Study of the mechanism of abortion caused by infection with the livestock pathogenic protozoan Neospora

2021 Fiscal Year Final Research Report

• Project/Area Number: 18H02335
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 42020:Veterinary medical science-related
• Research Institution: Obihiro University of Agriculture and Veterinary Medicine
• Principal Investigator: Nishikawa Yoshifumi 帯広畜産大学, 原虫病研究センター, 教授 (90431395)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: 原虫 / ネオスポラ / 流産 / 病原性

Outline of Final Research Achievements

The pathogenesis of Neospora-induced abnormal births was analyzed to prevent abortions in domestic animals due to infection with Neospora caninum. A mouse model of abnormal birth due to infection was established and the inflammatory response in utero-placental tissue was observed. We constructed a cell screening system based on the signal transduction of inflammatory response and found NcGRA7 as a protozoan-derived factor inducing abnormal birth. NcGRA7-deficient strain was generated and their virulence was tested in non-pregnant and pregnant mouse models, showing that NcGRA7 deficiency reduced the parasite virulence and increased normal pregnancy rates. Host protein X, which binds to NcGRA7, was also identified by mass spectrometry. Expression of NcGRA7 was also observed in tissue samples from bovine neosporosis, suggesting that NcGAR7 will be involved in Neospora abortion.

Free Research Field

感染免疫学

Academic Significance and Societal Importance of the Research Achievements

ネオスポラの感染は世界中に拡大しており、ウシに繁殖障害を引き起こすことから、地球規模での被害額は年間約数十億USドルにのぼる。しかし、ネオスポラ感染症に対する有効な治療法は開発されていないのが現状であり、ネオスポラ感染によるウシの流産に対する予防法・治療法の開発は最重要課題である。本研究では、ネオスポラの異常産誘発因子NcGRA7を同定し、異常産発生のメカニズムの一端を明らかにしており、ワクチンを含めた流産の予防法の開発において重要な研究成果を得ることができた。従って、本研究の成果によりネオスポラの防疫対策に貢献できれば、食料の生産性の向上や人類の食の安全の向上に直結すると考える。