鸭病毒性肠炎病毒CH强毒株感染鸭胚成纤维细胞的超微结构观察

通过超薄切片和透射电子显微镜技术对鸭病毒性肠炎病毒（DEV）CH强毒株在鸭胚成纤维细胞（DEF）中的形态结构进行了研究。结果发现，DEVCH强毒株病毒核酸呈圆形颗粒状，直径35～45nm，在胞核内常集中分布；病毒核衣壳呈圆形．直径90～100nm．在胞核和胞浆内都有分布；DEV核衣壳可根据所含核酸形态的差异分为空心核衣壳、内壁附有颗粒型核衣壳、同心圆形核衣壳和实心核衣壳；成熟的病毒粒子具有囊膜和皮层结构．呈圆形．直径150～300nm，存在于胞浆空泡内；DEV可在DEF中分别形成胞浆内和胞核内包涵体结构；伴随子代病毒在细胞内的出现，胞浆内迁出现豆英状、马蹄形、半圆形、圆形、同心圆形等与病毒发生有关的电子致密结构。     

鸭病毒性肠炎病毒CH强毒株在鸭胚成纤维细胞中形态发生学的研究

采用超薄切片和透射电子显微镜技术对鸭病毒性肠炎病毒CH强毒株（DEV-CHv）在鸭胚成纤维细胞（DEF）中的形态发生学进行了研究。结果表明，DEV-CHv吸附到DEF细胞上以后通过囊膜和细胞膜间发生融合的方式侵入宿主细胞；病毒在细胞核内完成病毒核酸的生成、核酸与衣壳的装配；病毒核衣壳通过核膜-内质网膜系统从细胞核转运到内质网池中并在内质网池中得到皮层结构；获得了皮层的DEV-CHv核衣壳通过出芽方式释放到细胞空泡内得到囊膜结构后成为成熟病毒；细胞空泡内的成熟DEV-CHv可通过细胞的胞吐作用被释放到细胞外，或在空泡破裂时被释放到细胞外。     

靶向鸭肠炎病毒NP基因RNAi对DEV增殖的影响

为探究核衣壳蛋白(NP)对鸭肠炎病毒(DEV)增殖的影响,笔者根据GenBank上DEV-NP基因序列,设计并构建pSilencer-DEV-NP,采用三种不同方式处理转染鸭胚成纤维(DEF)细胞后,应用荧光显微镜法和FQ-PCR法分析pSilencer-DEV-NP对DEV增殖的影响,结果显示:经荧光显微镜法观察,pSilencer-DEV-NP-l~4在DEF细胞中均呈现绿色荧光;FQ-PCR法扩增并计算,pSilencer-DEV-NP-l~4对DEV增殖的沉默效率分别为81.10%、72.69%、77.35%和67.69%;采用三种方法处理,pSilencer-DEV-NP-1对DEF细胞中DEV的增殖均有沉默作用,但沉默效率不尽一致,其中先后转染后感染时pSilencer-DEV-NP-1的沉默效果最好,在处理60h时沉默效率高达69.20%;同时转染和感染时pSilencer-DEV-NP-1的沉默效果次之,在处理48h时沉默效率最好仅达63.79%;先感染后转染时pSilencer-DEV-NP-1的沉默效果较差,在处理60h时沉默效率最高仅为52.58%。上述研究结果提示,核衣壳蛋白对鸭肠炎病毒增殖具有一定的影响,为阐明核衣壳蛋白在鸭肠炎病毒复制与增殖的作用机制奠定了理论基础。     

伪狂犬病病毒吉林分离株感染BHK-21细胞的超微结构变化

以猪伪狂犬病病毒(PRV)吉林分离株PRV-JL感染体外培养的BHK-21细胞为模型,通过透射电镜对PRV的形态发生学和宿主细胞超微结构的动态变化规律进行研究。结果显示,PRV能导致BHK-21细胞圆缩,并发生细胞融合,形成合胞体;电镜观察到的病毒粒子呈球形或椭圆形,成熟的病毒粒子直径大小为140~210 nm,未成熟病毒粒子直径为90~150 nm,多呈中空状,部分呈致密核芯。病毒吸附于细胞后以膜融合的方式进入细胞,在胞核内复制,装配好的病毒粒子以出芽的方式离开细胞核,获得最初的囊膜,进入胞浆;在胞浆内的病毒粒子又利用高尔基体的膜结构合成第2层囊膜,形成完整的病毒粒子;最后包裹有完整病毒粒子的高尔基囊泡与细胞膜发生融合,将病毒粒子释放到细胞外。感染细胞超微结构变化主要表现为:细胞胞浆空泡增多,内质网扩张,线粒体增生、嵴肿胀、脱落,最后空泡化,整个细胞裂解、破碎。     

