| Project/Area Number |
07456159
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Applied veterinary science
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| Research Institution | National Institute of Infectious Diseases |
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Principal Investigator |
KAMIYAMA Tsuneo NIID,Dept Vet.Sci., Division head, 獣医科学部, 室長 (70100071)
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| Co-Investigator(Kenkyū-buntansha) |
MATSUURA Yoshiharu NIID,2nd Dept.Virol., Division head, ウイルス第2部, 室長 (50157252)
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| Project Period (FY) |
1995 – 1997
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| Project Status |
Completed (Fiscal Year 1997)
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| Budget Amount *help |
¥2,500,000 (Direct Cost: ¥2,500,000)
Fiscal Year 1997: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1996: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Keywords | Zoonosis / Babesia microti / Cytokine / T cell clone / sero-epidemiology / バベシア症 / Babesia microti / 原虫 / バベシア原虫 / TGF |
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| Research Abstract |
Babesia microti is a malaria-like parasite transmitted from wild rodents to humans by ticks and responsible for severe illness and fatal outcome in immunocompromized hosts. Infection of T cell deficient mice with B.microti resulted in a high level of parasitemia which lasted for several months. Furthermore, adaptive transfer of T cells from normal BALB/c mice resulted in SCID mice being able to control the infection, indicating the importance of T cells in the protection. Because CD4^+ T cells were considered to be involved in protection against infection with B.microti, specific CD4^+ T cells were generated in vitro from recovered BALB/c mice and their protective activity was tested in vivo. The cells produced varying amounts of interferon (IFN)-g in vitro in response to parasite antigen. In passive transfer experiments, some but not all of the T cell clones tested exerted protective activity in the early phase after infection. There seemed to be no correlation between this protection and in vitro IFN-g production by the T cell clones. Although the protection was partial and short-lived, the result provided direct evidence that CD4^+ T cells play a crucial role in defense against B.microti. Sera from wild rodents captured at the central area of Japan were submitted for a retrospective sero-survey for anti-B.microti antibody. Western-blot analyzes revealed that 5 out of about 300 sera reacted with B.microti specific antigens of 30-100 kDa. This is the first seroepidemiological evidence which suggests presence of B.microti infection among wild rodents, at least in the past.
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