2003 Fiscal Year Final Research Report Summary
Survival strategy of intracellular Rhodococcus equi : the role of virulence plasmid.
| Project/Area Number |
12460140
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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 | Kitasato University |
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Principal Investigator |
TAKAI Shinji KITASATO UNIVERSITY, SCHOOL OF VETERINARY MEDICINE AND ANIMAL SCINECES, ASSOCIATE PROFESSOR, 獣医畜産学部, 助教授 (80137900)
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| Co-Investigator(Kenkyū-buntansha) |
MADARAME Hiroo AZABU UNIVERSITY, TEACHING ANIMAL HOSPITAL, ASSOCIATE PROFESSOR, 獣医学部, 助教授 (20173768)
SEKIZAKI Tsutomu NATIONAL INSTITUTE OF ANIMAL HEALTH, LABORATORY OF MOLECULAR BACTERIOLOGY, DIRECTOR, 病原機能研究室, 室長
KAKUDA Tsutomu KITASATO UNIVERSITY, SCHOOL OF VETERINARY MEDICINE AND ANIMAL SCINECES, LECTURER, 獣医畜産学部, 講師 (80317057)
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| Project Period (FY) |
2000 – 2003
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| Keywords | Rhodococcu equi / virulence plasmid / DNA sequence / pathogenicity / intracellular bacteri / macrophage / horse / virulence |
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| Research Abstract |
At least three virulence levels of Rhodococcus equi have been identified : virulence, intermediate virulence, and avirulence. Virulent R. equi is characterized by the presence of virulence-associated 15-to 17-kDa antigens (VapA), virulence plasmid DNA of 85 to 90 kb, and suppurative pneumonia in foals (mouse LD_<50>=10^6). R. equi strains of intermediate virulence are identified by a virulence associated 20-kDa antigen (VapB) and virulence plasmid DNA of 79 to 100 kb and are found in the submaxillary lymph nodes of pigs (mouse LD_<50>=10^7). To analyze the difference of virulence levels in R. equi, the virulence plasmid of the R. equi strain A3 of intermediate virulence (pREA3) was sequenced and compared with the DNA sequence of the virulence plasmid (p33701). pREA3 was 79,288 by and the plasmid encoded 71 open reading frames (ORFs). Of the 71 ORFs, 52 were found to be almost identical to those in the virulence plasmid (p33701). pREA3 also has a pathogenicity island containing 5 new virulence-associated protein (vap) genes [vapI, vapJ (2 copies), vapK, and vapL] located upstream of vapB. There was extensive homology in the region except the pathogenicity island between p33701 and pREA3. These results suggest that the difference in the structure and function of the pathogenicity islands between p33701 and pREA3 might be responsible for the difference in virulence levels of R. equi.
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