2023 Fiscal Year Final Research Report
Pathogenicity of microsporidian infecting masu salmon from Lake Biwa
| Project/Area Number |
21K05733
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Review Section |
Basic Section 40030:Aquatic bioproduction science-related
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| Research Institution | Okayama University of Science |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
柳田 哲矢 山口大学, 共同獣医学部, 准教授 (40431837)
白樫 正 近畿大学, 水産研究所, 准教授 (70565936)
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| Project Period (FY) |
2021-04-01 – 2024-03-31
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| Keywords | 寄生虫 / 微胞子虫 / サケマス類 / 病害性 / 生活環 |
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| Outline of Final Research Achievements |
In this study, the microsporidian which causes the newly found microsporidiosis in salmonids from Lake Biwa was described as Inodosporus fujiokai n. sp., based on the molecular and ultrastructural analyses. The genetic and ultrastructural data of the developmental stages in common prawn from Lake Biwa were also characterized. The artificial transmissions of I. fujiokai from common prawn to fishes were established, showing that there was a significant difference in susceptibility among salmonid fishes, Also, it demonstrated that I. fuijiokai could infect to the other taxonomically different fishes such as cyprinids. Further, real-time PCR technique (q-PCR) for I. fujiokai was developed, clarifying the intra-piscine time-course development and some light infections in Centrarchidae such as largemouth bass. Histopathological study suggested that rainbow trout died of myocarditis, however, the possible cause of death in the other fishes remained to be clarified.
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| Free Research Field |
魚病学
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| Academic Significance and Societal Importance of the Research Achievements |
従来、魚類寄生性微胞子虫類で魚類以外の宿主が介在する例は皆無であったが、他の動物群に寄生する微胞子虫では、蚊と水生ミジンコ類を交互に寄生する種類が記載されている。魚類寄生種でも魚類だけでの人為感染が成功しない例が数多くあるのみならず、エビ類寄生種と魚類寄生種のリボソームDNAの塩基配列が同一である種類も報告されている。本研究により、魚類と甲殻類を交互に宿主とする微胞子虫の生活環が解明されれば、他の魚類寄生種についても同様の生活環をもつことが示唆され、寄生虫学的な意義があるのみならず、感染メカニズムが解明され感染防除法が確立されることで、魚病学的さらに社会的な意義があることは明白である。
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