| Project/Area Number |
04044017
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| Research Category |
Grant-in-Aid for international Scientific Research
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| Allocation Type | Single-year Grants |
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| Section | Joint Research |
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| Research Institution | Hokkaido University |
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Principal Investigator |
ITAKURA Chitoshi Professor Faculty of Veterinary Medicine, Hokkaido Univ., 獣医学部, 教授 (30021695)
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| Co-Investigator(Kenkyū-buntansha) |
朴 南〓 全南大学, 獣医学部, 教授
李 栄純 ソウル大学, 獣医学部, 教授
OCHIAI Kenji Lecturer Faculty of Veterinary Medicine, Hokkaido Univ., 獣医学部, 講師 (80214162)
PARK Nam-yong Professor Veterinary College, Chonnam National Univ.
LEE Yong-soon Professor Veterinary College, Seoul National Univ.
朴 南やーん 全南大学, 獣医学部, 教授
御領 政信 北海道大学, 獣医学部, 助教授 (80153774)
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| Project Period (FY) |
1992 – 1993
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| Project Status |
Completed (Fiscal Year 1993)
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| Budget Amount *help |
¥10,200,000 (Direct Cost: ¥10,200,000)
Fiscal Year 1993: ¥5,400,000 (Direct Cost: ¥5,400,000)
Fiscal Year 1992: ¥4,800,000 (Direct Cost: ¥4,800,000)
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| Keywords | Rabbit hemorrhagic disease / Calicivirus / Hepatitis / Immunohistochemistry / Electron microscopy / Encephalitozoon / カリチウイルス / 急性壊死性肝炎 / Encephalitozoon病 / 伝染病 / ウイルス / 兎 |
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| Research Abstract |
The etiological investigation was made by using the liver homogenate of rabbits infected with rabbit hemorrhagic disease (RHD) virus which originated from Korea. A RHD virus was purified by CsCl density gradient centrifugation from the liver homogenate. The viral particles were 35 to 40 nm in diameter, with surface projections, and had a single major polypeptide of 63 KDa.
This purified virus was very high-virulent, and caused acute deaths in adult rabbits 20 to 96 hours after intramuscular injection or contact infection. The dead rabbits showed multiple solitary or focal necroses of hepatocytes, which were regarded as acute viral necrotizing hepatitis.
Electron-microscopically, many virus particles were detected in the cytoplasm of degenerated and necrotic hepatocytes. The hepatocytes were damaged directly by viruses. The etiological virus of RHD was identified as a calicivirus from the morphology and replication pattern.
Immunohistochemically, RHD virus antigen was detected in degenerative and necrotic hepatocytes of the liver tissue, suggesting that it replicated in these cells. RHD was diagnosed easily and clearly by using the this method.
It is known that RHD has never occurred in young rabbits less than two months old in Korea. This was also confirmed experimentally by the present investigation. This unsusceptibility to RHD virus in young rabbits might have relation with the hepatocytic receptors to it.
Nervous signs have occurred frequently in Korean RHD. We studied the central nervous system of RHD cases occurring in Korea. As a result, granulomatous encephalitis due to Encephali-tozoon cuniculi was found in them. Therefore, the signs were attributable to encephalitozoonosis and had no relationship with RHD.
Recently, RHD in Korea decreases in the incidence. It was considered that this is attributable to a decrease of rabbit population and the development of natural immuninization to RHD virus.
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