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Sample records for replication rna viruses

  1. Mutual Interference between Genomic RNA Replication and Subgenomic mRNA Transcription in Brome Mosaic Virus

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    Grdzelishvili, Valery Z.; Garcia-Ruiz, Hernan; Watanabe, Tokiko; Ahlquist, Paul

    2005-01-01

    Replication by many positive-strand RNA viruses includes genomic RNA amplification and subgenomic mRNA (sgRNA) transcription. For brome mosaic virus (BMV), both processes occur in virus-induced, membrane-associated compartments, require BMV replication factors 1a and 2a, and use negative-strand RNA3 as a template for genomic RNA3 and sgRNA syntheses. To begin elucidating their relations, we examined the interaction of RNA3 replication and sgRNA transcription in Saccharomyces cerevisiae expres...

  2. Inhibition of Monkeypox virus replication by RNA interference

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    Jahrling Peter B

    2009-11-01

    Full Text Available Abstract The Orthopoxvirus genus of Poxviridae family is comprised of several human pathogens, including cowpox (CPXV, Vaccinia (VACV, monkeypox (MPV and Variola (VARV viruses. Species of this virus genus cause human diseases with various severities and outcome ranging from mild conditions to death in fulminating cases. Currently, vaccination is the only protective measure against infection with these viruses and no licensed antiviral drug therapy is available. In this study, we investigated the potential of RNA interference pathway (RNAi as a therapeutic approach for orthopox virus infections using MPV as a model. Based on genome-wide expression studies and bioinformatic analysis, we selected 12 viral genes and targeted them by small interference RNA (siRNA. Forty-eight siRNA constructs were developed and evaluated in vitro for their ability to inhibit viral replication. Two genes, each targeted with four different siRNA constructs in one pool, were limiting to viral replication. Seven siRNA constructs from these two pools, targeting either an essential gene for viral replication (A6R or an important gene in viral entry (E8L, inhibited viral replication in cell culture by 65-95% with no apparent cytotoxicity. Further analysis with wild-type and recombinant MPV expressing green fluorescence protein demonstrated that one of these constructs, siA6-a, was the most potent and inhibited viral replication for up to 7 days at a concentration of 10 nM. These results emphasis the essential role of A6R gene in viral replication, and demonstrate the potential of RNAi as a therapeutic approach for developing oligonucleotide-based drug therapy for MPV and other orthopox viruses.

  3. RNA interference-mediated inhibition of Hepatitis B Virus replication

    Institute of Scientific and Technical Information of China (English)

    TANG Ni; ZHANG Bingqiang; YAN Ge; PU Dan; GAO Xiaolin; Tong-Chuan He; HUANG Ailong

    2004-01-01

    Persistent and recurrent infection of hepatitis B virus (HBV) represents one of the most common and severe viral infections of humans, and has caused a formidable health problem in the affected countries. Currently used antiviral drugs have a very limited success on controlling HBV replication and infection. RNA interference (RNAi), a process by which double-stranded RNA (dsRNA) directs sequence-specific degradation of target mRNA in mammalian and plant cells, has recently been used to knockdown gene expression in various species. In this study, we sought to determine whether RNAi-mediated silencing of HBV viral gene expression could lead to the effective inhibition of HBV replication. We first developed RNAi vectors that expressed small interfering RNA (siRNA) and targeted the HBV core or surface gene sequence. Our results demonstrated that these specific siRNAs efficiently reduced the levels of corresponding viral RNAs and proteins, and thus suppressed viral replication. Treatment with siRNA gave the greatest reduction in the levels of HBsAg (92%) and in HBeAg (85%) respectively in the cultured cell medium. Our findings further demonstrated that the RNAi-mediated antiviral effect was sequence-specific and dose-dependent. Therefore, our findings strongly suggest that RNAi-mediated silencing of HBV viral genes could effectively inhibit the replication of HBV, hence RNAi-based strategy should be further explored as a more efficacious antiviral therapy of HBV infection.

  4. Phosphatidic acid produced by phospholipase D promotes RNA replication of a plant RNA virus.

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    Kiwamu Hyodo

    2015-05-01

    Full Text Available Eukaryotic positive-strand RNA [(+RNA] viruses are intracellular obligate parasites replicate using the membrane-bound replicase complexes that contain multiple viral and host components. To replicate, (+RNA viruses exploit host resources and modify host metabolism and membrane organization. Phospholipase D (PLD is a phosphatidylcholine- and phosphatidylethanolamine-hydrolyzing enzyme that catalyzes the production of phosphatidic acid (PA, a lipid second messenger that modulates diverse intracellular signaling in various organisms. PA is normally present in small amounts (less than 1% of total phospholipids, but rapidly and transiently accumulates in lipid bilayers in response to different environmental cues such as biotic and abiotic stresses in plants. However, the precise functions of PLD and PA remain unknown. Here, we report the roles of PLD and PA in genomic RNA replication of a plant (+RNA virus, Red clover necrotic mosaic virus (RCNMV. We found that RCNMV RNA replication complexes formed in Nicotiana benthamiana contained PLDα and PLDβ. Gene-silencing and pharmacological inhibition approaches showed that PLDs and PLDs-derived PA are required for viral RNA replication. Consistent with this, exogenous application of PA enhanced viral RNA replication in plant cells and plant-derived cell-free extracts. We also found that a viral auxiliary replication protein bound to PA in vitro, and that the amount of PA increased in RCNMV-infected plant leaves. Together, our findings suggest that RCNMV hijacks host PA-producing enzymes to replicate.

  5. Membranous Replication Factories Induced by Plus-Strand RNA Viruses

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    Inés Romero-Brey

    2014-07-01

    Full Text Available In this review, we summarize the current knowledge about the membranous replication factories of members of plus-strand (+ RNA viruses. We discuss primarily the architecture of these complex membrane rearrangements, because this topic emerged in the last few years as electron tomography has become more widely available. A general denominator is that two “morphotypes” of membrane alterations can be found that are exemplified by flaviviruses and hepaciviruses: membrane invaginations towards the lumen of the endoplasmatic reticulum (ER and double membrane vesicles, representing extrusions also originating from the ER, respectively. We hypothesize that either morphotype might reflect common pathways and principles that are used by these viruses to form their membranous replication compartments.

  6. Beet yellows virus replicase and replicative compartments: parallels with other RNA viruses

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    Vladimir A. Gushchin

    2013-03-01

    Full Text Available In eukaryotic virus systems, infection leads to induction of membranous compartments in which replication occurs. Virus-encoded subunits of the replication complex mediate its interaction with membranes. As replication platforms, RNA viruses use the cytoplasmic surfaces of different membrane compartments, e.g., endoplasmic reticulum (ER, Golgi, endo/lysosomes, mitochondria, chloroplasts and peroxisomes. Closterovirus infections are accompanied by formation of multivesicular complexes from cell membranes of ER or mitochondrial origin. So far the mechanisms for vesicles formation have been obscure. In the replication-associated 1a polyprotein of Beet yellows virus (BYV and other closteroviruses, the region between the methyltransferase (MTR and helicase (HEL domains (1a central region, 1a CR is marginally conserved. Computer-assisted analysis predicts several putative membrane-binding domains in the BYV 1a CR. Transient expression of a hydrophobic segment (referred to here as CR-2 of the BYV 1a in Nicotiana benthamiana led to reorganization of the ER and formation of ~1-m mobile globules. We propose that the CR-2 may be involved in the formation of multivesicular complexes in BYV-infected cells. This provides analogy with membrane-associated proteins mediating the build-up of virus factories in cells infected with diverse positive-strand RNA viruses (alpha-like viruses, picorna-like viruses, flaviviruses, and nidoviruses and negative-strand RNA viruses (bunyaviruses.

  7. Beet yellows virus replicase and replicative compartments: parallels with other RNA viruses.

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    Gushchin, Vladimir A; Solovyev, Andrey G; Erokhina, Tatyana N; Morozov, Sergey Y; Agranovsky, Alexey A

    2013-01-01

    In eukaryotic virus systems, infection leads to induction of membranous compartments in which replication occurs. Virus-encoded subunits of the replication complex mediate its interaction with membranes. As replication platforms, RNA viruses use the cytoplasmic surfaces of different membrane compartments, e.g., endoplasmic reticulum (ER), Golgi, endo/lysosomes, mitochondria, chloroplasts, and peroxisomes. Closterovirus infections are accompanied by formation of multivesicular complexes from cell membranes of ER or mitochondrial origin. So far the mechanisms for vesicles formation have been obscure. In the replication-associated 1a polyprotein of Beet yellows virus (BYV) and other closteroviruses, the region between the methyltransferase and helicase domains (1a central region (CR), 1a CR) is marginally conserved. Computer-assisted analysis predicts several putative membrane-binding domains in the BYV 1a CR. Transient expression of a hydrophobic segment (referred to here as CR-2) of the BYV 1a in Nicotiana benthamiana led to reorganization of the ER and formation of ~1-μm mobile globules. We propose that the CR-2 may be involved in the formation of multivesicular complexes in BYV-infected cells. This provides analogy with membrane-associated proteins mediating the build-up of "virus factories" in cells infected with diverse positive-strand RNA viruses (alpha-like viruses, picorna-like viruses, flaviviruses, and nidoviruses) and negative-strand RNA viruses (bunyaviruses).

  8. DDX3 DEAD-box RNA helicase is required for hepatitis C virus RNA replication.

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    Ariumi, Yasuo; Kuroki, Misao; Abe, Ken-ichi; Dansako, Hiromichi; Ikeda, Masanori; Wakita, Takaji; Kato, Nobuyuki

    2007-12-01

    DDX3, a DEAD-box RNA helicase, binds to the hepatitis C virus (HCV) core protein. However, the role(s) of DDX3 in HCV replication is still not understood. Here we demonstrate that the accumulation of both genome-length HCV RNA (HCV-O, genotype 1b) and its replicon RNA were significantly suppressed in HuH-7-derived cells expressing short hairpin RNA targeted to DDX3 by lentivirus vector transduction. As well, RNA replication of JFH1 (genotype 2a) and release of the core into the culture supernatants were suppressed in DDX3 knockdown cells after inoculation of the cell culture-generated HCVcc. Thus, DDX3 is required for HCV RNA replication.

  9. Replication protein of tobacco mosaic virus cotranslationally binds the 5′ untranslated region of genomic RNA to enable viral replication

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    Kawamura-Nagaya, Kazue; Ishibashi, Kazuhiro; Huang, Ying-Ping; Miyashita, Shuhei; Ishikawa, Masayuki

    2014-01-01

    Genomic RNA of positive-strand RNA viruses replicate via complementary (i.e., negative-strand) RNA in membrane-bound replication complexes. Before replication complex formation, virus-encoded replication proteins specifically recognize genomic RNA molecules and recruit them to sites of replication. Moreover, in many of these viruses, selection of replication templates by the replication proteins occurs preferentially in cis. This property is advantageous to the viruses in several aspects of viral replication and evolution, but the underlying molecular mechanisms have not been characterized. Here, we used an in vitro translation system to show that a 126-kDa replication protein of tobacco mosaic virus (TMV), a positive-strand RNA virus, binds a 5′-terminal ∼70-nucleotide region of TMV RNA cotranslationally, but not posttranslationally. TMV mutants that carried nucleotide changes in the 5′-terminal region and showed a defect in the binding were unable to synthesize negative-strand RNA, indicating that this binding is essential for template selection. A C-terminally truncated 126-kDa protein, but not the full-length 126-kDa protein, was able to posttranslationally bind TMV RNA in vitro, suggesting that binding of the 126-kDa protein to the 70-nucleotide region occurs during translation and before synthesis of the C-terminal inhibitory domain. We also show that binding of the 126-kDa protein prevents further translation of the bound TMV RNA. These data provide a mechanistic explanation of how the 126-kDa protein selects replication templates in cis and how fatal collision between translating ribosomes and negative-strand RNA-synthesizing polymerases on the genomic RNA is avoided. PMID:24711385

  10. Inhibition of RNA recruitment and replication of an RNA virus by acridine derivatives with known anti-prion activities.

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    Zsuzsanna Sasvari

    Full Text Available BACKGROUND: Small molecule inhibitors of RNA virus replication are potent antiviral drugs and useful to dissect selected steps in the replication process. To identify antiviral compounds against Tomato bushy stunt virus (TBSV, a model positive stranded RNA virus, we tested acridine derivatives, such as chlorpromazine (CPZ and quinacrine (QC, which are active against prion-based diseases. METHODOLOGY/PRINCIPAL FINDINGS: Here, we report that CPZ and QC compounds inhibited TBSV RNA accumulation in plants and in protoplasts. In vitro assays revealed that the inhibitory effects of these compounds were manifested at different steps of TBSV replication. QC was shown to have an effect on multiple steps, including: (i inhibition of the selective binding of the p33 replication protein to the viral RNA template, which is required for recruitment of viral RNA for replication; (ii reduction of minus-strand synthesis by the tombusvirus replicase; and (iii inhibition of translation of the uncapped TBSV genomic RNA. In contrast, CPZ was shown to inhibit the in vitro assembly of the TBSV replicase, likely due to binding of CPZ to intracellular membranes, which are important for RNA virus replication. CONCLUSION/SIGNIFICANCE: Since we found that CPZ was also an effective inhibitor of other plant viruses, including Tobacco mosaic virus and Turnip crinkle virus, it seems likely that CPZ has a broad range of antiviral activity. Thus, these inhibitors constitute effective tools to study similarities in replication strategies of various RNA viruses.

  11. Phosphorylation of NS5A Serine-235 is essential to hepatitis C virus RNA replication and normal replication compartment formation

    Energy Technology Data Exchange (ETDEWEB)

    Eyre, Nicholas S., E-mail: nicholas.eyre@adelaide.edu.au [School of Biological Sciences and Research Centre for Infectious Diseases, University of Adelaide, Adelaide (Australia); Centre for Cancer Biology, SA Pathology, Adelaide (Australia); Hampton-Smith, Rachel J.; Aloia, Amanda L. [School of Biological Sciences and Research Centre for Infectious Diseases, University of Adelaide, Adelaide (Australia); Centre for Cancer Biology, SA Pathology, Adelaide (Australia); Eddes, James S. [Adelaide Proteomics Centre, School of Biological Sciences, University of Adelaide, Adelaide (Australia); Simpson, Kaylene J. [Victorian Centre for Functional Genomics, Peter MacCallum Cancer Centre, East Melbourne (Australia); The Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville (Australia); Hoffmann, Peter [Adelaide Proteomics Centre, School of Biological Sciences, University of Adelaide, Adelaide (Australia); Institute for Photonics and Advanced Sensing (IPAS), University of Adelaide, Adelaide (Australia); Beard, Michael R. [School of Biological Sciences and Research Centre for Infectious Diseases, University of Adelaide, Adelaide (Australia); Centre for Cancer Biology, SA Pathology, Adelaide (Australia)

    2016-04-15

    Hepatitis C virus (HCV) NS5A protein is essential for HCV RNA replication and virus assembly. Here we report the identification of NS5A phosphorylation sites Ser-222, Ser-235 and Thr-348 during an infectious HCV replication cycle and demonstrate that Ser-235 phosphorylation is essential for HCV RNA replication. Confocal microscopy revealed that both phosphoablatant (S235A) and phosphomimetic (S235D) mutants redistribute NS5A to large juxta-nuclear foci that display altered colocalization with known replication complex components. Using electron microscopy (EM) we found that S235D alters virus-induced membrane rearrangements while EM using ‘APEX2’-tagged viruses demonstrated S235D-mediated enrichment of NS5A in irregular membranous foci. Finally, using a customized siRNA screen of candidate NS5A kinases and subsequent analysis using a phospho-specific antibody, we show that phosphatidylinositol-4 kinase III alpha (PI4KIIIα) is important for Ser-235 phosphorylation. We conclude that Ser-235 phosphorylation of NS5A is essential for HCV RNA replication and normal replication complex formation and is regulated by PI4KIIIα. - Highlights: • NS5A residues Ser-222, Ser-235 and Thr-348 are phosphorylated during HCV infection. • Phosphorylation of Ser-235 is essential to HCV RNA replication. • Mutation of Ser-235 alters replication compartment localization and morphology. • Phosphatidylinositol-4 kinase III alpha is important for Ser-235 phosphorylation.

  12. Suppression of RNA interference increases alphavirus replication and virus-associated mortality in Aedes aegypti mosquitoes

    OpenAIRE

    Geiss Brian J; Phillips Aaron T; Scott Jaclyn C; Cirimotich Chris M; Olson Ken E

    2009-01-01

    Abstract Background Arthropod-borne viruses (arboviruses) can persistently infect and cause limited damage to mosquito vectors. RNA interference (RNAi) is a mosquito antiviral response important in restricting RNA virus replication and has been shown to be active against some arboviruses. The goal of this study was to use a recombinant Sindbis virus (SINV; family Togaviridae; genus Alphavirus) that expresses B2 protein of Flock House virus (FHV; family Nodaviridae; genus Alphanodavirus), a pr...

  13. THE INHIBITORY EFFECT OF ASTRAGALUS MEMBRANACEUS ON COXSACKIE B-3 VIRUS RNA REPLICATION

    Institute of Scientific and Technical Information of China (English)

    彭天庆; 杨英珍; HelgaRiesemann; ReinhardKandolf

    1995-01-01

    Using mice infected with coxsackie B-3 virus (CVB3) as a viral myocarditis model,we observed the inhibitory effect of Astragalus membranaceus (AM) on CVB3-RNA replication in myocardial tissue of mice by RNA-RNA in situ hybridization with negative-strand RNA probes labelled with 35S and quantitative imaging analysis of positive signals.The mechanism of its effect on CVB3-RNA replication has been inves-tigated by detection of beta-interferon (β-IFN) as well.Results showed that the copy numbers of CVB3-RNA as well as the histologic scores (necrosis) in myocardial tissues of infected-AM treated mice were sig-nificantly lower than those in infected and normal saline treated mice,suggesting that AM could inhibit the replication of CVB3-RNA,but its effect on CVB3-RNA replication had no correlation with induction of β-IFN.

  14. Ultrastructure of the replication sites of positive-strand RNA viruses

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    Harak, Christian; Lohmann, Volker, E-mail: volker_lohmann@med.uni-heidelberg.de

    2015-05-15

    Positive strand RNA viruses replicate in the cytoplasm of infected cells and induce intracellular membranous compartments harboring the sites of viral RNA synthesis. These replication factories are supposed to concentrate the components of the replicase and to shield replication intermediates from the host cell innate immune defense. Virus induced membrane alterations are often generated in coordination with host factors and can be grouped into different morphotypes. Recent advances in conventional and electron microscopy have contributed greatly to our understanding of their biogenesis, but still many questions remain how viral proteins capture membranes and subvert host factors for their need. In this review, we will discuss different representatives of positive strand RNA viruses and their ways of hijacking cellular membranes to establish replication complexes. We will further focus on host cell factors that are critically involved in formation of these membranes and how they contribute to viral replication. - Highlights: • Positive strand RNA viruses induce massive membrane alterations. • Despite the great diversity, replication complexes share many similarities. • Host factors play a pivotal role in replication complex biogenesis. • Use of the same host factors by several viruses hints to similar functions.

  15. RNA interference of influenza A virus replication by microRNA-adapted lentiviral loop short hairpin RNA.

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    Xu, Fang; Liu, Guanqun; Liu, Qiang; Zhou, Yan

    2015-10-01

    Limitations of the current vaccines and antivirals against influenza A virus (IAV) pandemic underscore the urgent need for developing novel anti-influenza strategies. RNA interference (RNAi) induced by small interfering RNA (siRNA) has become a powerful new means to inhibit viral infection in a gene-specific manner. However, the efficacy of the siRNA delivery platform and the relatively high cost of administration have hindered widespread application of siRNA. In this study, we developed a microRNA (miRNA)-30-based lentivirus delivery system by embedding a synthetic short hairpin RNA (shRNA) stem into the context of endogenous precursor of miRNA-30 (shRNAmir) to express a silencer of the influenza gene. We showed that the miRNA-based lentivirus vector was able to express and process a single nucleoprotein (NP)-targeting shRNAmir, which could potently inhibit IAV replication. We further showed that miRNA-based lentivirus vector carrying tandemly linked NP and polymerase PB1 shRNAmirs could express and process double shRNAmirs. Despite the relatively low levels of NP and PB1 miRNAs produced in the stably transduced cells, the combination of two miRNAs exerted a great degree of inhibition on influenza infection. Given the advantage of combinatorial RNAi in preventing emergence of mutant virus, miRNA-based lentiviral vectors are valuable tools for anitiviral activities. To the best of our knowledge, this is the first study demonstrating that a miRNA-based RNAi strategy can be applied for better control of influenza virus infection.

  16. Intersection of the multivesicular body pathway and lipid homeostasis in RNA replication by a positive-strand RNA virus.

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    Wang, Xiaofeng; Diaz, Arturo; Hao, Linhui; Gancarz, Brandi; den Boon, Johan A; Ahlquist, Paul

    2011-06-01

    Like many positive-strand RNA viruses, brome mosaic virus (BMV) RNA replication occurs in membrane-invaginated vesicular compartments. BMV RNA replication compartments show parallels with membrane-enveloped, budding retrovirus virions, whose release depends on the cellular multivesicular body (MVB) sorting pathway. BMV RNA replication compartments are not released from their parent membranes, but might depend on MVB functions for membrane invagination. Prior results show that BMV RNA replication is severely inhibited by deletion of the crucial MVB gene DOA4 or BRO1. We report here that involvement of DOA4 and BRO1 in BMV RNA replication is not dependent on the MVB pathway's membrane-shaping functions but rather is due to their roles in recycling ubiquitin from MVB cargos. We show that deleting DOA4 or BRO1 inhibits the ubiquitination- and proteasome-dependent activation of homologous transcription factors Mga2p and Spt23p, which regulate many lipid metabolism genes, including the fatty acid desaturase gene OLE1, which is essential for BMV RNA replication. However, Mga2p processing and BMV RNA replication are restored by supplementing free ubiquitin, which is depleted in doa4Δ and bro1Δ cells. The results identify Mga2p and Spt23p processing and lipid regulation as sensitive targets of ubiquitin depletion and correctly predict multiple effects of modulating additional host genes RFU1, UBP6, and UFD3. Our results also show that BMV RNA replication depends on additional Mga2p-regulated genes likely involved in lipid metabolism beyond OLE1. Among other points, these findings show the potential for blocking viral RNA replication by modulating lipid synthesis at multiple levels.

  17. Active RNA replication of hepatitis C virus downregulates CD81 expression.

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    Ke, Po-Yuan; Chen, Steve S-L

    2013-01-01

    So far how hepatitis C virus (HCV) replication modulates subsequent virus growth and propagation still remains largely unknown. Here we determine the impact of HCV replication status on the consequential virus growth by comparing normal and high levels of HCV RNA expression. We first engineered a full-length, HCV genotype 2a JFH1 genome containing a blasticidin-resistant cassette inserted at amino acid residue of 420 in nonstructural (NS) protein 5A, which allowed selection of human hepatoma Huh7 cells stably-expressing HCV. Short-term establishment of HCV stable cells attained a highly-replicating status, judged by higher expressions of viral RNA and protein as well as higher titer of viral infectivity as opposed to cells harboring the same genome without selection. Interestingly, maintenance of highly-replicating HCV stable cells led to decreased susceptibility to HCV pseudotyped particle (HCVpp) infection and downregulated cell surface level of CD81, a critical HCV entry (co)receptor. The decreased CD81 cell surface expression occurred through reduced total expression and cytoplasmic retention of CD81 within an endoplasmic reticulum -associated compartment. Moreover, productive viral RNA replication in cells harboring a JFH1 subgenomic replicon containing a similar blasticidin resistance gene cassette in NS5A and in cells robustly replicating full-length infectious genome also reduced permissiveness to HCVpp infection through decreasing the surface expression of CD81. The downregulation of CD81 surface level in HCV RNA highly-replicating cells thus interfered with reinfection and led to attenuated viral amplification. These findings together indicate that the HCV RNA replication status plays a crucial determinant in HCV growth by modulating the expression and intracellular localization of CD81.

  18. Active RNA replication of hepatitis C virus downregulates CD81 expression.

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    Po-Yuan Ke

    Full Text Available So far how hepatitis C virus (HCV replication modulates subsequent virus growth and propagation still remains largely unknown. Here we determine the impact of HCV replication status on the consequential virus growth by comparing normal and high levels of HCV RNA expression. We first engineered a full-length, HCV genotype 2a JFH1 genome containing a blasticidin-resistant cassette inserted at amino acid residue of 420 in nonstructural (NS protein 5A, which allowed selection of human hepatoma Huh7 cells stably-expressing HCV. Short-term establishment of HCV stable cells attained a highly-replicating status, judged by higher expressions of viral RNA and protein as well as higher titer of viral infectivity as opposed to cells harboring the same genome without selection. Interestingly, maintenance of highly-replicating HCV stable cells led to decreased susceptibility to HCV pseudotyped particle (HCVpp infection and downregulated cell surface level of CD81, a critical HCV entry (coreceptor. The decreased CD81 cell surface expression occurred through reduced total expression and cytoplasmic retention of CD81 within an endoplasmic reticulum -associated compartment. Moreover, productive viral RNA replication in cells harboring a JFH1 subgenomic replicon containing a similar blasticidin resistance gene cassette in NS5A and in cells robustly replicating full-length infectious genome also reduced permissiveness to HCVpp infection through decreasing the surface expression of CD81. The downregulation of CD81 surface level in HCV RNA highly-replicating cells thus interfered with reinfection and led to attenuated viral amplification. These findings together indicate that the HCV RNA replication status plays a crucial determinant in HCV growth by modulating the expression and intracellular localization of CD81.

  19. Hsp90 interacts specifically with viral RNA and differentially regulates replication initiation of Bamboo mosaic virus and associated satellite RNA.

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    Ying Wen Huang

    Full Text Available Host factors play crucial roles in the replication of plus-strand RNA viruses. In this report, a heat shock protein 90 homologue of Nicotiana benthamiana, NbHsp90, was identified in association with partially purified replicase complexes from BaMV-infected tissue, and shown to specifically interact with the 3' untranslated region (3' UTR of BaMV genomic RNA, but not with the 3' UTR of BaMV-associated satellite RNA (satBaMV RNA or that of genomic RNA of other viruses, such as Potato virus X (PVX or Cucumber mosaic virus (CMV. Mutational analyses revealed that the interaction occurs between the middle domain of NbHsp90 and domain E of the BaMV 3' UTR. The knockdown or inhibition of NbHsp90 suppressed BaMV infectivity, but not that of satBaMV RNA, PVX, or CMV in N. benthamiana. Time-course analysis further revealed that the inhibitory effect of 17-AAG is significant only during the immediate early stages of BaMV replication. Moreover, yeast two-hybrid and GST pull-down assays demonstrated the existence of an interaction between NbHsp90 and the BaMV RNA-dependent RNA polymerase. These results reveal a novel role for NbHsp90 in the selective enhancement of BaMV replication, most likely through direct interaction with the 3' UTR of BaMV RNA during the initiation of BaMV RNA replication.

  20. Small noncoding RNA modulates japanese encephalitis virus replication and translation in trans

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    Fan Yi-Hsin

    2011-11-01

    Full Text Available Abstract Background Sequence and structural elements in the 3'-untranslated region (UTR of Japanese encephalitis virus (JEV are known to regulate translation and replication. We previously reported an abundant accumulation of small subgenomic flaviviral RNA (sfRNA which is collinear with the highly conserved regions of the 3'-UTR in JEV-infected cells. However, function of the sfRNA in JEV life cycle remains unknown. Results Northern blot and real-time RT-PCR analyses indicated that the sfRNA becomes apparent at the time point at which minus-strand RNA (antigenome reaches a plateau suggesting a role for sfRNA in the regulation of antigenome synthesis. Transfection of minus-sense sfRNA into JEV-infected cells, in order to counter the effects of plus-sense sfRNA, resulted in higher levels of antigenome suggesting that the presence of the sfRNA inhibits antigenome synthesis. Trans-acting effect of sfRNA on JEV translation was studied using a reporter mRNA containing the luciferase gene fused to partial coding regions of JEV and flanked by the respective JEV UTRs. In vivo and in vitro translation revealed that sfRNA inhibited JEV translation. Conclusions Our results indicate that sfRNA modulates viral translation and replication in trans.

  1. Inhibition of hepatitis C virus replication by single-stranded RNA structural mimics

    Institute of Scientific and Technical Information of China (English)

    Robert; Smolic; Martina; Smolic; John; H; Andorfer; Catherine; H; Wu; Robert; M; Smith; George; Y; Wu

    2010-01-01

    AIM: To examine the effect of hepatitis C virus (HCV) structural mimics of regulatory regions of the genome on HCV replication.METHODS: HCV RNA structural mimics were constructed and tested in a HCV genotype 1b aBB7 replicon,and a Japanese fulminant hepatitis-1 (JFH-1) HCV genotype 2a infection model.All sequences were computer-predicted to adopt stem-loop structures identical to the corresponding elements in full-length viral RNA.Huh7.5 cells bearing the BB7 replicon or infected with JFH-1 virus were trans...

  2. Inhibition of IκB kinase by thalidomide increases hepatitis C virus RNA replication.

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    Rance, E; Tanner, J E; Alfieri, C

    2012-02-01

    Hepatic fibrosis is an integral element in the progression of chronic liver disease. Elevated hepatic interleukin (IL)-8 is an important contributor to fibrosis in patients chronically infected with the hepatitis C virus (HCV). Thalidomide has been used to reduce liver inflammation and fibrosis in HCV-infected patients, but its impact on HCV replication remains unclear. This study examined the effect of thalidomide on HCV replication in vitro. Results revealed that while thalidomide reduced IL-8 and nuclear factor kappa B (NF-κB) activity by 95% and 46% in Huh-7 cells, increasing concentrations of thalidomide correlated with a linear rise in HCV replication (17-fold at 200 μm). The NF-κB inhibitors, wedelolactone and NF-κB activation inhibitor-1, which mimic the actions of thalidomide by preventing phosphorylation and activation of IκB kinase (IKK) and hence block NF-κB activity, increased HCV RNA by 18- and 19-fold, respectively. During in vitro HCV replication in Huh-7 cells, we observed a 30% increase in IKKα protein and 55% decrease in NF-κB(p65)/RelA protein relative to cellular β-actin. Ectopic expression of IKKα to enhance the inactive form of IKK in cells undergoing virus replication led to a 13-fold increase in HCV RNA. Conversely, enhanced expression of NF-κB(p65)/RelA in infected cells resulted in a 17-fold reduction in HCV RNA. In conclusion, HCV RNA replication was significantly augmented by the inhibition of IKK activation and subsequent NF-κB signalling, whereas a restoration of NF-κB activity by the addition of NF-κB/RelA markedly reduced HCV replication. This study lends added importance to the role of the NF-κB signalling pathway in controlling HCV replication.

  3. Efficient Hepatitis Delta Virus RNA Replication in Avian Cells Requires a Permissive Factor(s) from Mammalian Cells

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    Liu, Yu-Tsueng; Brazas, Rob; Ganem, Don

    2001-01-01

    Hepatitis delta virus (HDV) is a highly pathogenic human RNA virus whose genome is structurally related to those of plant viroids. Although its spread from cell to cell requires helper functions supplied by hepatitis B virus (HBV), intracellular HDV RNA replication can proceed in the absence of HBV proteins. As HDV encodes no RNA-dependent RNA polymerase, the identity of the (presumably cellular) enzyme responsible for this reaction remains unknown. Here we show that, in contrast to mammalian...

  4. Zika Virus RNA Replication and Persistence in Brain and Placental Tissue

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    Rabeneck, Demi B.; Martines, Roosecelis B.; Reagan-Steiner, Sarah; Ermias, Yokabed; Estetter, Lindsey B.C.; Suzuki, Tadaki; Ritter, Jana; Keating, M. Kelly; Hale, Gillian; Gary, Joy; Muehlenbachs, Atis; Lambert, Amy; Lanciotti, Robert; Oduyebo, Titilope; Meaney-Delman, Dana; Bolaños, Fernando; Saad, Edgar Alberto Parra; Shieh, Wun-Ju; Zaki, Sherif R.

