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家蚕细小病毒样病毒(Bombyx mori parvo-like virus,BmPLV)是一种二分病毒,该病毒在家蚕中肠柱状细胞核内复制和包装,感染的细胞核呈现过分膨胀、细胞核孚尔根浓染等细胞病理学特征。病毒粒子直径20~24 nm,无囊膜呈球型。基因组为单链线性双分子DNA(VD1、VD2),分别独立包装在各自的衣壳中。病毒编码四个非结构蛋白NS1、NS2、NS3和pol(DNA聚合酶),一个主要结构蛋白VP及次要结构蛋白P133。其基因组末端反向重复序列可形成与BmPLV复制有关的"锅柄形"结构,以及含自身编码的DNA聚合酶的序列,推测该病毒与腺病毒复制方式相类似,依靠共价蛋白为起始物完成复制。 相似文献
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病毒属于一类非细胞结构、无自主繁殖能力的微生物,光镜下不易被发现,只有形成包涵体后才能用光镜来检测. 相似文献
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丙型肝炎病毒(Hepatitis C virus,HCV)是一种危害人类健康的病原体,感染人体后极易导致慢性肝炎,并能引起肝纤维化或脂肪肝,可能进一步发展成为肝硬化、肝癌等终末期肝病。尽管已被发现20多年,丙肝病毒的来源以及进化途径一直没有确定。与此同时,缺乏合适的动物模型严重阻碍HCV致病机理的研究。从2011年起,随着新型测序技术的应用,多种丙肝非灵长类同源病毒相继被发现,这些研究成果将在研究丙肝病毒来源、进化途径以及相关动物模型建立中起重要作用。 相似文献
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植物病毒的卫星病毒和卫星RNA 总被引:3,自引:0,他引:3
植物病毒的卫星病毒和卫星RNA陈金标(南京农业大学微生物系210095)病毒是一种无细胞结构的生物体,个体极小,约为20—400urn。Matthews将它定义为:病毒是丁组或多组核酸分子、它通常祛外完蛋白包裹,且只在适合的寄主细胞里复制。在这种细胞... 相似文献
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Intracellular vesicular stomatitis virus leader RNAs are found in nucleocapsid structures. 总被引:13,自引:10,他引:3 下载免费PDF全文
Previous studies demonstrated that cytoplasmic extracts of cells infected with vesicular stomatitis virus contain plus-strand leader RNAs which sediment at 18S on sucrose gradients as a complex with viral N protein. The work presented in this paper demonstrated that these 18S complexes were stable on CsCl density gradients, banding at a buoyant density near that of genome nucleocapsids, and exhibited a morphology in an electron microscope similar to the disk structures found in virus genome nucleocapsids. Minus-strand leader RNAs were also found in 18S complexes on sucrose gradients. Quantitation of intracellular leader RNA suggested that, late in infection, approximately three-quarters of total intracellular leader RNA was encapsidated. 相似文献
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Rotavirus replication: plus-sense templates for double-stranded RNA synthesis are made in viroplasms 下载免费PDF全文
Rotavirus plus-strand RNAs not only direct protein synthesis but also serve as templates for the synthesis of the segmented double-stranded RNA (dsRNA) genome. In this study, we identified short-interfering RNAs (siRNAs) for viral genes 5, 8, and 9 that suppressed the expression of NSP1, a nonessential protein; NSP2, a component of viral replication factories (viroplasms); and VP7, an outer capsid protein, respectively. The loss of NSP2 expression inhibited viroplasm formation, genome replication, virion assembly, and synthesis of the other viral proteins. In contrast, the loss of VP7 expression had no effect on genome replication; instead, it inhibited only outer-capsid morphogenesis. Similarly, neither genome replication nor any other event of the viral life cycle was affected by the loss of NSP1. The data indicate that plus-strand RNAs templating dsRNA synthesis within viroplasms are not susceptible to siRNA-induced RNase degradation. In contrast, plus-strand RNAs templating protein synthesis in the cytosol are susceptible to degradation and thus are not the likely source of plus-strand RNAs for dsRNA synthesis in viroplasms. Indeed, immunofluorescence analysis of bromouridine (BrU)-labeled RNA made in infected cells provided evidence that plus-strand RNAs are synthesized within viroplasms. Furthermore, transfection of BrU-labeled viral plus-strand RNA into infected cells suggested that plus-strand RNAs introduced into the cytosol do not localize to viroplasms. From these results, we propose that plus-strand RNAs synthesized within viroplasms are the primary source of templates for genome replication and that trafficking pathways do not exist within the cytosol that transport plus-strand RNAs to viroplasms. The lack of such pathways confounds the development of reverse genetics systems for rotavirus. 相似文献
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The hantavirus nucleocapsid protein recognizes specific features of the viral RNA panhandle and is altered in conformation upon RNA binding 总被引:2,自引:0,他引:2 下载免费PDF全文
