Rickettsia-like organism infection in a freshwater cultured fish Ophiocephalus argus C. in China  

作　　者：GUOQionglin JIAWeizhang HANXianpu CAITaozhen GONGXiaoning SUNXiaofeng 

机构地区：[1]InstituteofHydrobiology,ChineseAcademyofSciences,Wuhan430072,China

出　　处：《Progress in Natural Science:Materials International》2004年第5期417-422,共6页自然科学进展·国际材料（英文版）

基　　金：Supported by the National Natural Science Foundation of China (Grant No. 30371091)

摘　　要：From 2001 to 2002, a new and emergent infectious disease of Ophiocephalus argus occurred in a fishery in Hubei Province, China, with an incidence of 60%～70% and a mortality as high as 100%. The diseased fish showed an enlarged abdomen, the millet-like nodules in internal organs, and the swollen kidney which was composed of 5 ～ 10 sarcoma-like bodies in cream or gray-white colour or ulcerated into beandregs-like substance. Light microscopic observation revealed the basophilic or acidphilic inclusions in cytoplasm of the cells and the granulomas, a diffusive chronic inflammation in internal organs. Further analysis under an electron microscope indicated that the intracytoplasmic inclusions were rickettsia-like organisms (RLOs) that are either spherical or coccoid, with variable size, ranging from 0.5 ～ 1.5 μm in diameter, and enclosed within membrane-bound cytoplasmic vacuoles. RLO had a central nucleoid region with some fine filamentous structures and an electron-dense granule. Its cytoplasm contained abundant ribosomal bodies. Occasionally, RLO appeared to be divided by binary fission. RLOs were also observed in the homogenized tissue of infected fish. The results suggested that the death of cultured O. argus was caused by RLO infection.From 2001 to 2002, a new and emergent infectious disease of Ophiocephalus argus occurred in a fishery in Hubei Province, China, with an incidence of 60% -70% and a mortality as high as 100% . The diseased fish showed an enlarged abdomen, the millet-like nodules in internal organs, and the swollen kidney which was composed of 5 -10 sarcoma-like bodies in cream or gray-white colour or ulcerated into beandregs-like substance. Light microscopic observation revealed the basophilic or acidphilic inclusions in cytoplasm of the cells and the granulomas, a diffusive chronic inflammation in internal organs. Further analysis under an electron microscope indicated that the intracytoplasmic inclusions were rickettsia-like organisms (RLOs) that are either spherical or coccoid, with variable size, ranging from 0. 5 - 1. 5 μm in diameter, and enclosed within membrane-bound cytoplasmic vacuoles. RLO had a central nucleoid region with some fine filamentous structures and an electron-dense granule. Its cytoplasm contained abundant ribosomal bodies. Occasionally, RLO appeared to be divided by binary fission. RLOs were also observed in the homogenized tissue of infected fish. The results suggested that the death of cultured O. argus was caused by RLO infection.

关 键 词：snakeheaded fish (Ophiocephalus argus) rickettsia-like organism (RLO) INFECTION PATHOLOGY fish disease. 

分 类 号：S965.199[农业科学—水产养殖] S941.4[农业科学—水产科学]