    2017-01-01

    Zika virus is causally linked with congenital microcephaly and may be associated with pregnancy loss. However, the mechanisms of Zika virus intrauterine transmission and replication and its tropism and persistence in tissues are poorly understood. We tested tissues from 52 case-patients: 8 infants with microcephaly who died and 44 women suspected of being infected with Zika virus during pregnancy. By reverse transcription PCR, tissues from 32 (62%) case-patients (brains from 8 infants with microcephaly and placental/fetal tissues from 24 women) were positive for Zika virus. In situ hybridization localized replicative Zika virus RNA in brains of 7 infants and in placentas of 9 women who had pregnancy losses during the first or second trimester. These findings demonstrate that Zika virus replicates and persists in fetal brains and placentas, providing direct evidence of its association with microcephaly. Tissue-based reverse transcription PCR extends the time frame of Zika virus detection in congenital and pregnancy-associated infections. PMID:27959260

  5. Suppression of RNA interference increases alphavirus replication and virus-associated mortality in Aedes aegypti mosquitoes

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    Geiss Brian J

    2009-03-01

    Full Text Available Abstract Background Arthropod-borne viruses (arboviruses can persistently infect and cause limited damage to mosquito vectors. RNA interference (RNAi is a mosquito antiviral response important in restricting RNA virus replication and has been shown to be active against some arboviruses. The goal of this study was to use a recombinant Sindbis virus (SINV; family Togaviridae; genus Alphavirus that expresses B2 protein of Flock House virus (FHV; family Nodaviridae; genus Alphanodavirus, a protein that inhibits RNAi, to determine the effects of linking arbovirus infection with RNAi inhibition. Results B2 protein expression from SINV (TE/3'2J inhibited the accumulation of non-specific small RNAs in Aedes aegypti mosquito cell culture and virus-specific small RNAs both in infected cell culture and Ae. aegypti mosquitoes. More viral genomic and subgenomic RNA accumulated in cells and mosquitoes infected with TE/3'2J virus expressing B2 (TE/3'2J/B2 compared to TE/3'2J and TE/3'2J virus expressing GFP. TE/3'2J/B2 exhibited increased infection rates, dissemination rates, and infectious virus titers in mosquitoes following oral bloodmeal. Following infectious oral bloodmeal, significantly more mosquitoes died when TE/3'2J/B2 was ingested. The virus was 100% lethal following intrathoracic inoculation of multiple mosquito species and lethality was dose-dependent in Ae. aegypti. Conclusion We show that RNAi is active in Ae. aegypti cell culture and that B2 protein inhibits RNAi in mosquito cells when expressed by a recombinant SINV. Also, SINV more efficiently replicates in mosquito cells when RNAi is inhibited. Finally, TE/3'2J/B2 kills mosquitoes in a dose-dependent manner independent of infection route and mosquito species.

  6. [Determination of genomic and replicative RNA of hepatitis C virus in patients treated with interferon].

    Science.gov (United States)

    Zeilicoff, R; Ameigeiras, B; Ojeda, E; Isla Rodríguez, R; Grünbaum, S; Genero, M; Cappelletti, C; Tielli, G; Roatta, R; Koch, O

    1995-01-01

    We have investigated the presence of genomic and replicative RNA strands of hepatitis C virus in liver and serum. Eleven patients with proven chronic hepatitis C, received Interferon a2a 4,5 MU, three times a week during six months. RT-PCR was used with sense primer to detect the replicative strand and an antisense primer to identify genomic strand. Before treatment, genomic strands were present in liver and serum of all patients. Replicative strands were present in liver and serum in five and six cases, respectively. Seven out of eleven responded to treatment. In responders, genomic strands were absent in liver of 3 cases (43%) and replicative strands in liver of 4 (57%). In plasma genomic and replicative strands were absent in 5 (71%) and 7 (100%), respectively. In all non responders, genomic strands in liver and plasma remained present. Replicative strands in liver and plasma were present in 100% and 25%, respectively. Knodell score improved in 5 out of 7 responders and remained unchanged in 3 out of 4 non responders. In 2 out of 4 responders with genomic and replicative strands in liver, Knodell score remained unchanged or worse. In all non responders, genomic and replicative strands in liver were present and Knodell score remained unchanged or worse. Genomic and replicative strands in plasma tended to be negative after treatment in responders. Genomic strands in plasma remained present in non responders. Conversely, genomic and replicative strands in liver were present in all non responders. It seems to exist a relationship between genomic and replicative strands in liver and the same or worse Knodell score. After a follow up, it will be possible to determined whether responders who still present viral RNA in liver would be prone to a relapse.

  7. Inhibition of hepatitis C virus RNA replication by short hairpin RNA synthesized by T7 RNA polymerase in hepatitis C virus subgenomic replicons.

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    Hamazaki, Hiroyuki; Ujino, Saneyuki; Miyano-Kurosaki, Naoko; Shimotohno, Kunitada; Takaku, Hiroshi

    2006-05-12

    RNA interference (RNAi) is a cellular process that induces gene silencing by which small duplexes of RNA specifically target a homologous sequence for cleavage by cellular ribonucleases. Here, to test the RNAi method for blocking hepatitis C virus (HCV) RNA replication, we created four short hairpin RNAs (shRNAs) targeting the HCV internal ribosome entry site/Core gene transcript using T7 RNA polymerase. shRNA suppressed the replication of HCV RNA in the HCV replicon. On the other hand, short interfering RNAs synthesized using the T7 RNA polymerase system trigger a potent induction of interferon-alpha and -beta in a variety of cells. We examined whether the shRNAs synthesized using the T7 RNA polymerase system activated double-stranded RNA-dependent protein kinase, 2'-5' oligoadenylate synthetase, or interferon-regulatory factor-3. Our results demonstrated that the T7-transcribed shRNA did not activate these proteins in Huh-7 cells and the HCV replicon. These shRNAs are a promising new strategy for anti-HCV gene therapeutics.

  8. A SELEX-screened aptamer of human hepatitis B virus RNA encapsidation signal suppresses viral replication.

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    Hui Feng

    Full Text Available BACKGROUND: The specific interaction between hepatitis B virus (HBV polymerase (P protein and the ε RNA stem-loop on pregenomic (pg RNA is crucial for viral replication. It triggers both pgRNA packaging and reverse transcription and thus represents an attractive antiviral target. RNA decoys mimicking ε in P protein binding but not supporting replication might represent novel HBV inhibitors. However, because generation of recombinant enzymatically active HBV polymerase is notoriously difficult, such decoys have as yet not been identified. METHODOLOGY/PRINCIPAL FINDINGS: Here we used a SELEX approach, based on a new in vitro reconstitution system exploiting a recombinant truncated HBV P protein (miniP, to identify potential ε decoys in two large ε RNA pools with randomized upper stem. Selection of strongly P protein binding RNAs correlated with an unexpected strong enrichment of A residues. Two aptamers, S6 and S9, displayed particularly high affinity and specificity for miniP in vitro, yet did not support viral replication when part of a complete HBV genome. Introducing S9 RNA into transiently HBV producing HepG2 cells strongly suppressed pgRNA packaging and DNA synthesis, indicating the S9 RNA can indeed act as an ε decoy that competitively inhibits P protein binding to the authentic ε signal on pgRNA. CONCLUSIONS/SIGNIFICANCE: This study demonstrates the first successful identification of human HBV ε aptamers by an in vitro SELEX approach. Effective suppression of HBV replication by the S9 aptamer provides proof-of-principle for the ability of ε decoy RNAs to interfere with viral P-ε complex formation and suggests that S9-like RNAs may further be developed into useful therapeutics against chronic hepatitis B.

  9. Visualization and measurement of ATP levels in living cells replicating hepatitis C virus genome RNA.

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    Tomomi Ando

    Full Text Available Adenosine 5'-triphosphate (ATP is the primary energy currency of all living organisms and participates in a variety of cellular processes. Although ATP requirements during viral lifecycles have been examined in a number of studies, a method by which ATP production can be monitored in real-time, and by which ATP can be quantified in individual cells and subcellular compartments, is lacking, thereby hindering studies aimed at elucidating the precise mechanisms by which viral replication energized by ATP is controlled. In this study, we investigated the fluctuation and distribution of ATP in cells during RNA replication of the hepatitis C virus (HCV, a member of the Flaviviridae family. We demonstrated that cells involved in viral RNA replication actively consumed ATP, thereby reducing cytoplasmic ATP levels. Subsequently, a method to measure ATP levels at putative subcellular sites of HCV RNA replication in living cells was developed by introducing a recently-established Förster resonance energy transfer (FRET-based ATP indicator, called ATeam, into the NS5A coding region of the HCV replicon. Using this method, we were able to observe the formation of ATP-enriched dot-like structures, which co-localize with non-structural viral proteins, within the cytoplasm of HCV-replicating cells but not in non-replicating cells. The obtained FRET signals allowed us to estimate ATP concentrations within HCV replicating cells as ∼5 mM at possible replicating sites and ∼1 mM at peripheral sites that did not appear to be involved in HCV replication. In contrast, cytoplasmic ATP levels in non-replicating Huh-7 cells were estimated as ∼2 mM. To our knowledge, this is the first study to demonstrate changes in ATP concentration within cells during replication of the HCV genome and increased ATP levels at distinct sites within replicating cells. ATeam may be a powerful tool for the study of energy metabolism during replication of the viral genome.

  10. A Novel Mechanism Underlying the Innate Immune Response Induction upon Viral-Dependent Replication of Host Cell mRNA: A Mistake of +sRNA Viruses' Replicases

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    Delgui, Laura R.; Colombo, María I.

    2017-01-01

    Viruses are lifeless particles designed for setting virus-host interactome assuring a new generation of virions for dissemination. This interactome generates a pressure on host organisms evolving mechanisms to neutralize viral infection, which places the pressure back onto virus, a process known as virus-host cell co-evolution. Positive-single stranded RNA (+sRNA) viruses are an important group of viral agents illustrating this interesting phenomenon. During replication, their genomic +sRNA is employed as template for translation of viral proteins; among them the RNA-dependent RNA polymerase (RdRp) is responsible of viral genome replication originating double-strand RNA molecules (dsRNA) as intermediates, which accumulate representing a potent threat for cellular dsRNA receptors to initiate an antiviral response. A common feature shared by these viruses is their ability to rearrange cellular membranes to serve as platforms for genome replication and assembly of new virions, supporting replication efficiency increase by concentrating critical factors and protecting the viral genome from host anti-viral systems. This review summarizes current knowledge regarding cellular dsRNA receptors and describes prototype viruses developing replication niches inside rearranged membranes. However, for several viral agents it's been observed both, a complex rearrangement of cellular membranes and a strong innate immune antiviral response induction. So, we have included recent data explaining the mechanism by, even though viruses have evolved elegant hideouts, host cells are still able to develop dsRNA receptors-dependent antiviral response. PMID:28164038

  11. CNOT4-Mediated Ubiquitination of Influenza A Virus Nucleoprotein Promotes Viral RNA Replication

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    Yu-Chen Lin

    2017-05-01

    Full Text Available Influenza A virus (IAV RNA segments are individually packaged with viral nucleoprotein (NP and RNA polymerases to form a viral ribonucleoprotein (vRNP complex. We previously reported that NP is a monoubiquitinated protein which can be deubiquitinated by a cellular ubiquitin protease, USP11. In this study, we identified an E3 ubiquitin ligase, CNOT4 (Ccr4-Not transcription complex subunit 4, which can ubiquitinate NP. We found that the levels of viral RNA, protein, viral particles, and RNA polymerase activity in CNOT4 knockdown cells were lower than those in the control cells upon IAV infection. Conversely, overexpression of CNOT4 rescued viral RNP activity. In addition, CNOT4 interacted with the NP in the cell. An in vitro ubiquitination assay also showed that NP could be ubiquitinated by in vitro-translated CNOT4, but ubiquitination did not affect the protein stability of NP. Significantly, CNOT4 increased NP ubiquitination, whereas USP11 decreased it. Mass spectrometry analysis of ubiquitinated NP revealed multiple ubiquitination sites on the various lysine residues of NP. Three of these, K184, K227, and K273, are located on the RNA-binding groove of NP. Mutations of these sites to arginine reduced viral RNA replication. These results indicate that CNOT4 is a ubiquitin ligase of NP, and ubiquitination of NP plays a positive role in viral RNA replication.

  12. Modulation of the Host Lipid Landscape to Promote RNA Virus Replication: The Picornavirus Encephalomyocarditis Virus Converges on the Pathway Used by Hepatitis C Virus.

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    Cristina M Dorobantu

    2015-09-01

    Full Text Available Cardioviruses, including encephalomyocarditis virus (EMCV and the human Saffold virus, are small non-enveloped viruses belonging to the Picornaviridae, a large family of positive-sense RNA [(+RNA] viruses. All (+RNA viruses remodel intracellular membranes into unique structures for viral genome replication. Accumulating evidence suggests that picornaviruses from different genera use different strategies to generate viral replication organelles (ROs. For instance, enteroviruses (e.g. poliovirus, coxsackievirus, rhinovirus rely on the Golgi-localized phosphatidylinositol 4-kinase III beta (PI4KB, while cardioviruses replicate independently of the kinase. By which mechanisms cardioviruses develop their ROs is currently unknown. Here we show that cardioviruses manipulate another PI4K, namely the ER-localized phosphatidylinositol 4-kinase III alpha (PI4KA, to generate PI4P-enriched ROs. By siRNA-mediated knockdown and pharmacological inhibition, we demonstrate that PI4KA is an essential host factor for EMCV genome replication. We reveal that the EMCV nonstructural protein 3A interacts with and is responsible for PI4KA recruitment to viral ROs. The ensuing phosphatidylinositol 4-phosphate (PI4P proved important for the recruitment of oxysterol-binding protein (OSBP, which delivers cholesterol to EMCV ROs in a PI4P-dependent manner. PI4P lipids and cholesterol are shown to be required for the global organization of the ROs and for viral genome replication. Consistently, inhibition of OSBP expression or function efficiently blocked EMCV RNA replication. In conclusion, we describe for the first time a cellular pathway involved in the biogenesis of cardiovirus ROs. Remarkably, the same pathway was reported to promote formation of the replication sites of hepatitis C virus, a member of the Flaviviridae family, but not other picornaviruses or flaviviruses. Thus, our results highlight the convergent recruitment by distantly related (+RNA viruses of a host

  13. Modulation of the Host Lipid Landscape to Promote RNA Virus Replication: The Picornavirus Encephalomyocarditis Virus Converges on the Pathway Used by Hepatitis C Virus.

    Science.gov (United States)

    Dorobantu, Cristina M; Albulescu, Lucian; Harak, Christian; Feng, Qian; van Kampen, Mirjam; Strating, Jeroen R P M; Gorbalenya, Alexander E; Lohmann, Volker; van der Schaar, Hilde M; van Kuppeveld, Frank J M

    2015-09-01

    Cardioviruses, including encephalomyocarditis virus (EMCV) and the human Saffold virus, are small non-enveloped viruses belonging to the Picornaviridae, a large family of positive-sense RNA [(+)RNA] viruses. All (+)RNA viruses remodel intracellular membranes into unique structures for viral genome replication. Accumulating evidence suggests that picornaviruses from different genera use different strategies to generate viral replication organelles (ROs). For instance, enteroviruses (e.g. poliovirus, coxsackievirus, rhinovirus) rely on the Golgi-localized phosphatidylinositol 4-kinase III beta (PI4KB), while cardioviruses replicate independently of the kinase. By which mechanisms cardioviruses develop their ROs is currently unknown. Here we show that cardioviruses manipulate another PI4K, namely the ER-localized phosphatidylinositol 4-kinase III alpha (PI4KA), to generate PI4P-enriched ROs. By siRNA-mediated knockdown and pharmacological inhibition, we demonstrate that PI4KA is an essential host factor for EMCV genome replication. We reveal that the EMCV nonstructural protein 3A interacts with and is responsible for PI4KA recruitment to viral ROs. The ensuing phosphatidylinositol 4-phosphate (PI4P) proved important for the recruitment of oxysterol-binding protein (OSBP), which delivers cholesterol to EMCV ROs in a PI4P-dependent manner. PI4P lipids and cholesterol are shown to be required for the global organization of the ROs and for viral genome replication. Consistently, inhibition of OSBP expression or function efficiently blocked EMCV RNA replication. In conclusion, we describe for the first time a cellular pathway involved in the biogenesis of cardiovirus ROs. Remarkably, the same pathway was reported to promote formation of the replication sites of hepatitis C virus, a member of the Flaviviridae family, but not other picornaviruses or flaviviruses. Thus, our results highlight the convergent recruitment by distantly related (+)RNA viruses of a host lipid

  14. Alpha interferon induces distinct translational control programs to suppress hepatitis C virus RNA replication.

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    Wang, Chunfu; Pflugheber, Jill; Sumpter, Rhea; Sodora, Donald L; Hui, Daniel; Sen, Ganes C; Gale, Michael

    2003-04-01

    Hepatitis C virus (HCV) infection is treated with interferon (IFN)-based therapy. The mechanisms by which IFN suppresses HCV replication are not known, and only limited efficacy is achieved with therapy because the virus directs mechanisms to resist the host IFN response. In the present study we characterized the effects of IFN action upon the replication of two distinct quasispecies of an HCV replicon whose encoded NS5A protein exhibited differential abilities to bind and inhibit protein kinase R (PKR). Metabolic labeling experiments revealed that IFN had little overall effect upon HCV protein stability or polyprotein processing but specifically blocked translation of the HCV RNA, such that the replication of both viral quasispecies was suppressed by IFN treatment of the Huh7 host cells. However, within cells expressing an NS5A variant that inhibited PKR, we observed a reduced level of eukaryotic initiation factor 2 alpha subunit (eIF2alpha) phosphorylation and a concomitant increase in HCV protein synthetic rates, enhancement of viral RNA replication, and a partial rescue of viral internal ribosome entry site (IRES) function from IFN suppression. Assessment of the ribosome distribution of the HCV replicon RNA demonstrated that the NS5A-mediated block in eIF2alpha phosphorylation resulted in enhanced recruitment of the HCV RNA into polyribosome complexes in vivo but only partially rescued the RNA from polyribosome dissociation induced by IFN treatment. Examination of cellular proteins associated with HCV-translation complexes in IFN-treated cells identified the P56 protein as an eIF3-associated factor that fractionated with the initiator ribosome-HCV RNA complex. Importantly, we found that P56 could independently suppress HCV IRES function both in vitro and in vivo, but a mutant P56 that was unable to bind eIF3 had no suppressive action. We conclude that IFN blocks HCV replication through translational control programs involving PKR and P56 to, respectively

  15. Inhibition of hepatitis B virus gene expression and replication by artificial microRNA

    Institute of Scientific and Technical Information of China (English)

    Yu-Feng Gao; Li Yu; Wei Wei; Jia-Bin Li; Qing-Li Luo; Ji-Long Shen

    2008-01-01

    AIM: To investigate the inhibitory effects of hepatitis B virus (HBV) replication and expression by transfecting artificial microRNA (amiRNA) into HepG2.2.15 cells.METHODS: Three amiRNA-HBV plasmids were constructed and transfected into HepG2.2.15 cells.HBV antigen secretion was detected in the cells with transient and stable transfection by time-resolved fluoroimmunoassays (TRFIA). HBV DNA replication was examined by fluorescence quantitative PCR, and the level of HBV S mRNA was measured by semi-quantitative RT-PCR.RESULTS: The efficiency of transient transfection of the vectors into 2.2.15 cells was 55%-60%. All the vectors had significant inhibition effects on HBsAg and HBeAg at 72 h and 96 h after transfection (P< 0.01 for all). The secretion of HBsAg and HBeAginto the supernatant was in hibited by 49.8% + 4.7%and 39.9% ± 6.7%, respectively, at 72 h in amiRNA-HBV-S608 plasmid transfection group. The copy of HBVDNA within culture supernatant was also significantlydecreased at 72 h and 96 h after transfection (P <0.01 for all). In the cells with stable transfection, the secretion of HBsAg and HBeAg into the supernatant was significantly inhibited in all three transfection groups (P < 0.01 for all, vs negative control). The copies of HBV DNA were inhibited by 33.4% ± 3.0%,60.8% ± 2.3% and 70.1% ± 3.3%, respectively.CONCLUSION: In HepG2.2.15 cells, HBV replication and expression could be inhibited by artificial microRNA targeting the HBV S coding region. Vector-based artificial microRNA could be a promising therapeutic approach for chronic HBV infection.

  16. Hepatitis B virus replication

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Hepadnaviruses, including human hepatitis B virus (HBV), replicate through reverse transcription of an RNA intermediate, the pregenomic RNA (pgRNA). Despite this kinship to retroviruses, there are fundamental differences beyond the fact that hepadnavirions contain DNA instead of RNA. Most peculiar is the initiation of reverse transcription: it occurs by protein-priming, is strictly committed to using an RNA hairpin on the pgRNA,ε, as template, and depends on cellular chaperones;moreover, proper replication can apparently occur only in the specialized environment of intact nucleocapsids.This complexity has hampered an in-depth mechanistic understanding. The recent successful reconstitution in the test tube of active replication initiation complexes from purified components, for duck HBV (DHBV),now allows for the analysis of the biochemistry of hepadnaviral replication at the molecular level. Here we review the current state of knowledge at all steps of the hepadnaviral genome replication cycle, with emphasis on new insights that turned up by the use of such cellfree systems. At this time, they can, unfortunately,not be complemented by three-dimensional structural information on the involved components. However, at least for the s RNA element such information is emerging,raising expectations that combining biophysics with biochemistry and genetics will soon provide a powerful integrated approach for solving the many outstanding questions. The ultimate, though most challenging goal,will be to visualize the hepadnaviral reverse transcriptase in the act of synthesizing DNA, which will also have strong implications for drug development.

  17. Role of RNA Structures in Genome Terminal Sequences of the Hepatitis C Virus for Replication and Assembly▿ †

    Science.gov (United States)

    Friebe, Peter; Bartenschlager, Ralf

    2009-01-01

    Hepatitis C virus (HCV) is a positive-strand RNA virus replicating its genome via a negative-strand [(−)] intermediate. Little is known about replication signals residing in the 3′ end of HCV (−) RNA. Recent studies identified seven stem-loop structures (SL-I′, -IIz′, -IIy′, -IIIa′, -IIIb′, -IIIcdef′, and -IV′) in this region. In the present study, we mapped the minimal region required for RNA replication to SL-I′ and -IIz′, functionally confirmed the SL-IIz′ structure, and identified SL-IIIa′ to -IV′ as auxiliary replication elements. In addition, we show that the 5′ nontranslated region of the genome most likely does not contain cis-acting RNA structures required for RNA packaging into infectious virions. PMID:19740989

  18. Role of RNA structures in genome terminal sequences of the hepatitis C virus for replication and assembly.

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    Friebe, Peter; Bartenschlager, Ralf

    2009-11-01

    Hepatitis C virus (HCV) is a positive-strand RNA virus replicating its genome via a negative-strand [(-)] intermediate. Little is known about replication signals residing in the 3' end of HCV (-) RNA. Recent studies identified seven stem-loop structures (SL-I', -IIz', -IIy', -IIIa', -IIIb', -IIIcdef', and -IV') in this region. In the present study, we mapped the minimal region required for RNA replication to SL-I' and -IIz', functionally confirmed the SL-IIz' structure, and identified SL-IIIa' to -IV' as auxiliary replication elements. In addition, we show that the 5' nontranslated region of the genome most likely does not contain cis-acting RNA structures required for RNA packaging into infectious virions.

  19. Post-transcriptional inhibition of hepatitis C virus replication through small interference RNA

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    Rehman Sidra

    2011-03-01

    Full Text Available Abstract Background Hepatitis C Virus (HCV infection is a major health problem throughout world that causes acute and chronic infection which resulted in liver fibrosis, hepatocellular carcinoma and death. The only therapy currently available for HCV infection is the combination of pegylated interferon alpha (PEG-IFN α and ribavirin. This therapy can effectively clear the virus infection in only 50% of infected individuals. Hence, there is a dire need to develop antiviral agents against HCV. Results This study was design to examine the ability of exogenous small interfering RNAs (siRNAs to block the replication of HCV in human liver cells. In the present study six 21-bp siRNAs were designed against different regions of HCV non-structural genes (NS2, NS3 serine protease/helicase, NS4Band NS5B RNA dependent RNA polymerase. siRNAs were labeled as NS2si241, NS3si-229, NS3si-858, NS4Bsi-166, NS5Bsi-241 and NS5Bsi-1064. We found that siRNAs against HCV NS2- NS5B efficiently inhibit HCV replication in Huh-7 cells. Our results demonstrated that siRNAs directed against HCV NS3 (NS3si-229 and NS3si-858 showed 58% and 88% reduction in viral titer respectively. Moreover, NS4Bsi-166 and NS5Bsi-1064 exhibited a dramatic reduction in HCV viral RNA and resulted in greater than 90% inhibition at a 20 μM concentration, while NS2si-241 showed 27% reduction in viral titer. No significant inhibition was detected in cells transfected with the negative control siRNA. Conclusion Our results suggest that siRNAs targeting against HCV non-structural genes (NS2-NS5B efficiently inhibit HCV replication and combination of these siRNAs of different targets and interferon will be better option to treat HCV infection throughout the world.

  20. Replication and encapsidation of the viroid-like satellite RNA of lucerne transient streak virus are supported in divergent hosts by cocksfoot mottle virus and turnip rosette virus.

    Science.gov (United States)

    Sehgal, O P; Sinha, R C; Gellatly, D L; Ivanov, I; AbouHaidar, M G

    1993-04-01

    Cocksfoot mottle sobemovirus supports replication and encapsidation of the viroid-like satellite RNA (sat-RNA) of lucerne transient streak virus (LTSV) in two monocotyledonous species, Triticum aestivum and Dactylis glomerata. Additionally, LTSV sat-RNA replicates effectively in the presence of turnip rosette sobemovirus in Brassica rapa, Raphanus raphanistrum and Sinapsis arvensis, but not in Thlaspi arvense or Nicotiana bigelovii, indicating that host species markedly influence this interaction. Previous reports of the association between LTSV sat-RNA and helper sobemoviruses were limited to dicotyledonous hosts. Our results demonstrate that the biological interaction between these two entities spans divergent dicotyledonous and monocotyledonous species.

  1. Three-dimensional analysis of a viral RNA replication complex reveals a virus-induced mini-organelle.

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    Benjamin G Kopek

    2007-09-01

    Full Text Available Positive-strand RNA viruses are the largest genetic class of viruses and include many serious human pathogens. All positive-strand RNA viruses replicate their genomes in association with intracellular membrane rearrangements such as single- or double-membrane vesicles. However, the exact sites of RNA synthesis and crucial topological relationships between relevant membranes, vesicle interiors, surrounding lumens, and cytoplasm generally are poorly defined. We applied electron microscope tomography and complementary approaches to flock house virus (FHV-infected Drosophila cells to provide the first 3-D analysis of such replication complexes. The sole FHV RNA replication factor, protein A, and FHV-specific 5-bromouridine 5'-triphosphate incorporation localized between inner and outer mitochondrial membranes inside approximately 50-nm vesicles (spherules, which thus are FHV-induced compartments for viral RNA synthesis. All such FHV spherules were outer mitochondrial membrane invaginations with interiors connected to the cytoplasm by a necked channel of approximately 10-nm diameter, which is sufficient for ribonucleotide import and product RNA export. Tomographic, biochemical, and other results imply that FHV spherules contain, on average, three RNA replication intermediates and an interior shell of approximately 100 membrane-spanning, self-interacting protein As. The results identify spherules as the site of protein A and nascent RNA accumulation and define spherule topology, dimensions, and stoichiometry to reveal the nature and many details of the organization and function of the FHV RNA replication complex. The resulting insights appear relevant to many other positive-strand RNA viruses and support recently proposed structural and likely evolutionary parallels with retrovirus and double-stranded RNA virus virions.

  2. Control of the rescue and replication of Semliki Forest virus recombinants by the insertion of miRNA target sequences.

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    Kaspar Ratnik

    Full Text Available Due to their broad cell- and tissue-tropism, alphavirus-based replication-competent vectors are of particular interest for anti-cancer therapy. These properties may, however, be potentially hazardous unless the virus infection is controlled. While the RNA genome of alphaviruses precludes the standard control techniques, host miRNAs can be used to down-regulate viral replication. In this study, target sites from ubiquitous miRNAs and those of miRNAs under-represented in cervical cancer cells were inserted into replication-competent DNA/RNA layered vectors of Semliki Forest virus. It was found that in order to achieve the most efficient suppression of recombinant virus rescue, the introduced target sequences must be fully complementary to those of the corresponding miRNAs. Target sites of ubiquitous miRNAs, introduced into the 3' untranslated region of the viral vector, profoundly reduced the rescue of recombinant viruses. Insertion of the same miRNA targets into coding region of the viral vector was approximately 300-fold less effective. Viruses carrying these miRNAs were genetically unstable and rapidly lost the target sequences. This process was delayed, but not completely prevented, by miRNA inhibitors. Target sites of miRNA under-represented in cervical cancer cells had much smaller but still significant effects on recombinant virus rescue in cervical cancer-derived HeLa cells. Over-expression of miR-214, one of these miRNAs, reduced replication of the targeted virus. Though the majority of rescued viruses maintained the introduced miRNA target sequences, genomes with deletions of these sequences were also detected. Thus, the low-level repression of rescue and replication of targeted virus in HeLa cells was still sufficient to cause genetic instability.

  3. Control of the rescue and replication of Semliki Forest virus recombinants by the insertion of miRNA target sequences.

    Science.gov (United States)

    Ratnik, Kaspar; Viru, Liane; Merits, Andres

    2013-01-01

    Due to their broad cell- and tissue-tropism, alphavirus-based replication-competent vectors are of particular interest for anti-cancer therapy. These properties may, however, be potentially hazardous unless the virus infection is controlled. While the RNA genome of alphaviruses precludes the standard control techniques, host miRNAs can be used to down-regulate viral replication. In this study, target sites from ubiquitous miRNAs and those of miRNAs under-represented in cervical cancer cells were inserted into replication-competent DNA/RNA layered vectors of Semliki Forest virus. It was found that in order to achieve the most efficient suppression of recombinant virus rescue, the introduced target sequences must be fully complementary to those of the corresponding miRNAs. Target sites of ubiquitous miRNAs, introduced into the 3' untranslated region of the viral vector, profoundly reduced the rescue of recombinant viruses. Insertion of the same miRNA targets into coding region of the viral vector was approximately 300-fold less effective. Viruses carrying these miRNAs were genetically unstable and rapidly lost the target sequences. This process was delayed, but not completely prevented, by miRNA inhibitors. Target sites of miRNA under-represented in cervical cancer cells had much smaller but still significant effects on recombinant virus rescue in cervical cancer-derived HeLa cells. Over-expression of miR-214, one of these miRNAs, reduced replication of the targeted virus. Though the majority of rescued viruses maintained the introduced miRNA target sequences, genomes with deletions of these sequences were also detected. Thus, the low-level repression of rescue and replication of targeted virus in HeLa cells was still sufficient to cause genetic instability.

  4. SiRNA Inhibits Replication of Langat Virus, a Member of the Tick-Borne Encephalitis Virus Complex in Organotypic Rat Brain Slices

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    Maffioli, Carola; Grandgirard, Denis; Leib, Stephen L.; Engler, Olivier

    2012-01-01

    Tick-borne encephalitis virus is the causative agent of tick-borne encephalitis, a potentially fatal neurological infection. Tick-borne encephalitis virus belongs to the family of flaviviruses and is transmitted by infected ticks. Despite the availability of vaccines, approximately 2000–3000 cases of tick-borne encephalitis occur annually in Europe for which no curative therapy is available. The antiviral effects of RNA mediated interference by small interfering RNA (siRNA) was evaluated in cell culture and organotypic hippocampal cultures. Langat virus, a flavivirus highly related to Tick-borne encephalitis virus exhibits low pathogenicity for humans but retains neurovirulence for rodents. Langat virus was used for the establishment of an in vitro model of tick-borne encephalitis. We analyzed the efficacy of 19 siRNA sequences targeting different regions of the Langat genome to inhibit virus replication in the two in vitro systems. The most efficient suppression of virus replication was achieved by siRNA sequences targeting structural genes and the 3′ untranslated region. When siRNA was administered to HeLa cells before the infection with Langat virus, a 96.5% reduction of viral RNA and more than 98% reduction of infectious virus particles was observed on day 6 post infection, while treatment after infection decreased the viral replication by more than 98%. In organotypic hippocampal cultures the replication of Langat virus was reduced by 99.7% by siRNA sequence D3. Organotypic hippocampal cultures represent a suitable in vitro model to investigate neuronal infection mechanisms and treatment strategies in a preserved three-dimensional tissue architecture. Our results demonstrate that siRNA is an efficient approach to limit Langat virus replication in vitro. PMID:22984545

  5. A Defective Interfering Influenza RNA Inhibits Infectious Influenza Virus Replication in Human Respiratory Tract Cells: A Potential New Human Antiviral

    Directory of Open Access Journals (Sweden)

    Claire M. Smith

    2016-08-01

    Full Text Available Defective interfering (DI viruses arise during the replication of influenza A virus and contain a non-infective version of the genome that is able to interfere with the production of infectious virus. In this study we hypothesise that a cloned DI influenza A virus RNA may prevent infection of human respiratory epithelial cells with infection by influenza A. The DI RNA (244/PR8 was derived by a natural deletion process from segment 1 of influenza A/PR/8/34 (H1N1; it comprises 395 nucleotides and is packaged in the DI virion in place of a full-length genome segment 1. Given intranasally, 244/PR8 DI virus protects mice and ferrets from clinical influenza caused by a number of different influenza A subtypes and interferes with production of infectious influenza A virus in cells in culture. However, evidence that DI influenza viruses are active in cells of the human respiratory tract is lacking. Here we show that 244/PR8 DI RNA is replicated by an influenza A challenge virus in human lung diploid fibroblasts, bronchial epithelial cells, and primary nasal basal cells, and that the yield of challenge virus is significantly reduced in a dose-dependent manner indicating that DI influenza virus has potential as a human antiviral.