Hantaviruses are tripartite negative-sense RNA viruses and members of the Bunyaviridae family. The nucleocapsid (N) protein is the principal structural component of the viral capsid. N forms a stable trimer that specifically recognizes the panhandle structure formed by the viral RNA termini. We used trimeric glutathione S-transferase (GST)-N protein and small RNA panhandles to examine the requirements for specific recognition by Sin Nombre hantavirus N. Trimeric GST-N recognizes the panhandles of the three viral RNAs (S, M, and L) with high affinity, whereas the corresponding plus-strand panhandles of the complementary RNA are recognized with lower affinity. Based on analysis of nucleotide substitutions that alter either the higher-order structure of the panhandle or the primary sequence of the panhandle, both secondary structure and primary sequence are necessary for stable interaction with N. A panhandle 23 nucleotides long is necessary and sufficient for high-affinity binding by N, and stoichiometry calculations indicate that a single N trimer interacts with a single panhandle. Surprisingly, displacement of the panhandle structure away from the terminus does not eliminate recognition by N. The binding of N to the panhandle is an entropy-driven process resulting in initial stable N-RNA interaction followed by a conformational change in N. Taken together, these data provide insight into the molecular events that take place during interaction of N with the panhandle and suggest that specific high-affinity interaction between an RNA binding domain of trimeric N and the panhandle is required for encapsidation of the three viral RNAs. 相似文献
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The synthesis of minus-strand RNA was studied in cell cultures infected with the heat-resistant strain of Sindbis virus and with temperature-sensitive (ts) belonging to complementation groups A, B, F, and G, all of which exhibited an RNA-negative (RNA-) phenotype when infection was initiated and maintained at 39 degrees C, the nonpermissive temperature. When infected cultures were shifted from 28 degrees C (the permissive temperature) to 39 degrees C at 3 h postinfection, the synthesis of viral minus-strand RNA ceased in cultures infected with ts mutants of complementation groups B and F, but continued in cultures infected with the parental virus and mutans of complementation groups A and G. In cultures infected with ts11 of complementation group B, the synthesis of viral minus-strand RNA ceased, whereas the synthesis of 42S and 26S plus-strand RNAs continued for at least 5 h after the shift to 39 degrees C. However, when ts11-infected cultures were returned to 28 degrees C 1 h after the shift to 39 degrees C, the synthesis of viral minus-strand RNA resumed, and the rate of viral RNA synthesis increased. The recovery of minus-strand synthesis translation of new proteins. We conclude that at least one viral function is required for alphavirus minus-strand synthesis that is not required for plus-strand synthesis. In cultures infected with ts6 of complementation group F, the syntheses of both viral plus-strand and minus-strand RNAs were drastically reduced after the shift to 39 degrees C. Since ts6 failed to synthesize both plus-strand and minus-strand RNAs after the shift to 39 degrees C, at least one common viral component appears to be required for the synthesis of both minus-strand and plus-strand RNAs. 相似文献
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Vesicular stomatitis virus in Drosophila melanogaster cells: lack of leader RNA transport into the nuclei and frequent abortion of the replication step. 总被引:2,自引:2,他引:0 下载免费PDF全文
In cultured Drosophila melanogaster cells, vesicular stomatitis virus (VSV) establishes a persistent, noncytopathic infection. No inhibition of host macromolecular synthesis occurs. We studied the synthesis of VSV plus-strand leader RNA, which may be directly involved in vertebrate host synthesis shut-off. Leader RNA accumulated in Drosophila cell cytoplasm, but in low amounts, it was either free or associated to structures larger than the leader RNA-N protein complexes found in vertebrate cells. Only a few leader RNA copies migrated into the cell nucleus; no increase of this transport was observed at any time during the virus cycle. Viral RNAs complementary to the 3' end of the genome and ranging in size from the leader to several hundred nucleotides were found to accumulate in Drosophila cell cytoplasm. Their synthesis was inhibited in the presence of cycloheximide, which blocks all protein synthesis and VSV replication. Correlation between the absence of VSV cytopathogenicity in Drosophila cells and the lack of leader RNA transport into their nuclei is discussed, as well as the possible relationship between the restriction of viral synthesis and the frequent initiation of an abortive replication step. 相似文献
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Unique mode of transcription in vitro by Vesicular stomatitis virus 总被引:26,自引:0,他引:26