鸭病毒性肠炎病毒强毒株的形态发生学与超微病理学研究

应用透射电镜和超薄切片技术,研究鸭病毒性肠炎病毒(duck enteritis virus,DEV)CH强毒株人工感染成年鸭后,病毒在宿主细胞内的形态发生及各组织器官的超微结构变化.结果表明,感染后不同时间剖杀及发病后死亡鸭的肝、肠、脾、胸腺、法氏囊等组织器官中,均观察到典型的疱疹病毒粒子.病毒主要的靶细胞为淋巴细胞、网状内皮细胞、成纤维细胞、巨噬细胞、血管内皮细胞、肠道上皮细胞、肠道平滑肌细胞和肝细胞等.DEV的核衣壳有空心型、致密核心型、双环型和内壁附有颗粒型四种形态,存在胞核和胞浆两种装配方式.病毒核衣壳可在核内获得皮层,通过核内膜获得囊膜成为成熟病毒;也可通过内外核膜进入胞浆,在其中获得皮层,然后在各种质膜上获得囊膜,最后成熟病毒释放到细胞外.伴随着病毒的复制、装配和成熟,细胞中出现多种核内和胞浆包涵体、核内致密病毒核酸颗粒、微管和中空短管以及胞浆内膜包裹的电子致密小体、双层管等病毒相关结构.超微研究表明,组织细胞有坏死和凋亡两种变化.坏死细胞肿胀甚至破裂,线粒体肿胀空泡化,粗面内质网扩张,核糖体脱落,有的细胞器甚至完全崩解,染色质或固缩或溶解.凋亡细胞则染色质聚集,胞浆凝聚深染,细胞膜上有大量空泡,并有凋亡小体形成.细胞坏死与凋亡往往同时存在,疾病发生过程中,脾、胸腺、法氏囊以及小肠固有层中的淋巴细胞凋亡数量明显增多.

Morphogenesis and Ultrastructural Pathology of Duck Enteritis Virus Virulent Strain

The morphogenetic process of duck enteritis virus(DEV)in vivo and the ultrastructural changes of host cells were observed and analysed by using electron microscopic techniques after ducks had been infected experimentally by DEV.The investigation showed that the typical herpesvirus virions could be found in the nucleus and the cytoplasm of liver,small intestine,spleen,thymus,bursa of Fabricius.The target cells that virus mainly attacked were lymphocytes,reticular endothelial cells,fibrocytes,macrophages,endothelial cells of blood vessel,intestinal epithelial cells and smooth muscle cells of intestine,hepatocytes etc.Nucleocapsids were divided into four types:empty nucleocapsids;nucleocapsids containing electron-dense internal core structure;nucleocapsids containing an internal concentric ring-shaped structure;nucleocapsids containing electron-dense particles in close proximity to the inner capsid wall.Nucleocapsids assembled both in nucleus and cytoplasm.There were two types of maturation according to our observation.One was that nucleocapsids obtained its tegument in the nucleus and acquired envelope on the inner nuclear membrane.Another was nucleocapsids entered cytoplasm through nuclear membrane,obtained their tegument in the cytoplasm,and acquired envelope on the plasma membrane,finally released to the extracellular space.With the replication,assembly and maturation of the virus,some structures(intracytoplasmic inclusion body and intranuclear inclusion body,electron-dense nucleic acid granules,microtubes,hollow tubes,cytoplasmic membrane coated electron-dense bodies)were observed.Ultrastructural changes of host cells included necrosis and apoptosis according to our observation.The number of apoptotic lymphocytes in spleen,thymus,bursa of Fabricius and lamina propria of small intestine increased after being infected with DEV.