  6. Adenovirus vectors lacking virus-associated RNA expression enhance shRNA activity to suppress hepatitis C virus replication

    Science.gov (United States)

    Pei, Zheng; Shi, Guoli; Kondo, Saki; Ito, Masahiko; Maekawa, Aya; Suzuki, Mariko; Saito, Izumu; Suzuki, Tetsuro; Kanegae, Yumi

    2013-12-01

    First-generation adenovirus vectors (FG AdVs) expressing short-hairpin RNA (shRNA) effectively downregulate the expressions of target genes. However, this vector, in fact, expresses not only the transgene product, but also virus-associated RNAs (VA RNAs) that disturb cellular RNAi machinery. We have established a production method for VA-deleted AdVs lacking expression of VA RNAs. Here, we showed that the highest shRNA activity was obtained when the shRNA was inserted not at the popularly used E1 site, but at the E4 site. We then compared the activities of shRNAs against hepatitis C virus (HCV) expressed from VA-deleted AdVs or conventional AdVs. The VA-deleted AdVs inhibited HCV production much more efficiently. Therefore, VA-deleted AdVs were more effective than the currently used AdVs for shRNA downregulation, probably because of the lack of competition between VA RNAs and the shRNAs. These VA-deleted AdVs might enable more effective gene therapies for chronic hepatitis C.

  7. Traffic jam on the cellular secretory pathway generated by a replication protein from a plant RNA virus.

    Science.gov (United States)

    Hyodo, Kiwamu; Kaido, Masanori; Okuno, Tetsuro

    2014-01-01

    Although positive-strand RNA [(+)RNA] viruses have a limited coding capacity, they can replicate efficiently in host cells because of their ability to use host-derived proteins, membranes, lipids, and metabolites, and to rewire cellular trafficking pathways. Previously, we showed that a plant RNA virus, the Red clover necrotic mosaic virus (RCNMV), hijacked Arf1 and Sar1, which are small GTPases that regulate the biogenesis of COPI and COPII vesicles, respectively, for viral RNA replication. These small GTPases are relocated from appropriate subcellular compartments to the viral RNA replication sites by p27 replication protein, which raises the possibility that RCNMV interferes with the cellular secretory pathway. Here, we examined this possibility by using green fluorescent protein-fused rice SCAMP1 and Arabidopsis LRR84A as secretory pathway marker proteins and showed that p27 inhibited the trafficking of these proteins. RCNMV-mediated inhibition of the host secretion pathway and its possible impact on plant-virus interaction are discussed.

  8. Ascorbic acid inhibits replication and infectivity of avian RNA tumor virus

    Energy Technology Data Exchange (ETDEWEB)

    BISSELL, MINA J; HATIE, CARROLL; FARSON, DEBORAH A.; SCHWARZ, RICHARD I.; SOO, WHAI-JEN

    1980-04-01

    Ascorbic acid, at nontoxic concentrations, causes a substantial reduction in the ability of avian tumor viruses to replicate in both primary avian tendon cells and chicken embryo fibroblasts. The virus-infected cultures appear to be less transformed in the presence of ascorbic acid by the criteria of morphology, reduced glucose uptake, and increased collagen synthesis. The vitamin does not act by altering the susceptibility of the cells to initial infection and transformation, but instead appears to interfere with the spread of infection through a reduction in virus replication and virus infectivity. The effect is reversible and requires the continuous presence of the vitamin in the culture medium.

  9. Cytoplasmic translocation of polypyrimidine tract-binding protein and its binding to viral RNA during Japanese encephalitis virus infection inhibits virus replication.

    Directory of Open Access Journals (Sweden)

    Deepika Bhullar

    Full Text Available Japanese encephalitis virus (JEV has a single-stranded, positive-sense RNA genome containing a single open reading frame flanked by the 5'- and 3'-non-coding regions (NCRs. The virus genome replicates via a negative-sense RNA intermediate. The NCRs and their complementary sequences in the negative-sense RNA are the sites for assembly of the RNA replicase complex thereby regulating the RNA synthesis and virus replication. In this study, we show that the 55-kDa polypyrimidine tract-binding protein (PTB interacts in vitro with both the 5'-NCR of the positive-sense genomic RNA--5NCR(+, and its complementary sequence in the negative-sense replication intermediate RNA--3NCR(-. The interaction of viral RNA with PTB was validated in infected cells by JEV RNA co-immunoprecipitation and JEV RNA-PTB colocalization experiments. Interestingly, we observed phosphorylation-coupled translocation of nuclear PTB to cytoplasmic foci that co-localized with JEV RNA early during JEV infection. Our studies employing the PTB silencing and over-expression in cultured cells established an inhibitory role of PTB in JEV replication. Using RNA-protein binding assay we show that PTB competitively inhibits association of JEV 3NCR(- RNA with viral RNA-dependent RNA polymerase (NS5 protein, an event required for the synthesis of the plus-sense genomic RNA. cAMP is known to promote the Protein kinase A (PKA-mediated PTB phosphorylation. We show that cells treated with a cAMP analogue had an enhanced level of phosphorylated PTB in the cytoplasm and a significantly suppressed JEV replication. Data presented here show a novel, cAMP-induced, PTB-mediated, innate host response that could effectively suppress JEV replication in mammalian cells.

  10. Inhibition of avian leukosis virus replication by vector-based RNA interference

    Science.gov (United States)

    RNAi has recently emerged as a promising antiviral technique in vertebrates. To date, most studies have used exogenous short interfering RNAs (siRNAs) to inhibit viral replication, though vectors expressing short hairpin RNAs (shRNA-mirs) in the context of a modified endogenous micro-RNA (miRNA) are...

  11. Kinases required in hepatitis C virus entry and replication highlighted by small interference RNA screening.

    Science.gov (United States)

    Trotard, Maud; Lepère-Douard, Charlotte; Régeard, Morgane; Piquet-Pellorce, Claire; Lavillette, Dimitri; Cosset, François-Loic; Gripon, Philippe; Le Seyec, Jacques

    2009-11-01

    The entry pathway of the hepatitis C virus (HCV), a major human pathogen, into the cell is incompletely defined. To better characterize this viral life cycle stage, we screened a small interfering RNA library dedicated to the membrane trafficking and remodeling with the infection model of Huh-7.5.1 cells by HCV pseudoparticles (HCVpp). Results showed that the down-regulation of different factors implied in clathrin-mediated endocytosis (CME) inhibits HCVpp cell infection. In addition, knockdown of the phosphatidylinositol 4-kinase type III-alpha (PI4KIIIalpha) prevented infection by HCVpp or by cell-culture grown JFH-1-based HCV. Moreover, the replication activity of an HCV replicon was also affected by the PI4KIIIalpha knockdown. Additional investigations on the different members of the PI4K family revealed that the presence of PI4KIIIbeta in the host cells influenced their susceptibility to HCVpp infection and their capacity to sustain the HCV replication. The PI4KIII involvement during the HCV life cycle seemed to occur by other ways than the control of the CME or of the membranous expression of HCV receptors. Finally, our library screening completed data on the CME-dependant entry route of HCV and identified 2 kinases, PI4KIIIalpha and beta, as relevant potential therapeutic targets.

  12. Multiple functions of the 32K and 60K proteins in cowpea mosaic virus RNA replication.

    NARCIS (Netherlands)

    Peters, S.A.

    1994-01-01

    Cowpea mosaic virus (CPMV) is the type member of the comoviridae , a group of 14 different plant viruses that have a divided genome consisting of two plus-strand RNAs. These RNAs, designated B-RNA and M-RNA, have a small protein, VPg, attached to the 5'-end and a poly(A) tail at the 3'-end and are s

  13. Small interfering RNA targeting the nonstructural gene 1 transcript inhibits influenza A virus replication in experimental mice.

    Science.gov (United States)

    Rajput, Roopali; Khanna, Madhu; Kumar, Prashant; Kumar, Binod; Sharma, Sonal; Gupta, Neha; Saxena, Latika

    2012-12-01

    Nonstructural protein 1 (NS1) of influenza A viruses counteracts the host immune response against the influenza viruses by not only inhibiting the nuclear export and maturation of host cell messenger RNA (mRNA), but by also blocking the double-stranded RNA-activated protein kinase-mediated inhibition of viral RNA translation. Reduction of NS1 gene product in the host cell may be a potent antiviral strategy to provide protection against the influenza virus infection. We used small interfering RNAs (siRNAs) synthesized against the viral mRNA to down regulate the NS1 gene and observed its effect on inhibition of virus replication. When NS1 gene-specific siRNA were transfected in Madin Darby canine kidney (MDCK) cells followed by influenza A virus infection, approximately 60% inhibition in intracellular levels of NS1 RNA was observed. When siRNA was administered in BALB/c mice, 92% reduction in the levels of NS1 gene expression in mice lungs was observed. A significant reduction in the lung virus titers and cytokine levels was also detected in the presence of siRNAs as compared with the untreated control. The study was validated by the use of selectively disabled mutants of each set of siRNA. Our findings suggest that siRNA targeted against NS1 gene of influenza A virus can provide considerable protection to the virus-infected host cells and may be used as potential candidates for nucleic acid-based antiviral therapy for prevention of influenza A virus infection.

  14. Quasispecies spatial models for RNA viruses with different replication modes and infection strategies.

    Directory of Open Access Journals (Sweden)

    Josep Sardanyés

    Full Text Available Empirical observations and theoretical studies suggest that viruses may use different replication strategies to amplify their genomes, which impact the dynamics of mutation accumulation in viral populations and therefore, their fitness and virulence. Similarly, during natural infections, viruses replicate and infect cells that are rarely in suspension but spatially organized. Surprisingly, most quasispecies models of virus replication have ignored these two phenomena. In order to study these two viral characteristics, we have developed stochastic cellular automata models that simulate two different modes of replication (geometric vs stamping machine for quasispecies replicating and spreading on a two-dimensional space. Furthermore, we explored these two replication models considering epistatic fitness landscapes (antagonistic vs synergistic and different scenarios for cell-to-cell spread, one with free superinfection and another with superinfection inhibition. We found that the master sequences for populations replicating geometrically and with antagonistic fitness effects vanished at low critical mutation rates. By contrast, the highest critical mutation rate was observed for populations replicating geometrically but with a synergistic fitness landscape. Our simulations also showed that for stamping machine replication and antagonistic epistasis, a combination that appears to be common among plant viruses, populations further increased their robustness by inhibiting superinfection. We have also shown that the mode of replication strongly influenced the linkage between viral loci, which rapidly reached linkage equilibrium at increasing mutations for geometric replication. We also found that the strategy that minimized the time required to spread over the whole space was the stamping machine with antagonistic epistasis among mutations. Finally, our simulations revealed that the multiplicity of infection fluctuated but generically increased along

  15. Inhibition of hepatitis B virus replication with linear DNA sequences expressing antiviral micro-RNA shuttles

    Energy Technology Data Exchange (ETDEWEB)

    Chattopadhyay, Saket; Ely, Abdullah; Bloom, Kristie; Weinberg, Marc S. [Antiviral Gene Therapy Research Unit, University of the Witwatersrand (South Africa); Arbuthnot, Patrick, E-mail: Patrick.Arbuthnot@wits.ac.za [Antiviral Gene Therapy Research Unit, University of the Witwatersrand (South Africa)

    2009-11-20

    RNA interference (RNAi) may be harnessed to inhibit viral gene expression and this approach is being developed to counter chronic infection with hepatitis B virus (HBV). Compared to synthetic RNAi activators, DNA expression cassettes that generate silencing sequences have advantages of sustained efficacy and ease of propagation in plasmid DNA (pDNA). However, the large size of pDNAs and inclusion of sequences conferring antibiotic resistance and immunostimulation limit delivery efficiency and safety. To develop use of alternative DNA templates that may be applied for therapeutic gene silencing, we assessed the usefulness of PCR-generated linear expression cassettes that produce anti-HBV micro-RNA (miR) shuttles. We found that silencing of HBV markers of replication was efficient (>75%) in cell culture and in vivo. miR shuttles were processed to form anti-HBV guide strands and there was no evidence of induction of the interferon response. Modification of terminal sequences to include flanking human adenoviral type-5 inverted terminal repeats was easily achieved and did not compromise silencing efficacy. These linear DNA sequences should have utility in the development of gene silencing applications where modifications of terminal elements with elimination of potentially harmful and non-essential sequences are required.

  16. Knockdown of DNA ligase IV/XRCC4 by RNA interference inhibits herpes simplex virus type I DNA replication.

    Science.gov (United States)

    Muylaert, Isabella; Elias, Per

    2007-04-13

    Herpes simplex virus has a linear double-stranded DNA genome with directly repeated terminal sequences needed for cleavage and packaging of replicated DNA. In infected cells, linear genomes rapidly become endless. It is currently a matter of discussion whether the endless genomes are circles supporting rolling circle replication or arise by recombination of linear genomes forming concatemers. Here, we have examined the role of mammalian DNA ligases in the herpes simplex virus, type I (HSV-1) life cycle by employing RNA interference (RNAi) in human 1BR.3.N fibroblasts. We find that RNAi-mediated knockdown of DNA ligase IV and its co-factor XRCC4 causes a hundred-fold reduction of virus yield, a small plaque phenotype, and reduced DNA synthesis. The effect is specific because RNAi against DNA ligase I or DNA ligase III fail to reduce HSV-1 replication. Furthermore, RNAi against DNA ligase IV and XRCC4 does not affect replication of adenovirus. In addition, high multiplicity infections of HSV-1 in human DNA ligase IV-deficient cells reveal a pronounced delay of production of infectious virus. Finally, we demonstrate that formation of endless genomes is inhibited by RNAi-mediated depletion of DNA ligase IV and XRCC4. Our results suggests that DNA ligase IV/XRCC4 serves an important role in the replication cycle of herpes viruses and is likely to be required for the formation of the endless genomes early during productive infection.

  17. Eilat virus, a unique alphavirus with host range restricted to insects by RNA replication.

    Science.gov (United States)

    Nasar, Farooq; Palacios, Gustavo; Gorchakov, Rodion V; Guzman, Hilda; Da Rosa, Amelia P Travassos; Savji, Nazir; Popov, Vsevolod L; Sherman, Michael B; Lipkin, W Ian; Tesh, Robert B; Weaver, Scott C

    2012-09-04

    Most alphaviruses and many other arboviruses are mosquito-borne and exhibit a broad host range, infecting many different vertebrates including birds, rodents, equids, humans, and nonhuman primates. Consequently, they can be propagated in most vertebrate and insect cell cultures. This ability of arboviruses to infect arthropods and vertebrates is usually essential for their maintenance in nature. However, several flaviviruses have recently been described that infect mosquitoes but not vertebrates, although the mechanism of their host restriction has not been determined. Here we describe a unique alphavirus, Eilat virus (EILV), isolated from a pool of Anopheles coustani mosquitoes from the Negev desert of Israel. Phylogenetic analyses placed EILV as a sister to the Western equine encephalitis antigenic complex within the main clade of mosquito-borne alphaviruses. Electron microscopy revealed that, like other alphaviruses, EILV virions were spherical, 70 nm in diameter, and budded from the plasma membrane of mosquito cells in culture. EILV readily infected a variety of insect cells with little overt cytopathic effect. However, in contrast to typical mosquito-borne alphaviruses, EILV could not infect mammalian or avian cell lines, and viral as well as RNA replication could not be detected at 37 °C or 28 °C. Evolutionarily, these findings suggest that EILV lost its ability to infect vertebrate cells. Thus, EILV seems to be mosquito-specific and represents a previously undescribed complex within the genus Alphavirus. Reverse genetic studies of EILV may facilitate the discovery of determinants of alphavirus host range that mediate disease emergence.

  18. Temperature sensitive influenza A virus genome replication results from low thermal stability of polymerase-cRNA complexes

    Directory of Open Access Journals (Sweden)

    Tiley Laurence S

    2006-08-01

    Full Text Available Abstract Background The RNA-dependent RNA polymerase of Influenza A virus is a determinant of viral pathogenicity and host range that is responsible for transcribing and replicating the negative sense segmented viral genome (vRNA. Transcription produces capped and polyadenylated mRNAs whereas genome replication involves the synthesis of an alternative plus-sense transcript (cRNA with unmodified termini that is copied back to vRNA. Viral mRNA transcription predominates at early stages of viral infection, while later, negative sense genome replication is favoured. However, the "switch" that regulates the transition from transcription to replication is poorly understood. Results We show that temperature strongly affects the balance between plus and minus-sense RNA synthesis with high temperature causing a large decrease in vRNA accumulation, a moderate decrease in cRNA levels but (depending on genome segment either increased or unchanged levels of mRNA. We found no evidence implicating cellular heat shock protein activity in this effect despite the known association of hsp70 and hsp90 with viral polymerase components. Temperature-shift experiments indicated that polymerase synthesised at 41°C maintained transcriptional activity even though genome replication failed. Reduced polymerase association with viral RNA was seen in vivo and in confirmation of this, in vitro binding assays showed that temperature increased the rate of dissociation of polymerase from both positive and negative sense promoters. However, the interaction of polymerase with the cRNA promoter was particularly heat labile, showing rapid dissociation even at 37°C. This suggested that vRNA synthesis fails at elevated temperatures because the polymerase does not bind the promoter. In support of this hypothesis, a mutant cRNA promoter with vRNA-like sequence elements supported vRNA synthesis at higher temperatures than the wild-type promoter. Conclusion The differential stability of

  19. Identification of Proteins Bound to Dengue Viral RNA In Vivo Reveals New Host Proteins Important for Virus Replication

    Directory of Open Access Journals (Sweden)

    Stacia L. Phillips

    2016-01-01

    Full Text Available Dengue virus is the most prevalent cause of arthropod-borne infection worldwide. Due to the limited coding capacity of the viral genome and the complexity of the viral life cycle, host cell proteins play essential roles throughout the course of viral infection. Host RNA-binding proteins mediate various aspects of virus replication through their physical interactions with viral RNA. Here we describe a technique designed to identify such interactions in the context of infected cells using UV cross-linking followed by antisense-mediated affinity purification and mass spectrometry. Using this approach, we identified interactions, several of them novel, between host proteins and dengue viral RNA in infected Huh7 cells. Most of these interactions were subsequently validated using RNA immunoprecipitation. Using small interfering RNA (siRNA-mediated gene silencing, we showed that more than half of these host proteins are likely involved in regulating virus replication, demonstrating the utility of this method in identifying biologically relevant interactions that may not be identified using traditional in vitro approaches.

  20. Identification of valid reference genes for microRNA expression studies in a hepatitis B virus replicating liver cell line

    DEFF Research Database (Denmark)

    Jacobsen, Kari Stougaard; Nielsen, Kirstine Overgaard; Nordmann Winther, Thilde;

    2016-01-01

    BACKGROUND: MicroRNAs are regulatory molecules and suggested as non-invasive biomarkers for molecular diagnostics and prognostics. Altered expression levels of specific microRNAs are associated with hepatitis B virus infection and hepatocellular carcinoma. We previously identified differentially...... of hepatitis B virus expression vectors. RT-qPCR is the preferred method for microRNA studies, and a careful normalisation strategy, verifying the optimal set of reference genes, is decisive for correctly evaluating microRNA expression levels. The aim of this study was to provide valid reference genes...... identified miR-24-3p, miR-151a-5p, and miR-425-5p as the most valid combination of reference genes for microRNA RT-qPCR studies in our hepatitis B virus replicating HepG2 cell model....

  1. Epithelial Distribution and Replication of Foot-and-Mouth Disease Virus RNA in Infected Pigs

    DEFF Research Database (Denmark)

    Durand, S.; Murphy, C.; Zhang, Z.

    2008-01-01

    Although the pathogenesis of foot-and-mouth disease (FMD) has been extensively investigated relatively few studies have addressed the localization of FMD virus (FMDV) and in particular its replication in relation to the typical in-vivo sites of FMD lesions. In the present study, pigs were infecte...

  2. Analysis of classical swine fever virus RNA replication determinants using replicons

    DEFF Research Database (Denmark)

    Risager, Peter Christian; Fahnøe, Ulrik; Gullberg, Maria;

    2013-01-01

    Self-replicating RNAs (replicons), with or without reporter gene sequences, derived from the genome of the Paderborn strain of classical swine fever virus (CSFV) have been produced. The full-length viral cDNA, propagated within a bacterial artificial chromosome (BAC), was modified by targeted...

  3. Picornaviruses and nuclear functions: targeting a cellular compartment distinct from the replication site of a positive-strand RNA virus

    Directory of Open Access Journals (Sweden)

    Dylan eFlather

    2015-06-01

    Full Text Available The compartmentalization of DNA replication and gene transcription in the nucleus and protein production in the cytoplasm is a defining feature of eukaryotic cells. The nucleus functions to maintain the integrity of the nuclear genome of the cell and to control gene expression based on intracellular and environmental signals received through the cytoplasm. The spatial separation of the major processes that lead to the expression of protein-coding genes establishes the necessity of a transport network to allow biomolecules to translocate between these two regions of the cell. The nucleocytoplasmic transport network is therefore essential for regulating normal cellular functioning. The Picornaviridae virus family is one of many viral families that disrupt the nucleocytoplasmic trafficking of cells to promote viral replication. Picornaviruses contain positive-sense, single-stranded RNA genomes and replicate in the cytoplasm of infected cells. As a result of the limited coding capacity of these viruses, cellular proteins are required by these intracellular parasites for both translation and genomic RNA replication. Being of messenger RNA polarity, a picornavirus genome can immediately be translated upon entering the cell cytoplasm. However, the replication of viral RNA requires the activity of RNA-binding proteins, many of which function in host gene expression, and are consequently localized to the nucleus. As a result, picornaviruses disrupt nucleocytoplasmic trafficking to exploit protein functions normally localized to a different cellular compartment from which they translate their genome to facilitate efficient replication. Furthermore, picornavirus proteins are also known to enter the nucleus of infected cells to limit host-cell transcription and down-regulate innate antiviral responses. The interactions of picornavirus proteins and host-cell nuclei are extensive, required for a productive infection, and are the focus of this review.

  4. Picornaviruses and nuclear functions: targeting a cellular compartment distinct from the replication site of a positive-strand RNA virus.

    Science.gov (United States)

    Flather, Dylan; Semler, Bert L

    2015-01-01

    The compartmentalization of DNA replication and gene transcription in the nucleus and protein production in the cytoplasm is a defining feature of eukaryotic cells. The nucleus functions to maintain the integrity of the nuclear genome of the cell and to control gene expression based on intracellular and environmental signals received through the cytoplasm. The spatial separation of the major processes that lead to the expression of protein-coding genes establishes the necessity of a transport network to allow biomolecules to translocate between these two regions of the cell. The nucleocytoplasmic transport network is therefore essential for regulating normal cellular functioning. The Picornaviridae virus family is one of many viral families that disrupt the nucleocytoplasmic trafficking of cells to promote viral replication. Picornaviruses contain positive-sense, single-stranded RNA genomes and replicate in the cytoplasm of infected cells. As a result of the limited coding capacity of these viruses, cellular proteins are required by these intracellular parasites for both translation and genomic RNA replication. Being of messenger RNA polarity, a picornavirus genome can immediately be translated upon entering the cell cytoplasm. However, the replication of viral RNA requires the activity of RNA-binding proteins, many of which function in host gene expression, and are consequently localized to the nucleus. As a result, picornaviruses disrupt nucleocytoplasmic trafficking to exploit protein functions normally localized to a different cellular compartment from which they translate their genome to facilitate efficient replication. Furthermore, picornavirus proteins are also known to enter the nucleus of infected cells to limit host-cell transcription and down-regulate innate antiviral responses. The interactions of picornavirus proteins and host-cell nuclei are extensive, required for a productive infection, and are the focus of this review.

  5. Phosphorylation of hepatitis C virus RNA polymerases ser29 and ser42 by protein kinase C-related kinase 2 regulates viral RNA replication.

    Science.gov (United States)

    Han, Song-Hee; Kim, Seong-Jun; Kim, Eun-Jung; Kim, Tae-Eun; Moon, Jae-Su; Kim, Geon-Woo; Lee, Seung-Hoon; Cho, Kun; Yoo, Jong Shin; Son, Woo Sung; Rhee, Jin-Kyu; Han, Seung Hyun; Oh, Jong-Won

    2014-10-01

    Hepatitis C virus (HCV) nonstructural protein 5B (NS5B), an RNA-dependent RNA polymerase (RdRp), is the key enzyme for HCV RNA replication. We previously showed that HCV RdRp is phosphorylated by protein kinase C-related kinase 2 (PRK2). In the present study, we used biochemical and reverse-genetics approaches to demonstrate that HCV NS5B phosphorylation is crucial for viral RNA replication in cell culture. Two-dimensional phosphoamino acid analysis revealed that PRK2 phosphorylates NS5B exclusively at its serine residues in vitro and in vivo. Using in vitro kinase assays and mass spectrometry, we identified two phosphorylation sites, Ser29 and Ser42, in the Δ1 finger loop region that interacts with the thumb subdomain of NS5B. Colony-forming assays using drug-selectable HCV subgenomic RNA replicons revealed that preventing phosphorylation by Ala substitution at either Ser29 or Ser42 impairs HCV RNA replication. Furthermore, reverse-genetics studies using HCV infectious clones encoding phosphorylation-defective NS5B confirmed the crucial role of these PRK2 phosphorylation sites in viral RNA replication. Molecular-modeling studies predicted that the phosphorylation of NS5B stabilizes the interactions between its Δ1 loop and thumb subdomain, which are required for the formation of the closed conformation of NS5B known to be important for de novo RNA synthesis. Collectively, our results provide evidence that HCV NS5B phosphorylation has a positive regulatory role in HCV RNA replication. While the role of RNA-dependent RNA polymerases (RdRps) in viral RNA replication is clear, little is known about their functional regulation by phosphorylation. In this study, we addressed several important questions about the function and structure of phosphorylated hepatitis C virus (HCV) nonstructural protein 5B (NS5B). Reverse-genetics studies with HCV replicons encoding phosphorylation-defective NS5B mutants and analysis of their RdRp activities revealed previously unidentified

  6. Replication of honey bee-associated RNA viruses across multiple bee species in apple orchards of Georgia, Germany and Kyrgyzstan.

    Science.gov (United States)

    Radzevičiūtė, Rita; Theodorou, Panagiotis; Husemann, Martin; Japoshvili, George; Kirkitadze, Giorgi; Zhusupbaeva, Aigul; Paxton, Robert J

    2017-06-01

    The essential ecosystem service of pollination is provided largely by insects, which are considered threatened by diverse biotic and abiotic global change pressures. RNA viruses are one such pressure, and have risen in prominence as a major threat for honey bees (Apis mellifera) and global apiculture, as well as a risk factor for other bee species through pathogen spill-over between managed honey bees and sympatric wild pollinator communities. Yet despite their potential role in global bee decline, the prevalence of honey bee-associated RNA viruses in wild bees is poorly known from both geographic and taxonomic perspectives. We screened members of pollinator communities (honey bees, bumble bees and other wild bees belonging to four families) collected from apple orchards in Georgia, Germany and Kyrgyzstan for six common honey bee-associated RNA virus complexes encompassing nine virus targets. The Deformed wing virus complex (DWV genotypes A and B) had the highest prevalence across all localities and host species and was the only virus complex found in wild bee species belonging to all four studied families. Based on amplification of negative-strand viral RNA, we found evidence for viral replication in wild bee species of DWV-A/DWV-B (hosts: Andrena haemorrhoa and several Bombus spp.) and Black queen cell virus (hosts: Anthophora plumipes, several Bombus spp., Osmia bicornis and Xylocopa spp.). Viral amplicon sequences revealed that DWV-A and DWV-B are regionally distinct but identical in two or more bee species at any one site, suggesting virus is shared amongst sympatric bee taxa. This study demonstrates that honey bee associated RNA viruses are geographically and taxonomically widespread, likely infective in wild bee species, and shared across bee taxa. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. Modulation of the Host Lipid Landscape to Promote RNA Virus Replication : The Picornavirus Encephalomyocarditis Virus Converges on the Pathway Used by Hepatitis C Virus

    NARCIS (Netherlands)

    Dorobantu, Cristina M; Albulescu, Lucian; Harak, Christian; Feng, Qian; van Kampen, Mirjam; Strating, Jeroen R P M; Gorbalenya, Alexander E; Lohmann, Volker; van der Schaar, Hilde M; van Kuppeveld, Frank J M

    2015-01-01

    Cardioviruses, including encephalomyocarditis virus (EMCV) and the human Saffold virus, are small non-enveloped viruses belonging to the Picornaviridae, a large family of positive-sense RNA [(+)RNA] viruses. All (+)RNA viruses remodel intracellular membranes into unique structures for viral genome

  8. Identification of a novel human tRNA(Ser(CGA)) functional in murine leukemia virus replication

    DEFF Research Database (Denmark)

    Lund, Anders Henrik; Schmitz, A; Pedersen, F S

    2000-01-01

    (CGA)) was detected in cell lines of human, monkey and mouse origin. The UCG codon is the most rarely used codon in human genes. The cloned human tRNA(Ser(CGA)) gene encodes an 85 nucleotide, intron-less tRNA, contains a consensus split intragenic promoter and is located at region p21.3-22.2 on chromosome 6......We have identified a human tRNA(Ser) isoacceptor matching the UCG codon. The tRNA was discovered via its ability to act in reverse transcription of a murine leukemia virus vector containing a complementary tRNA primer binding site (Lund et al., Nucleic Acids Res., 28 (2000) 791-799). The tRNA(Ser....... The integrity and functionality of the cloned tRNA(Ser(CGA)) gene was verified by in vitro transcription analysis in HeLa nuclear extracts....

  9. Stimulation of poliovirus RNA synthesis and virus maturation in a HeLa cell-free in vitro translation-RNA replication system by viral protein 3CDpro

    Directory of Open Access Journals (Sweden)

    Wimmer Eckard

    2005-11-01

    Full Text Available Abstract Poliovirus protein 3CDpro possesses both proteinase and RNA binding activities, which are located in the 3Cpro domain of the protein. The RNA polymerase (3Dpol domain of 3CDpro modulates these activities of the protein. We have recently shown that the level of 3CDpro in HeLa cell-free in vitro translation-RNA replication reactions is suboptimal for efficient virus production. However, the addition of either 3CDpro mRNA or of purified 3CDpro protein to in vitro reactions, programmed with viral RNA, results in a 100-fold increase in virus yield. Mutational analyses of 3CDpro indicated that RNA binding by the 3Cpro domain and the integrity of interface I in the 3Dpol domain of the protein are both required for function. The aim of these studies was to determine the exact step or steps at which 3CDpro enhances virus yield and to determine the mechanism by which this occurs. Our results suggest that the addition of extra 3CDpro to in vitro translation RNA-replication reactions results in a mild enhancement of both minus and plus strand RNA synthesis. By examining the viral particles formed in the in vitro reactions on sucrose gradients we determined that 3CDpro has only a slight stimulating effect on the synthesis of capsid precursors but it strikingly enhances the maturation of virus particles. Both the stimulation of RNA synthesis and the maturation of the virus particles are dependent on the presence of an intact RNA binding site within the 3Cpro domain of 3CDpro. In addition, the integrity of interface I in the 3Dpol domain of 3CDpro is required for efficient production of mature virus. Surprisingly, plus strand RNA synthesis and virus production in in vitro reactions, programmed with full-length transcript RNA, are not enhanced by the addition of extra 3CDpro. Our results indicate that the stimulation of RNA synthesis and virus maturation by 3CDpro in vitro is dependent on the presence of a VPg-linked RNA template.

  10. Functional significance of a hepta nucleotide motif present at the junction of Cucumber mosaic virus satellite RNA multimers in helper-virus dependent replication.

    Science.gov (United States)

    Seo, Jang-Kyun; Kwon, Sun-Jung; Chaturvedi, Sonali; Choi, Soon Ho; Rao, A L N

    2013-01-20

    Satellite RNAs (satRNA) associated with Cucumber mosaic virus (CMV) have been shown to generate multimers during replication. We have discovered that multimers of a CMV satRNA generated in the absence of its helper virus (HV) are characterized by the addition of a hepta nucleotide motif (HNM) at the monomer junctions. Here, we evaluated the functional significance of HNM in HV-dependent replication by ectopically expressing wild type and mutant forms of satRNA multimers in planta either in (+) or (-)-strand polarity. Comparative replication profiles revealed that (-)-strand multimers with complementary HNM (cHNM) are the preferred initial templates for HV-dependent replication than (-)-strand monomers and multimers lacking the cHNM. Further mutational analyses of the HNM accentuate that preservation of the sequence and native length of HNM is obligatory for efficient replication of satRNA. A model implicating the significance of HNM in HV-dependent production of monomeric and multimeric forms of satRNA is presented.

