B病毒感染及防治

B病毒（B virus）,国际病毒分类委员会将其称为猕猴疱疹病毒1型（Cercopithecine herpesvirus 1,CeHV-1）,拉丁文名为猴疱疹病毒（Herpesvirus simiae）,属于疱疹病毒科、α疱疹病毒亚科、单纯疱疹病毒属.在35种非人灵长类疱疹病毒中,只有B病毒对人有致病性.     

丝状病毒研究进展

１９９１年丝状病毒科的分类正式公式,它包括马堡病毒（ＭＢＧＶ）和埃博拉病毒（ＥＢＯＶ）,近年来埃博拉病毒在中非重新出现,频频流行,引起世界极大关注。本文从病毒生物学性状,致病性与免疫性,微生物学检查和防治原则等方面综述了近年的研究成果。     

禽流感研究进展

流行性感冒病毒分为甲、乙、丙3型。禽流感（avian influenza,AI）是由甲型流感病毒引起的禽类急性传染病,又称真性鸡瘟（fowl plague）。该病被世界动物卫生组织（OIE）定为A类传染病,我国也将其列为一类动物疫病。禽流感可分为不引起明显症状,仅使染病禽类体内产生病毒抗体的非致病性禽流感,可使禽类出现轻度呼吸道症状、食量减少、产蛋量下降并有零星死亡的低致病性禽流感以及可致染病禽类“全军覆没”的高致病性禽流感。     

脑心肌炎病毒VPl蛋白100位氨基酸的突变导致其对小鼠致病性的改变

作为脑心肌炎病毒（EMCV）的天然宿主,感染小鼠能引发多种疾病,其中包括脑炎、心肌炎及糖尿病．本研究利用之前构建完成的EMCV分离毒株BJC3的野生型感染性克隆,采用定点突变方法构建了4个VPl第100位氨基酸突变的突变株感染性克隆（VPt第100位氨基酸分别突变为丝氨酸、丙氨酸、异亮氨酸和脯氨酸）并获得了拯救病毒．虽然各突变病毒及野生型亲本拯救病毒在BHK-21细胞上形成的噬斑大小有所不同,但各病毒在BHK-21细胞上的复制水平未见差异．通过对突变病毒致病性进行系统分析,探究了VPl第100位氨基酸在病毒致病性及感染后疾病表型中所起的重要作用．结果表明,异亮氨酸和脯氨酸突变病毒对小鼠的致死率降低,脑中病毒载量减少且脑组织损伤轻微,而丝氨酸和丙氨酸突变病毒表现了与野生型亲本病毒相似的高致病性．结果证实,EMCVVPl第100位苏氨酸在病毒的体内复制中起重要作用,其突变会导致病毒对小鼠致病性的改变．     

关于禽流感病毒的通用疫苗

当前靶向表面蛋白的疫苗可驱使抗原变异,其结果或是导致更高致病性病毒的出现,或是产生抗原上不同的病毒能逃逸疫苗接种下的控制从而在宿主人群中生存下来。通常的流感疫苗是靶向高度易变的表面蛋白且不能抗异源病毒的攻击。诱导抗流感保守表位的免疫应答的疫苗可提供抗异源病毒攻击的保护作用。作者在此文中报道了用经修饰的痘病毒Ankara（MVA）与腺病毒（Ad）表达核蛋白和基质蛋白（NP＋M1）的融合体形成重组体用其接种的后果,以序贯的疫苗接种方式在不同年龄的鸡中进行试验,发现是安全和具免疫原性的。用干扰素-y（IFN-y）斑点试验法评估第二针接种后的细胞免疫应答。卵内Ad初免孵化后4周用MVA加强免疫对近交系和远交系小鸡都是最具免疫原性的方式。近交系鸡（C151）用致病性的禽流感病毒（LPAI）H7N7攻击。用Ad-NP＋M1初免、MVA-NP＋M1加强的小鸡在感染后的第17天,根据空斑试验测定雕泄殖腔病毒排量比用含非相关抗原的重组病毒的免疫者减少了。这种初步的效力可证明鸟中的概念骀证：含流感病毒内部抗原的病毒载体诱导鸡的T细胞应答可能是研制流感疫苗有效的策略,这种疫荏可诱导抗禽流感的异源保护作用。     

