In order to study the taxonomic status of a spherical virus and its cytopathic effect on the cells ofMere-trix meretrix, transmission electron microscopy (TEM) was used to observe pathological cell changes in the mori-bund clams and the ultrastructure of the virus. The virus particles were first purified by combining differential cen-trifugation, potassium tartrate cushion ultracentrifugation, and CsCl density gradient centrifugation. The results showed that there were a large number of virus particles in the intercellular substance and cytoplasm of the gill, digestive diverticula, mantle, and digestive tract. The virus particles were spherical, approximately 45 to 55 nm in diameter, of a non-envelope structure, and showed no ambit between the core and nucleocapsid surrounding the cytoplasm. Obvious pathological changes caused by the virus were that the endoplasmic reticulum swelled and mostly turned into vesicles, the nuclear chromatin condensed, the mitochondria swelled and dissolved, the muscle fiber disarrayed, and the number of lysosomes increased. The virus particles were purified at a concentration of 150000 g for 20 h, showed isometric symmetry, were approximately 60 to 75 nm in diameter, showed obvious cap-somers on the surface of the virions, and had a buoyant density of 1.554 to 1.582 g/mL on the isopycnic CsCl gra-dient. The results of this paper supply fundamental data for the study ofMeretrix meretrixpathogens.%为研究一种球形病毒引起的文蛤(Meretrix meretrix)细胞病理变化及该病毒的分类地位,作者运用透射电镜对异常死亡文蛤的细胞病理变化及感染的病毒粒子进行了超微结构观察,并通过差速离心、酒石酸钾超速离心和氯化铯密度梯度离心结合等方法对首次对该病毒粒子进行了分离纯化。结果表明：患病个体的鳃、消化盲囊、消化道和外套膜均大量存在一种病毒颗粒,该病毒呈球形,无囊膜,直径45~55 nm,核心与核衣壳间无明显界限,未发现病毒包涵体,该病毒存在于细胞间质及被破坏的细胞质中。该病毒粒子的感染引起的细胞病理变化主要表现为：细胞核染色质集聚,溶酶体增多,线粒体肿涨,粗面内质网膨胀,肌原纤维排列混乱,细胞结构变得无规则直至解体。病毒粗提液于4℃150000 g氯化铯密度梯度离心20 h可该病毒粒子提纯,经纯化后负染显示,该病毒粒子呈球形,二十面体对称,无囊膜,直径在60~75 nm,表面结构粗糙,壳粒结构较明显,该病毒粒子在氯化铯中的浮密度为1.554~1.582 g/mL。本文结果为文蛤死亡病原的研究提供了基础资料。
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