  11. A whole-genome RNA interference screen for human cell factors affecting myxoma virus replication.

    Science.gov (United States)

    Teferi, Wondimagegnehu M; Dodd, Kristopher; Maranchuk, Rob; Favis, Nicole; Evans, David H

    2013-04-01

    Myxoma virus (MYXV) provides an important model for investigating host-pathogen interactions. Recent studies have also highlighted how mutations in transformed human cells can expand the host range of this rabbit virus. Although virus growth depends upon interactions between virus and host proteins, the nature of these interactions is poorly understood. To address this matter, we performed small interfering RNA (siRNA) screens for genes affecting MYXV growth in human MDA-MB-231 cells. By using siRNAs targeting the whole human genome (21,585 genes), a subset of human phosphatases and kinases (986 genes), and also a custom siRNA library targeting selected statistically significant genes ("hits") and nonsignificant genes ("nonhits") of the whole human genome screens (88 genes), we identified 711 siRNA pools that promoted MYXV growth and 333 that were inhibitory. Another 32 siRNA pools (mostly targeting the proteasome) were toxic. The overall overlap in the results was about 25% for the hits and 75% for the nonhits. These pro- and antiviral genes can be clustered into pathways and related groups, including well-established inflammatory and mitogen-activated protein kinase pathways, as well as clusters relating to β-catenin and the Wnt signaling cascade, the cell cycle, and cellular metabolism. The validity of a subset of these hits was independently confirmed. For example, treating cells with siRNAs that might stabilize cells in G(1), or inhibit passage into S phase, stimulated MYXV growth, and these effects were reproduced by trapping cells at the G(1)/S boundary with an inhibitor of cyclin-dependent kinases 4/6. By using 2-deoxy-D-glucose and plasmids carrying the gene for phosphofructokinase, we also confirmed that infection is favored by aerobic glycolytic metabolism. These studies provide insights into how the growth state and structure of cells affect MYXV growth and how these factors might be manipulated to advantage in oncolytic virus therapy.

  12. Alphavirus polymerase and RNA replication.

    Science.gov (United States)

    Pietilä, Maija K; Hellström, Kirsi; Ahola, Tero

    2017-01-16

    Alphaviruses are typically arthropod-borne, and many are important pathogens such as chikungunya virus. Alphaviruses encode four nonstructural proteins (nsP1-4), initially produced as a polyprotein P1234. nsP4 is the core RNA-dependent RNA polymerase but all four nsPs are required for RNA synthesis. The early replication complex (RC) formed by the polyprotein P123 and nsP4 synthesizes minus RNA strands, and the late RC composed of fully processed nsP1-nsP4 is responsible for the production of genomic and subgenomic plus strands. Different parts of nsP4 recognize the promoters for minus and plus strands but the binding also requires the other nsPs. The alphavirus polymerase has been purified and is capable of de novo RNA synthesis only in the presence of the other nsPs. The purified nsP4 also has terminal adenylyltransferase activity, which may generate the poly(A) tail at the 3' end of the genome. Membrane association of the nsPs is vital for replication, and alphaviruses induce membrane invaginations called spherules, which form a microenvironment for RNA synthesis by concentrating replication components and protecting double-stranded RNA intermediates. The RCs isolated as crude membrane preparations are active in RNA synthesis in vitro, but high-resolution structure of the RC has not been achieved, and thus the arrangement of viral and possible host components remains unknown. For some alphaviruses, Ras-GTPase-activating protein (Src-homology 3 (SH3) domain)-binding proteins (G3BPs) and amphiphysins have been shown to be essential for RNA replication and are present in the RCs. Host factors offer an additional target for antivirals, as only few alphavirus polymerase inhibitors have been described.

  13. Evaluation of canonical siRNA and Dicer substrate RNA for inhibition of hepatitis C virus genome replication--a comparative study.

    Directory of Open Access Journals (Sweden)

    Bruno Carneiro

    Full Text Available Hepatitis C virus (HCV frequently establishes persistent infections in the liver, leading to the development of chronic hepatitis and, potentially, to liver cirrhosis and hepatocellular carcinoma at later stages. The objective of this study was to test the ability of five Dicer substrate siRNAs (DsiRNA to inhibit HCV replication and to compare these molecules to canonical 21 nt siRNA. DsiRNA molecules were designed to target five distinct regions of the HCV genome - the 5' UTR and the coding regions for NS3, NS4B, NS5A or NS5B. These molecules were transfected into Huh7.5 cells that stably harboured an HCV subgenomic replicon expressing a firefly luciferase/neoR reporter (SGR-Feo-JFH-1 and were also tested on HCVcc-infected cells. All of the DsiRNAs inhibited HCV replication in both the subgenomic system and HCVcc-infected cells. When DsiRNAs were transfected prior to infection with HCVcc, the inhibition levels reached 99.5%. When directly compared, canonical siRNA and DsiRNA exhibited similar potency of virus inhibition. Furthermore, both types of molecules exhibited similar dynamics of inhibition and frequencies of resistant mutants after 21 days of treatment. Thus, DsiRNA molecules are as potent as 21 nt siRNAs for the inhibition of HCV replication and may provide future approaches for HCV therapy if the emergence of resistant mutants can be addressed.

  14. Enrichment of Phosphatidylethanolamine in Viral Replication Compartments via Co-opting the Endosomal Rab5 Small GTPase by a Positive-Strand RNA Virus

    Science.gov (United States)

    Xu, Kai; Nagy, Peter D.

    2016-01-01

    Positive-strand RNA viruses build extensive membranous replication compartments to support replication and protect the virus from antiviral responses by the host. These viruses require host factors and various lipids to form viral replication complexes (VRCs). The VRCs built by Tomato bushy stunt virus (TBSV) are enriched with phosphatidylethanolamine (PE) through a previously unknown pathway. To unravel the mechanism of PE enrichment within the TBSV replication compartment, in this paper, the authors demonstrate that TBSV co-opts the guanosine triphosphate (GTP)-bound active form of the endosomal Rab5 small GTPase via direct interaction with the viral replication protein. Deletion of Rab5 orthologs in a yeast model host or expression of dominant negative mutants of plant Rab5 greatly decreases TBSV replication and prevents the redistribution of PE to the sites of viral replication. We also show that enrichment of PE in the viral replication compartment is assisted by actin filaments. Interestingly, the closely related Carnation Italian ringspot virus, which replicates on the boundary membrane of mitochondria, uses a similar strategy to the peroxisomal TBSV to hijack the Rab5-positive endosomes into the viral replication compartments. Altogether, usurping the GTP-Rab5–positive endosomes allows TBSV to build a PE-enriched viral replication compartment, which is needed to support peak-level replication. Thus, the Rab family of small GTPases includes critical host factors assisting VRC assembly and genesis of the viral replication compartment. PMID:27760128

  15. Role of RNA structure and RNA binding activity of foot-and-mouth disease virus 3C protein in VPg uridylylation and virus replication

    DEFF Research Database (Denmark)

    Nayak, A.; Goodfellow, I. G.; Woolaway, K. E.;

    2006-01-01

    The uridylylation of the VPg peptide primer is the first stage in the replication of picornavirus RNA. This process can be achieved in vitro using purified components, including 3B (VPg) with the RNA dependent RNA polymerase (3D(pol)), the precursor 3CD, and an RNA template containing the cre/bus...

  16. Selection of functional tRNA primers and primer binding site sequences from a retroviral combinatorial library: identification of new functional tRNA primers in murine leukemia virus replication

    DEFF Research Database (Denmark)

    Lund, Anders Henrik; Duch, M; Pedersen, F S

    2000-01-01

    . While most of the selected primer binding sites are complementary to the 3'-end of tRNA((Pro)), we also retrieved PBS sequences matching four other tRNA molecules and demonstrate that Akv murine leukemia virus vectors may efficiently replicate using tRNA(Arg(CCU)), tRNA(Phe(GAA))and a hitherto unknown......Retroviral reverse transcription is initiated from a cellular tRNA molecule and all known exogenous isolates of murine leukemia virus utilise a tRNA(Pro)molecule. While several studies suggest flexibility in murine leukemia virus primer utilisation, studies on human immunodeficiency virus and avian...... retro-viruses have revealed evidence of molecular adapt-ation towards the specific tRNA isoacceptor used as replication primer. In this study, murine leukemia virus tRNA utilisation is investigated by in vivo screening of a retroviral vector combinatorial library with randomised primer binding sites...

  17. Detection of intrahepatic replication of hepatitis C virus RNA by in situ hybridization and comparison with histopathology.

    Science.gov (United States)

    Negro, F; Pacchioni, D; Shimizu, Y; Miller, R H; Bussolati, G; Purcell, R H; Bonino, F

    1992-01-01

    A nonisotopic in situ hybridization (NISH) assay was used to detect hepatitis C virus (HCV) RNA. A synthetic oligonucleotide complementary to bases 252-301 of the highly conserved 5' noncoding region of the HCV genome was end-labeled by terminal deoxynucleotidyltransferase using digoxigenin-conjugated dUTP. The hybridized oligomer was revealed by an immunohistochemical reaction after incubation with an alkaline phosphatase-conjugated anti-digoxigenin antibody and subsequent amplification with a complex of alkaline phosphatase and anti-alkaline phosphatase antibodies. The intracellular distribution of HCV RNA was monitored in the livers of two chimpanzees experimentally infected with the H strain of HCV and compared with the serum alanine aminotransferase activity, serum HCV RNA, and liver histopathology. Most cells were stained in the cytoplasm as early as 2 days after inoculation, 1 and 2 days, respectively, before the appearance of viral RNA in the serum. The time course of HCV RNA replication was correlated with increases in serum alanine aminotransferase. However, neither one paralleled the appearance of liver cell necrosis nor showed any correlation with the inflammatory response. The NISH signal was not found in liver biopsy specimens taken from these two animals before inoculation with HCV, from chimpanzees with acute hepatitis type A, B, or delta, or from two animals never experimentally infected with any hepatitis agent; moreover, it disappeared when the positive specimens were predigested with RNase and it was not observed after hybridization of positive controls with a labeled oligomer unrelated to HCV RNA. Thus, detection of liver HCV RNA by NISH is a sensitive and specific method for studying HCV replication at the cellular level. Intracellular replication of HCV did not appear to be associated with histopathologic changes in the liver, although the correlation with increases of liver enzyme activity in the serum suggested possible damage to the liver

  18. In Vitro Synthesized RNA Generated from cDNA Clones of Both Genomic Components of Cucurbit yellow stunting disorder virus Replicates in Cucumber Protoplasts

    Science.gov (United States)

    Owen, Carolyn A.; Moukarzel, Romy; Huang, Xiao; Kassem, Mona A.; Eliasco, Eleonora; Aranda, Miguel A.; Coutts, Robert H. A.; Livieratos, Ioannis C.

    2016-01-01

    Cucurbit yellow stunting disorder virus (CYSDV), a bipartite whitefly-transmitted virus, constitutes a major threat to commercial cucurbit production worldwide. Here, construction of full-length CYSDV RNA1 and RNA2 cDNA clones allowed the in vitro synthesis of RNA transcripts able to replicate in cucumber protoplasts. CYSDV RNA1 proved competent for replication; transcription of both polarities of the genomic RNA was detectable 24 h post inoculation. Hybridization of total RNA extracted from transfected protoplasts or from naturally CYSDV-infected cucurbits revealed high-level transcription of the p22 subgenomic RNA species. Replication of CYSDV RNA2 following co-transfection with RNA1 was also observed, with similar transcription kinetics. A CYSDV RNA2 cDNA clone (T3CM8Δ) comprising the 5′- and 3′-UTRs plus the 3′-terminal gene, generated a 2.8 kb RNA able to replicate to high levels in protoplasts in the presence of CYSDV RNA1. The clone T3CM8Δ will facilitate reverse genetics studies of CYSDV gene function and RNA replication determinants. PMID:27314380

  19. In Vitro Synthesized RNA Generated from cDNA Clones of Both Genomic Components of Cucurbit yellow stunting disorder virus Replicates in Cucumber Protoplasts

    Directory of Open Access Journals (Sweden)

    Carolyn A. Owen

    2016-06-01

    Full Text Available Cucurbit yellow stunting disorder virus (CYSDV, a bipartite whitefly-transmitted virus, constitutes a major threat to commercial cucurbit production worldwide. Here, construction of full-length CYSDV RNA1 and RNA2 cDNA clones allowed the in vitro synthesis of RNA transcripts able to replicate in cucumber protoplasts. CYSDV RNA1 proved competent for replication; transcription of both polarities of the genomic RNA was detectable 24 h post inoculation. Hybridization of total RNA extracted from transfected protoplasts or from naturally CYSDV-infected cucurbits revealed high-level transcription of the p22 subgenomic RNA species. Replication of CYSDV RNA2 following co-transfection with RNA1 was also observed, with similar transcription kinetics. A CYSDV RNA2 cDNA clone (T3CM8Δ comprising the 5′- and 3′-UTRs plus the 3′-terminal gene, generated a 2.8 kb RNA able to replicate to high levels in protoplasts in the presence of CYSDV RNA1. The clone T3CM8Δ will facilitate reverse genetics studies of CYSDV gene function and RNA replication determinants.

  20. In Vitro Synthesized RNA Generated from cDNA Clones of Both Genomic Components of Cucurbit yellow stunting disorder virus Replicates in Cucumber Protoplasts.

    Science.gov (United States)

    Owen, Carolyn A; Moukarzel, Romy; Huang, Xiao; Kassem, Mona A; Eliasco, Eleonora; Aranda, Miguel A; Coutts, Robert H A; Livieratos, Ioannis C

    2016-06-14

    Cucurbit yellow stunting disorder virus (CYSDV), a bipartite whitefly-transmitted virus, constitutes a major threat to commercial cucurbit production worldwide. Here, construction of full-length CYSDV RNA1 and RNA2 cDNA clones allowed the in vitro synthesis of RNA transcripts able to replicate in cucumber protoplasts. CYSDV RNA1 proved competent for replication; transcription of both polarities of the genomic RNA was detectable 24 h post inoculation. Hybridization of total RNA extracted from transfected protoplasts or from naturally CYSDV-infected cucurbits revealed high-level transcription of the p22 subgenomic RNA species. Replication of CYSDV RNA2 following co-transfection with RNA1 was also observed, with similar transcription kinetics. A CYSDV RNA2 cDNA clone (T3CM8Δ) comprising the 5'- and 3'-UTRs plus the 3'-terminal gene, generated a 2.8 kb RNA able to replicate to high levels in protoplasts in the presence of CYSDV RNA1. The clone T3CM8Δ will facilitate reverse genetics studies of CYSDV gene function and RNA replication determinants.

  1. Inhibition of avian leukosis virus subgroup J replication by miRNA targeted against env.

    Science.gov (United States)

    Wang, Wei; Zhang, Zai-Ping; Tian, Jin; Xiao, Zhi-Guang; Meng, Qing-Wen

    2013-08-01

    No effective vaccine has been developed against the subgroup J avian leukosis virus (ALV-J). The genetic diversity of ALV-J might be related to the env gene, therefore, we selected conserved sequences of the env gene and designed interference sequence. In this study, microRNAs (miRNAs) were designed and synthesized, corresponding to conserved regions of the env gene. These miRNAs were cloned into the linearized eukaryotic expression vector. The recombinant plasmids were transfected into DF-1 cells. After transfection, the cells were inoculated with ALV-J. In reporter assays, the transfection efficiency is 80% by indirect immunofluorescence (IFA). Expression of the virus envelope glycoprotein was measured by IFA and western blotting assays. The relative expression of env gene was determined using quantitative PCR. Our results show that the mi-env 231 and mi-env 1384 could effectively suppress the replication of ALV-J with an efficiency of 68.7-75.2%. These data suggest that the miRNAs targeting the env can inhibit replication of ALV-J efficiently. This finding provides evidence that miRNAs could be used as a potential tool against ALV infection.

  2. The C-Terminal Domain of Chikungunya Virus nsP2 Independently Governs Viral RNA Replication, Cytopathicity, and Inhibition of Interferon Signaling

    OpenAIRE

    Fros, J. J.; van der Maten, E.; Vlak, J. M.; Pijlman, G.P.

    2013-01-01

    Alphavirus nonstructural protein 2 (nsP2) has pivotal roles in viral RNA replication, host cell shutoff, and inhibition of antiviral responses. Mutations that individually rendered other alphaviruses noncytopathic were introduced into chikungunya virus nsP2. Results show that (i) nsP2 mutation P718S only in combination with KR649AA or adaptive mutation D711G allowed noncytopathic replicon RNA replication, (ii) prohibiting nsP2 nuclear localization abrogates inhibition of antiviral interferon-...

  3. The C-terminal domain of chikungunya virus nsP2 independently governs viral RNA replication, cytopathicity, and inhibition of interferon signaling.

    Science.gov (United States)

    Fros, Jelke J; van der Maten, Erika; Vlak, Just M; Pijlman, Gorben P

    2013-09-01

    Alphavirus nonstructural protein 2 (nsP2) has pivotal roles in viral RNA replication, host cell shutoff, and inhibition of antiviral responses. Mutations that individually rendered other alphaviruses noncytopathic were introduced into chikungunya virus nsP2. Results show that (i) nsP2 mutation P718S only in combination with KR649AA or adaptive mutation D711G allowed noncytopathic replicon RNA replication, (ii) prohibiting nsP2 nuclear localization abrogates inhibition of antiviral interferon-induced JAK-STAT signaling, and (iii) nsP2 independently affects RNA replication, cytopathicity, and JAK-STAT signaling.

  4. MicroRNA-23b Promotes Avian Leukosis Virus Subgroup J (ALV-J) Replication by Targeting IRF1.

    Science.gov (United States)

    Li, Zhenhui; Chen, Biao; Feng, Min; Ouyang, Hongjia; Zheng, Ming; Ye, Qiao; Nie, Qinghua; Zhang, Xiquan

    2015-05-18

    Avian leukosis virus subgroup J (ALV-J) can cause several different leukemia-like proliferative diseases in the hemopoietic system of chickens. Here, we investigated the transcriptome profiles and miRNA expression profiles of ALV-J-infected and uninfected chicken spleens to identify the genes and miRNAs related to ALV-J invasion. In total, 252 genes and 167 miRNAs were differentially expressed in ALV-J-infected spleens compared to control uninfected spleens. miR-23b expression was up-regulated in ALV-J-infected spleens compared with the control spleens, and transcriptome analysis revealed that the expression of interferon regulatory factor 1 (IRF1) was down-regulated in ALV-J-infected spleens compared to uninfected spleens. A dual-luciferase reporter assay showed that IRF1 was a direct target of miR-23b. miR-23b overexpression significantly (P = 0.0022) decreased IRF1 mRNA levels and repressed IRF1-3'-UTR reporter activity. In vitro experiments revealed that miR-23b overexpression strengthened ALV-J replication, whereas miR-23b loss of function inhibited ALV-J replication. IRF1 overexpression inhibited ALV-J replication, and IRF1 knockdown enhanced ALV-J replication. Moreover, IRF1 overexpression significantly (P = 0.0014) increased IFN-β expression. In conclusion, these results suggested that miR-23b may play an important role in ALV-J replication by targeting IRF1.

  5. TRIM79α, an interferon-stimulated gene product, restricts tick-borne encephalitis virus replication by degrading the viral RNA polymerase

    OpenAIRE

    Taylor, R. Travis; Lubick, Kirk J.; Robertson, Shelly J.; Broughton, James P.; Bloom, Marshall E.; Bresnahan, Wade A.; Best, Sonja M.

    2011-01-01

    In response to virus infection, type I interferons (IFNs) induce several genes, most of whose functions are largely unknown. Here we show that the tripartite motif (TRIM) protein, TRIM79α, is an IFN-stimulated gene (ISG) product that specifically targets tick-borne encephalitis virus (TBEV), a Flavivirus that causes encephalitides in humans. TRIM79α restricts TBEV replication by mediating lysosome-dependent degradation of the flavivirus NS5 protein, an RNA-dependent RNA polymerase essential f...

  6. Expanding the host range of small insect RNA viruses: Providence virus (Carmotetraviridae) infects and replicates in a human tissue culture cell line.

    Science.gov (United States)

    Jiwaji, Meesbah; Short, James Roswell; Dorrington, Rosemary Ann

    2016-10-01

    Tetraviruses are small, positive (+ve)-sense ssRNA viruses that infect the midgut cells of lepidopteran larvae. Providence virus (PrV) is the only member of the family Carmotetraviridae (previously Tetraviridae). PrV particles exhibit the characteristic tetraviral T=4 icosahedral symmetry, but PrV is distinct from other tetraviruses with respect to genome organization and viral non-structural proteins. Currently, PrV is the only tetravirus known to infect and replicate in lepidopteran cell culture lines. In this report we demonstrate, using immunofluorescence microscopy, that PrV infects and replicates in a human tissue culture cell line (HeLa), producing infectious virus particles. We also provide evidence for PrV replication in vitro in insect, mammalian and plant cell-free systems. This study challenges the long-held view that tetraviruses have a narrow host range confined to one or a few lepidopteran species and highlights the need to consider the potential for apparently non-infectious viruses to be transferred to new hosts in the laboratory.

  7. Persistent hepatitis C virus RNA replication in haemophiliacs: role of co-infection with human immunodeficiency virus.

    Science.gov (United States)

    Chambost, H; Gerolami, V; Halfon, P; Thuret, I; Michel, G; Sicardi, F; Rousseau, S; Perrimond, H; Cartouzou, G

    1995-11-01

    In order to evaluate the evolution of transfusional hepatitis C in haemophiliacs, we performed a retrospective study of ALT levels and HCV viraemia with a RNA PCR assay in 57 patients. We found that the vast majority of HCV-infected patients remained viraemic (43/57 = 75%) and higher ALT levels correlated with HCV viraemia. Although indicators of the transfusional viral load (age, severity of haemophilia) and HBV co-infection did not correlate with HCV RNA replication, HIV seropositivity was strongly associated with persistence of HCV viraemia (23/25 = 92% in HIV-positive versus 20/32 = 62% in HIV-negative patients), without any correlation with CD4 counts. Genotyping of HCV in the 43 viraemic patients shows more frequent genotype 1 in the HIV-seropositive group (14/23) than in the seronegative group (6/20). Our data emphasize that besides the role of the immunodeficiency status, the genotypes of HCV might be involved in the differences observed in terms of HCV RNA replication between the HIV-seropositive and seronegative haemophiliacs.

  8. An amphipathic alpha-helix controls multiple roles of brome mosaic virus protein 1a in RNA replication complex assembly and function.

    Directory of Open Access Journals (Sweden)

    Ling Liu

    2009-03-01

    Full Text Available Brome mosaic virus (BMV protein 1a has multiple key roles in viral RNA replication. 1a localizes to perinuclear endoplasmic reticulum (ER membranes as a peripheral membrane protein, induces ER membrane invaginations in which RNA replication complexes form, and recruits and stabilizes BMV 2a polymerase (2a(Pol and RNA replication templates at these sites to establish active replication complexes. During replication, 1a provides RNA capping, NTPase and possibly RNA helicase functions. Here we identify in BMV 1a an amphipathic alpha-helix, helix A, and use NMR analysis to define its structure and propensity to insert in hydrophobic membrane-mimicking micelles. We show that helix A is essential for efficient 1a-ER membrane association and normal perinuclear ER localization, and that deletion or mutation of helix A abolishes RNA replication. Strikingly, mutations in helix A give rise to two dramatically opposite 1a function phenotypes, implying that helix A acts as a molecular switch regulating the intricate balance between separable 1a functions. One class of helix A deletions and amino acid substitutions markedly inhibits 1a-membrane association and abolishes ER membrane invagination, viral RNA template recruitment, and replication, but doubles the 1a-mediated increase in 2a(Pol accumulation. The second class of helix A mutations not only maintains efficient 1a-membrane association but also amplifies the number of 1a-induced membrane invaginations 5- to 8-fold and enhances viral RNA template recruitment, while failing to stimulate 2a(Pol accumulation. The results provide new insights into the pathways of RNA replication complex assembly and show that helix A is critical for assembly and function of the viral RNA replication complex, including its central role in targeting replication components and controlling modes of 1a action.

  9. Specific anti-viral effects of RNA interference on replication and expression of hepatitis B virus in mice

    Institute of Scientific and Technical Information of China (English)

    WU Ying; HUANG Ai-long; TANG Ni; ZHANG Bing-qiang; LU Nian-fang

    2005-01-01

    Background RNA interference (RNAi) is a powerful tool to silence gene expression post-transcriptionally. Our previous study has demonstrated that small interfering RNAs (siRNAs) have sufficiently inhibited hepatitis B virus (HBV) replication and expression in vitro. In this study we observed the RNAi-mediated inhibitory effects on HBV replication in mice models and accessed the specificity of these effects.Methods A mutant RNAi vector (pSI-C mut) with two base pairs different from the original target gene sequence at the RNAi vector (pSI-C) was constructed according to the method described in this study. A mouse model of acute hepatitis B virus infection was established by injecting naked plasmid pHBV1.3 via the tail vein with acute circulatory overload. pSI-C, pSI-C mut and the irrelevant RNAi control plasmid for green fluorescent protein (GFP) gene, pSIGFP were respectively delivered with pHBV1.3 by tail vein injection method. Six days post injection, enzyme-linked immunosorbent assay (ELISA) assay was used to measure the concentration of HBV surface antigen (HBsAg) in mouse serum, immunohistochemical straining method was used to visualize the expressin of HBV core protein (HBcAg) in liver tissues, and the transcriptional level of HBV C mRNA in liver tissues was detectedd by reverse transcriptase PCR (RT-PCR) analysis.Results Injection of pSI-C exerted magnificent and specific inhibitory effects on the replication and expression of HBV in the murine model. After 6-day post-injection (p.i.), the OD values were shown to be 5.07±1.07 in infecting group and 0.62±0.59 in pSI-C group. The concentration of HBsAg in pSI-C group was significantly lower than that in infecting group (P<0.01). Liver intracellular synthesis of viral core protein was sharply reduced to 0.9%±0.1%, compared with 5.4%±1.2% of positive hepatocytes in infecting group (P<0.01), and the transcriptional level of HBV C mRNA was greatly reduced by 84.7%. However, the irrelevant RNAi control plasmid

  10. Long non-coding RNA GAS5 inhibited hepatitis C virus replication by binding viral NS3 protein.

    Science.gov (United States)

    Qian, Xijing; Xu, Chen; Zhao, Ping; Qi, Zhongtian

    2016-05-01

    HCV infection has a complex and dynamic process which involves a large number of viral and host factors. Long non-coding RNA GAS5 inhibits liver fibrosis and liver tumor migration and invasion. However, the contribution of GAS5 on HCV infection remains unknown. In this study, GAS5 was gradually upregulated during HCV infection in Huh7 cells. In addition, GAS5 attenuated virus replication with its 5' end sequences, as confirmed by different GAS5 truncations. Moreover, this 5' end sequences showed RNA-protein interaction with HCV NS3 protein that could act as a decoy to inhibit its functions, which contributed to the suppression of HCV replication. Finally, the innate immune responses remained low in HCV infected Huh7 cells, ruling out the possibility of GAS5 to modulate innate immunity. Thus, HCV stimulated endogenous GAS5 can suppress HCV infection by acting as HCV NS3 protein decoy, providing a potential role of GAS5 as a diagnostic or therapeutic target.

  11. 5'PPP-RNA induced RIG-I activation inhibits drug-resistant avian H5N1 as well as 1918 and 2009 pandemic influenza virus replication

    Directory of Open Access Journals (Sweden)

    García-Sastre Adolfo

    2010-05-01

    Full Text Available Abstract Background Emergence of drug-resistant strains of influenza viruses, including avian H5N1 with pandemic potential, 1918 and 2009 A/H1N1 pandemic viruses to currently used antiviral agents, neuraminidase inhibitors and M2 Ion channel blockers, underscores the importance of developing novel antiviral strategies. Activation of innate immune pathogen sensor Retinoic Acid Inducible Gene-I (RIG-I has recently been shown to induce antiviral state. Results In the present investigation, using real time RT-PCR, immunofluorescence, immunoblot, and plaque assay we show that 5'PPP-containing single stranded RNA (5'PPP-RNA, a ligand for the intracytoplasmic RNA sensor, RIG-I can be used as a prophylactic agent against known drug-resistant avian H5N1 and pandemic influenza viruses. 5'PPP-RNA treatment of human lung epithelial cells inhibited replication of drug-resistant avian H5N1 as well as 1918 and 2009 pandemic influenza viruses in a RIG-I and type 1 interferon dependant manner. Additionally, 5'PPP-RNA treatment also inhibited 2009 H1N1 viral replication in vivo in mice. Conclusions Our findings suggest that 5'PPP-RNA mediated activation of RIG-I can suppress replication of influenza viruses irrespective of their genetic make-up, pathogenicity, and drug-sensitivity status.

  12. Tomato bushy stunt virus and DI RNAs as a model for studying mechanisms of RNA virus replication, pathogenicity and recombination. Final technical report for 1994--1997

    Energy Technology Data Exchange (ETDEWEB)

    Morris, T.J. [Univ. of Nebraska, Lincoln, NE (United States). School of Biological Sciences; Jackson, A.O. [Univ. of California, Berkeley, CA (United States). Dept. of Plant Biology

    1997-12-31

    Tomato bushy stunt virus (TBSV) is a small icosahedral virus with a very broad host-range. The symptoms of systemic infection range from mild mosaic to severe necrosis that often results in death. The genome of TBSV is composed of a single plus stranded RNA molecule with five genes. Two 5 inch genes are translated from the viral RNA, and the remaining three are translated from two subgenomic RNAs. Prior to the DOE supported studies, TBSV gene function had been assigned solely on the basis of sequence similarity with other virus genes of known function. The two 5 inch proximal genes (p33 and p92) were thought to be involved in viral replication, the middle gene encoded the capsid protein (p41), but no clear function was assigned to two nested 3 inch genes (p19 and p22), although it was suggested that at least one could be involved in movement. This research has determined the roles of each of the viral genes in the infection process, and the authors have obtained considerable genetic information pertinent to the contributions of the coat protein and the nested genes to the disease phenotypes observed in several host plants. They have also identified another genetic element with a short open reading frame in the 3 inch-noncoding region of the genome that provides a host-dependent replication function.

  13. A positive-strand RNA virus uses alternative protein-protein interactions within a viral protease/cofactor complex to switch between RNA replication and virion morphogenesis

    Science.gov (United States)

    Rey, Félix A.

    2017-01-01

    The viruses of the family Flaviviridae possess a positive-strand RNA genome and express a single polyprotein which is processed into functional proteins. Initially, the nonstructural (NS) proteins, which are not part of the virions, form complexes capable of genome replication. Later on, the NS proteins also play a critical role in virion formation. The molecular basis to understand how the same proteins form different complexes required in both processes is so far unknown. For pestiviruses, uncleaved NS2-3 is essential for virion morphogenesis while NS3 is required for RNA replication but is not functional in viral assembly. Recently, we identified two gain of function mutations, located in the C-terminal region of NS2 and in the serine protease domain of NS3 (NS3 residue 132), which allow NS2 and NS3 to substitute for uncleaved NS2-3 in particle assembly. We report here the crystal structure of pestivirus NS3-4A showing that the NS3 residue 132 maps to a surface patch interacting with the C-terminal region of NS4A (NS4A-kink region) suggesting a critical role of this contact in virion morphogenesis. We show that destabilization of this interaction, either by alanine exchanges at this NS3/4A-kink interface, led to a gain of function of the NS3/4A complex in particle formation. In contrast, RNA replication and thus replicase assembly requires a stable association between NS3 and the NS4A-kink region. Thus, we propose that two variants of NS3/4A complexes exist in pestivirus infected cells each representing a basic building block required for either RNA replication or virion morphogenesis. This could be further corroborated by trans-complementation studies with a replication-defective NS3/4A double mutant that was still functional in viral assembly. Our observations illustrate the presence of alternative overlapping surfaces providing different contacts between the same proteins, allowing the switch from RNA replication to virion formation. PMID:28151973

  14. The host-dependent interaction of alpha-importins with influenza PB2 polymerase subunit is required for virus RNA replication.

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    Patricia Resa-Infante

    Full Text Available The influenza virus polymerase is formed by the PB1, PB2 and PA subunits and is required for virus transcription and replication in the nucleus of infected cells. As PB2 is a relevant host-range determinant we expressed a TAP-tagged PB2 in human cells and isolated intracellular complexes. Alpha-importin was identified as a PB2-associated factor by proteomic analyses. To study the relevance of this interaction for virus replication we mutated the PB2 NLS and analysed the phenotype of mutant subunits, polymerase complexes and RNPs. While mutant PB2 proteins showed reduced nuclear accumulation, they formed polymerase complexes normally when co expressed with PB1 and PA. However, mutant RNPs generated with a viral CAT replicon showed up to hundred-fold reduced CAT accumulation. Rescue of nuclear localisation of mutant PB2 by insertion of an additional SV40 TAg-derived NLS did not revert the mutant phenotype of RNPs. Furthermore, determination of recombinant RNP accumulation in vivo indicated that PB2 NLS mutations drastically reduced virus RNA replication. These results indicate that, above and beyond its role in nuclear accumulation, PB2 interaction with alpha-importins is required for virus RNA replication. To ascertain whether PB2-alpha-importin binding could contribute to the adaptation of H5N1 avian viruses to man, their association in vivo was determined. Human alpha importin isoforms associated efficiently to PB2 protein of an H3N2 human virus but bound to diminished and variable extents to PB2 from H5N1 avian or human strains, suggesting that the function of alpha importin during RNA replication is important for the adaptation of avian viruses to the human host.

