| Project/Area Number |
16K21396
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| Research Category |
Grant-in-Aid for Young Scientists (B)
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| Allocation Type | Multi-year Fund |
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| Research Field |
Infectious disease medicine
Bacteriology (including mycology)
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| Research Institution | Tokyo University of Pharmacy and Life Science |
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Principal Investigator |
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| Project Period (FY) |
2016-04-01 – 2019-03-31
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| Project Status |
Completed (Fiscal Year 2018)
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| Budget Amount *help |
¥4,030,000 (Direct Cost: ¥3,100,000、Indirect Cost: ¥930,000)
Fiscal Year 2018: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2017: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Fiscal Year 2016: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
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| Keywords | 無莢膜型肺炎球菌 / 形質転換 / PspK / ワクチン / 無莢膜型 / 肺炎球菌 / 莢膜型 / 莢膜 / 無莢膜 |
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| Outline of Final Research Achievements |
pspK-harbouring nonencapsulated pneumococci (pspK+NESP) have emerged, and their occurrence has been gradually increasing. This study aimed to determine the cause of the spread of pspK+NESP. First, a pspK-deletion strain (ΔpspK) was constructed by replacing pspK with ermB. Purified genomic DNA from ΔpspK was mixed with encapsulated pneumococci. Consequently, the capsule region was lost, and the encapsulated strain became NESP. The NESP strain has a higher fitness than that of the parent strain. Resistance to phagocytosis by macrophages, ability to adhere to epithelial cells, and biofilm formation were also assessed. pspK+NESP did not show resistance to phagocytosis, but did showed greater epithelial cell adherence and biofilm formation. Taken together, encapsulated pneumococci can become NESP by acquiring pspK, and the increasing prevalence of NESP could be attributed to greater fitness, host cell adherence, and biofilm formation.
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| Academic Significance and Societal Importance of the Research Achievements |
肺炎球菌の無莢膜型株はこれまで病原性がないとされほとんど注目されてこなかった。しかし、ワクチンの導入とともにpspK保持無莢膜株が顕在化してきている。本研究から、莢膜保持株は無莢膜株のゲノムDNAを取り込み容易に無莢膜化すること、無莢膜型株は莢膜保持株と比較し、フィットネス、付着性、バイオフィルム形成能が高く生存しやすいことが示唆された。すなわち、本研究成果は、無莢膜株がワクチンからのエスケープ機構になることを示唆するものであり、無莢膜株にも注目すべきであることを示すものである。
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