1991 Fiscal Year Final Research Report Summary
Studies on the pathogenesis of tubulo-nephrosis or -nephritis due to infectious
| Project/Area Number |
01480101
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
基礎獣医学
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| Research Institution | Hokkaido University |
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Principal Investigator |
ITAKURA Chitoshi Hokkaido Univ., Dept. of Comp. Pathol., Prof., 獣医学部, 教授 (30021695)
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| Co-Investigator(Kenkyū-buntansha) |
OCHIAI Kenji Hokkaido, Univ., Dept. of Comp. Pathol., Assis. Prof., 獣医学部, 助手 (80214162)
GORYO Masanobu Hokkaido, Univ., Dept. of Comp. Pathol., Assoc. Prof., 獣医学部, 助教授 (80153774)
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| Project Period (FY) |
1989 – 1991
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| Keywords | Infectious bronchitis virus / Nephritis / Nephritis / Coronavirus / Budding / Tracheitis / Pneumonia / Chicken |
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| Research Abstract |
Tubulo-nephrosis or -nephritis due to infectious bronchitis virus (IBV) has occurred mostly in broiler chickens less than 3 weeks of age in Japan. The morbidity reached occasionally into about 10%.
In 1991, we encountered tubulo-nephrosis or -nephritis in 151- and 158-day-old layer chickens on a farm located in Hokkaido. We isolated an IBV (HB-976) from them. When HB-976 strain was inoculated into day-old SPF chicks, more than 90% of them died between 4 and 8 days postinoculation. The dead birds showed histologically acute tubulonephrosis, tracheitis and pneumonia. Electronmicroscopically, the urinary tubular epithelial cells revealed swollen mitochondria with vacuolation, increase in polysomes, and increase in membrane-limitted vacuoles. IBV particles were frequent in their cytoplasm or vacuoles, showing budding from the membrane of the cytoplasmic vacuoles. Some of these involved cells were necrotic, while others remained revealing the viral replication. Immunohistochemically, IBV antigens were demonstrated in the urinary tubular epithelia.
From the results obtained here, it was concluded that the tubulonephrosis was initiated with viral replication. However, the viral replication in the tubular epithelia continued for a long time without the cell destruction. In addition, it was recognized that a virulent IBV strain is present in the field chickens.
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