  15. The C-terminal domain of chikungunya virus nsP2 independently governs viral RNA replication, cytopathicity, and inhibition of interferon signaling

    NARCIS (Netherlands)

    Fros, J.J.; Maten, van der E.; Vlak, J.M.; Pijlman, G.P.

    2013-01-01

    Alphavirus nonstructural protein 2 (nsP2) has pivotal roles in viral RNA replication, host cell shutoff, and inhibition of antiviral responses. Mutations that individually rendered other alphaviruses noncytopathic were introduced into chikungunya virus nsP2. Results show that (i) nsP2 mutation P718S

  16. The C-terminal domain of chikungunya virus nsP2 independently governs viral RNA replication, cytopathicity, and inhibition of interferon signaling

    NARCIS (Netherlands)

    Fros, J.J.; Maten, van der E.; Vlak, J.M.; Pijlman, G.P.

    2013-01-01

    Alphavirus nonstructural protein 2 (nsP2) has pivotal roles in viral RNA replication, host cell shutoff, and inhibition of antiviral responses. Mutations that individually rendered other alphaviruses noncytopathic were introduced into chikungunya virus nsP2. Results show that (i) nsP2 mutation P718S

  17. Non coding extremities of the seven influenza virus type C vRNA segments: effect on transcription and replication by the type C and type A polymerase complexes

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    van der Werf Sylvie

    2008-10-01

    Full Text Available Abstract Background The transcription/replication of the influenza viruses implicate the terminal nucleotide sequences of viral RNA, which comprise sequences at the extremities conserved among the genomic segments as well as variable 3' and 5' non-coding (NC regions. The plasmid-based system for the in vivo reconstitution of functional ribonucleoproteins, upon expression of viral-like RNAs together with the nucleoprotein and polymerase proteins has been widely used to analyze transcription/replication of influenza viruses. It was thus shown that the type A polymerase could transcribe and replicate type A, B, or C vRNA templates whereas neither type B nor type C polymerases were able to transcribe and replicate type A templates efficiently. Here we studied the importance of the NC regions from the seven segments of type C influenza virus for efficient transcription/replication by the type A and C polymerases. Results The NC sequences of the seven genomic segments of the type C influenza virus C/Johannesburg/1/66 strain were found to be more variable in length than those of the type A and B viruses. The levels of transcription/replication of viral-like vRNAs harboring the NC sequences of the respective type C virus segments flanking the CAT reporter gene were comparable in the presence of either type C or type A polymerase complexes except for the NS and PB2-like vRNAs. For the NS-like vRNA, the transcription/replication level was higher after introduction of a U residue at position 6 in the 5' NC region as for all other segments. For the PB2-like vRNA the CAT expression level was particularly reduced with the type C polymerase. Analysis of mutants of the 5' NC sequence in the PB2-like vRNA, the shortest 5' NC sequence among the seven segments, showed that additional sequences within the PB2 ORF were essential for the efficiency of transcription but not replication by the type C polymerase complex. Conclusion In the context of a PB2-like reporter

  18. Addition of polyadenylate sequences to virus-specific RNA during adenovirus replication.

    Science.gov (United States)

    Philipson, L; Wall, R; Glickman, G; Darnell, J E

    1971-11-01

    Adenovirus-specific nuclear and polysomal RNA, both early and late in the infectious cycle, contain a covalently linked region of polyadenylic acid 150-250 nucleotides long. A large proportion of the adenovirus-specific messenger RNA contains poly(A). As revealed by hybridization experiments, the poly(A) is not transcribed from adenovirus DNA. Furthermore, an adenosine analogue, cordycepin, blocks the synthesis of poly(A) and also inhibits the accumulation of adenovirus messenger RNA on polysomes. Addition of poly(A) to viral RNA may involve a host-controlled mechanism that regulates the processing and transport of messenger RNA.

  19. In vitro antiviral activity of circular triple helix forming oligonucleotide RNA towards Feline Infectious Peritonitis virus replication.

    Science.gov (United States)

    Choong, Oi Kuan; Mehrbod, Parvaneh; Tejo, Bimo Ario; Omar, Abdul Rahman

    2014-01-01

    Feline Infectious Peritonitis (FIP) is a severe fatal immune-augmented disease in cat population. It is caused by FIP virus (FIPV), a virulent mutant strain of Feline Enteric Coronavirus (FECV). Current treatments and prophylactics are not effective. The in vitro antiviral properties of five circular Triple-Helix Forming Oligonucleotide (TFO) RNAs (TFO1 to TFO5), which target the different regions of virulent feline coronavirus (FCoV) strain FIPV WSU 79-1146 genome, were tested in FIPV-infected Crandell-Rees Feline Kidney (CRFK) cells. RT-qPCR results showed that the circular TFO RNAs, except TFO2, inhibit FIPV replication, where the viral genome copy numbers decreased significantly by 5-fold log10 from 10(14) in the virus-inoculated cells to 10(9) in the circular TFO RNAs-transfected cells. Furthermore, the binding of the circular TFO RNA with the targeted viral genome segment was also confirmed using electrophoretic mobility shift assay. The strength of binding kinetics between the TFO RNAs and their target regions was demonstrated by NanoITC assay. In conclusion, the circular TFOs have the potential to be further developed as antiviral agents against FIPV infection.

  20. In Vitro Antiviral Activity of Circular Triple Helix Forming Oligonucleotide RNA towards Feline Infectious Peritonitis Virus Replication

    Directory of Open Access Journals (Sweden)

    Oi Kuan Choong

    2014-01-01

    Full Text Available Feline Infectious Peritonitis (FIP is a severe fatal immune-augmented disease in cat population. It is caused by FIP virus (FIPV, a virulent mutant strain of Feline Enteric Coronavirus (FECV. Current treatments and prophylactics are not effective. The in vitro antiviral properties of five circular Triple-Helix Forming Oligonucleotide (TFO RNAs (TFO1 to TFO5, which target the different regions of virulent feline coronavirus (FCoV strain FIPV WSU 79-1146 genome, were tested in FIPV-infected Crandell-Rees Feline Kidney (CRFK cells. RT-qPCR results showed that the circular TFO RNAs, except TFO2, inhibit FIPV replication, where the viral genome copy numbers decreased significantly by 5-fold log10 from 1014 in the virus-inoculated cells to 109 in the circular TFO RNAs-transfected cells. Furthermore, the binding of the circular TFO RNA with the targeted viral genome segment was also confirmed using electrophoretic mobility shift assay. The strength of binding kinetics between the TFO RNAs and their target regions was demonstrated by NanoITC assay. In conclusion, the circular TFOs have the potential to be further developed as antiviral agents against FIPV infection.

  1. Small interfering RNAs targeting peste des petits ruminants virus M mRNA increase virus-mediated fusogenicity and inhibit viral replication in vitro.

    Science.gov (United States)

    Liu, Fuxiao; Wu, Xiaodong; Zou, Yanli; Li, Lin; Liu, Shan; Chi, Tianying; Wang, Zhiliang

    2015-11-01

    Peste des petits ruminants (PPR), caused by peste des petits ruminants virus (PPRV), is an acute or subacute, highly contagious and economically important disease of small ruminants. The PPRV is classified into the genus Morbillivirus in the family Paramyxoviridae. The PPRV matrix (M) protein possesses an intrinsic ability to bind to lipid membranes, and plays a crucial role in viral assembly and further budding. In this study, three different small interfering RNAs (siRNA) were designed on the basis of translated region for PPRV Nigeria 75/1M mRNA, and were subsequently synthesized for their transfection into Vero-SLAM cells, followed by infection with PPRVs. The results showed that two out of three siRNAs robustly induced cell-to-cell fusion as early as 36h post-infection with PPRVs, effectively suppressed expression of the M protein by interference for the M mRNA, and eventually inhibited viral replication in vitro. These findings led us to speculate that siRNA-mediated knockdown of the M protein would alter its interaction with viral glycoproteins, thus exacerbating intercellular fusion but hampering virus release. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Delayed Newcastle disease virus replication using RNA interference to target the nucleoprotein

    Science.gov (United States)

    Each year millions of chickens die from Newcastle disease virus (NDV) worldwide, leading to economic and food losses. Current vaccination campaigns have limitations including cost, administration, and thermostability. These problems are heightened in the developing world where constraints are more...

  3. Zn(2+ inhibits coronavirus and arterivirus RNA polymerase activity in vitro and zinc ionophores block the replication of these viruses in cell culture.

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    Aartjan J W te Velthuis

    Full Text Available Increasing the intracellular Zn(2+ concentration with zinc-ionophores like pyrithione (PT can efficiently impair the replication of a variety of RNA viruses, including poliovirus and influenza virus. For some viruses this effect has been attributed to interference with viral polyprotein processing. In this study we demonstrate that the combination of Zn(2+ and PT at low concentrations (2 µM Zn(2+ and 2 µM PT inhibits the replication of SARS-coronavirus (SARS-CoV and equine arteritis virus (EAV in cell culture. The RNA synthesis of these two distantly related nidoviruses is catalyzed by an RNA-dependent RNA polymerase (RdRp, which is the core enzyme of their multiprotein replication and transcription complex (RTC. Using an activity assay for RTCs isolated from cells infected with SARS-CoV or EAV--thus eliminating the need for PT to transport Zn(2+ across the plasma membrane--we show that Zn(2+ efficiently inhibits the RNA-synthesizing activity of the RTCs of both viruses. Enzymatic studies using recombinant RdRps (SARS-CoV nsp12 and EAV nsp9 purified from E. coli subsequently revealed that Zn(2+ directly inhibited the in vitro activity of both nidovirus polymerases. More specifically, Zn(2+ was found to block the initiation step of EAV RNA synthesis, whereas in the case of the SARS-CoV RdRp elongation was inhibited and template binding reduced. By chelating Zn(2+ with MgEDTA, the inhibitory effect of the divalent cation could be reversed, which provides a novel experimental tool for in vitro studies of the molecular details of nidovirus replication and transcription.

  4. Expression of plasmid-based shRNA against the E1 and nsP1 genes effectively silenced Chikungunya virus replication.

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    Shirley Lam

    Full Text Available BACKGROUND: Chikungunya virus (CHIKV is a re-emerging alphavirus that causes chikungunya fever and persistent arthralgia in humans. Currently, there is no effective vaccine or antiviral against CHIKV infection. Therefore, this study evaluates whether RNA interference which targets at viral genomic level may be a novel antiviral strategy to inhibit the medically important CHIKV infection. METHODS: Plasmid-based small hairpin RNA (shRNA was investigated for its efficacy in inhibiting CHIKV replication. Three shRNAs designed against CHIKV Capsid, E1 and nsP1 genes were transfected to establish stable shRNA-expressing cell clones. Following infection of stable shRNA cells clones with CHIKV at M.O.I. 1, viral plaque assay, Western blotting and transmission electron microscopy were performed. The in vivo efficacy of shRNA against CHIKV replication was also evaluated in a suckling murine model of CHIKV infection. RESULTS: Cell clones expressing shRNAs against CHIKV E1 and nsP1 genes displayed significant inhibition of infectious CHIKV production, while shRNA Capsid demonstrated a modest inhibitory effect as compared to scrambled shRNA cell clones and non-transfected cell controls. Western blot analysis of CHIKV E2 protein expression and transmission electron microscopy of shRNA E1 and nsP1 cell clones collectively demonstrated similar inhibitory trends against CHIKV replication. shRNA E1 showed non cell-type specific anti-CHIKV effects and broad-spectrum silencing against different geographical strains of CHIKV. Furthermore, shRNA E1 clones did not exert any inhibition against Dengue virus and Sindbis virus replication, thus indicating the high specificity of shRNA against CHIKV replication. Moreover, no shRNA-resistant CHIKV mutant was generated after 50 passages of CHIKV in the stable cell clones. More importantly, strong and sustained anti-CHIKV protection was conferred in suckling mice pre-treated with shRNA E1. CONCLUSION: Taken together, these

  5. Replicative homeostasis II: Influence of polymerase fidelity on RNA virus quasispecies biology: Implications for immune recognition, viral autoimmunity and other "virus receptor" diseases

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    Sallie Richard

    2005-08-01

    Full Text Available Abstract Much of the worlds' population is in active or imminent danger from established infectious pathogens, while sporadic and pandemic infections by these and emerging agents threaten everyone. RNA polymerases (RNApol generate enormous genetic and consequent antigenic heterogeneity permitting both viruses and cellular pathogens to evade host defences. Thus, RNApol causes more morbidity and premature mortality than any other molecule. The extraordinary genetic heterogeneity defining viral quasispecies results from RNApol infidelity causing rapid cumulative genomic RNA mutation a process that, if uncontrolled, would cause catastrophic loss of sequence integrity and inexorable quasispecies extinction. Selective replication and replicative homeostasis, an epicyclical regulatory mechanism dynamically linking RNApol fidelity and processivity with quasispecies phenotypic diversity, modulating polymerase fidelity and, hence, controlling quasispecies behaviour, prevents this happening and also mediates immune escape. Perhaps more importantly, ineluctable generation of broad phenotypic diversity after viral RNA is translated to protein quasispecies suggests a mechanism of disease that specifically targets, and functionally disrupts, the host cell surface molecules – including hormone, lipid, cell signalling or neurotransmitter receptors – that viruses co-opt for cell entry. This mechanism – "Viral Receptor Disease (VRD" – may explain so-called "viral autoimmunity", some classical autoimmune disorders and other diseases, including type II diabetes mellitus, and some forms of obesity. Viral receptor disease is a unifying hypothesis that may also explain some diseases with well-established, but multi-factorial and apparently unrelated aetiologies – like coronary artery and other vascular diseases – in addition to diseases like schizophrenia that are poorly understood and lack plausible, coherent, pathogenic explanations.

  6. Transient replication of Hepatitis C Virus sub-genomic RNA in murine cell lines is enabled by miR-122 and varies with cell passage.

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    Patricia A Thibault

    Full Text Available Hepatitis C Virus (HCV is a serious global health problem, infecting almost 3% of the world's population. The lack of model systems for studying this virus limit research options in vaccine and therapeutic development, as well as for studying the pathogenesis of chronic HCV infection. Herein we make use of the liver-specific microRNA miR-122 to render mouse cell lines permissive to HCV replication in an attempt to develop additional model systems for the identification of new features of the virus and its life cycle. We have determined that some wild-type and knockout mouse cell lines--NCoA6 and PKR knockout embryonic fibroblasts--can be rendered permissive to transient HCV sub-genomic RNA replication upon addition of miR-122, but we did not observe replication of full-length HCV RNA in these cells. However, other wild-type and knockout cell lines cannot be rendered permissive to HCV replication by addition of miR-122, and in fact, different NCoA6 and PKR knockout cell line passages and isolates from the same mice demonstrated varying permissiveness phenotypes and eventually complete loss of permissiveness. When we tested knockdown of NCoA6 and PKR in Huh7.5 cells, we saw no substantial impact in sub-genomic HCV replication, which we would expect if these genes were inhibitory to the virus' life cycle. This leads us to conclude that along with the influence of specific gene knockouts there are additional factors within the cell lines that affect their permissiveness for HCV replication; we suggest that these may be epigenetically regulated, or modulated by cell line immortalization and transformation.

  7. mRNA decay factor AUF1 binds the internal ribosomal entry site of enterovirus 71 and inhibits virus replication.

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    Jing-Yi Lin

    Full Text Available AU-rich element binding factor 1 (AUF1 has a role in the replication cycles of different viruses. Here we demonstrate that AUF1 binds the internal ribosome entry site (IRES of enterovirus 71 (EV71 and negatively regulates IRES-dependent translation. During EV71 infection, AUF1 accumulates in the cytoplasm where viral replication occurs, whereas AUF1 localizes predominantly in the nucleus in mock-infected cells. AUF1 knockdown in infected cells increases IRES activity and synthesis of viral proteins. Taken together, the results suggest that AUF1 interacts with the EV71 IRES to negatively regulate viral translation and replication.

  8. Plant RNA binding proteins for control of RNA virus infection

    OpenAIRE

    Huh, Sung Un; Paek, Kyung-Hee

    2013-01-01

    Plant RNA viruses have effective strategies to infect host plants through either direct or indirect interactions with various host proteins, thus suppressing the host immune system. When plant RNA viruses enter host cells exposed RNAs of viruses are recognized by the host immune system through processes such as siRNA-dependent silencing. Interestingly, some host RNA binding proteins have been involved in the inhibition of RNA virus replication, movement, and translation through RNA-specific b...

  9. Transgene-mediated suppression of the RNA interference pathway in Aedes aegypti interferes with gene silencing and enhances Sindbis virus and dengue virus type 2 replication.

    Science.gov (United States)

    Khoo, C C H; Doty, J B; Heersink, M S; Olson, K E; Franz, A W E

    2013-02-01

    RNA interference (RNAi) is the major innate antiviral pathway in Aedes aegypti that responds to replicating arboviruses such as dengue virus (DENV) and Sindbis virus (SINV). On the one hand, the mosquito's RNAi machinery is capable of completely eliminating DENV2 from Ae. aegypti. On the other, transient silencing of key genes of the RNAi pathway increases replication of SINV and DENV2, allowing the viruses to temporally overcome dose-dependent midgut infection and midgut escape barriers (MEB) more efficiently. Here we expressed Flock house virus B2 (FHV-B2) from the poly-ubiquitin (PUb) promoter in Ae. aegypti using the ΦC31 site-directed recombination system to investigate the impact of transgene-mediated RNAi pathway suppression on infections with SINV-TR339eGFP and DENV2-QR94, the latter of which has been shown to be confronted with a strong MEB in Ae. aegypti. FHV-B2 was constitutively expressed in midguts of sugar- and blood-fed mosquitoes of transgenic line PUbB2 P61. B2 over-expression suppressed RNA silencing of carboxypeptidase A-1 (AeCPA-1) in midgut tissue of PUbB2 P61 mosquitoes. Following oral challenge with SINV-TR339eGFP or DENV2-QR94, mean titres in midguts of PUbB2 P61 females were significantly higher at 7 days post-bloodmeal (pbm) than in those of nontransgenic control mosquitoes. At 14 days pbm, infection rates of carcasses were significantly increased in PubB2 P61 mosquitoes infected with SINV-TR339eGFP. Following infection with DENV2-QR94, midgut infection rates were significantly increased in the B2-expressing mosquitoes at 14 days pbm. However, B2 expression in PUbB2 P61 did not increase the DENV2-QR94 dissemination rate, indicating that the infection phenotype was not primarily controlled by RNAi. © 2013 Royal Entomological Society.

  10. Regulation of Semliki Forest virus RNA replication: a model for the control of alphavirus pathogenesis in invertebrate hosts.

    Science.gov (United States)

    Kim, Kyongmin Hwang; Rümenapf, Tillmann; Strauss, Ellen G; Strauss, James H

    2004-05-20

    Alphavirus nonstructural proteins are translated as a polyprotein that is ultimately cleaved into four mature proteins called nsP1, nsP2, nsP3, and nsP4 from their order in the polyprotein. The role of this nonstructural polyprotein, of cleavage intermediates, and of mature proteins in synthesis of Semliki Forest virus (SFV) RNA has been studied using mutants unable to cleave one or more of the sites in the nonstructural polyprotein or that had the arginine sense codon between nsP3 and nsP4 changed to an opal termination codon. The results were compared with those obtained for Sindbis virus (SINV), which has a naturally occurring opal codon between nsP2 and nsP3. We found that (1) an active nonstructural protease in nsP2 is required for RNA synthesis. This protease is responsible for all three cleavages in the nonstructural polyprotein. (2) Cleavage between nsP3 and nsP4 (the viral RNA polymerase) is required for RNA synthesis by SFV. (3) SFV mutants that are able to produce only polyprotein P123 and nsP4 synthesize minus-strand RNA early after infection as efficiently as SF wild type but are defective in the synthesis of plus-strand RNA. The presence of sense or opal following nsP3 did not affect this result. At 30 degrees C, they give rise to low yields of virus after a delay, but at 39 degrees C, they are nonviable. (4) SFV mutants that produce nsP1, P23, nsP4, as well as the precursor P123 are viable but produce an order of magnitude less virus than wild type at 30 degrees C and two orders of magnitude less virus at 39 degrees C. The ratio of subgenomic mRNA to genomic RNA is much reduced in these mutants relative to the parental viruses. (5) At 30 degrees C, the variants containing an opal codon grow as well as or slightly better than the corresponding virus with a sense codon. At 39 degrees C, however, the opal variants produce significantly more virus. These results support the conclusion that SFV and SINV, and by extension all alphaviruses, regulate their

  11. A novel functional site in the PB2 subunit of influenza A virus essential for acetyl-CoA interaction, RNA polymerase activity, and viral replication.

    Science.gov (United States)

    Hatakeyama, Dai; Shoji, Masaki; Yamayoshi, Seiya; Hirota, Takenori; Nagae, Monami; Yanagisawa, Shin; Nakano, Masahiro; Ohmi, Naho; Noda, Takeshi; Kawaoka, Yoshihiro; Kuzuhara, Takashi

    2014-09-05

    The PA, PB1, and PB2 subunits, components of the RNA-dependent RNA polymerase of influenza A virus, are essential for viral transcription and replication. The PB2 subunit binds to the host RNA cap (7-methylguanosine triphosphate (m(7)GTP)) and supports the endonuclease activity of PA to "snatch" the cap from host pre-mRNAs. However, the structure of PB2 is not fully understood, and the functional sites remain unknown. In this study, we describe a novel Val/Arg/Gly (VRG) site in the PB2 cap-binding domain, which is involved in interaction with acetyl-CoA found in eukaryotic histone acetyltransferases (HATs). In vitro experiments revealed that the recombinant PB2 cap-binding domain that includes the VRG site interacts with acetyl-CoA; moreover, it was found that this interaction could be blocked by CoA and various HAT inhibitors. Interestingly, m(7)GTP also inhibited this interaction, suggesting that the same active pocket is capable of interacting with acetyl-CoA and m(7)GTP. To elucidate the importance of the VRG site on PB2 function and viral replication, we constructed a PB2 recombinant protein and recombinant viruses including several patterns of amino acid mutations in the VRG site. Substitutions of the valine and arginine residues or of all 3 residues of the VRG site to alanine significantly reduced the binding ability of PB2 to acetyl-CoA and its RNA polymerase activity. Recombinant viruses containing the same mutations could not be replicated in cultured cells. These results indicate that the PB2 VRG sequence is a functional site that is essential for acetyl-CoA interaction, RNA polymerase activity, and viral replication. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  12. Antiviral Innate Immune Response Interferes with the Formation of Replication-Associated Membrane Structures Induced by a Positive-Strand RNA Virus

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    Diede Oudshoorn

    2016-12-01

    Full Text Available Infection with nidoviruses like corona- and arteriviruses induces a reticulovesicular network of interconnected endoplasmic reticulum (ER-derived double-membrane vesicles (DMVs and other membrane structures. This network is thought to accommodate the viral replication machinery and protect it from innate immune detection. We hypothesized that the innate immune response has tools to counteract the formation of these virus-induced replication organelles in order to inhibit virus replication. Here we have investigated the effect of type I interferon (IFN treatment on the formation of arterivirus-induced membrane structures. Our approach involved ectopic expression of arterivirus nonstructural proteins nsp2 and nsp3, which induce DMV formation in the absence of other viral triggers of the interferon response, such as replicating viral RNA. Thus, this setup can be used to identify immune effectors that specifically target the (formation of virus-induced membrane structures. Using large-scale electron microscopy mosaic maps, we found that IFN-β treatment significantly reduced the formation of the membrane structures. Strikingly, we also observed abundant stretches of double-membrane sheets (a proposed intermediate of DMV formation in IFN-β-treated samples, suggesting the disruption of DMV biogenesis. Three interferon-stimulated gene products, two of which have been reported to target the hepatitis C virus replication structures, were tested for their possible involvement, but none of them affected membrane structure formation. Our study reveals the existence of a previously unknown innate immune mechanism that antagonizes the viral hijacking of host membranes. It also provides a solid basis for further research into the poorly understood interactions between the innate immune system and virus-induced replication structures.

  13. A suboptimal 5' splice site downstream of HIV-1 splice site A1 is required for unspliced viral mRNA accumulation and efficient virus replication

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    Stoltzfus C Martin

    2006-02-01

    Full Text Available Abstract Background Inefficient alternative splicing of the human immunodeficiency virus type 1(HIV-1 primary RNA transcript results in greater than half of all viral mRNA remaining unspliced. Regulation of HIV-1 alternative splicing occurs through the presence of suboptimal viral 5' and 3' splice sites (5' and 3'ss, which are positively regulated by exonic splicing enhancers (ESE and negatively regulated by exonic splicing silencers (ESS and intronic splicing silencers (ISS. We previously showed that splicing at HIV-1 3'ss A2 is repressed by ESSV and enhanced by the downstream 5'ss D3 signal. Disruption of ESSV results in increased vpr mRNA accumulation and exon 3 inclusion, decreased accumulation of unspliced viral mRNA, and decreased virus production. Results Here we show that optimization of the 5'ss D2 signal results in increased splicing at the upstream 3'ss A1, increased inclusion of exon 2 into viral mRNA, decreased accumulation of unspliced viral mRNA, and decreased virus production. Virus production from the 5'ss D2 and ESSV mutants was rescued by transient expression of HIV-1 Gag and Pol. We further show that the increased inclusion of either exon 2 or 3 does not significantly affect the stability of viral mRNA but does result in an increase and decrease, respectively, in HIV-1 mRNA levels. The changes in viral mRNA levels directly correlate with changes in tat mRNA levels observed upon increased inclusion of exon 2 or 3. Conclusion These results demonstrate that splicing at HIV-1 3'ss A1 is regulated by the strength of the downstream 5'ss signal and that suboptimal splicing at 3'ss A1 is necessary for virus replication. Furthermore, the replication defective phenotype resulting from increased splicing at 3'ss A1 is similar to the phenotype observed upon increased splicing at 3'ss A2. Further examination of the role of 5'ss D2 and D3 in the alternative splicing of 3'ss A1 and A2, respectively, is necessary to delineate a role for non

  14. Lipid droplet-binding protein TIP47 regulates hepatitis C Virus RNA replication through interaction with the viral NS5A protein.

    Directory of Open Access Journals (Sweden)

    Dorothee A Vogt

    Full Text Available The nonstructural protein NS5A has emerged as a new drug target in antiviral therapies for Hepatitis C Virus (HCV infection. NS5A is critically involved in viral RNA replication that takes place at newly formed membranes within the endoplasmic reticulum (membranous web and assists viral assembly in the close vicinity of lipid droplets (LDs. To identify host proteins that interact with NS5A, we performed a yeast two-hybrid screen with the N-terminus of NS5A (amino acids 1-31, a well-studied α-helical domain important for the membrane tethering of NS5A. Our studies identified the LD-associated host protein, Tail-Interacting Protein 47 (TIP47 as a novel NS5A interaction partner. Coimmunoprecipitation experiments in Huh7 hepatoma cells confirmed the interaction of TIP47 with full-length NS5A. shRNA-mediated knockdown of TIP47 caused a more than 10-fold decrease in the propagation of full-length infectious HCV in Huh7.5 hepatoma cells. A similar reduction was observed when TIP47 was knocked down in cells harboring an autonomously replicating HCV RNA (subgenomic replicon, indicating that TIP47 is required for efficient HCV RNA replication. A single point mutation (W9A in NS5A that disrupts the interaction with TIP47 but preserves proper subcellular localization severely decreased HCV RNA replication. In biochemical membrane flotation assays, TIP47 cofractionated with HCV NS3, NS5A, NS5B proteins, and viral RNA, and together with nonstructural viral proteins was uniquely distributed to lower-density LD-rich membrane fractions in cells actively replicating HCV RNA. Collectively, our data support a model where TIP47--via its interaction with NS5A--serves as a novel cofactor for HCV infection possibly by integrating LD membranes into the membranous web.

  15. hnRNP A2/B1 interacts with influenza A viral protein NS1 and inhibits virus replication potentially through suppressing NS1 RNA/protein levels and NS1 mRNA nuclear export

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yimeng; Zhou, Jianhong; Du, Yuchun, E-mail: ydu@uark.edu

    2014-01-20

    The NS1 protein of influenza viruses is a major virulence factor and exerts its function through interacting with viral/cellular RNAs and proteins. In this study, we identified heterogeneous nuclear ribonucleoprotein A2/B1 (hnRNP A2/B1) as an interacting partner of NS1 proteins by a proteomic method. Knockdown of hnRNP A2/B1 by small interfering RNA (siRNA) resulted in higher levels of NS vRNA, NS1 mRNA, and NS1 protein in the virus-infected cells. In addition, we demonstrated that hnRNP A2/B1 proteins are associated with NS1 and NS2 mRNAs and that knockdown of hnRNP A2/B1 promotes transport of NS1 mRNA from the nucleus to the cytoplasm in the infected cells. Lastly, we showed that knockdown of hnRNP A2/B1 leads to enhanced virus replication. Our results suggest that hnRNP A2/B1 plays an inhibitory role in the replication of influenza A virus in host cells potentially through suppressing NS1 RNA/protein levels and NS1 mRNA nucleocytoplasmic translocation. - Highlights: • Cellular protein hnRNP A2/B1 interacts with influenza viral protein NS1. • hnRNP A2/B1 suppresses the levels of NS1 protein, vRNA and mRNA in infected cells. • hnRNP A2/B1 protein is associated with NS1 and NS2 mRNAs. • hnRNP A2/B1 inhibits the nuclear export of NS1 mRNAs. • hnRNP A2/B1 inhibits influenza virus replication.

  16. hnRNP A2/B1 interacts with influenza A viral protein NS1 and inhibits virus replication potentially through suppressing NS1 RNA/protein levels and NS1 mRNA nuclear export.

    Science.gov (United States)

    Wang, Yimeng; Zhou, Jianhong; Du, Yuchun

    2014-01-20

    The NS1 protein of influenza viruses is a major virulence factor and exerts its function through interacting with viral/cellular RNAs and proteins. In this study, we identified heterogeneous nuclear ribonucleoprotein A2/B1 (hnRNP A2/B1) as an interacting partner of NS1 proteins by a proteomic method. Knockdown of hnRNP A2/B1 by small interfering RNA (siRNA) resulted in higher levels of NS vRNA, NS1 mRNA, and NS1 protein in the virus-infected cells. In addition, we demonstrated that hnRNP A2/B1 proteins are associated with NS1 and NS2 mRNAs and that knockdown of hnRNP A2/B1 promotes transport of NS1 mRNA from the nucleus to the cytoplasm in the infected cells. Lastly, we showed that knockdown of hnRNP A2/B1 leads to enhanced virus replication. Our results suggest that hnRNP A2/B1 plays an inhibitory role in the replication of influenza A virus in host cells potentially through suppressing NS1 RNA/protein levels and NS1 mRNA nucleocytoplasmic translocation.

  17. Interactions between p27 and p88 replicase proteins of Red clover necrotic mosaic virus play an essential role in viral RNA replication and suppression of RNA silencing via the 480-kDa viral replicase complex assembly.

    Science.gov (United States)

    Mine, Akira; Hyodo, Kiwamu; Takeda, Atsushi; Kaido, Masanori; Mise, Kazuyuki; Okuno, Tetsuro

    2010-11-25

    Red clover necrotic mosaic virus (RCNMV), a positive-sense RNA virus with a bipartite genome, encodes p27 and p88 replicase proteins that are required for viral RNA replication and suppression of RNA silencing. In this study, we identified domains in p27 and p88 responsible for their protein-protein interactions using in vitro pull-down assays with the purified recombinant proteins. Coimmunoprecipitation analysis in combination with blue-native polyacrylamide gel electrophoresis using mutated p27 proteins showed that both p27-p27 and p27-p88 interactions are essential for the formation of the 480-kDa complex, which has RCNMV-specific RNA-dependent RNA polymerase activity. Furthermore, we found a good correlation between the accumulated levels of the 480-kDa complex and replication levels and the suppression of RNA silencing activity. Our results indicate that interactions between RCNMV replicase proteins play an essential role in viral RNA replication and in suppressing RNA silencing via the 480-kDa replicase complex assembly.

  18. Chikungunya virus infectivity, RNA replication and non-structural polyprotein processing depend on the nsP2 protease's active site cysteine residue.