兔出血症病毒在细胞培养和组织中的形态发生

在电镜下系统地观察了感染后的细胞培养和组织中兔出血症病毒（ Ｒ Ｈ Ｄ Ｖ）的形态发生。感染早期，在细胞核内可见电子致密颗粒（１５ ｎｍ ）和未成熟的病毒颗粒 （２５ ｎｍ ）。中期，在细胞核和胞浆内出现大量成熟的病毒颗粒（３４ ｎｍ ），并发现部分核内病毒通过扩大的核膜孔、核膜溶解扩大的核孔和乳头状突起的核膜向胞浆释放。感染末期，核染色质消失，核内大量感染病毒清淅可见。最终细胞溶解，病毒颗粒释放至细胞间隙。提示 Ｒ Ｈ Ｄ Ｖ 是在核内复制和装配的，应归属于细小病毒科。本试验结果不排除同时存在另一种小 Ｒ Ｎ Ａ 病毒。     

人工感染鸭病毒性肠炎急性病例超微结构变化

用鸭病毒性肠炎病毒（Duck enteritis virus，DEV）CH强毒株感染成年鸭复制鸭病毒性肠炎急性病例，分别于接种后不同时间，取心、肝、肾、脾、胸腺、十二指肠、法氏囊、脑和胰组织，制作超薄切片，电镜观察。结果表明：病变最早发生于肝和肾，而鸭死亡后以免疫器官和消化器官损伤最严重；各种细胞的变化主要表现为细胞肿胀，染色质或浓缩、碎裂或溶解，线粒体溶解成空泡样结构，其他细胞器破坏；脾、胸腺、法氏囊以及小肠固有层中的淋巴细胞在感染24h后，在出现细胞坏死的同时还出现较为明显的细胞凋亡变化；而鸭死亡后淋巴细胞主要表现为黑洞核样变化，整个细胞凝聚深染，染色质固缩，细胞浆均质深染，细胞膜模糊或不完整。     

狂犬病病毒抗原的形态学定位

利用免疫胶体金标记技术,对感染BHK—21细胞的鹿狂犬病病毒抗原进行了形态学定位.透射电镜观察,发现病毒粒子囊膜表面的圆端和侧面以及核衣壳均被免疫金颗粒所标记,囊膜平齐端无免疫金颗粒附着.病毒感染细胞时,以其圆端和侧面吸附于宿主细胞膜.据此从形态学角度证明,成熟病毒粒子抗原存在于核衣壳以及囊膜的圆端和侧表面,囊膜平齐端无病毒抗原.     

BV147感染Vero细胞的超微结构

应用电镜对1997年本实验室从野外捕获的恒河猴分离的BV147在Vero细胞上的形态发生和增殖规律进行了观察。结果表明，新分离为BV147是疱疹病毒属成员，在细胞核内复制、增殖，在核内膜以“出芽方式”获得囊膜而达到成熟，通过细胞的胞吐或胞系统排到细胞外，接毒后18h病毒主要在核内，24h则可在核膜间隙、胞浆和细胞外见到大量成熟病毒颗粒。     

传染性喉气管炎病毒在鸡胚肾细胞上的增殖特性

用电镜对鸡传染性喉气管炎病毒（ＩＬＴＶ）强毒（王岗株），弱毒（疫苗株）感染鸡胚肾细胞进行了观察。观察到一些特殊的毒浆结构、管状结构及呈“二分裂相”的核衣壳结构，探讨它们形成的可能机制和功能，描述了核内、胞质中核衣壳获得囊膜过可能过程。发现ＩＬＴＶ可能存在胞质装配途径。通过电镜手段比较了强、弱毒株正在感染细胞内增殖差异情况。     

鸭瘟病毒分子生物学探讨

鸭瘟病毒属疱疹病毒科、α-疱疹病毒亚科,病毒粒子呈球形,有囊膜的线状双股DNA,与蛋白缠绕形成病毒核心,大小约为150 kb,两端为末端重复序列,中间有内部重复序列.衣壳为对称的二十面体,外观呈六角形,它由162个相互连接呈放射状排列且有中空轴孔的壳粒组成.核衣壳外为外膜,其绕以囊膜形成成熟的病毒粒子.囊膜蛋白为病毒的主要保护性抗原,介导病毒进入细胞,促进病毒的成熟与释放.文中对病毒形态结构、蛋白特性等方面进行论述,以期为更清楚地认识该病毒的特性提供参考资料.     

