Lifestyles of plant viruses

The vast majority of well-characterized eukaryotic viruses are those that cause acute or chronic infections in humans and domestic plants and animals. However, asymptomatic persistent viruses have been described in animals, and are thought to be sources for emerging acute viruses. Although not previously described in these terms, there are also many viruses of plants that maintain a persistent lifestyle. They have been largely ignored because they do not generally cause disease. The persistent viruses in plants belong to the family Partitiviridae or the genus Endornavirus. These groups also have members that infect fungi. Phylogenetic analysis of the partitivirus RNA-dependent RNA polymerase genes suggests that these viruses have been transmitted between plants and fungi. Additional families of viruses traditionally thought to be fungal viruses are also found frequently in plants, and may represent a similar scenario of persistent lifestyles, and some acute or chronic viruses of crop plants may maintain a persistent lifestyle in wild plants. Persistent, chronic and acute lifestyles of plant viruses are contrasted from both a functional and evolutionary perspective, and the potential role of these lifestyles in host evolution is discussed.     

A Recombinant Antibody-Expressing Influenza Virus Delays Tumor Growth in a Mouse Model

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Technical advancement in plant virus diagnosis – an appraisal

Plants infected by a wide range of viruses often cause important agronomic and economic losses worldwide. Detection of plant viruses is becoming more challenging as globalisation of trade, particularly the ornamental plants, and the potential effects of climate change facilitate movement of viruses and their vectors, thereby transforming the diagnostic landscape. Under such circumstances, detection of viruses at premature stages of infection by use of rapid, sensitive and accurate detection methods seems crucial to ensure safe and sustainable agriculture and as such reduces economic losses. For proper identification, detection technique needs to be rapid, most accurate and inexpensive, as it forms the key step in developing appropriate practical solutions to manage plant virus diseases that pose continuous threats to the viability of certain horticultural and agricultural industries. This review is concerned with the advancement in techniques in the diagnosis of viruses in plants.     

Serological relationships of five nuclear polyhedrosis viruses from lepidopterous species

The serological relationships of five nuclear polyhedrosis viruses (NPV) were investigated using the immunodiffusion technique with intragel absorption. Reciprocal tests demonstrated that virion fractions from Autographa californica multiple embedded virus (MEV), Heliothis armigera MEV, and H. zea single embedded virus (SEV) are not related to each other or to virions from Trichoplusia ni SEV and Pseudoplusia includens SEV. Virion fractions of T. ni and P. includens NPV were shown to be closely related, sharing several antigens. Matrix fractions possessed a common group antigen and one or two antigens specific for the individual NPV with the exception that T. ni and P. includens NPV shared one of these antigens. The specific antigens of the matrix fraction were also shared with the homologous virion fraction.     

极端嗜盐多形性古菌病毒HRPV13的分离鉴定及生物学特性

【背景】与感染细菌和真核生物的病毒相比,目前发现的古菌病毒数量很少,但是却展现出形态多样性。因此,分离和鉴定新的古菌病毒具有重要意义。【目的】为了进一步了解古菌病毒的多样性,我们从青海省翡翠湖水样中分离到一株新的嗜盐古菌病毒株,研究其生物学特性并进行分类。【方法】首先通过挑取单菌落法分离嗜盐古菌,通过噬菌斑法获得嗜盐古菌病毒,PEG 6000两步沉淀法和CsCl密度梯度离心对病毒颗粒进行浓缩和纯化,用醋酸双氧铀对病毒负染染色,在透射电镜下观察病毒形态,提取病毒基因组后进行测序并进行生物信息学分析,以三氯乙酸法制备病毒蛋白样品并进行SDS-PAGE分析,分别用考马斯亮蓝和苏丹黑B染色并观察其蛋白和脂质条带。【结果】在以Halorubrum属极端嗜盐古菌K2菌株为敏感菌的双层平板上分离到了一株嗜盐古菌病毒,其噬菌斑为浊斑,透射电镜下呈多形性包膜病毒状,直径60 nm左右;含有9333bp大小的双链环状DNA基因组,与已报道的β多形包膜病毒属(Betapleolipovirus)的HRPV11、HRPV12和HRPV10具有约75%的一致性,是该属的一个病毒新种。根据形态及基因组特征,将其归...     