    Science.gov (United States)

    Rausalu, Kai; Utt, Age; Quirin, Tania; Varghese, Finny S; Žusinaite, Eva; Das, Pratyush Kumar; Ahola, Tero; Merits, Andres

    2016-11-15

    Chikungunya virus (CHIKV), genus Alphavirus, family Togaviridae, has a positive-stand RNA genome approximately 12 kb in length. In infected cells, the genome is translated into non-structural polyprotein P1234, an inactive precursor of the viral replicase, which is activated by cleavages carried out by the non-structural protease, nsP2. We have characterized CHIKV nsP2 using both cell-free and cell-based assays. First, we show that Cys478 residue in the active site of CHIKV nsP2 is indispensable for P1234 processing. Second, the substrate requirements of CHIKV nsP2 are quite similar to those of nsP2 of related Semliki Forest virus (SFV). Third, substitution of Ser482 residue, recently reported to contribute to the protease activity of nsP2, with Ala has almost no negative effect on the protease activity of CHIKV nsP2. Fourth, Cys478 to Ala as well as Trp479 to Ala mutations in nsP2 completely abolished RNA replication in CHIKV and SFV trans-replication systems. In contrast, trans-replicases with Ser482 to Ala mutation were similar to wild type counterparts. Fifth, Cys478 to Ala as well as Trp479 to Ala mutations in nsP2 abolished the rescue of infectious virus from CHIKV RNA transcripts while Ser482 to Ala mutation had no effect. Thus, CHIKV nsP2 is a cysteine protease.

  19. Intracellular Detection of Viral Transcription and Replication Using RNA FISH

    Science.gov (United States)

    2016-05-26

    Chapter 14. Intracellular detection of viral transcription and replication using RNA FISH i. Summary/Abstract Many hemorrhagic fever viruses...examine the mechanisms in which viruses replicate, assemble, and traffic through the cell. An additional benefit of this method is that the robust...Visualization of single RNA transcripts in situ. Science, 1998. 280(5363): p. 585-90. 4. Jambo, K.C., et al., Small alveolar macrophages are infected

  20. Combination of small interfering RNA and lamivudine on inhibition of human B virus replication in HepG2.2.15 cells

    Institute of Scientific and Technical Information of China (English)

    Gui-Qiu Li; Wei-Zhen Xu; Jing-Xia Wang; Wen-Wei Deng; Di Li; Hong-Xi Gu

    2007-01-01

    AIM: To observe the inhibition of hepatitis B virus (HBV) replication and expression by combination of siRNA and lamivudine in HepG2.2.15 cells.METHODS: Recombinant plasmid psil-HBV was constructed and transfected into HepG2.2.15 cells. The transfected cells were cultured in lamivudine-containing medium (0.05 μmol/L) and harvested at 48, 72 and 96 h. The concentration of HBeAg and HBsAg was determined using ELISA. HBV DMA replication was examined by realtime PCR and the level of HBV mRNA was measured by RT-PCR.RESULTS: In HepG2.2.15 cells treated with combination of siRNA and lamivudine, the secretion of HBeAg and HBsAg into the supernatant was found to be inhibited by 91.80% and 82.40% (2.89 ± 0.48 vs 11.73±0.38,P<0.05;4.59±0.57 vs 16.25±O.48,P<0.05) at 96 h,respectively;the number of HBV DNA copies within culture medium was also significantly decreased at 96 h (1.04±0.26 vs 8.35±0.33,P<0.05).Moreover,mRNA concentration in HepG2.2.15 cells treated with combination of siRNA and lamivudine was obviously lower compared to those treated either with siRNA or lamivudine (19.44±0.17 vs 33.27±0.21 or 79.9±0.13,P<O.05).CONCLUSION:Combination of siRNA and lamivudine is more effective in inhibiting HBV replication as compared to the single use of siRNA or lamivudine in HepG2.2.15 cells.

  1. The molecular biology of Bluetongue virus replication.

    Science.gov (United States)

    Patel, Avnish; Roy, Polly

    2014-03-01

    The members of Orbivirus genus within the Reoviridae family are arthropod-borne viruses which are responsible for high morbidity and mortality in ruminants. Bluetongue virus (BTV) which causes disease in livestock (sheep, goat, cattle) has been in the forefront of molecular studies for the last three decades and now represents the best understood orbivirus at a molecular and structural level. The complex nature of the virion structure has been well characterised at high resolution along with the definition of the virus encoded enzymes required for RNA replication; the ordered assembly of the capsid shell as well as the protein and genome sequestration required for it; and the role of host proteins in virus entry and virus release. More recent developments of Reverse Genetics and Cell-Free Assembly systems have allowed integration of the accumulated structural and molecular knowledge to be tested at meticulous level, yielding higher insight into basic molecular virology, from which the rational design of safe efficacious vaccines has been possible. This article is centred on the molecular dissection of BTV with a view to understanding the role of each protein in the virus replication cycle. These areas are important in themselves for BTV replication but they also indicate the pathways that related viruses, which includes viruses that are pathogenic to man and animals, might also use providing an informed starting point for intervention or prevention.

  2. Bovine Mx1 enables resistance against foot-and-mouth disease virus in naturally susceptible cells by inhibiting the replication of viral RNA.

    Science.gov (United States)

    Wang, H-M; Xia, X-Z; Hu, G-X; Yu, L; He, H-B

    2016-03-01

    Innate immunity, especially the anti-viral genes, exerts an important barrier function in preventing viral infections. Myxovirus-resistant (Mx) gene take an anti-viral role, whereas its effects on foot-and-mouth disease virus (FMDV) in naturally susceptible cells are still unclear. The bovine primary fetal tracheal epithelial cell line BPTE-siMx1, in which bovine Mx1 gene was silenced, was established and treated with IFN alpha for 6 hr before FMDV infection. The copy numbers of the negative and positive strand viral RNA were determined by strand-specific real-time fluorescence quantitative RT-PCR. The TCID50 of BPTE-siMx1 cells increased at least 17-fold as compared to control cells BPTE-LacZ at 8 hr post infection, thus silencing of bovine Mx1 could promote the replication of FMDV. The amount of both the negative and positive strand viral RNA in BPTE-siMx1 cells significantly increased as compared to BPTE-LacZ cells, indicating that the replication levels of viral RNA were promoted by silencing bovine Mx1. The bovine Mx1 gene could provide resistance against FMDV in the bovine primary fetal tracheal epithelial cells via suppressing the replication of viral RNA.

  3. 人工microRNA抗乙型肝炎病毒效果初探%Artificial microRNA Can Suppress Hepatitis B Virus Replication Efficiently In Vitro

    Institute of Scientific and Technical Information of China (English)

    赵海峰; 李丹丹; 李英; 胡伟; 王学军; 王升启

    2011-01-01

    Objective: To screen artificial microRNA (amiRNA) which can inhibit hepatitis B virus (HBV) replication in vitro. Methods: amiRNA targeted HBV conserved regions were designed and cloned into the vector pcDNA6.2-GW/EmGFP-miR. The inhibition rate of different amiRNA were compared by cotransfection amiRNA vectors and the HBV replicon vector pHBV1.31 into HepG2 cells. After 72 h, HBsAg, HBeAg and HBV DNA were assayed and analyzed. Results: amiRNA can suppress HBV replication efficiently in vitro. Conclusion: amiRNA as a potential anti-HBV technology shound be studied deeply in future.%目的:设计靶向乙型肝炎病毒(HBV)基因保守区的人工microRNA (amiRNA),考察其对HBV基因表达的抑制作用.方法:比对HBV全基因组现有序列,选择保守区设计amiRNA,定向克隆到pcDNA6.2-GW/EmGFP-miR载体,将amiRNA载体与HBV复制载体pHBV1.31共转染HepG2细胞,72 h后收取细胞上清,ELISA检测HBV表面抗原(HBsAg)及e抗原(HBeAg)的含量,荧光定量PCR检测HBV DNA含量.结果:amiRNA可显著抑制细胞上清HBsAg、HBeAg和HBV DNA的水平.结论:amiRNA作为防治HBV感染的潜在有效手段之一值得进一步深入研究.

  4. Inhibition of host protein synthesis by Sindbis virus: correlation with viral RNA replication and release of nuclear proteins to the cytoplasm.

    Science.gov (United States)

    Sanz, Miguel A; García-Moreno, Manuel; Carrasco, Luis

    2015-04-01

    Infection of mammalian cells by Sindbis virus (SINV) profoundly blocks cellular mRNA translation. Experimental evidence points to viral non-structural proteins (nsPs), in particular nsP2, as the mediator of this inhibition. However, individual expression of nsP1, nsP2, nsP3 or nsP1-4 does not block cellular protein synthesis in BHK cells. Trans-complementation of a defective SINV replicon lacking most of the coding region for nsPs by the co-expression of nsP1-4 propitiates viral RNA replication at low levels, and inhibition of cellular translation is not observed. Exit of nuclear proteins including T-cell intracellular antigen and polypyrimidine tract-binding protein is clearly detected in SINV-infected cells, but not upon the expression of nsPs, even when the defective replicon was complemented. Analysis of a SINV variant with a point mutation in nsP2, exhibiting defects in the shut-off of host protein synthesis, indicates that both viral RNA replication and the release of nuclear proteins to the cytoplasm are greatly inhibited. Furthermore, nucleoside analogues that inhibit cellular and viral RNA synthesis impede the blockade of host mRNA translation, in addition to the release of nuclear proteins. Prevention of the shut-off of host mRNA translation by nucleoside analogues is not due to the inhibition of eIF2α phosphorylation, as this prevention is also observed in PKR(-/-) mouse embryonic fibroblasts that do not phosphorylate eIF2α after SINV infection. Collectively, our observations are consistent with the concept that for the inhibition of cellular protein synthesis to occur, viral RNA replication must take place at control levels, leading to the release of nuclear proteins to the cytoplasm.

  5. Cellular microRNA miR-181b inhibits replication of mink enteritis virus by repression of non-structural protein 1 translation.

    Science.gov (United States)

    Sun, Jia-zeng; Wang, Jigui; Yuan, Daoli; Wang, Shuang; Li, Zhili; Yi, Bao; Mao, Yaping; Hou, Qiang; Liu, Weiquan

    2013-01-01

    Mink enteritis virus (MEV) is one of the most important viral pathogens in the mink industry. Recent studies have showed that microRNAs (miRNAs), small noncoding RNAs of length ranging from 18-23 nucleotides (nt) participate in host-pathogen interaction networks; however, whether or not miRNAs are involved in MEV infection has not been reported. Our study revealed that miRNA miR-181b inhibited replication of MEV in the feline kidney (F81) cell line by targeting the MEV non-structural protein 1 (NS1) messenger RNA (mRNA) coding region, resulting in NS1 translational repression, while MEV infection reduced miR-181b expression. This is the first description of cellular miRNAs modulating MEV infection in F81 cells, providing further insight into the mechanisms of viral infection, and may be useful in development of naturally-occurring miRNAs antiviral strategies.

  6. Detection of foot-and-mouth disease virus RNA in pharyngeal epithelium biopsy samples obtained from infected cattle: Investigation of possible sites of virus replication and persistence

    DEFF Research Database (Denmark)

    Stenfeldt, Anna Carolina; Belsham, Graham

    2012-01-01

    was used to investigate the level of FMDV RNA present at this site at sequential time points during the infection. Results were compared to measurements of virus excretion in samples of oropharyngeal fluid collected at corresponding time points. Possible sites of virus persistence were investigated through...... measurements of the levels of FMDV RNA in the DSP as well as mandibular and retropharyngeal lymph nodes beyond 28 days after infection. Results indicated only low levels of FMDV RNA present in samples of pharyngeal epithelia during both early and persistent phases of infection with significantly higher levels...

  7. Hibiscus chlorotic ringspot virus coat protein is essential for cell-to-cell and long-distance movement but not for viral RNA replication.

    Directory of Open Access Journals (Sweden)

    Shengniao Niu

    Full Text Available Hibiscus chlorotic ringspot virus (HCRSV is a member of the genus Carmovirus in the family Tombusviridae. In order to study its coat protein (CP functions on virus replication and movement in kenaf (Hibiscus cannabinus L., two HCRSV mutants, designated as p2590 (A to G in which the first start codon ATG was replaced with GTG and p2776 (C to G in which proline 63 was replaced with alanine, were constructed. In vitro transcripts of p2590 (A to G were able to replicate to a similar level as wild type without CP expression in kenaf protoplasts. However, its cell-to-cell movement was not detected in the inoculated kenaf cotyledons. Structurally the proline 63 in subunit C acts as a kink for β-annulus formation during virion assembly. Progeny of transcripts derived from p2776 (C to G was able to move from cell-to-cell in inoculated cotyledons but its long-distance movement was not detected. Virions were not observed in partially purified mutant virus samples isolated from 2776 (C to G inoculated cotyledons. Removal of the N-terminal 77 amino acids of HCRSV CP by trypsin digestion of purified wild type HCRSV virions resulted in only T = 1 empty virus-like particles. Taken together, HCRSV CP is dispensable for viral RNA replication but essential for cell-to-cell movement, and virion is required for the virus systemic movement. The proline 63 is crucial for HCRSV virion assembly in kenaf plants and the N-terminal 77 amino acids including the β-annulus domain is required in T = 3 assembly in vitro.

  8. Expression of MicroRNA miR-122 Facilitates an Efficient Replication in Nonhepatic Cells upon Infection with Hepatitis C Virus

    Science.gov (United States)

    Fukuhara, Takasuke; Kambara, Hiroto; Shiokawa, Mai; Ono, Chikako; Katoh, Hiroshi; Morita, Eiji; Okuzaki, Daisuke; Maehara, Yoshihiko; Koike, Kazuhiko

    2012-01-01

    Hepatitis C virus (HCV) is one of the most common etiologic agents of chronic liver diseases, including liver cirrhosis and hepatocellular carcinoma. In addition, HCV infection is often associated with extrahepatic manifestations (EHM), including mixed cryoglobulinemia and non-Hodgkin's lymphoma. However, the mechanisms of cell tropism of HCV and HCV-induced EHM remain elusive, because in vitro propagation of HCV has been limited in the combination of cell culture-adapted HCV (HCVcc) and several hepatic cell lines. Recently, a liver-specific microRNA called miR-122 was shown to facilitate the efficient propagation of HCVcc in several hepatic cell lines. In this study, we evaluated the importance of miR-122 on the replication of HCV in nonhepatic cells. Among the nonhepatic cell lines expressing functional HCV entry receptors, Hec1B cells derived from human uterus exhibited a low level of replication of the HCV genome upon infection with HCVcc. Exogenous expression of miR-122 in several cells facilitates efficient viral replication but not production of infectious particles, probably due to the lack of hepatocytic lipid metabolism. Furthermore, expression of mutant miR-122 carrying a substitution in a seed domain was required for efficient replication of mutant HCVcc carrying complementary substitutions in miR-122-binding sites, suggesting that specific interaction between miR-122 and HCV RNA is essential for the enhancement of viral replication. In conclusion, although miR-122 facilitates efficient viral replication in nonhepatic cells, factors other than miR-122, which are most likely specific to hepatocytes, are required for HCV assembly. PMID:22593164

  9. Sequence-specific cleavage of BM2 gene transcript of influenza B virus by 10-23 catalytic motif containing DNA enzymes significantly inhibits viral RNA translation and replication.

    Science.gov (United States)

    Kumar, Binod; Kumar, Prashant; Rajput, Roopali; Saxena, Latika; Daga, Mradul K; Khanna, Madhu

    2013-10-01

    One of the hallmarks of progression of influenza virus replication is the step involving the virus uncoating that occurs in the host cytoplasm. The BM2 ion channel protein of influenza B virus is highly conserved and is essentially required during the uncoating processes of virus, thus an attractive target for designing antiviral drugs. We screened several DNA enzymes (Dzs) containing the 10-23 catalytic motif against the influenza B virus BM2 RNA. Dzs directed against the predicted single-stranded bulge regions showed sequence-specific cleavage activities. The Dz209 not only showed significant intracellular reduction of BM2 gene expression in transient-expression system but also provided considerable protection against influenza B virus challenge in MDCK cells. Our findings suggest that the Dz molecule can be used as selective and effective inhibitor of viral RNA replication, and can be explored further for development of a potent therapeutic agent against influenza B virus infection.

  10. Self-replicating alphavirus RNA vaccines.

    Science.gov (United States)

    Ljungberg, Karl; Liljeström, Peter

    2015-02-01

    Recombinant nucleic acids are considered as promising next-generation vaccines. These vaccines express the native antigen upon delivery into tissue, thus mimicking live attenuated vaccines without having the risk of reversion to pathogenicity. They also stimulate the innate immune system, thus potentiating responses. Nucleic acid vaccines are easy to produce at reasonable cost and are stable. During the past years, focus has been on the use of plasmid DNA for vaccination. Now mRNA and replicon vaccines have come into focus as promising technology platforms for vaccine development. This review discusses self-replicating RNA vaccines developed from alphavirus expression vectors. These replicon vaccines can be delivered as RNA, DNA or as recombinant virus particles. All three platforms have been pre-clinically evaluated as vaccines against a number of infectious diseases and cancer. Results have been very encouraging and propelled the first human clinical trials, the results of which have been promising.

  11. Nidovirus replication structures : hijacking membranes to support viral RNA synthesis

    NARCIS (Netherlands)

    Knoops, Kèvin

    2011-01-01

    Positive-stranded RNA viruses replicate in the cytoplasm of host cells and their replication complexes are associated with modified cell membranes. We investigated the structure of the nidovirus-induced membrane modifications and found that nidoviruses transform the endoplasmic reticulum into a reti

  12. Chikungunya virus infectivity, RNA replication and non-structural polyprotein processing depend on the nsP2 protease’s active site cysteine residue

    Science.gov (United States)

    Rausalu, Kai; Utt, Age; Quirin, Tania; Varghese, Finny S.; Žusinaite, Eva; Das, Pratyush Kumar; Ahola, Tero; Merits, Andres

    2016-01-01

    Chikungunya virus (CHIKV), genus Alphavirus, family Togaviridae, has a positive-stand RNA genome approximately 12 kb in length. In infected cells, the genome is translated into non-structural polyprotein P1234, an inactive precursor of the viral replicase, which is activated by cleavages carried out by the non-structural protease, nsP2. We have characterized CHIKV nsP2 using both cell-free and cell-based assays. First, we show that Cys478 residue in the active site of CHIKV nsP2 is indispensable for P1234 processing. Second, the substrate requirements of CHIKV nsP2 are quite similar to those of nsP2 of related Semliki Forest virus (SFV). Third, substitution of Ser482 residue, recently reported to contribute to the protease activity of nsP2, with Ala has almost no negative effect on the protease activity of CHIKV nsP2. Fourth, Cys478 to Ala as well as Trp479 to Ala mutations in nsP2 completely abolished RNA replication in CHIKV and SFV trans-replication systems. In contrast, trans-replicases with Ser482 to Ala mutation were similar to wild type counterparts. Fifth, Cys478 to Ala as well as Trp479 to Ala mutations in nsP2 abolished the rescue of infectious virus from CHIKV RNA transcripts while Ser482 to Ala mutation had no effect. Thus, CHIKV nsP2 is a cysteine protease. PMID:27845418

  13. Reinitiated viral RNA-dependent RNA polymerase resumes replication at a reduced rate

    NARCIS (Netherlands)

    Vilfan, I.D.; Candelli, A.; Hage, S.; Aalto, A.P.; Poranen, M.M.; Bamford, D.H.; Dekker, N.H.

    2008-01-01

    RNA-dependent RNA polymerases (RdRP) form an important class of enzymes that is responsible for genome replication and transcription in RNA viruses and involved in the regulation of RNA interference in plants and fungi. The RdRP kinetics have been extensively studied, but pausing, an important regul

  14. The NS3 and NS4A genes as the targets of RNA interference inhibit replication of Japanese encephalitis virus in vitro and in vivo.

    Science.gov (United States)

    Yuan, Lei; Wu, Rui; Liu, Hanyang; Wen, Xintian; Huang, Xiaobo; Wen, Yiping; Ma, Xiaoping; Yan, Qigui; Huang, Yong; Zhao, Qin; Cao, Sanjie

    2016-12-15

    Japanese encephalitis virus (JEV) is a mosquito-borne flavivirus that can cause acute encephalitis with a high fatality rate. RNA interference (RNAi) is a powerful tool to silence gene expression and a potential therapy for virus infection. In this study, the antiviral ability of eight shRNA expression plasmids targeting different sites of the NS3 and NS4A genes of JEV was determined in BHK21 cells and mice. The pGP-NS3-3 and pGP-NS4A-4 suppressed 93.9% and 82.0% of JEV mRNA in cells, respectively. The virus titer in cells was reduced approximately 950-fold by pretreating with pGP-NS3-4, and 640-fold by pretreating with pGP-NS4A-4. The results of western blot and immunofluorescence analysis showed JEV E protein and viral load in cells were remarkably inhibited by shRNA expression plasmids. The viral load in brains of mice pretreated with pGP-NS3-4 or pGP-NS4A-4 were reduced approximately 2400-fold and 800-fold, respectively, and the survival rate of mice challenged with JEV were 70% and 50%, respectively. However, the antiviral ability of shRNA expression plasmids was decreased over time. This study indicates that RNAi targeting of the NS3 and NS4A genes of JEV can sufficiently inhibit the replication of JEV in vitro and in vivo, and NS3 and NS4A genes might be potential targets of molecular therapy for JEV infection. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Assembly of alphavirus replication complexes from RNA and protein components in a novel trans-replication system in mammalian cells.

    Science.gov (United States)

    Spuul, Pirjo; Balistreri, Giuseppe; Hellström, Kirsi; Golubtsov, Andrey V; Jokitalo, Eija; Ahola, Tero

    2011-05-01

    For positive-strand RNA viruses, the viral genomic RNA also acts as an mRNA directing the translation of the replicase proteins of the virus. Replication takes place in association with cytoplasmic membranes, which are heavily modified to create specific replication compartments. Here we have expressed by plasmid DNA transfection the large replicase polyprotein of Semliki Forest virus (SFV) in mammalian cells from a nonreplicating mRNA and provided a separate RNA containing the replication signals. The replicase proteins were able to efficiently and specifically replicate the template in trans, leading to accumulation of RNA and marker gene products expressed from the template RNA. The replicase proteins and double-stranded RNA replication intermediates localized to structures similar to those seen in SFV-infected cells. Using correlative light electron microscopy (CLEM) with fluorescent marker proteins to relocate those transfected cells, in which active replication was ongoing, abundant membrane modifications, representing the replication complex spherules, were observed both at the plasma membrane and in intracellular endolysosomes. Thus, replication complexes are faithfully assembled and localized in the trans-replication system. We demonstrated, using CLEM, that the replication proteins alone or a polymerase-negative polyprotein mutant together with the template did not give rise to spherule formation. Thus, the trans-replication system is suitable for cell biological dissection and examination in a mammalian cell environment, and similar systems may be possible for other positive-strand RNA viruses.

  16. RNA Interference-Guided Targeting of Hepatitis C Virus Replication with Antisense Locked Nucleic Acid-Based Oligonucleotides Containing 8-oxo-dG Modifications.

    Science.gov (United States)

    Mutso, Margit; Nikonov, Andrei; Pihlak, Arno; Žusinaite, Eva; Viru, Liane; Selyutina, Anastasia; Reintamm, Tõnu; Kelve, Merike; Saarma, Mart; Karelson, Mati; Merits, Andres

    2015-01-01

    The inhibitory potency of an antisense oligonucleotide depends critically on its design and the accessibility of its target site. Here, we used an RNA interference-guided approach to select antisense oligonucleotide target sites in the coding region of the highly structured hepatitis C virus (HCV) RNA genome. We modified the conventional design of an antisense oligonucleotide containing locked nucleic acid (LNA) residues at its termini (LNA/DNA gapmer) by inserting 8-oxo-2'-deoxyguanosine (8-oxo-dG) residues into the central DNA region. Obtained compounds, designed with the aim to analyze the effects of 8-oxo-dG modifications on the antisense oligonucleotides, displayed a unique set of properties. Compared to conventional LNA/DNA gapmers, the melting temperatures of the duplexes formed by modified LNA/DNA gapmers and DNA or RNA targets were reduced by approximately 1.6-3.3°C per modification. Comparative transfection studies showed that small interfering RNA was the most potent HCV RNA replication inhibitor (effective concentration 50 (EC50): 0.13 nM), whereas isosequential standard and modified LNA/DNA gapmers were approximately 50-fold less efficient (EC50: 5.5 and 7.1 nM, respectively). However, the presence of 8-oxo-dG residues led to a more complete suppression of HCV replication in transfected cells. These modifications did not affect the efficiency of RNase H cleavage of antisense oligonucleotide:RNA duplexes but did alter specificity, triggering the appearance of multiple cleavage products. Moreover, the incorporation of 8-oxo-dG residues increased the stability of antisense oligonucleotides of different configurations in human serum.

  17. RNA Interference-Guided Targeting of Hepatitis C Virus Replication with Antisense Locked Nucleic Acid-Based Oligonucleotides Containing 8-oxo-dG Modifications.

    Directory of Open Access Journals (Sweden)

    Margit Mutso

    Full Text Available The inhibitory potency of an antisense oligonucleotide depends critically on its design and the accessibility of its target site. Here, we used an RNA interference-guided approach to select antisense oligonucleotide target sites in the coding region of the highly structured hepatitis C virus (HCV RNA genome. We modified the conventional design of an antisense oligonucleotide containing locked nucleic acid (LNA residues at its termini (LNA/DNA gapmer by inserting 8-oxo-2'-deoxyguanosine (8-oxo-dG residues into the central DNA region. Obtained compounds, designed with the aim to analyze the effects of 8-oxo-dG modifications on the antisense oligonucleotides, displayed a unique set of properties. Compared to conventional LNA/DNA gapmers, the melting temperatures of the duplexes formed by modified LNA/DNA gapmers and DNA or RNA targets were reduced by approximately 1.6-3.3°C per modification. Comparative transfection studies showed that small interfering RNA was the most potent HCV RNA replication inhibitor (effective concentration 50 (EC50: 0.13 nM, whereas isosequential standard and modified LNA/DNA gapmers were approximately 50-fold less efficient (EC50: 5.5 and 7.1 nM, respectively. However, the presence of 8-oxo-dG residues led to a more complete suppression of HCV replication in transfected cells. These modifications did not affect the efficiency of RNase H cleavage of antisense oligonucleotide:RNA duplexes but did alter specificity, triggering the appearance of multiple cleavage products. Moreover, the incorporation of 8-oxo-dG residues increased the stability of antisense oligonucleotides of different configurations in human serum.

  18. Ultrastructural Characterization of Zika Virus Replication Factories

    Directory of Open Access Journals (Sweden)

    Mirko Cortese

    2017-02-01

    Full Text Available A global concern has emerged with the pandemic spread of Zika virus (ZIKV infections that can cause severe neurological symptoms in adults and newborns. ZIKV is a positive-strand RNA virus replicating in virus-induced membranous replication factories (RFs. Here we used various imaging techniques to investigate the ultrastructural details of ZIKV RFs and their relationship with host cell organelles. Analyses of human hepatic cells and neural progenitor cells infected with ZIKV revealed endoplasmic reticulum (ER membrane invaginations containing pore-like openings toward the cytosol, reminiscent to RFs in Dengue virus-infected cells. Both the MR766 African strain and the H/PF/2013 Asian strain, the latter linked to neurological diseases, induce RFs of similar architecture. Importantly, ZIKV infection causes a drastic reorganization of microtubules and intermediate filaments forming cage-like structures surrounding the viral RF. Consistently, ZIKV replication is suppressed by cytoskeleton-targeting drugs. Thus, ZIKV RFs are tightly linked to rearrangements of the host cell cytoskeleton.

  19. Internal RNA Replication Elements are Prevalent in Tombusviridae

    Directory of Open Access Journals (Sweden)

    Beth L Nicholson

    2012-08-01

    Full Text Available Internal replication elements (IREs are RNA structures that are present at internal positions in the genomes of different types of plus-strand RNA viruses. Members of the genus Tombusvirus (family Tombusviridae contain an IRE within the polymerase coding region of their genomes and this RNA element participates in both genome targeting to sites of replication and replicase complex assembly. Here we propose that other members of the virus family Tombusviridae also possess comparable IREs. Through sequence and structural analyses, candidate IREs in several genera of this family were identified, including aureusviruses, necroviruses, carmoviruses and pelarspoviruses. The results from subsequent mutational analysis of selected proposed IREs were consistent with a critical role for these structures in viral genome accumulation during infections. Our study supports the existence of IREs in several genera in Tombusviridae and points to previously unappreciated similarities in genome replication strategies between members of this virus family.

  20. Efficient inhibition of human immunodeficiency virus replication using novel modified microRNA-30a targeting 3′-untranslated region transcripts

    Science.gov (United States)

    NEJATI, AHMAD; SHAHMAHMOODI, SHOHREH; AREFIAN, EHSAN; SHOJA, ZABIHOLLAH; MARASHI, SAYED-MAHDI; TABATABAIE, HAMIDEH; MOLLAEI-KANDELOUS, YAGHOUB; SOLEIMANI, MASOUD; NATEGH, RAKHSHANDEH

    2016-01-01

    RNA interference (RNAi)-based gene therapy is currently considered to be a combinatorial anti-human immunodeficiency virus-1 (HIV-1) therapy. Although artificial polycistronic microRNAs (miRs) can reduce HIV-1 escape mutant variants, this approach may increase the risk of side effects. The present study aimed to optimize the efficiency of anti-HIV RNAi gene therapy in order to reduce the cell toxicity induced by multi-short hairpin RNA expression. An artificial miR-30a-3′-untranslated region (miR-3-UTR) obtained from a single RNA polymerase II was used to simultaneously target all viral transcripts. The results of the present study demonstrated that HIV-1 replication was significantly inhibited in the cells with the miR-3-UTR construct, suggesting that miR-3′-UTR may serve as a promising tool for RNAi-based gene therapy in the treatment of HIV-1. PMID:27168813

  1. Cellular microRNA miR-181b inhibits replication of mink enteritis virus by repression of non-structural protein 1 translation.

    Directory of Open Access Journals (Sweden)

    Jia-zeng Sun

    Full Text Available Mink enteritis virus (MEV is one of the most important viral pathogens in the mink industry. Recent studies have showed that microRNAs (miRNAs, small noncoding RNAs of length ranging from 18-23 nucleotides (nt participate in host-pathogen interaction networks; however, whether or not miRNAs are involved in MEV infection has not been reported. Our study revealed that miRNA miR-181b inhibited replication of MEV in the feline kidney (F81 cell line by targeting the MEV non-structural protein 1 (NS1 messenger RNA (mRNA coding region, resulting in NS1 translational repression, while MEV infection reduced miR-181b expression. This is the first description of cellular miRNAs modulating MEV infection in F81 cells, providing further insight into the mechanisms of viral infection, and may be useful in development of naturally-occurring miRNAs antiviral strategies.

  2. An antioxidant resveratrol significantly enhanced replication of hepatitis C virus

    Institute of Scientific and Technical Information of China (English)

    Mitsuyasu; Nakamura; Masanori; Ikeda; Ryota; Hokari; Nobuyuki; Kato; Toshifumi; Hibi; Soichiro; Miura

    2010-01-01

    AIM:To elucidate the effect of antioxidants,resveratrol (RVT)and astaxanthin(AXN),on hepatitis C virus(HCV) replication. METHODS:We investigated the effect of recent popular antioxidant supplements on replication of the HCV replicon system OR6.RVT is a strong antioxidant and a kind of polyphenol that inhibits replication of various viruses.AXN is also a strong antioxidant.The replication of HCV RNA was assessed by the luciferase reporter assay.An additive effect of antioxidants on antiviral effects of inter...

  3. Receptor tyrosine kinase signaling regulates replication of the peste des petits ruminants virus.

    Science.gov (United States)

    Chaudhary, K; Chaubey, K K; Singh, S V; Kumar, N

    2015-03-01

    In this study, we found out that blocking the receptor tyrosine kinase (RTK) signaling in Vero cells by tryphostin AG879 impairs the in vitro replication of the peste des petits ruminants virus (PPRV). A reduced virus replication in Trk1-knockdown (siRNA) Vero cells confirmed the essential role of RTK in the virus replication, in particular a specific regulation of viral RNA synthesis. These data represent the first evidence that the RTK signaling regulates replication of a morbillivirus.

  4. [Physicochemical properties of Teschen disease virus RNA].

    Science.gov (United States)

    Tsybanov, S Zh; Sergeev, V A; Balysheva, V I

    1982-01-01

    The specific infectivity of virion RNA of teschen disease virus in a sensitive PP cell culture was 4-5 lg TCD50/ml per 1 microgram RNA. When virion RNA was inoculated into cell cultures insusceptible to the native virus, the virus replicated to a titre of 2.0-3.5 lg TCD50/ml. The molecular weight of virion RNA determined by two independent methods was 2.7 x 10(6) daltons. Tm calculated from the curve of virion RNA melting temperature was 57 degrees C. The double-stranded replicative form of RNA recovered from virus-infected PP cells was shown to have sucrose gradient sedimentation coefficient of 20 S. The specific infectivity was 2-3 lg TCD50/ml per 1 microgram of RNA.