Electron microscopic studies of the morphogenesis of duck enteritis virus

The morphogenesis of duck enteritis virus (DEV) and distribution in vivo were observed by electron microscopy after ducks were infected experimentally with DEV virulent strain. The investigation showed that a few typical herpesvirus virions and nucleocapsids were first observed in the spleen, thymus, and bursa of Fabricius (BF), and many nucleocapsids, mature viruses, and viral inclusion bodies could be found in the nucleus and cytoplasm of infected liver, small intestine, spleen, thymus, and BF when the ducks died. Nucleocapsids assembled both in nucleus and cytoplasm and could be divided into four different types according to their structures. Typical herpesvirus, light particles (L-particles), and virions without tegument could be observed at the same time. With the replication, assembly, and maturation of the viruses, intracytoplasmic and intranuclear inclusion bodies, electron-density particles, microtubules, hollow tubes, and coated electron-density bodies were observed in infected cells.     

Pathogenesis of duck plague in the bursa of Fabricius, thymus, and spleen.

White Pekin ducks were inoculated orally with duck plague virus and killed at 24-hour intervals after inoculation. Spleen, thymus, and bursa of Fabricius were collected and examined by light, fluorescent, and electron microscopy. Necrosis of lymphocytes occurred in the bursa of Fabricius, thymus, splenic periarteriolar lymphoid sheath (T lymphocytes), and splenic germinal centers (B lymphocytes). Viral nucleocapsids were present in the karyoplasm of lymphocytes, but these cells necrotized before virions were formed. Periarteriolar reticular sheath cells and sinusoidal lining cells in the spleen, epithelial cells in Hassall's corpuscle of the thymus, epithelial cells between the cortex and medulla of the follicles in the bursa of Fabricius, and macrophages in all 3 tissues contained nucleocapsids in the nuclei and virions in cytoplasmic vacuoles before necrosis occurred.     

动物3种DNA病毒在宿主细胞内形态发生比较

对猪细小病毒(PPV)、牛疱疹病毒2型(BHV2)和犬腺病毒1型(CAV1)3种动物DNA病毒在宿主细胞内的增殖、释放方式以及所致细胞结构的变化,通过电镜进行了观察比较.(1)这3种动物DNA病毒的复制和装配过程均发生在细胞核内,以毒浆结构(Viroplast)或核内包涵体为增殖场所和物质基础,但并非都形成结晶样结构.(2)有囊膜的BHV2,其核壳体在细胞核内装配完成后,从核内膜上以出芽方式获得囊膜,然后进入核周池,聚集的病毒使核外膜向胞质方向隆起,形成病毒性包涵体而脱离核外膜,并逐渐向细胞膜的方向移动,最后从细胞膜的破损处以病毒包涵体形式释放到细胞间隙.而无囊膜的CAV1,核壳体在细胞核内装配完成后,从细胞核膜破损处或细胞核崩解后进入细胞质,待整个细胞崩解后才能释放出来.无囊膜的PPV,在核壳体装配完成后,成堆地以病毒流的方式,从扩张的核孔释放到细胞质中,待细胞崩解后再释放出来.(3)3种病毒增殖时,宿主细胞的固有细胞器,如线粒体、内质网以及溶酶体等均出现不同程度的超微结构变化,并能诱导宿主细胞出现一些新的结构,除毒浆结构外,还有管状结构、细纤维样结构、周期性结构和髓膜样结构等,其中周期性结构仅见于BHV2感染.     