Antiviral discovery in toxic cyanobacteria: Low hanging fruit in the age of pandemics

The power of novel vaccination technologies and their rapid development were elucidated clearly during the COVID-19 pandemic. At the same time, it also became clear that there is an urgent need to discover and manufacture new antivirals that target emerging viral threats. Toxic species of cyanobacteria produce a range of bioactive compounds that makes them good candidates for drug discovery. Nevertheless, few studies demonstrate the antiviral potential of cyanobacteria. This is partly due to the lack of specific and simple protocols designed for the rapid detection of antiviral activity in cyanobacteria and partly because specialized facilities for work with pathogenic viruses are few and far between. We therefore developed an easy method for the screening of cyanobacterial cultures for antiviral activity and used our private culture collection of non-pathogenic virus isolates to show that antiviral activity is a prominent feature in the cyanobacterium Microcystis aeruginosa. In this proof-of-concept study, we show that M. aeruginosa extracts from three different cyanobacterial strains delay infection of diatom-infecting single-stranded DNA and single-stranded RNA viruses by up to 2 days. Our work shows the ease with which cyanobacteria from culture collections can be screened for antiviral activity and highlights the potential of cyanobacteria as an excellent source for the discovery of novel antiviral compounds, warranting further investigation.     

CHARACTERIZATION OF HaRNAV,A SINGLE‐STRANDED RNA VIRUS CAUSING LYSIS OF HETEROSIGMA AKASHIWO (RAPHIDOPHYCEAE)1

HaRNAV, a novel virus that infects the toxic bloom‐forming alga Heterosigma akashiwo (Hada) Hada ex Hada et Chihara, was characterized based on morphology, pathology, nucleic acid type, structural proteins, and the range of host strains that it infects. HaRNAV is a 25‐nm single‐stranded RNA (ssRNA) virus with a genome size of approximately 9100 nucleotides. This is the first report of an ssRNA virus that causes lysis of a phytoplankton species. The virus particle is sensitive to chloroform and contains at least five structural proteins ranging in apparent size from 24 to 34 kDa. HaRNAV infection causes swelling of the endoplasmic reticulum and progeny virus particles assemble in the cytoplasm of the host, frequently in crystalline arrays. The infectivity of HaRNAV was tested against 15 strains of H. akashiwo isolated from Japanese waters, the Northeast Pacific, and the Northwest Atlantic. HaRNAV caused lysis of three strains from the Northeast Pacific and two strains from Japan but none from the Northwest Atlantic. The characterization of HaRNAV demonstrates that HaRNAV is a novel type of phytoplankton virus but has some similarities with plant viruses belonging to the Sequiviridae and to other known ssRNA viruses. Further genomic analysis, however, is necessary to determine any phylogenetic relationships. The discovery of HaRNAV emphasizes the diversity of H. akashiwo viral pathogens and, more importantly, algal–virus pathogens and the complexity of virus–host interactions in the environment.     

毒源烟草试管保存技术的研究

经三年连续试验,用试管保存含马铃薯X病毒(PVX)、马铃薯Y病毒(PVY)、烟草花叶病毒(TMV)的毒源烟草,结果证明毒源烟草可在试管中正常生长发育。负染法和免疫电镜捕获法检测结果证明,试管毒源烟草不同生育期,体内的病毒含量不同;试管毒源烟草在管外土壤中栽培可正常生长发育,并表现出相应的症状,接种指示植物试验证明其侵染力与温室内保存的毒源效果相同。     

Immunocapture RT-PCR detection of Bean common mosaic virus and strain blackeye cowpea mosaic in common bean and black gram in India

The strains of Bean common mosaic virus (BCMV) and blackeye cowpea mosaic (BICM), genus Potyvirus, were detected from 25 common bean and 14 black gram seeds among 142 seed samples collected from different legume-growing regions of India. The samples were subjected to a growing-on test, an indicator plant test, an electron microscopic observations, an enzyme linked immunosorbent assay and an immunocapture RT-PCR. The incidence of the two tested viruses in common bean and black gram seed samples was 1–6% and 0.5–3.5%, respectively in growing-on test evaluations. Electron microscopic observations revealed filamentous virion particles from the leaves of plants showing characteristic virus disease symptoms in growing-on and host inoculation tests. The identity of the strains was confirmed by immunocapture RT-PCR, with a final amplification product of approximately 700 bp for BCMV and BCMV–BICM. The complete identity of the two viruses was further confirmed by nucleotide sequencing of the partial coat protein and 3′-UTR regions. The sequences of the four BCMV and BCMV–BICM isolates each consisted of 583–622 and 550–577 nucleotides. The present report confirms the widespread nature of these two serious potyviruses in the two most important legume crops in India.     