  5. Dengue virus binding and replication by platelets.

    Science.gov (United States)

    Simon, Ayo Y; Sutherland, Michael R; Pryzdial, Edward L G

    2015-07-16

    Dengue virus (DENV) infection causes ∼200 million cases of severe flulike illness annually, escalating to life-threatening hemorrhagic fever or shock syndrome in ∼500,000. Although thrombocytopenia is typical of both mild and severe diseases, the mechanism triggering platelet reduction is incompletely understood. As a probable initiating event, direct purified DENV-platelet binding was followed in the current study by quantitative reverse transcription-polymerase chain reaction and confirmed antigenically. Approximately 800 viruses specifically bound per platelet at 37°C. Fewer sites were observed at 25°C, the blood bank storage temperature (∼350 sites), or 4°C, known to attenuate virus cell entry (∼200 sites). Dendritic cell-specific intercellular adhesion molecule-3-grabbing nonintegrin (DC-SIGN) and heparan sulfate proteoglycan were implicated as coreceptors because only the combination of anti-DC-SIGN and low-molecular-weight heparin prevented binding. Interestingly, at 37°C and 25°C, platelets replicated the positive sense single-stranded RNA genome of DENV by up to ∼4-fold over 7 days. Further time course experiments demonstrated production of viral NS1 protein, which is known to be highly antigenic in patient serum. The infectivity of DENV intrinsically decayed in vitro, which was moderated by platelet-mediated generation of viable progeny. This was shown using a transcription inhibitor and confirmed by freeze-denatured platelets being incapable of replicating the DENV genome. For the first time, these data demonstrate that platelets directly bind DENV saturably and produce infectious virus. Thus, expression of antigen encoded by DENV is a novel consideration in the pathogen-induced thrombocytopenia mechanism. These results furthermore draw attention to the possibility that platelets may produce permissive RNA viruses in addition to DENV.

  6. Identification of a new dengue virus inhibitor that targets the viral NS4B protein and restricts genomic RNA replication

    NARCIS (Netherlands)

    Cleef, K.W.R. van; Overheul, G.J.; Thomassen, M.C.; Kaptein, S.J.; Davidson, A.D.; Jacobs, M.; Neyts, J.; Kuppeveld, F.J.M. van; Rij, R.P. van

    2013-01-01

    Dengue virus (DENV) is an important human arthropod-borne virus with a major impact on public health. Nevertheless, a licensed vaccine or specific treatment is still lacking. We therefore screened the NIH Clinical Collection (NCC), a library of drug-like small molecules, for inhibitors of DENV repli

  7. Nuclear proteins hijacked by mammalian cytoplasmic plus strand RNA viruses

    Energy Technology Data Exchange (ETDEWEB)

    Lloyd, Richard E., E-mail: rlloyd@bcm.edu

    2015-05-15

    Plus strand RNA viruses that replicate in the cytoplasm face challenges in supporting the numerous biosynthetic functions required for replication and propagation. Most of these viruses are genetically simple and rely heavily on co-opting cellular proteins, particularly cellular RNA-binding proteins, into new roles for support of virus infection at the level of virus-specific translation, and building RNA replication complexes. In the course of infectious cycles many nuclear-cytoplasmic shuttling proteins of mostly nuclear distribution are detained in the cytoplasm by viruses and re-purposed for their own gain. Many mammalian viruses hijack a common group of the same factors. This review summarizes recent gains in our knowledge of how cytoplasmic RNA viruses use these co-opted host nuclear factors in new functional roles supporting virus translation and virus RNA replication and common themes employed between different virus groups. - Highlights: • Nuclear shuttling host proteins are commonly hijacked by RNA viruses to support replication. • A limited group of ubiquitous RNA binding proteins are commonly hijacked by a broad range of viruses. • Key virus proteins alter roles of RNA binding proteins in different stages of virus replication.

  8. Interaction of Sesbania mosaic virus (SeMV) RNA-dependent RNA polymerase (RdRp) with the p10 domain of polyprotein 2a and its implications in SeMV replication.

    Science.gov (United States)

    Govind, Kunduri; Bakshi, Arindam; Savithri, Handanahal S

    2014-01-01

    Identification of viral encoded proteins that interact with RNA-dependent RNA polymerase (RdRp) is an important step towards unraveling the mechanism of replication. Sesbania mosaic virus (SeMV) RdRp was shown to interact strongly with p10 domain of polyprotein 2a and moderately with the protease domain. Mutational analysis suggested that the C-terminal disordered domain of RdRp is involved in the interaction with p10. Coexpression of full length RdRp and p10 resulted in formation of RdRp-p10 complex which showed significantly higher polymerase activity than RdRp alone. Interestingly, CΔ43 RdRp also showed a similar increase in activity. Thus, p10 acts as a positive regulator of RdRp by interacting with the C-terminal disordered domain of RdRp.

  9. Co-opted oxysterol-binding ORP and VAP proteins channel sterols to RNA virus replication sites via membrane contact sites.

    Science.gov (United States)

    Barajas, Daniel; Xu, Kai; de Castro Martín, Isabel Fernández; Sasvari, Zsuzsanna; Brandizzi, Federica; Risco, Cristina; Nagy, Peter D

    2014-10-01

    Viruses recruit cellular membranes and subvert cellular proteins involved in lipid biosynthesis to build viral replicase complexes and replication organelles. Among the lipids, sterols are important components of membranes, affecting the shape and curvature of membranes. In this paper, the tombusvirus replication protein is shown to co-opt cellular Oxysterol-binding protein related proteins (ORPs), whose deletion in yeast model host leads to decreased tombusvirus replication. In addition, tombusviruses also subvert Scs2p VAP protein to facilitate the formation of membrane contact sites (MCSs), where membranes are juxtaposed, likely channeling lipids to the replication sites. In all, these events result in redistribution and enrichment of sterols at the sites of viral replication in yeast and plant cells. Using in vitro viral replication assay with artificial vesicles, we show stimulation of tombusvirus replication by sterols. Thus, co-opting cellular ORP and VAP proteins to form MCSs serves the virus need to generate abundant sterol-rich membrane surfaces for tombusvirus replication.

  10. Quantitative estimation of Nipah virus replication kinetics in vitro

    Directory of Open Access Journals (Sweden)

    Hassan Sharifah

    2006-06-01

    Full Text Available Abstract Background Nipah virus is a zoonotic virus isolated from an outbreak in Malaysia in 1998. The virus causes infections in humans, pigs, and several other domestic animals. It has also been isolated from fruit bats. The pathogenesis of Nipah virus infection is still not well described. In the present study, Nipah virus replication kinetics were estimated from infection of African green monkey kidney cells (Vero using the one-step SYBR® Green I-based quantitative real-time reverse transcriptase-polymerase chain reaction (qRT-PCR assay. Results The qRT-PCR had a dynamic range of at least seven orders of magnitude and can detect Nipah virus from as low as one PFU/μL. Following initiation of infection, it was estimated that Nipah virus RNA doubles at every ~40 minutes and attained peak intracellular virus RNA level of ~8.4 log PFU/μL at about 32 hours post-infection (PI. Significant extracellular Nipah virus RNA release occurred only after 8 hours PI and the level peaked at ~7.9 log PFU/μL at 64 hours PI. The estimated rate of Nipah virus RNA released into the cell culture medium was ~0.07 log PFU/μL per hour and less than 10% of the released Nipah virus RNA was infectious. Conclusion The SYBR® Green I-based qRT-PCR assay enabled quantitative assessment of Nipah virus RNA synthesis in Vero cells. A low rate of Nipah virus extracellular RNA release and low infectious virus yield together with extensive syncytial formation during the infection support a cell-to-cell spread mechanism for Nipah virus infection.

  11. The IFITMs Inhibit Zika Virus Replication

    Directory of Open Access Journals (Sweden)

    George Savidis

    2016-06-01

    Full Text Available Zika virus has emerged as a severe health threat with a rapidly expanding range. The IFITM family of restriction factors inhibits the replication of a broad range of viruses, including the closely related flaviruses West Nile virus and dengue virus. Here, we show that IFITM1 and IFITM3 inhibit Zika virus infection early in the viral life cycle. Moreover, IFITM3 can prevent Zika-virus-induced cell death. These results suggest that strategies to boost the actions and/or levels of the IFITMs might be useful for inhibiting a broad range of emerging viruses.

  12. DNA intercalator stimulates influenza transcription and virus replication

    Directory of Open Access Journals (Sweden)

    Poon Leo LM

    2011-03-01

    Full Text Available Abstract Influenza A virus uses its host transcription machinery to facilitate viral RNA synthesis, an event that is associated with cellular RNA polymerase II (RNAPII. In this study, various RNAPII transcription inhibitors were used to investigate the effect of RNAPII phosphorylation status on viral RNA transcription. A low concentration of DNA intercalators, such as actinomycin D (ActD, was found to stimulate viral polymerase activity and virus replication. This effect was not observed in cells treated with RNAPII kinase inhibitors. In addition, the loss of RNAPIIa in infected cells was due to the shift of nonphosphorylated RNAPII (RNAPIIa to hyperphosphorylated RNAPII (RNAPIIo.

  13. DNA intercalator stimulates influenza transcription and virus replication.

    Science.gov (United States)

    Li, Olive T W; Poon, Leo L M

    2011-03-15

    Influenza A virus uses its host transcription machinery to facilitate viral RNA synthesis, an event that is associated with cellular RNA polymerase II (RNAPII). In this study, various RNAPII transcription inhibitors were used to investigate the effect of RNAPII phosphorylation status on viral RNA transcription. A low concentration of DNA intercalators, such as actinomycin D (ActD), was found to stimulate viral polymerase activity and virus replication. This effect was not observed in cells treated with RNAPII kinase inhibitors. In addition, the loss of RNAPII(a) in infected cells was due to the shift of nonphosphorylated RNAPII (RNAPII(a)) to hyperphosphorylated RNAPII (RNAPII(o)).

  14. Host ESCRT proteins are required for bromovirus RNA replication compartment assembly and function.

    Directory of Open Access Journals (Sweden)

    Arturo Diaz

    2015-03-01

    Full Text Available Positive-strand RNA viruses genome replication invariably is associated with vesicles or other rearranged cellular membranes. Brome mosaic virus (BMV RNA replication occurs on perinuclear endoplasmic reticulum (ER membranes in ~70 nm vesicular invaginations (spherules. BMV RNA replication vesicles show multiple parallels with membrane-enveloped, budding retrovirus virions, whose envelopment and release depend on the host ESCRT (endosomal sorting complexes required for transport membrane-remodeling machinery. We now find that deleting components of the ESCRT pathway results in at least two distinct BMV phenotypes. One group of genes regulate RNA replication and the frequency of viral replication complex formation, but had no effect on spherule size, while a second group of genes regulate RNA replication in a way or ways independent of spherule formation. In particular, deleting SNF7 inhibits BMV RNA replication > 25-fold and abolishes detectable BMV spherule formation, even though the BMV RNA replication proteins accumulate and localize normally on perinuclear ER membranes. Moreover, BMV ESCRT recruitment and spherule assembly depend on different sets of protein-protein interactions from those used by multivesicular body vesicles, HIV-1 virion budding, or tomato bushy stunt virus (TBSV spherule formation. These and other data demonstrate that BMV requires cellular ESCRT components for proper formation and function of its vesicular RNA replication compartments. The results highlight growing but diverse interactions of ESCRT factors with many viruses and viral processes, and potential value of the ESCRT pathway as a target for broad-spectrum antiviral resistance.

  15. Host ESCRT proteins are required for bromovirus RNA replication compartment assembly and function.

    Science.gov (United States)

    Diaz, Arturo; Zhang, Jiantao; Ollwerther, Abigail; Wang, Xiaofeng; Ahlquist, Paul

    2015-03-01

    Positive-strand RNA viruses genome replication invariably is associated with vesicles or other rearranged cellular membranes. Brome mosaic virus (BMV) RNA replication occurs on perinuclear endoplasmic reticulum (ER) membranes in ~70 nm vesicular invaginations (spherules). BMV RNA replication vesicles show multiple parallels with membrane-enveloped, budding retrovirus virions, whose envelopment and release depend on the host ESCRT (endosomal sorting complexes required for transport) membrane-remodeling machinery. We now find that deleting components of the ESCRT pathway results in at least two distinct BMV phenotypes. One group of genes regulate RNA replication and the frequency of viral replication complex formation, but had no effect on spherule size, while a second group of genes regulate RNA replication in a way or ways independent of spherule formation. In particular, deleting SNF7 inhibits BMV RNA replication > 25-fold and abolishes detectable BMV spherule formation, even though the BMV RNA replication proteins accumulate and localize normally on perinuclear ER membranes. Moreover, BMV ESCRT recruitment and spherule assembly depend on different sets of protein-protein interactions from those used by multivesicular body vesicles, HIV-1 virion budding, or tomato bushy stunt virus (TBSV) spherule formation. These and other data demonstrate that BMV requires cellular ESCRT components for proper formation and function of its vesicular RNA replication compartments. The results highlight growing but diverse interactions of ESCRT factors with many viruses and viral processes, and potential value of the ESCRT pathway as a target for broad-spectrum antiviral resistance.

  16. siRNA-mediated inhibition of HBV replication and expression

    Institute of Scientific and Technical Information of China (English)

    Xiao-Nan Zhang; Wei Xiong; Jia-Dong Wang; Yun-Wen Hu; Li Xiang; Zheng-Hong Yuan

    2004-01-01

    AIM: RNA interference (RNAi) is a newly discovered phenomenon provoked by dsRNA. The dsRNA is initially cleaved by Dicer into 21-23 nt small interfering RNA (siRNA)and can then specifically target homologous mRNA for degradation by cellular ribonucleases. RNAi has been successfully utilized to down-regulate the endogenous gene expression or suppress the replication of various pathogens in mammalian cells. In this study, we investigated whether vector-based siRNA promoted by U6 (pSilencer1.0-U6)could efficiently inhibit HBV replication in cell culture.METHODS: pSilencer vectors with inserts targeting on different regions of HBV genome were constructed. These plasmids were co-transfected with pHBV3.8 into Huh-7 cells via lipofection and viral antigens were measured by ELISA.Viral RNA was analyzed by Northern blot. The mRNA of MxA and 2′-5′OAS was reverse transcribed and quantified by real-time PCR.RESULTS: Vector-based siRNA could potently reduce hepatitis B virus antigen expression in transient replicative cell culture. Furthermore, Northern blot analysis showed that viral RNA was effectively degraded, thus eliminating the messengers for protein expression as well as template for reverse transcription. Real-time PCR analysis of cellular MxA and 2′-5′OAS gene expression revealed that vectorbased siRNA did not provoke the interferon pathway which reassured the specificity of the vector-based RNA interference technique.CONCLUSION: Our results indicate that RNA interference may be a potential tool to control HBV infection.

  17. Origin of the membrane compartment for cowpea mosaic virus replication

    NARCIS (Netherlands)

    Carette, J.E.

    2002-01-01

    Replication of many positive-stranded RNA viruses takes place in association with intracellular membranes. Often these membranes are induced upon infection by vesiculation or rearrangement of membranes from different organelles including the early and late endomembrane system. Upon infection of cowp

  18. RNA interference targets arbovirus replication in Culicoides cells.

    Science.gov (United States)

    Schnettler, Esther; Ratinier, Maxime; Watson, Mick; Shaw, Andrew E; McFarlane, Melanie; Varela, Mariana; Elliott, Richard M; Palmarini, Massimo; Kohl, Alain

    2013-03-01

    Arboviruses are transmitted to vertebrate hosts by biting arthropod vectors such as mosquitoes, ticks, and midges. These viruses replicate in both arthropods and vertebrates and are thus exposed to different antiviral responses in these organisms. RNA interference (RNAi) is a sequence-specific RNA degradation mechanism that has been shown to play a major role in the antiviral response against arboviruses in mosquitoes. Culicoides midges are important vectors of arboviruses, known to transmit pathogens of humans and livestock such as bluetongue virus (BTV) (Reoviridae), Oropouche virus (Bunyaviridae), and likely the recently discovered Schmallenberg virus (Bunyaviridae). In this study, we investigated whether Culicoides cells possess an antiviral RNAi response and whether this is effective against arboviruses, including those with double-stranded RNA (dsRNA) genomes, such as BTV. Using reporter gene-based assays, we established the presence of a functional RNAi response in Culicoides sonorensis-derived KC cells which is effective in inhibiting BTV infection. Sequencing of small RNAs from KC and Aedes aegypti-derived Aag2 cells infected with BTV or the unrelated Schmallenberg virus resulted in the production of virus-derived small interfering RNAs (viRNAs) of 21 nucleotides, similar to the viRNAs produced during arbovirus infections of mosquitoes. In addition, viRNA profiles strongly suggest that the BTV dsRNA genome is accessible to a Dicer-type nuclease. Thus, we show for the first time that midge cells target arbovirus replication by mounting an antiviral RNAi response mainly resembling that of other insect vectors of arboviruses.

  19. Sensing of RNA viruses

    DEFF Research Database (Denmark)

    Jensen, Søren; Thomsen, Allan Randrup

    2012-01-01

    pathogen-associated molecular patterns have emerged in great detail. This review presents an overview of our current knowledge regarding the receptors used to detect RNA virus invasion, the molecular structures these receptors sense, and the involved downstream signaling pathways.......Our knowledge regarding the contribution of the innate immune system in recognizing and subsequently initiating a host response to an invasion of RNA virus has been rapidly growing over the last decade. Descriptions of the receptors involved and the molecular mechanisms they employ to sense viral...

  20. Neither the RNA nor the Proteins of Open Reading Frames 3a and 3b of the Coronavirus Infectious Bronchitis Virus Are Essential for Replication

    Science.gov (United States)

    Hodgson, Teri; Britton, Paul; Cavanagh, Dave

    2006-01-01

    Gene 3 of infectious bronchitis virus is tricistronic; open reading frames (ORFs) 3a and 3b encode two small nonstructural (ns) proteins, 3a and 3b, of unknown function, and a third, structural protein E, is encoded by ORF 3c. To determine if either the 3a or the 3b protein is required for replication, we first modified their translation initiation codons to prevent translation of the 3a and 3b proteins from recombinant infectious bronchitis viruses (rIBVs). Replication in primary chick kidney (CK) cells and in chicken embryos was not affected. In chicken tracheal organ cultures (TOCs), the recombinant rIBVs reached titers similar to those of the wild-type virus, but in the case of viruses lacking the 3a protein, the titer declined reproducibly earlier. Translation of the IBV E protein is believed to be initiated by internal entry of ribosomes at a structure formed by the sequences corresponding to ORFs 3a and 3b. To assess the necessity of this mechanism, we deleted most of the sequence representing 3a and 3b to produce a gene in which ORF 3c (E) was adjacent to the gene 3 transcription-associated sequence. Western blot analysis revealed that the recombinant IBV produced fivefold less E protein. Nevertheless, titers produced in CK cells, embryos, and TOCs were similar to those of the wild-type virus, although they declined earlier in TOCs, probably due to the absence of the 3a protein. Thus, neither the tricistronic arrangement of gene 3, the internal initiation of translation of E protein, nor the 3a and 3b proteins are essential for replication per se, suggesting that these proteins are accessory proteins that may have roles in vivo. PMID:16352554

  1. Roles for endocytic trafficking and phosphatidylinositol 4-kinase III alpha in hepatitis C virus replication

    OpenAIRE

    Kristi L. Berger; Cooper, Jacob D.; Nicholas S. Heaton; Yoon, Rosa; Oakland, Todd E.; Jordan, Tristan X.; Mateu, Guaniri; Grakoui, Arash; Randall, Glenn

    2009-01-01

    Hepatitis C virus (HCV) reorganizes cellular membranes to establish sites of replication. The required host pathways and the mechanism of cellular membrane reorganization are poorly characterized. Therefore, we interrogated a customized small interfering RNA (siRNA) library that targets 140 host membrane-trafficking genes to identify genes required for both HCV subgenomic replication and infectious virus production. We identified 7 host cofactors of viral replication, including Cdc42 and Rock...

  2. RNA Replication and Membrane Modification Require the Same Functions of Alphavirus Nonstructural Proteins.

    Science.gov (United States)

    Kallio, Katri; Hellström, Kirsi; Jokitalo, Eija; Ahola, Tero

    2015-11-18

    The alphaviruses induce membrane invaginations known as spherules as their RNA replication sites. Here, we show that inactivation of any function (polymerase, helicase, protease, or membrane association) essential for RNA synthesis also prevents the generation of spherule structures in a Semliki Forest virus trans-replication system. Mutants capable of negative-strand synthesis, including those defective in RNA capping, gave rise to spherules. Recruitment of RNA to membranes in the absence of spherule formation was not detected.

  3. Regulation of arginine methyltransferase 3 by a Wolbachia-induced microRNA in Aedes aegypti and its effect on Wolbachia and dengue virus replication.

    Science.gov (United States)

    Zhang, Guangmei; Hussain, Mazhar; Asgari, Sassan

    2014-10-01

    The gram-negative endosymbiotic bacteria, Wolbachia, have been found to colonize a wide range of invertebrates, including over 40% of insect species. Best known for host reproductive manipulations, some strains of Wolbachia have been shown to reduce the host life span by about 50% and inhibit replication and transmission of dengue virus (DENV) in the mosquito vector, Aedes aegypti. The molecular mechanisms underlying these effects still are not well understood. Our previous studies showed that Wolbachia uses host microRNAs (miRNAs) to manipulate host gene expression for its efficient maintenance and limiting replication of DENV in Ae. aegypti. Protein arginine methyltransferases are structurally and functionally conserved proteins from yeast to human. In mammals, it has been reported that protein arginine methyltransferases such as PRMT1, 5 and 6 could regulate replication of different viruses. Ae. aegypti contains eight members of protein arginine methyltransferases (AaArgM1-8). Here, we show that the wMelPop strain of Wolbachia introduced into Ae. aegypti significantly induces the expression of AaArgM3. Interestingly, we found that Wolbachia uses aae-miR-2940, which is highly upregulated in Wolbachia-infected mosquitoes, to upregulate the expression of AaArgM3. Silencing of AaArgM3 in a mosquito cell line led to a significant reduction in Wolbachia replication, but had no effect on the replication of DENV. These results provide further evidence that Wolbachia uses the host miRNAs to manipulate host gene expression and facilitate colonization in Ae. aegypti mosquito.

  4. The RNA synthesis machinery of negative-stranded RNA viruses

    Energy Technology Data Exchange (ETDEWEB)

    Ortín, Juan, E-mail: jortin@cnb.csic.es [Department of Molecular and Cellular Biology, Centro Nacional de Biotecnología (CSIC) and CIBER de Enfermedades Respiratorias (ISCIII), Madrid (Spain); Martín-Benito, Jaime, E-mail: jmartinb@cnb.csic.es [Department of Macromolecular Structures, Centro Nacional de Biotecnología (CSIC), Madrid (Spain)

    2015-05-15

    The group of Negative-Stranded RNA Viruses (NSVs) includes many human pathogens, like the influenza, measles, mumps, respiratory syncytial or Ebola viruses, which produce frequent epidemics of disease and occasional, high mortality outbreaks by transmission from animal reservoirs. The genome of NSVs consists of one to several single-stranded, negative-polarity RNA molecules that are always assembled into mega Dalton-sized complexes by association to many nucleoprotein monomers. These RNA-protein complexes or ribonucleoproteins function as templates for transcription and replication by action of the viral RNA polymerase and accessory proteins. Here we review our knowledge on these large RNA-synthesis machines, including the structure of their components, the interactions among them and their enzymatic activities, and we discuss models showing how they perform the virus transcription and replication programmes. - Highlights: • Overall organisation of NSV RNA synthesis machines. • Structure and function of the ribonucleoprotein components: Atomic structure of the RNA polymerase complex. • Commonalities and differences between segmented- and non-segmented NSVs. • Transcription versus replication programmes.

  5. Destabilization of PDK1 by Hsp90 inactivation suppresses hepatitis C virus replication through inhibition of PRK2-mediated viral RNA polymerase phosphorylation.

    Science.gov (United States)

    Kim, Mi-Gyeong; Moon, Jae-Su; Kim, Eun-Jung; Lee, Seung-Hoon; Oh, Jong-Won

    2012-04-27

    Heat shock protein 90 (Hsp90), which chaperones multiple client proteins, has been shown to be implicated in HCV replication. Pharmacological inhibitors of Hsp90 display an anti-HCV activity. However, little is known about the mechanisms of regulation of HCV replication by Hsp90. Here, we show that Hsp90 inhibition by 17-(dimethylaminoethylamino)-17-demethoxygeldanamycin (17-DMAG) destabilizes phosphoinositide-dependent kinase-1 (PDK1), an upstream kinase of the protein kinase C-related kinase 2 (PRK2) responsible for phosphorylation of HCV RNA polymerase, through the proteosome pathway. Destabilization of PDK1 led to inhibition of phosphorylation of the viral RNA polymerase through a decrease in the abundance of active form PRK2 level. Consequently, Hsp90 inhibition resulted in suppression of HCV replication both in human hepatoma Huh7 cells harboring an HCV subgenomic replicon and in HCV-infected cells. 17-DMAG treatment did not interfere with HCV internal ribosome entry site-mediated translation and the cell cycle in Huh7 cells. Co-treatment of 17-DMAG with interferon-α or HA1077, an inhibitor of PRK2, enhanced the anti-HCV activity of 17-DMAG. Taken together, these findings suggest that Hsp90 plays a critical role in the regulation of HCV RNA polymerase phosphorylation via the PDK1-PRK2 signaling pathway.

  6. RNA chaperones encoded by RNA viruses

    Institute of Scientific and Technical Information of China (English)

    Jie Yang; Hongjie Xia; Qi Qian; Xi Zhou

    2015-01-01

    RNAs are functionally diverse macromolecules whose proper functions rely strictly upon their correct tertiary structures. However, because of their high structural flexibility, correct folding of RNAs is challenging and slow. Therefore, cells and viruses encode a variety of RNA remodeling proteins, including helicases and RNA chaperones. In RNA viruses, these proteins are believed to play pivotal roles in all the processes involving viral RNAs during the life cycle. RNA helicases have been studied extensively for decades, whereas RNA chaperones, particularly virus-encoded RNA chaperones, are often overlooked. This review describes the activities of RNA chaperones encoded by RNA viruses, particularly the ones identified and characterized in recent years, and the functions of these proteins in different steps of viral life cycles, and presents an overview of this unique group of proteins.

  7. RNA topology remoulds electrostatic stabilization of viruses

    CERN Document Server

    Erdemci-Tandogan, Gonca; van der Schoot, Paul; Podgornik, Rudolf; Zandi, Roya

    2013-01-01

    Simple RNA viruses efficiently encapsulate their genome into a nano-sized protein shell-the capsid. Spontaneous co-assembly of the genome and the capsid proteins is driven predominantly by electrostatic interactions between the negatively charged RNA and the positively charged inner capsid wall. Using field theoretic formulation we show that the inherently branched RNA secondary structure allows viruses to {\\sl maximize} the amount of encapsulated genome and make assembly more efficient, allowing viral RNAs to out-compete cellular RNAs during replication in infected host cells.

  8. Multiscale modeling of virus replication and spread.

    Science.gov (United States)

    Kumberger, Peter; Frey, Felix; Schwarz, Ulrich S; Graw, Frederik

    2016-07-01

    Replication and spread of human viruses is based on the simultaneous exploitation of many different host functions, bridging multiple scales in space and time. Mathematical modeling is essential to obtain a systems-level understanding of how human viruses manage to proceed through their life cycles. Here, we review corresponding advances for viral systems of large medical relevance, such as human immunodeficiency virus-1 (HIV-1) and hepatitis C virus (HCV). We will outline how the combination of mathematical models and experimental data has advanced our quantitative knowledge about various processes of these pathogens, and how novel quantitative approaches promise to fill remaining gaps.

  9. RNA-dependent RNA polymerases from cowpea mosaic virus-infected cowpea leaves

    NARCIS (Netherlands)

    Dorssers, L.C.J.

    1983-01-01

    The aim of the research described in this thesis was the purification and identification of the RNA-dependent RNA polymerase engaged in replicating viral RNA in cowpea mosaic virus (CPMV)- infected cowpea leaves.Previously, an RNA-dependent RNA polymerase produced upon infection of Vigna unguiculata

  10. Dengue virus replicates and accumulates in Aedes aegypti salivary glands.

    Science.gov (United States)

    Raquin, Vincent; Lambrechts, Louis

    2017-07-01

    Dengue virus (DENV) is an RNA virus transmitted among humans by mosquito vectors, mainly Aedes aegypti. DENV transmission requires viral dissemination from the mosquito midgut to the salivary glands. During this process the virus undergoes several population bottlenecks, which are stochastic reductions in population size that restrict intra-host viral genetic diversity and limit the efficiency of natural selection. Despite the implications for virus transmission and evolution, DENV replication in salivary glands has not been directly demonstrated. Here, we used a strand-specific quantitative RT-PCR assay to demonstrate that negative-strand DENV RNA is produced in Ae. aegypti salivary glands, providing conclusive evidence that viral replication occurs in this tissue. Furthermore, we showed that the concentration of DENV genomic RNA in salivary glands increases significantly over time, indicating that active replication likely replenishes DENV genetic diversity prior to transmission. These findings improve our understanding of the biological determinants of DENV fitness and evolution. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. Replication of biotinylated human immunodeficiency viruses.

    Science.gov (United States)

    Belshan, Michael; Matthews, John M; Madson, Christian J

    2011-01-01

    Previous work demonstrated recently the adaptation of the Escherichia coli biotin ligase BirA - biotin acceptor sequence (BAS) labeling system to produce human immunodeficiency virus type 1 viruses with biotinylated integrase (NLXIN(B)) and matrix (NLXMA(B)) proteins (Belshan et al., 2009). This report describes the construction of an HIV permissive cell line stably expressing BirA (SupT1.BirA). Consistent with the results in the previous report, NLXMA(B) replicated similar to wild-type levels and expressed biotinylated Gag and MA proteins in the SupT1.BirA cells, whereas the replication of NLXIN(B) was reduced severely. Three additional HIV type 2 (HIV-2) viruses were constructed with the BAS inserted into the vpx and vpr accessory genes. Two BAS insertions were made into the C-terminal half of the Vpx, including one internal insertion, and one at the N-terminus of Vpr. All three viruses were replication competent in the SupT1.BirA cells and their target proteins biotinylated efficiently and incorporated into virions. These results demonstrate the potential utility of the biotinylation system to label and capture HIV protein complexes in the context of replicating virus.

  12. Genes and sequences involved in the replication of cowpea mosaic virus RNAs

    NARCIS (Netherlands)

    Eggen, R.

    1989-01-01

    The aim of the studies described in this thesis was to gain more insight in the complex molecular mechanisms underlying the RNA replication of the cowpea mosaic virus genome. Previously the replication of CPMV RNA has been examined extensively with crude membrane fractions prepared from CP

  13. Genes and sequences involved in the replication of cowpea mosaic virus RNAs.

    NARCIS (Netherlands)

    Eggen, R.

    1989-01-01

    The aim of the studies described in this thesis was to gain more insight in the complex molecular mechanisms underlying the RNA replication of the cowpea mosaic virus genome. Previously the replication of CPMV RNA has been examined extensively with crude membrane fractions prepared from CPMV inf

  14. Low oxygen tension enhances hepatitis C virus replication.

    Science.gov (United States)

    Vassilaki, N; Kalliampakou, K I; Kotta-Loizou, I; Befani, C; Liakos, P; Simos, G; Mentis, A F; Kalliaropoulos, A; Doumba, P P; Smirlis, D; Foka, P; Bauhofer, O; Poenisch, M; Windisch, M P; Lee, M E; Koskinas, J; Bartenschlager, R; Mavromara, P

    2013-03-01

    Low oxygen tension exerts a significant effect on the replication of several DNA and RNA viruses in cultured cells. In vitro propagation of hepatitis C virus (HCV) has thus far been studied under atmospheric oxygen levels despite the fact that the liver tissue microenvironment is hypoxic. In this study, we investigated the efficiency of HCV production in actively dividing or differentiating human hepatoma cells cultured under low or atmospheric oxygen tensions. By using both HCV replicons and infection-based assays, low oxygen was found to enhance HCV RNA replication whereas virus entry and RNA translation were not affected. Hypoxia signaling pathway-focused DNA microarray and real-time quantitative reverse transcription-PCR (qRT-PCR) analyses revealed an upregulation of genes related to hypoxic stress, glycolytic metabolism, cell growth, and proliferation when cells were kept under low (3% [vol/vol]) oxygen tension, likely reflecting cell adaptation to anaerobic conditions. Interestingly, hypoxia-mediated enhancement of HCV replication correlated directly with the increase in anaerobic glycolysis and creatine kinase B (CKB) activity that leads to elevated ATP production. Surprisingly, activation of hypoxia-inducible factor alpha (HIF-α) was not involved in the elevation of HCV replication. Instead, a number of oncogenes known to be associated with glycolysis were upregulated and evidence that these oncogenes contribute to hypoxia-mediated enhancement of HCV replication was obtained. Finally, in liver biopsy specimens of HCV-infected patients, the levels of hypoxia and anaerobic metabolism markers correlated with HCV RNA levels. These results provide new insights into the impact of oxygen tension on the intricate HCV-host cell interaction.