鸭坦布苏病毒E蛋白结构与功能的研究进展

鸭坦布苏病毒病是一种由鸭坦布苏病毒（Duck tembusu virus, DTMUV）引起雏鸭出现神经症状、种鸭生产性能降低、蛋鸭产蛋性能大幅下降的传染性疾病。DTMUV编码3种结构蛋白（C, E, prM），其中E蛋白作为DTMUV重要的免疫原性蛋白，其各结构域的氨基酸位点突变可对病毒粒子的致病性产生不同影响。本文总结了目前关于DTMUV E蛋白的研究进展，包括结构特点和关键毒力位点分析、其在病毒入侵细胞过程的功能与诱导细胞凋亡等的最新研究、以及蛋白抗原表位的最新发现。为进一步探究DTMUV E蛋白的致病机理奠定理论基础。     

巨大病毒的发现及研究进展

人们发现第一个病毒以来,病毒学科取得了迅猛的发展,人们对病毒大小的认知也已经基本成型。21世纪初,科学家发现了拟菌病毒,开启了巨大病毒的大门,此后人们又陆续发现了多种巨大病毒。这些病毒体积较大,基因复杂,已经超出了以往以大小区分病毒的标准,其体积和基因组大小甚至与很多原核和真核生物相当。此外,科学家们还发现了数种能够感染巨大病毒和其他核质大DNA病毒(nucleocytoplasmic large DNA virus,NCLDV)的病毒,将其命名为噬病毒体。这一系列新发现极大地触动了人们对病毒认识的知识体系,并导致了关于病毒起源与进化问题的讨论,这在病毒学史上具有重大的意义。     

泡沫病毒基因组结构及其调节蛋白的功能

泡沫病毒（Ｓｐｕｍａｖｉｒｕｓｅｓ）传统上被分为反转录病毒科的泡沫病毒亚科,按１９９１年Ｃｕｌｅｎ的分类系统,泡沫病毒属复杂反转录病毒中的一个属。对泡沫病毒的研究远滞后于其它反转录病毒,这主要是由于至今未能确定其致病性。泡沫病毒可能与神经性病变相关的...     

我国新分离虫媒病毒的初步鉴定

1990－1994年,从新疆地区的蚊、蜱和病人血清分离了多株病毒,为了明确这些病毒的分类地位,对其中的20株病毒进行了组织培养细胞感染实验和血清学检验,对部分毒株做了动物接种实验和理化性质鉴定。结果显示：20株病毒均可使BHK－21细胞病变（1－3天）,主要表现为细胞圆宿、聚集,融合,破碎,脱落等;致Vero细胞病变为2－4天;15株病毒致C6／36细胞病变（2－4天）,5株病毒对C6／36细胞连续观察7天未见细胞病变。11株病毒对乳鼠2－4天致死,对成年鼠2－5天致死。选取6株病毒进行理化性质鉴定,4株病毒（90260、91002、91004和91028）对5－氟脱氧尿苷耐受,对乙醚和酸敏感,提示为有膜RNA病毒;一株病毒（90265）对5－氟脱氧尿苷、乙醚和酸均敏感,提示为有膜DNA病毒;另一株病毒（9059）对5－氟脱氧尿苷耐受,对乙醚和酸也耐受,提示可能为无膜RNA肠道病毒。20株病毒中,17株病毒与甲病毒、乙型脑炎病毒和布尼亚病毒的特异性免疫腹水不反应,提示这些病毒中可能不存在甲病毒、黄病毒和布尼亚病毒;3株病毒（90260、91002和91004）只与甲病毒的特异性免疫腹水反应,与乙型脑炎病毒和布尼亚病毒的不反应,提示这三株病毒为甲病毒。     

河蟹颤抖病病毒的分离纯化及其动物致病性试验

将人工复制发病的河蟹（中华绒螯蟹）组织匀浆。离心上清经聚乙二醇（PEG6000）沉淀,再经分子筛层析,分部收集分别测定256-300nm的吸光值,各收集峰用PEG20000,于4℃浓缩,制作负染标本经透射电镜观察,发现在第一峰浓缩液中存在大量球状病毒颗粒,大小50-100nm。用纯化的病毒进行动物致病性试验,接种石蟹（锯齿华溪蟹）发生“颤抖病”,并用ELISA双抗体夹心法进行检测,显示感染石蟹较对照石蟹有明显差异。     

