aquatic science, and related fields
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| Research Institution | Ehime University |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
仲山 慶 愛媛大学, 沿岸環境科学研究センター, 講師 (80380286)
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| Project Period (FY) |
2019-06-28 – 2024-03-31
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| Keywords | スクーチカ症 / トキソイド / Miamiensis avidus |
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| Outline of Final Research Achievements |
Genome editing experiments were planned to identify the virulence factor in extracellular proteases secreted by the causative agent of scuticociliatosis, Miamiensis avidus. Prior to the genome editing experiments, we examined the conditions for protein expression experiments in M. avidus, however were unable to induce protein expression using the promoter of the housekeeping gene of the parasite in addition to the promoters of mammalian and Tetrahymena.
From the results of genome analyses in M. avidus, cathepsin L, a known virulence factor in many parasites, was detected. It was expressed by a cell-free protein expression system, and Japanese flounder was immunized with the recombinant protein. The immobilized antibody titers of their sera were measured, which were as high as 100-fold or more. However, infection experiments did not confirm the efficacy of the vaccine.
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| Free Research Field |
魚病学
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| Academic Significance and Societal Importance of the Research Achievements |
ゲノム編集を行うために、スクーチカ症の原因繊毛虫Miamiensis avidusの組換体の作製を試みたが、同じ繊毛虫でモデル生物であるテトラヒメナと異なり、タンパク質発現実験が困難であることが明らかとなった。本課題で検討されたエレクトロポレーションの条件、プロモーター探索、形質転換体選択用の薬剤などの結果は、今後のM. avidusにおける組換体作製に重要な知見となる。
本虫の組換えカテプシンL（rCat）をヒラメに免疫したが、ワクチン効果は認められなかった。しかしながら、ヒラメ血清は本虫を不動化したことから、rCatは十分な抗原性を有することが明らかにされた。
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