| Project/Area Number |
06807028
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Bacteriology (including Mycology)
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| Research Institution | Kitasato University |
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Principal Investigator |
TSUBAKI Shiro Kitasato University, Faculty of Veterinary Medicine, Professor, 獣医畜産学部, 教授 (70050507)
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| Co-Investigator(Kenkyū-buntansha) |
TAKAI Shinji Kitasato University, Faculty of Veterinary Medicine, Associate Professor, 獣医畜産学部, 助教授 (80137900)
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| Project Period (FY) |
1994 – 1996
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| Project Status |
Completed (Fiscal Year 1996)
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| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1996: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1995: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1994: ¥800,000 (Direct Cost: ¥800,000)
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| Keywords | Rhodococcus equi / pathogeincity / AIDS / virulence / plasmid / antigens / human / Phodococcus equi, / プラスミド, / AIDS, / 病原生、 / ヒト、 / 塩基配列、 / Rhodoccus equi / 馬 / Rhodococcus / equi |
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| Research Abstract |
Rhodococcus equi is a facultative, intracellular, Gram-positive coccobacillus that causes chronic, suppurative bronchopneumonia and enteritis and is associated with high mortality in 1- to 3-month-old foals. Recently, R.equi has emerged as an important pulmonary pathogen among immunosuppressed patients, especially those with HIV infection. We have recently reported that the 15- to 17-kDa antigens of R.equi are associated with virulence in foals and mice (10^6 bacteria needed for lethality), and that the presence of large plasmids (85-kb and 90-kb virulence plasmids) is essential for virulence and expression of 15- to 17-kDa antigens. More recently, we reported that some AIDS isolates contained a 20-kDa antigen by immunoblotting and were intermediately virulent (10^7 bacteria needed for lethality) in mice. Moreover, these isolates contained one of four distinct large plasmids of 79 to 95 kb in size. Virulent R.equi having 15- to 17-kDa antigens has been isolated frequently from horses and their environment, but the source of an intermediately virulent R.equi having a 20-kDa antigen is poorly understood. Then, we analyzed antigens of R.equi isolates from the submaxillary lymph nodes of pigs by immunoblotting using monoclonal antibodies against these virulence-associated antigens. Immunoblots of whole-cell antigen preparations of R.equi pig isolates revealed the presence of a 20-kDa antigen in almost all the pig isolates studied, and these isolates were intermediately virulent for mice. We also demonstrated that the expression of a 20-kDa antigen and its pathogenicity in mice were associated strongly with the presence of five large, distinct plasmids of 79 to 95 kb in size, and two of the five plasmids from pig isolates were the same sizes as those from human isolates.
Further studies are needed to elucidate the pathogenicities of R.equiisolates from patients with AIDS,and reveal the source and route of infection in humans.
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