Entry and Disassembly of Large DNA Viruses: Electron Microscopy Leads the Way

Nucleocytoplasmic large DNA viruses are a steadily growing group of viruses that infect a wide range of hosts and are characterized by large particle dimensions and genome sizes. Understanding how they enter into the host cell and deliver their genome in the cytoplasm is therefore particularly intriguing. Here, we review the current knowledge on the entry of two of the best-characterized nucleocytoplasmic large DNA viruses: the poxvirus Vaccinia virus (VACV) and the giant virus Mimivirus. While previous studies on VACV had proposed both direct fusion at the plasma membrane and endocytosis as entry routes, more recent biochemical and morphological data argue for macropinocytosis as well. Notably, direct imaging by electron microscopy (EM) also supported the existence of parallel ways of entry for VACV. Instead, all the giant viruses studied so far only enter cells by phagocytosis as observed by EM, and we discuss the mechanisms for opening of the particle, fusion of the viral and phagosomal membranes and genome delivery via a unique portal, specific for each giant virus. VACV core uncoating, in contrast, remains a morphologically ill-defined process. We argue that correlated light and electron microscopy methods are required to study VACV entry and uncoating in a direct and systematic manner. Such EM studies should also address whether entry of single particles and viral aggregates is different and thus provide an explanation for the different modes of entry described in the literature.     

Evolutionary dynamics of giant viruses and their virophages

Giant viruses contain large genomes, encode many proteins atypical for viruses, replicate in large viral factories, and tend to infect protists. The giant virus replication factories can in turn be infected by so called virophages, which are smaller viruses that negatively impact giant virus replication. An example is Mimiviruses that infect the protist Acanthamoeba and that are themselves infected by the virophage Sputnik. This study examines the evolutionary dynamics of this system, using mathematical models. While the models suggest that the virophage population will evolve to increasing degrees of giant virus inhibition, it further suggests that this renders the virophage population prone to extinction due to dynamic instabilities over wide parameter ranges. Implications and conditions required to avoid extinction are discussed. Another interesting result is that virophage presence can fundamentally alter the evolutionary course of the giant virus. While the giant virus is predicted to evolve toward increasing its basic reproductive ratio in the absence of the virophage, the opposite is true in its presence. Therefore, virophages can not only benefit the host population directly by inhibiting the giant viruses but also indirectly by causing giant viruses to evolve toward weaker phenotypes. Experimental tests for this model are suggested.     

Giant viruses,giant chimeras: The multiple evolutionary histories of Mimivirus genes

Background  

Although capable to evolve, viruses are generally considered non-living entities because they are acellular and devoid of metabolism. However, the recent publication of the genome sequence of the Mimivirus, a giant virus that parasitises amoebas, strengthened the idea that viruses should be included in the tree of life. In fact, the first phylogenetic analyses of a few Mimivirus genes that are also present in cellular lineages suggested that it could define an independent branch in the tree of life in addition to the three domains, Bacteria, Archaea and Eucarya.     

Giant viruses in the oceans: the 4th Algal Virus Workshop

Giant double-stranded DNA viruses (such as record breaking Acanthamoeba polyphaga Mimivirus), with particle sizes of 0.2 to 0.6 μm, genomes of 300 kbp to 1.200 kbp, and commensurate complex gene contents, constitute an evolutionary mystery. They challenge the common vision of viruses, traditionally seen as highly streamlined genomes optimally fitted to the smallest possible -filterable- package. Such giant viruses are now discovered in increasing numbers through the systematic sampling of ocean waters as well as freshwater aquatic environments, where they play a significant role in controlling phyto- and bacterio- plankton populations. The 4^th algal virus workshop showed that the study of these ecologically important viruses is now massively entering the genomic era, promising a better understanding of their diversity and, hopefully, some insights on their origin and the evolutionary forces that shaped their genomes.     

Proteorhodopsin genes in giant viruses

Viruses with large genomes encode numerous proteins that do not directly participate in virus biogenesis but rather modify key functional systems of infected cells. We report that a distinct group of giant viruses infecting unicellular eukaryotes that includes Organic Lake Phycodnaviruses and Phaeocystis globosa virus encode predicted proteorhodopsins that have not been previously detected in viruses. Search of metagenomic sequence data shows that putative viral proteorhodopsins are extremely abundant in marine environments. Phylogenetic analysis suggests that giant viruses acquired proteorhodopsins via horizontal gene transfer from proteorhodopsin-encoding protists although the actual donor(s) could not be presently identified. The pattern of conservation of the predicted functionally important amino acid residues suggests that viral proteorhodopsin homologs function as sensory rhodopsins. We hypothesize that viral rhodopsins modulate light-dependent signaling, in particular phototaxis, in infected protists. This article was reviewed by Igor B. Zhulin and Laksminarayan M. Iyer. For the full reviews, see the Reviewers?? reports section.     

