Wang Wen, Gu Zhifeng
College of Biological Sciences, Nanjing Normal University, China.
Dis Aquat Organ. 2002 Mar 11;48(2):149-53. doi: 10.3354/dao048149.
We report the discovery of a rickettsia-like organism (RLO) in cultured freshwater Chinese mitten crab Eriocheir sinensis. The RLO caused tremor disease and was apparently responsible for a mass mortality (30 to 90%) in 2 provinces in southeast China. Moribund crabs were investigated from different districts during outbreaks in 1999 and 2000. With electron microscopy, 3 different pathogens were detected in moribund crabs: a rickettsia-like organism (RLO), virus-like particles (VLP) and a microsporidian-like protozoan (MLP). Based on the high prevalence, infection intensity and cytopathological signs, the RLO was considered to be the probable cause of the high mortality. Both VLP and MLP occurred at low prevalences and were considered secondary infections. The RLO was 0.22 to 0.35 microm in diameter, granular or clavate, bounded by a cell wall and membrane, and possessed no nucleus but a nucleoid was present. When dividing, RLOs occurred in irregular shapes, such as dumbbells, awls, and crescents. The RLOs exhibited a predilection for muscle and connective tissues and were probably transported to various tissues and organs by hemocytes.
我们报告了在养殖的中华绒螯蟹中发现一种立克次氏体样生物（RLO）。该RLO引发了颤抖病，显然导致了中国东南部两个省份的大规模死亡（30%至90%）。在1999年和2000年疫情爆发期间，对来自不同地区的濒死螃蟹进行了调查。通过电子显微镜，在濒死螃蟹中检测到3种不同病原体：一种立克次氏体样生物（RLO）、病毒样颗粒（VLP）和一种微孢子虫样原生动物（MLP）。基于高患病率、感染强度和细胞病理学迹象，RLO被认为是高死亡率的可能原因。VLP和MLP的患病率都很低，被认为是继发感染。RLO直径为0.22至0.35微米，呈颗粒状或棒状，有细胞壁和细胞膜包裹，无细胞核但有拟核。分裂时，RLO呈现不规则形状，如哑铃形、锥形和新月形。RLO倾向于存在于肌肉和结缔组织中，可能通过血细胞转运到各种组织和器官。