Gene amplification and expression by RNA viruses and potential for further application to plant gene transfer

The great majority of plant viruses encapsidate messenger-sense ssRNA and have no natural DNA phase in their life cycle. Despite their RNA nature, essentially any desired change can be introduced into such genomes by using recombinant DNA techniques with suitably constructed, expressible viral cDNA clones. For some viruses such as brome mosaic virus, these methods have been used to define the sequences controlling RNA-directed genomic RNA replication and the expression of internal genes via subgenomic mRNAs. The results suggest a surprising degree of genetic flexibility, which appears to be reflected in the varied gene complements and genetic organizations of presumably related plant and animal RNA viruses sharing conserved replication genes. Foreign genes inserted in such RNA virus genomes can be amplified and expressed to a high level in transfected plant cells. In addition to the potential use of such viruses as episomal expression vectors, it should be possible to couple the viral pathways of RNA-dependent RNA synthesis to amplify and to further regulate the expression of genes transformed into plant chromosomes.     

三重RT-PCR同步检测马铃薯多种病毒影响因素

根据病毒外壳蛋白区序列设计PVX、PVS特异性引物对,根据P1基因区序列设计PVA特异性引物对,应用三重RT-PCR同步检测马铃薯X病毒,马铃薯A病毒及马铃薯S病毒,分别得到562bp、255bp、182bp大小的扩增片段。试验从反转录反应、PCR反应及循环条件3方面讨论了试剂和循环条件对三重RT-PCR同步检测3种病毒的影响。结果表明反转录反应中dNTPs浓度、3种病毒下游引物浓度比例对整个反应影响较大;其次是PCR反应中MgC12浓度和退火温度;反转录时间,循环条件对RT-PCR影响较小。     

流感病毒抗原性变异研究进展

简要概述了流感病毒的结构特征和HA1区的功能,并着重介绍了国内外有关流感病毒HA基因抗原变异性学说及其研究进展.     

Baculoviruses as Vectors in Mammalian Cells

The Baculoviridae are a large family of enveloped DNA viruses exclusively pathogenic to arthropods. Baculoviruses have been extensively used in insect cell-based recombinant protein expression system and as biological pesticides. They have been deomostrated to be safe to mammals, birds and fish. Recently, baculoviruses has been shown to transduce different mammalian cells in spite of the fact that they cannot replicate in mammalian cells (11, 73, 76). This has resulted in the development of baculoviruses as mammalian expression systems and even as vestors for gene therapy.     

Aptamers Against Viral Hepatitis： from Rational Design to Practical Application

Aptamers are short nucleic acids or peptides that strongly bind to a protein of interest and functionally inhibit a given target protein at the intracellular level. Besides high affinity and specificity, aptamers have several advantages over traditional antibodies. Hence, they have been broadly selected to develop antiviral agents for therapeutic applications against hepatitis B and C viruses (HBV, HCV). This review provides a summary of in vitro selection and characterization of aptamers against viral hepatitis, which is of practical significance in drug discovery.     

Poikilotherm vertebrate cell lines and viruses: A current listing for fishes

Summary A survey of the literature and of work being done in vertebrate cell culture shows that there are currently in existence and available to investigators some 61 cell lines representing 17 families and 36 species of fish. The literature of fish virology shows that at least 17 fish viruses have been isolated and that at least 15 others have been visualized by electron microscopy. A minimum of four major virus groups—rhabdovirus, orthomyxovirus, iridovirus and herpesvirus—are known from fish. Original references, key reviews and sources of cell lines are given.     

Virus diseases in aquaculture

World Journal of Microbiology and Biotechnology -     

2000年～2007年山东省风疹病毒分子流行病学研究

本研究对使用Vero细胞、RK13细胞或Vero/SLAM细胞从2000年～2007年山东省6个市风疹暴发和散发病例的咽拭子标本中所分离的风疹病毒,用RT-PCR方法扩增其E1基因的1107个核苷酸片段,并对其PCR产物进行序列测定和分析。结果提示,在基于WHO基因定型靶序列739个核苷酸片段构建的基因亲缘关系树上,16株风疹病毒株分属三个基因型:1E(12株)、1F(1株)和2A(3株)。1E基因型于2001年在山东省首次检测到,并逐年成为我省风疹病毒流行的优势基因型,其中,2006～2007年间流行的1E基因型风疹病毒与2001年和2002年流行的1E基因型风疹病毒存在差异,但无明显的时间和地理分布倾向;1F基因型和2A基因型分别于2000年、2001年分离到,至2007年间未再出现;3株2A基因型风疹病毒与我国风疹疫苗株(BRDII)密切相关。16株风疹病毒大部分核苷酸的突变为无义突变,氨基酸序列高度保守,均无重要抗原位点的改变;山东省2001～2007年间分离的所有1E基因型风疹病毒在E1蛋白的第338位氨基酸发生相同突变(Leu338→Phe338),以往报道相同。