Preliminary study on duck enteritis virus-induced lymphocyte apoptosis in vivo

We studied apoptosis induced by duck enteritis virus (DEV) in vivo, focusing on the lymphoid organs that constitute the main targets for infection: thymus, bursa of Fabricius (BF), and spleen. Fifty Pekin ducks were inoculated subcutaneously with a virulent strain of DEV. The morphology of lymphoid organs of these infected ducks was observed by light microscopy and transmission electron microscopy. Cell death by classical necrosis was observed in lymphocytes of the DEV-infected thymus, BF, and spleen. Lymphocyte apoptosis also was observed at the same time, and it was further confirmed by in situ terminal deoxynucleotidyl transferase dUTP nick-end labeling and agarose gel electrophoresis. We conclude that apoptosis and necrosis of lymphocytes induced by DEV infection resulted in the depletion of lymphocytes and that apoptosis of lymphocytes may play an important role in the pathogenesis of duck viral enteritis.     

Intriguing interplay between viral proteins during herpesvirus assembly or: the herpesvirus assembly puzzle

Herpes virions are complex particles that consist of more than 30 different virally encoded proteins. The molecular basis of how this complicated structure is assembled is only recently beginning to emerge. After replication in the host cell nucleus viral DNA is incorporated into preformed capsids which leave the nucleus by budding at the inner nuclear membrane resulting in the formation of primary enveloped virions in the perinuclear space. The primary envelope then fuses with the outer leaflet of the nuclear membrane, thereby releasing nucleocapsids into the cytoplasm. Final envelopment including the acquisition of more than 15 tegument and more than 10 envelope (glyco)proteins occurs by budding into Golgi-derived vesicles. Mature virions are released after fusion of the vesicle membrane with the plasma membrane of the cell. Thus, herpesvirus morphogenesis requires a sequence of envelopment--de-envelopment--re-envelopment processes which are distinct not only in the subcellular compartments in which they occur but also in the viral proteins involved. This review summarizes recent advances in our understanding of the complex protein-protein interactions involved in herpesvirus assembly and egress.     

Pathogenesis of digestive tract lesions in duck plague.

White Pekin ducklings were inoculated orally with duck plague virus. Tissues from the digestive tract were collected daily after inoculation and examined by light, electron and fluorescent microscopy. There were necrosis and degeneration of stratified squamous epithelium of the esophagus and cloaca, epithelium of intestinal crypt and esophageal submucosal glands, macrophages in the lamina propria, and submucosal fibrocytes and lymphocytes. Submucosal hemorrhages occurred after degeneration and necrosis of lymphocytes, macrophages, fibrocytes and epithelial cells. Viral antigens were detected in all these cells by use of fluorescein-labeled antibodies. With the electron microscope, nucleocapsids were seen in the nuclei, budding through the inner nuclear membrane; enveloped virions were present in cytoplasmic vacuoles of macrophages, epithelial cells and fibrocytes. In lymphocytes, nucleocapsids were also in the nuclei, but karyorrhexis and cytolysis occurred before viral maturation was completed.     

Pathogenicity of a low-virulence duck virus enteritis isolate with apparent immunosuppressive ability

Duck enteritis virus (DEV) was isolated from commercial 2-to-6-wk-old white Pekin ducks experiencing 25%-30% mortality and high morbidity. Secondary infections with Pasteurella multocida, Riemerella anatipestifer, and Escherichia coli were frequently seen in affected ducks. The isolated virus was identical to the prototype DEV by virus neutralization test but differed from the classic DEV by causing lymphoid organ atrophy and inconsistent hemorrhagic lesions in the intestinal annular bands. Attempts to reproduce the disease in white Pekin ducks were unsuccessful until the virulence of the virus was increased by three passages in Muscovy ducklings. Significant thymic atrophy (P < or = 0.001) was detected during the first 10 days postinfection (DPI), but thymus size returned to normal by 17-24 DPI. However, bursal atrophy increased significantly (P < or = 0.001) from 4 DPI until the end of the experiment (39 DPI). Reduction in body weight was significant (P < or = 0.05) between 4 and 6 DPI. There was massive depletion of thymic and bursal lymphocytes with lymphoid necrosis in the thymus, bursa, spleen, and Harderian gland. Eosinophilic intranuclear inclusions were observed in thymus, bursa, spleen, esophagus, cloaca, liver, conjunctiva, and Harderian gland. Occasional intracytoplasmic inclusions were also found scattered in the epithelial cells of conjunctiva, esophagus, bursa of Fabricius, and cloaca. Virus was recovered from experimentally infected ducks from thymus, bursa, spleen, liver, kidneys, trigeminal ganglion, and cloaca during the first 10 days of infection. These findings suggest that a low-virulent DEV can cause a massive lymphoid atrophy and can sustain immunosuppression as noted by the secondary bacterial infection.