A bag of genes and surprises: Giant viruses continue to fascinate researchers for their role in eukaryote evolution and ecology

Giant viruses continue to yield fascinating discoveries from ancient eukaryotic immune defenses to viruses’ role in the global carbon cycle. Subject Categories: Ecology, Microbiology, Virology & Host Pathogen Interaction

The identification of the first giant virus shook up the field of virology in 2003 and challenged common ideas about the early evolution of viruses and eukaryotes (La Scola et al, 2003). Since, more giant viruses from different host species have been discovered, along with virophages that are viral parasites of giant viruses. It has also become increasingly clear that giant viruses and their parasites are not just another curiosity from an ecological niche but do play an important role in eukaryotic evolution and also perhaps in global marine carbon cycles. Notwithstanding, the evolution and ecology of giant viruses has become a fascinating field of study in itself.     

Role of receptor binding specificity in influenza A virus transmission and pathogenesis

The recent emergence of a novel avian A/H7N9 influenza virus in poultry and humans in China, as well as laboratory studies on adaptation and transmission of avian A/H5N1 influenza viruses, has shed new light on influenza virus adaptation to mammals. One of the biological traits required for animal influenza viruses to cross the species barrier that received considerable attention in animal model studies, in vitro assays, and structural analyses is receptor binding specificity. Sialylated glycans present on the apical surface of host cells can function as receptors for the influenza virus hemagglutinin (HA) protein. Avian and human influenza viruses typically have a different sialic acid (SA)‐binding preference and only few amino acid changes in the HA protein can cause a switch from avian to human receptor specificity. Recent experiments using glycan arrays, virus histochemistry, animal models, and structural analyses of HA have added a wealth of knowledge on receptor binding specificity. Here, we review recent data on the interaction between influenza virus HA and SA receptors of the host, and the impact on virus host range, pathogenesis, and transmission. Remaining challenges and future research priorities are also discussed.     

A rapid genome-wide analysis of isolated giant viruses using MinION sequencing

Following the discovery of Acanthamoeba polyphaga mimivirus, diverse giant viruses have been isolated. However, only a small fraction of these isolates have been completely sequenced, limiting our understanding of the genomic diversity of giant viruses. MinION is a portable and low-cost long-read sequencer that can be readily used in a laboratory. Although MinION provides highly error-prone reads that require correction through additional short-read sequencing, recent studies assembled high-quality microbial genomes only using MinION sequencing. Here, we evaluated the accuracy of MinION-only genome assemblies for giant viruses by re-sequencing a prototype marseillevirus. Assembled genomes presented over 99.98% identity to the reference genome with a few gaps, demonstrating a high accuracy of the MinION-only assembly. As a proof of concept, we de novo assembled five newly isolated viruses. Average nucleotide identities to their closest known relatives suggest that the isolates represent new species of marseillevirus, pithovirus and mimivirus. The assembly of subsampled reads demonstrated that their taxonomy and genomic composition could be analysed at the 50× sequencing coverage. We also identified a pithovirus gene whose homologues were detected only in metagenome-derived relatives. Collectively, we propose that MinION-only assembly is an effective approach to rapidly perform a genome-wide analysis of isolated giant viruses.     

Paramyxovirus assembly and budding: Building particles that transmit infections

The paramyxoviruses define a diverse group of enveloped RNA viruses that includes a number of important human and animal pathogens. Examples include human respiratory syncytial virus and the human parainfluenza viruses, which cause respiratory illnesses in young children and the elderly; measles and mumps viruses, which have caused recent resurgences of disease in developed countries; the zoonotic Hendra and Nipah viruses, which have caused several outbreaks of fatal disease in Australia and Asia; and Newcastle disease virus, which infects chickens and other avian species. Like other enveloped viruses, paramyxoviruses form particles that assemble and bud from cellular membranes, allowing the transmission of infections to new cells and hosts. Here, we review recent advances that have improved our understanding of events involved in paramyxovirus particle formation. Contributions of viral matrix proteins, glycoproteins, nucleocapsid proteins, and accessory proteins to particle formation are discussed, as well as the importance of host factor recruitment for efficient virus budding. Trafficking of viral structural components within infected cells is described, together with mechanisms that allow for the selection of specific sites on cellular membranes for the coalescence of viral proteins in preparation of bud formation and virion release.