| Project/Area Number |
17K08835
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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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| Research Field |
Bacteriology (including mycology)
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| Research Institution | University of Shizuoka |
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Principal Investigator |
OHASHI NORIO 静岡県立大学, 食品栄養科学部, 教授 (10169039)
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| Project Period (FY) |
2017-04-01 – 2022-03-31
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| Project Status |
Completed (Fiscal Year 2021)
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| Budget Amount *help |
¥4,810,000 (Direct Cost: ¥3,700,000、Indirect Cost: ¥1,110,000)
Fiscal Year 2019: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Fiscal Year 2018: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Fiscal Year 2017: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
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| Keywords | Rickettsia japonica / Japanese spotted fever / Rickettsia sp. LON / Rickettsia sp. G4 / Coxiella-like symbiont / Haemaphysalis / Tick / Rickettsia / マダニ / Coxiella様共生細菌 / 感染症 / 日本紅斑熱 / リケッチア / L929 / THP-1 / 共生細菌 / 生殖系統 / 両性生殖 / 単為生殖 / メタ16S解析 / 細菌 / 生態学 / 微生物 |
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| Outline of Final Research Achievements |
Rickettsia japonica that causes Japanese spotted fever, nonpathogenic rickettsiae, and Coxiella-like symbionts (CLE) are a group of endogenous bacteria in ticks. It is known that these bacteria are passed on to the tick's offspring by vertical transmission. We found that (i) the nonpathogenic Rickettsia sp. LON harbored by Haemaphysalis longicornis ticks becomes absent in ticks with the unique parthenogenetic reproductive system, (ii) pathogenic R. japonica and nonpathogenic Rickettsia sp. G4 possessed by Haemaphysalis histricis ticks are both a copy number of 100-1,000,000 per tick, (iii) Haemaphysalis tick species and CLE species are co-evolved, and (iv) 4 out of 24 haplotypes of H. histricis ticks possess pathogenic R. japonica. These results are expected to contribute greatly to the control of tick-borne infectious diseases in Japan in the future.
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| Academic Significance and Societal Importance of the Research Achievements |
本研究の学術的意義としては、(i) 日本紅斑熱を引き起こすリケッチア(Rj)のマダニ内のコピー数を明らかにしたこと、(ii) マダニ内の病原性Rjと非病原性R-G4を識別できる検出法を開発したこと、(iii) 単為生殖系のマダニではリケッチアが消えていくことを見出したこと、(iv) マダニ種とCLE種が共種分化していることを発見したこと、(v) マダニのあるハプロタイプが病原性Rjを保有していることが判ったこと、などである。社会的意義としては、公衆衛生上、日本紅斑熱の多発地域での啓発活動に役立つ知見が得られたことと考える。
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