  15. Cost-effective method of siRNA preparation and its application to inhibit hepatitis B virus replication in HepG2 cells

    Institute of Scientific and Technical Information of China (English)

    Zhi-Kang Qian; Bao-Qin Xuan; Tai-Shan Min; Jian-Feng Xu; Lin Li; Wei-Da Huang

    2005-01-01

    AIM: To find a cost-effective method of preparation of short interfering RNAs based on cloning, fermentation,digestion and purification (CFDP) and test its feasibility to inhibit hepatitis B virus replication in cell culture.METHODS: We constructed an expression vector containing T7 and tac promoter in a head-to-head orientation.cDNA fragment of interest was cloned into this vector between the opposing promoters. dsRNAs were expressed with this vector in Escherichia coli, and purified by affinity chromatography using CF 11 column. They were digested by RNase Ⅲ in a buffer containing manganese ions, then separated on 15% non-denaturing PAGE, and the siRNAs about 25 bp in length were recovered. siRNAs prepared with CFDP were co-transfected with target gene expression plasmid into human cell lines with lipofectamine 2000 to test their inhibition efficiency.RESULTS: siRNAs corresponding to part of the hepatitis3 virus polymerase gene (siHBVP) prepared by CFDP specifically and dramatically suppressed the virus protein expression. The HBsAg expression level was reduced to 10% that of the control by co-transfection of 60 nmol/L siHBVP in SMMC7721 cells. Dose-dependent effect on suppression of HBsAg and HBeAg expression was observed in HepG2 cells. The highest inhibition rate was kept at 70% during the six days after transfection of 7.5 nmol/L siHBVP.CONCLUSION: We show CFDP is a very promising method to prepare therapeutic agents in anti-virus applications.

  16. Chikungunya virus infectivity, RNA replication and non-structural polyprotein processing depend on the nsP2 protease’s active site cysteine residue

    OpenAIRE

    Kai Rausalu; Age Utt; Tania Quirin; Varghese, Finny S.; Eva Žusinaite; Pratyush Kumar Das; Tero Ahola; Andres Merits

    2016-01-01

    Chikungunya virus (CHIKV), genus Alphavirus, family Togaviridae, has a positive-stand RNA genome approximately 12 kb in length. In infected cells, the genome is translated into non-structural polyprotein P1234, an inactive precursor of the viral replicase, which is activated by cleavages carried out by the non-structural protease, nsP2. We have characterized CHIKV nsP2 using both cell-free and cell-based assays. First, we show that Cys478 residue in the active site of CHIKV nsP2 is indispensa...

  17. Conserved elements within the genome of foot-and mouth disease virus; their influence on virus replication

    DEFF Research Database (Denmark)

    Kjær, Jonas; Poulsen, Line D.; Vinther, Jeppe

    ) has identified a conserved RNA structure within the 3Dpol coding region (the RNA-dependent RNA polymerase) which might have an important role in virus replication. The FMDV 2A peptide, another conserved element, is responsible for the primary “cleavage” at its own C-terminus (2A/2B junction......DNA containing Gaussia luciferase. RNA transcripts were generated in vitro from the plasmids, and introduced into BHK cells by electroporation. The replication efficiency was assessed by measurement of luciferase activity or by rescue of mutant viruses. The rescued viruses derived from the 2A mutant cDNAs were......Objectives: Several conserved elements within the genome of foot-and-mouth disease virus (FMDV) have been identified, e.g. the IRES. Such elements can be crucial for the efficient replication of the genomic RNA. Previously, SHAPE analysis of the entire FMDV genome (Poulsen et al., 2016 submitted...

  18. The clinically approved antiviral drug sofosbuvir inhibits Zika virus replication

    Science.gov (United States)

    Sacramento, Carolina Q.; de Melo, Gabrielle R.; de Freitas, Caroline S.; Rocha, Natasha; Hoelz, Lucas Villas Bôas; Miranda, Milene; Fintelman-Rodrigues, Natalia; Marttorelli, Andressa; Ferreira, André C.; Barbosa-Lima, Giselle; Abrantes, Juliana L.; Vieira, Yasmine Rangel; Bastos, Mônica M.; de Mello Volotão, Eduardo; Nunes, Estevão Portela; Tschoeke, Diogo A.; Leomil, Luciana; Loiola, Erick Correia; Trindade, Pablo; Rehen, Stevens K.; Bozza, Fernando A.; Bozza, Patrícia T.; Boechat, Nubia; Thompson, Fabiano L.; de Filippis, Ana M. B.; Brüning, Karin; Souza, Thiago Moreno L.

    2017-01-01

    Zika virus (ZIKV) is a member of the Flaviviridae family, along with other agents of clinical significance such as dengue (DENV) and hepatitis C (HCV) viruses. Since ZIKV causes neurological disorders during fetal development and in adulthood, antiviral drugs are necessary. Sofosbuvir is clinically approved for use against HCV and targets the protein that is most conserved among the members of the Flaviviridae family, the viral RNA polymerase. Indeed, we found that sofosbuvir inhibits ZIKV RNA polymerase, targeting conserved amino acid residues. Sofosbuvir inhibited ZIKV replication in different cellular systems, such as hepatoma (Huh-7) cells, neuroblastoma (SH-Sy5y) cells, neural stem cells (NSC) and brain organoids. In addition to the direct inhibition of the viral RNA polymerase, we observed that sofosbuvir also induced an increase in A-to-G mutations in the viral genome. Together, our data highlight a potential secondary use of sofosbuvir, an anti-HCV drug, against ZIKV. PMID:28098253

  19. Structure and replication of hepatitis delta virus

    African Journals Online (AJOL)

    STORAGESEVER

    2008-12-29

    Dec 29, 2008 ... Unidade de Biologia Molecular, Centro de Malária e outras Doenças Tropicais, Instituto de Higiene e Medicina Tropical, ... molecules of both delta antigens (Ryu et al., 1993). This ..... Glenn JS, Watson JA, Havel CM, White JO (1992). ... HDV RNA encoding the large delta antigen cannot replicate. J. Gen.

  20. Anti-HCV RNA Aptamers Targeting the Genomic cis-Acting Replication Element

    Directory of Open Access Journals (Sweden)

    Alfredo Berzal-Herranz

    2011-12-01

    Full Text Available Hepatitis C virus (HCV replication is dependent on the existence of several highly conserved functional genomic RNA domains. The cis-acting replication element (CRE, located within the 3' end of the NS5B coding region of the HCV genome, has been shown essential for efficient viral replication. Its sequence and structural features determine its involvement in functional interactions with viral RNA-dependent RNA polymerase and distant RNA domains of the viral genome. This work reports the use of an in vitro selection strategy to select aptamer RNA molecules against the complete HCV-CRE. After six selection cycles, five potential target sites were identified within this domain. Inhibition assays using a sample of representative aptamers showed that the selected RNAs significantly inhibit the replication (>80% of a subgenomic HCV replicon in Huh-7 cell cultures. These results highlight the potential of aptamer RNA molecules as therapeutic antiviral agents.

  1. Porcine Epidemic Diarrhea Virus Induces Autophagy to Benefit Its Replication

    Directory of Open Access Journals (Sweden)

    Xiaozhen Guo

    2017-03-01

    Full Text Available The new porcine epidemic diarrhea (PED has caused devastating economic losses to the swine industry worldwide. Despite extensive research on the relationship between autophagy and virus infection, the concrete role of autophagy in porcine epidemic diarrhea virus (PEDV infection has not been reported. In this study, autophagy was demonstrated to be triggered by the effective replication of PEDV through transmission electron microscopy, confocal microscopy, and Western blot analysis. Moreover, autophagy was confirmed to benefit PEDV replication by using autophagy regulators and RNA interference. Furthermore, autophagy might be associated with the expression of inflammatory cytokines and have a positive feedback loop with the NF-κB signaling pathway during PEDV infection. This work is the first attempt to explore the complex interplay between autophagy and PEDV infection. Our findings might accelerate our understanding of the pathogenesis of PEDV infection and provide new insights into the development of effective therapeutic strategies.

  2. Suramin inhibits chikungunya virus replication through multiple mechanisms.

    Science.gov (United States)

    Albulescu, Irina C; van Hoolwerff, Marcella; Wolters, Laura A; Bottaro, Elisabetta; Nastruzzi, Claudio; Yang, Shih Chi; Tsay, Shwu-Chen; Hwu, Jih Ru; Snijder, Eric J; van Hemert, Martijn J

    2015-09-01

    Chikungunya virus (CHIKV) is a mosquito-borne alphavirus that causes severe and often persistent arthritis. In recent years, millions of people have been infected with this virus for which registered antivirals are still lacking. Using our recently established in vitro assay, we discovered that the approved anti-parasitic drug suramin inhibits CHIKV RNA synthesis (IC50 of ∼5μM). The compound inhibited replication of various CHIKV isolates in cell culture with an EC50 of ∼80μM (CC50>5mM) and was also active against Sindbis virus and Semliki Forest virus. In vitro studies hinted that suramin interferes with (re)initiation of RNA synthesis, whereas time-of-addition studies suggested it to also interfere with a post-attachment early step in infection, possibly entry. CHIKV (nsP4) mutants resistant against favipiravir or ribavirin, which target the viral RNA polymerase, did not exhibit cross-resistance to suramin, suggesting a different mode of action. The assessment of the activity of a variety of suramin-related compounds in cell culture and the in vitro assay for RNA synthesis provided more insight into the moieties required for antiviral activity. The antiviral effect of suramin-containing liposomes was also analyzed. Its approved status makes it worthwhile to explore the use of suramin to prevent and/or treat CHIKV infections.

  3. Systematic identification of novel, essential host genes affecting bromovirus RNA replication.

    Directory of Open Access Journals (Sweden)

    Brandi L Gancarz

    Full Text Available Positive-strand RNA virus replication involves viral proteins and cellular proteins at nearly every replication step. Brome mosaic virus (BMV is a well-established model for dissecting virus-host interactions and is one of very few viruses whose RNA replication, gene expression and encapsidation have been reproduced in the yeast Saccharomyces cerevisiae. Previously, our laboratory identified ∼100 non-essential host genes whose loss inhibited or enhanced BMV replication at least 3-fold. However, our isolation of additional BMV-modulating host genes by classical genetics and other results underscore that genes essential for cell growth also contribute to BMV RNA replication at a frequency that may be greater than that of non-essential genes. To systematically identify novel, essential host genes affecting BMV RNA replication, we tested a collection of ∼900 yeast strains, each with a single essential gene promoter replaced by a doxycycline-repressible promoter, allowing repression of gene expression by adding doxycycline to the growth medium. Using this strain array of ∼81% of essential yeast genes, we identified 24 essential host genes whose depleted expression reproducibly inhibited or enhanced BMV RNA replication. Relevant host genes are involved in ribosome biosynthesis, cell cycle regulation and protein homeostasis, among other cellular processes. BMV 2a(Pol levels were significantly increased in strains depleted for a heat shock protein (HSF1 or proteasome components (PRE1 and RPT6, suggesting these genes may affect BMV RNA replication by directly or indirectly modulating 2a(Pol localization, post-translational modification or interacting partners. Investigating the diverse functions of these newly identified essential host genes should advance our understanding of BMV-host interactions and normal cellular pathways, and suggest new modes of virus control.

  4. Systematic identification of novel, essential host genes affecting bromovirus RNA replication.

    Science.gov (United States)

    Gancarz, Brandi L; Hao, Linhui; He, Qiuling; Newton, Michael A; Ahlquist, Paul

    2011-01-01

    Positive-strand RNA virus replication involves viral proteins and cellular proteins at nearly every replication step. Brome mosaic virus (BMV) is a well-established model for dissecting virus-host interactions and is one of very few viruses whose RNA replication, gene expression and encapsidation have been reproduced in the yeast Saccharomyces cerevisiae. Previously, our laboratory identified ∼100 non-essential host genes whose loss inhibited or enhanced BMV replication at least 3-fold. However, our isolation of additional BMV-modulating host genes by classical genetics and other results underscore that genes essential for cell growth also contribute to BMV RNA replication at a frequency that may be greater than that of non-essential genes. To systematically identify novel, essential host genes affecting BMV RNA replication, we tested a collection of ∼900 yeast strains, each with a single essential gene promoter replaced by a doxycycline-repressible promoter, allowing repression of gene expression by adding doxycycline to the growth medium. Using this strain array of ∼81% of essential yeast genes, we identified 24 essential host genes whose depleted expression reproducibly inhibited or enhanced BMV RNA replication. Relevant host genes are involved in ribosome biosynthesis, cell cycle regulation and protein homeostasis, among other cellular processes. BMV 2a(Pol) levels were significantly increased in strains depleted for a heat shock protein (HSF1) or proteasome components (PRE1 and RPT6), suggesting these genes may affect BMV RNA replication by directly or indirectly modulating 2a(Pol) localization, post-translational modification or interacting partners. Investigating the diverse functions of these newly identified essential host genes should advance our understanding of BMV-host interactions and normal cellular pathways, and suggest new modes of virus control.

  5. RNA Replicons - A New Approach for Influenza Virus Immunoprophylaxis

    Directory of Open Access Journals (Sweden)

    Gert Zimmer

    2010-01-01

    Full Text Available RNA replicons are derived from either positive- or negative-strand RNA viruses. They represent disabled virus vectors that are not only avirulent, but also unable to revert to virulence. Due to autonomous RNA replication, RNA replicons are able to drive high level, cytosolic expression of recombinant antigens stimulating both the humoral and the cellular branch of the immune system. This review provides an update on the available literature covering influenza virus vaccines based on RNA replicons. The pros and cons of these vaccine strategies will be discussed and future perspectives disclosed.

  6. Unusual loop-sequence flexibility of the proximal RNA replication element in EMCV.

    Directory of Open Access Journals (Sweden)

    Jan Zoll

    Full Text Available Picornaviruses contain stable RNA structures at the 5' and 3' ends of the RNA genome, OriL and OriR involved in viral RNA replication. The OriL RNA element found at the 5' end of the enterovirus genome folds into a cloverleaf-like configuration. In vivo SELEX experiments revealed that functioning of the poliovirus cloverleaf depends on a specific structure in this RNA element. Little is known about the OriL of cardioviruses. Here, we investigated structural aspects and requirements of the apical loop of proximal stem-loop SL-A of mengovirus, a strain of EMCV. Using NMR spectroscopy, we showed that the mengovirus SL-A apical loop consists of an octaloop. In vivo SELEX experiments demonstrated that a large number of random sequences are tolerated in the apical octaloop that support virus replication. Mutants in which the SL-A loop size and the length of the upper part of the stem were varied showed that both stem-length and stability of the octaloop are important determinants for viral RNA replication and virus reproduction. Together, these data show that stem-loop A plays an important role in virus replication. The high degree of sequence flexibility and the lack of selective pressure on the octaloop argue against a role in sequence specific RNA-protein or RNA-RNA interactions in which octaloop nucleotides are involved.

  7. BARE retrotransposons are translated and replicated via distinct RNA pools.

    Directory of Open Access Journals (Sweden)

    Wei Chang

    Full Text Available The replication of Long Terminal Repeat (LTR retrotransposons, which can constitute over 80% of higher plant genomes, resembles that of retroviruses. A major question for retrotransposons and retroviruses is how the two conflicting roles of their transcripts, in translation and reverse transcription, are balanced. Here, we show that the BARE retrotransposon, despite its organization into just one open reading frame, produces three distinct classes of transcripts. One is capped, polyadenylated, and translated, but cannot be copied into cDNA. The second is not capped or polyadenylated, but is destined for packaging and ultimate reverse transcription. The third class is capped, polyadenylated, and spliced to favor production of a subgenomic RNA encoding only Gag, the protein forming virus-like particles. Moreover, the BARE2 subfamily, which cannot synthesize Gag and is parasitic on BARE1, does not produce the spliced sub-genomic RNA for translation but does make the replication competent transcripts, which are packaged into BARE1 particles. To our knowledge, this is first demonstration of distinct RNA pools for translation and transcription for any retrotransposon.

  8. Silencing of hepatitis C virus replication by a non-viral vector based on solid lipid nanoparticles containing a shRNA targeted to the internal ribosome entry site (IRES).

    Science.gov (United States)

    Torrecilla, Josune; Del Pozo-Rodríguez, Ana; Solinís, María Ángeles; Apaolaza, Paola S; Berzal-Herranz, Beatriz; Romero-López, Cristina; Berzal-Herranz, Alfredo; Rodríguez-Gascón, Alicia

    2016-10-01

    Gene silencing mediated by RNAi has gained increasing interest as an alternative for the treatment of infectious diseases such as refractory hepatitis C virus (HCV) infection. In this work we have designed and evaluated a non-viral vector based on solid lipid nanoparticles (SLN) bearing hyaluronic acid, protamine and a short hairpin RNA (shRNA74) targeted to the Internal Ribosome Entry Site (IRES) of the HCV. The vector was able to inhibit the expression of the HCV IRES in Huh-7 cells, with the inhibition level dependent on the shRNA74 to SLN ratio and on the shRNA74 dose added to the culture cells. The nanocarrier was also able to inhibit the replication in human hepatoma cells supporting a subgenomic HCV replicon (Huh-7 NS3-3'). The vector was quickly and efficiently internalized by the cells, and endocytosis was the most productive uptake mechanism for silencing. Clathrin-mediated endocytosis and to a lesser extent caveolae/lipid raft-mediated endocytosis were identified as endocytic mechanisms involved in the cell uptake. Internalization via the CD44 receptor was also involved, although this entry route seems to be less productive for silencing than endocytosis. The vector did not induce either hemolysis or agglutination of red cells in vitro, which was indicative of good biocompatibility. In summary, we have shown for the first time the ability of a non-viral SLN-based vector to silence a HCV replicon.

  9. Efficient Interaction between Arenavirus Nucleoprotein (NP) and RNA-Dependent RNA Polymerase (L) Is Mediated by the Virus Nucleocapsid (NP-RNA) Template.

    Science.gov (United States)

    Iwasaki, Masaharu; Ngo, Nhi; Cubitt, Beatrice; de la Torre, Juan C

    2015-05-01

    In this study, we document that efficient interaction between arenavirus nucleoprotein (NP) and RNA-dependent RNA polymerase (L protein), the two trans-acting viral factors required for both virus RNA replication and gene transcription, requires the presence of virus-specific RNA sequences located within the untranslated 5' and 3' termini of the viral genome.

  10. Equine infectious anemia virus replication is upregulated during differentiation of blood monocytes from acutely infected horses.

    OpenAIRE

    Sellon, D C; Walker, K M; Russell, K E; Perry, S T; Covington, P; Fuller, F J

    1996-01-01

    Equine infectious anemia virus is a lentivirus that replicates in mature tissue macrophages of horses. Ponies were infected with equine infectious anemia virus. During febrile episodes, proviral DNA was detectable, but viral mRNA was not detectable. As cultured blood monocytes from these ponies differentiated into macrophages, viral expression was upregulated. In situ hybridization confirmed that viral transcription occurred in mature macrophages.

  11. RNA conformational changes in the life cycles of RNA viruses, viroids, and virus-associated RNAs.

    Science.gov (United States)

    Simon, Anne E; Gehrke, Lee

    2009-01-01

    The rugged nature of the RNA structural free energy landscape allows cellular RNAs to respond to environmental conditions or fluctuating levels of effector molecules by undergoing dynamic conformational changes that switch on or off activities such as catalysis, transcription or translation. Infectious RNAs must also temporally control incompatible activities and rapidly complete their life cycle before being targeted by cellular defenses. Viral genomic RNAs must switch between translation and replication, and untranslated subviral RNAs must control other activities such as RNA editing or self-cleavage. Unlike well characterized riboswitches in cellular RNAs, the control of infectious RNA activities by altering the configuration of functional RNA domains has only recently been recognized. In this review, we will present some of these molecular rearrangements found in RNA viruses, viroids and virus-associated RNAs, relating how these dynamic regions were discovered, the activities that might be regulated, and what factors or conditions might cause a switch between conformations.

  12. The Acyclic Retinoid Peretinoin Inhibits Hepatitis C Virus Replication and Infectious Virus Release in Vitro

    Science.gov (United States)

    Shimakami, Tetsuro; Honda, Masao; Shirasaki, Takayoshi; Takabatake, Riuta; Liu, Fanwei; Murai, Kazuhisa; Shiomoto, Takayuki; Funaki, Masaya; Yamane, Daisuke; Murakami, Seishi; Lemon, Stanley M.; Kaneko, Shuichi

    2014-04-01

    Clinical studies suggest that the oral acyclic retinoid Peretinoin may reduce the recurrence of hepatocellular carcinoma (HCC) following surgical ablation of primary tumours. Since hepatitis C virus (HCV) infection is a major cause of HCC, we assessed whether Peretinoin and other retinoids have any effect on HCV infection. For this purpose, we measured the effects of several retinoids on the replication of genotype 1a, 1b, and 2a HCV in vitro. Peretinoin inhibited RNA replication for all genotypes and showed the strongest antiviral effect among the retinoids tested. Furthermore, it reduced infectious virus release by 80-90% without affecting virus assembly. These effects could be due to reduced signalling from lipid droplets, triglyceride abundance, and the expression of mature sterol regulatory element-binding protein 1c and fatty acid synthase. These negative effects of Peretinoin on HCV infection may be beneficial in addition to its potential for HCC chemoprevention in HCV-infected patients.

  13. The Tat protein of human immunodeficiency virus-1 enhances hepatitis C virus replication through interferon gamma-inducible protein-10

    Directory of Open Access Journals (Sweden)

    Qu Jing

    2012-04-01

    Full Text Available Abstract Background Co-infection with human immunodeficiency virus-1 (HIV-1 and hepatitis C virus (HCV is associated with faster progression of liver disease and an increase in HCV persistence. However, the mechanism by which HIV-1 accelerates the progression of HCV liver disease remains unknown. Results HIV-1/HCV co-infection is associated with increased expression of interferon gamma-induced protein-10 (IP-10 mRNA in peripheral blood mononuclear cells (PBMCs. HCV RNA levels were higher in PBMCs of patients with HIV-1/HCV co-infection than in patients with HCV mono-infection. HIV-1 Tat and IP-10 activated HCV replication in a time-dependent manner, and HIV-1 Tat induced IP-10 production. In addition, the effect of HIV-1 Tat on HCV replication was blocked by anti-IP-10 monoclonal antibody, demonstrating that the effect of HIV-1 Tat on HCV replication depends on IP-10. Taken together, these results suggest that HIV-1 Tat protein activates HCV replication by upregulating IP-10 production. Conclusions HIV-1/HCV co-infection is associated with increased expression of IP-10 mRNA and replication of HCV RNA. Furthermore, both HIV-1 Tat and IP-10 activate HCV replication. HIV-1 Tat activates HCV replication by upregulating IP-10 production. These results expand our understanding of HIV-1 in HCV replication and the mechanism involved in the regulation of HCV replication mediated by HIV-1 during co-infection.

  14. Hepatitis C virus RNA functionally sequesters miR-122

    DEFF Research Database (Denmark)

    Luna, Joseph M; Scheel, Troels K H; Danino, Tal

    2015-01-01

    Hepatitis C virus (HCV) uniquely requires the liver-specific microRNA-122 for replication, yet global effects on endogenous miRNA targets during infection are unexplored. Here, high-throughput sequencing and crosslinking immunoprecipitation (HITS-CLIP) experiments of human Argonaute (AGO) during...

  15. Flaviviral Replication Complex: Coordination between RNA Synthesis and 5'-RNA Capping.

    Science.gov (United States)

    Klema, Valerie J; Padmanabhan, Radhakrishnan; Choi, Kyung H

    2015-08-13

    Genome replication in flavivirus requires (-) strand RNA synthesis, (+) strand RNA synthesis, and 51-RNA capping and methylation. To carry out viral genome replication, flavivirus assembles a replication complex, consisting of both viral and host proteins, on the cytoplasmic side of the endoplasmic reticulum (ER) membrane. Two major components of the replication complex are the viral non-structural (NS) proteins NS3 and NS5. Together they possess all the enzymatic activities required for genome replication, yet how these activities are coordinated during genome replication is not clear. We provide an overview of the flaviviral genome replication process, the membrane-bound replication complex, and recent crystal structures of full-length NS5. We propose a model of how NS3 and NS5 coordinate their activities in the individual steps of (-) RNA synthesis, (+) RNA synthesis, and 51-RNA capping and methylation.

  16. Inhibition of porcine reproductive and respiratory syndrome virus replication with exosome-transferred artificial microRNA targeting the 3' untranslated region.

    Science.gov (United States)

    Zhu, Li; Bao, Liping; Zhang, Xinyu; Xia, Xiaoli; Sun, Huaichang

    2015-10-01

    Porcine reproductive and respiratory syndrome (PRRS) is an economically important swine disease. As part of the development of RNA interference (RNAi) strategy against the disease, in this study a recombinant adenovirus (rAd) expressing the artificial microRNA (amiRNA) targeting the 3' untranslated region (UTR) was used to investigate the exosome-mediated amiRNA transfer from different pig cell types to porcine alveolar macrophages (PAMs). Quantitative RT-PCR showed that the sequence-specific amiRNA was expressed in and secreted via exosomes from the rAd-transduced pig kidney cell line PK-15, PAM cell line 3D4/163, kidney fibroblast cells (PFCs) and endometrial endothelial cells (PEECs) with different secretion efficiencies. Fluorescent microscopy revealed that the dye-labeled amiRNA-containing exosomes of different cell origins were efficiently taken up by all of the five types of pig cells tested, including primary PAMs. Quantitative RT-PCR showed that the amiRNA-containing exosomes of different cell origins were taken up by primary PAMs in both time- and dose-dependent manners. Both quantitative RT-PCR and viral titration assays showed that the exosome-delivered amiRNA had potent anti-viral effects against three different PRRSV strains. These data suggest that the exosomes derived from pig cells could serve as an efficient miRNA transfer vehicle, and that the exosome-delivered amiRNA had potent anti-viral effects against different PRRSV strains.

  17. DDX3 DEAD-Box RNA Helicase Is Required for Hepatitis C Virus RNA Replication▿

    OpenAIRE

    2007-01-01

    DDX3, a DEAD-box RNA helicase, binds to the hepatitis C virus (HCV) core protein. However, the role(s) of DDX3 in HCV replication is still not understood. Here we demonstrate that the accumulation of both genome-length HCV RNA (HCV-O, genotype 1b) and its replicon RNA were significantly suppressed in HuH-7-derived cells expressing short hairpin RNA targeted to DDX3 by lentivirus vector transduction. As well, RNA replication of JFH1 (genotype 2a) and release of the core into the culture supern...

  18. Nucleocytoplasmic transport of nucleocapsid proteins of enveloped RNA viruses

    Directory of Open Access Journals (Sweden)

    Wahyu eWulan

    2015-06-01

    Full Text Available Most viruses with non-segmented single stranded RNA genomes complete their life cycle in the cytoplasm of infected cells. However, despite undergoing replication in the cytoplasm, the structural proteins of some of these RNA viruses localize to the nucleus at specific times in the virus life cycle, primarily early in infection. Limited evidence suggests that this enhances successful viral replication by interfering with or inhibiting the host antiviral response. Nucleocapsid proteins of RNA viruses have a well-established, essential cytoplasmic role in virus replication and assembly. Intriguingly, nucleocapsid proteins of some RNA viruses also localize to the nucleus/nucleolus of infected cells. Their nuclear function is less well understood although significant advances have been made in recent years. This review will focus on the nucleocapsid protein of cytoplasmic enveloped RNA viruses, including their localization to the nucleus/nucleolus and function therein. A greater understanding of the nuclear localization of nucleocapsid proteins has the potential to enhance therapeutic strategies as it can be a target for the development of live-attenuated vaccines or antiviral drugs.

  19. A critical role of a cellular membrane traffic protein in poliovirus RNA replication.

    Directory of Open Access Journals (Sweden)

    George A Belov

    2008-11-01

    Full Text Available Replication of many RNA viruses is accompanied by extensive remodeling of intracellular membranes. In poliovirus-infected cells, ER and Golgi stacks disappear, while new clusters of vesicle-like structures form sites for viral RNA synthesis. Virus replication is inhibited by brefeldin A (BFA, implicating some components(s of the cellular secretory pathway in virus growth. Formation of characteristic vesicles induced by expression of viral proteins was not inhibited by BFA, but they were functionally deficient. GBF1, a guanine nucleotide exchange factor for the small cellular GTPases, Arf, is responsible for the sensitivity of virus infection to BFA, and is required for virus replication. Knockdown of GBF1 expression inhibited virus replication, which was rescued by catalytically active protein with an intact N-terminal sequence. We identified a mutation in GBF1 that allows growth of poliovirus in the presence of BFA. Interaction between GBF1 and viral protein 3A determined the outcome of infection in the presence of BFA.

  20. Adenovirus-mediated shRNA interference against HSV-1 replication in vitro.

    Science.gov (United States)

    Song, Bo; Liu, Xinjing; Wang, Qingzhi; Zhang, Rui; Yang, Ting; Han, Zhiqiang; Xu, Yuming

    2016-12-01

    The UL29 and UL28 proteins encoded by herpes simplex virus type 1 (HSV-1) are critical for its replication and packaging, respectively. Research has demonstrated that synthesized siRNA molecules targeting the UL29 gene are able to suppress HSV-2 replication and the UL28-null HSV-1 gene cannot form infectious viruses in vitro. Silencing the UL28 and UL29 genes by RNAi might lead to the development of novel antiviral agents for the treatment of HSV-1 infections. Two kinds of short hairpin RNAs (shRNAs) targeting the UL29 and UL28 genes were chemically synthesized and then delivered into cells by a replication-defective human adenovirus type 5 (Adv5) vector. (-) shRNAs targeting none of the genome of HSV-1 were used as the control. Vero cells were inoculated with Ad-UL28shRNA or Ad-UL29shRNA at a multiplicity of infection (MOI) of 100 and challenged 24 h later with HSV-1 at an MOI of 0.01 to inhibit HSV-1 replication, as measured by the level of the corresponding RNA and proteins. In addition, the amount of progeny virus was assessed at daily intervals. The antiviral effects of Ad-shRNAs at ongoing HSV-1 infection were explored at 12 h after inoculation of the HSV-1. The results showed that the shRNAs delivered by Adv5 significantly suppressed HSV-1 replication in vitro, as determined by the levels of viral RNA transcription, viral protein synthesis, and viral production. The Ad-UL28shRNA and Ad-UL29shRNA suppressed the replication of HSV-1, respectively, compared with the control group (P HSV-1 infection (P HSV-1 infection.

  1. Cyclophilin A binds to the viral RNA and replication proteins, resulting in inhibition of tombusviral replicase assembly.

    Science.gov (United States)

    Kovalev, Nikolay; Nagy, Peter D

    2013-12-01

    Replication of plus-stranded RNA viruses is greatly affected by numerous host-encoded proteins that act as restriction factors. Cyclophilins, which are a large family of cellular prolyl isomerases, have been found to inhibit Tomato bushy stunt tombusvirus (TBSV) replication in a Saccharomyces cerevisiae model based on genome-wide screens and global proteomics approaches. In this report, we further characterize single-domain cyclophilins, including the mammalian cyclophilin A and plant Roc1 and Roc2, which are orthologs of the yeast Cpr1p cyclophilin, a known inhibitor of TBSV replication in yeast. We found that recombinant CypA, Roc1, and Roc2 strongly inhibited TBSV replication in a cell-free replication assay. Additional in vitro studies revealed that CypA, Roc1, and Roc2 cyclophilins bound to the viral replication proteins, and CypA and Roc1 also bound to the viral RNA. These interactions led to inhibition of viral RNA recruitment, the assembly of the viral replicase complex, and viral RNA synthesis. A catalytically inactive mutant of CypA was also able to inhibit TBSV replication in vitro due to binding to the replication proteins and the viral RNA. Overexpression of CypA and its mutant in yeast or plant leaves led to inhibition of tombusvirus replication, confirming that CypA is a restriction factor for TBSV. Overall, the current work has revealed a regulatory role for the cytosolic single-domain Cpr1-like cyclophilins in RNA virus replication.

  2. Inhibition of respiratory syncytial virus replication and virus-induced p38 kinase activity by berberine.

    Science.gov (United States)

    Shin, Han-Bo; Choi, Myung-Soo; Yi, Chae-Min; Lee, Jun; Kim, Nam-Jung; Inn, Kyung-Soo

    2015-07-01

    Respiratory syncytial virus (RSV) causes severe lower respiratory tract infection and poses a major public health threat worldwide. No effective vaccines or therapeutics are currently available; berberine, an isoquinoline alkaloid from various medicinal plants, has been shown to exert antiviral and several other biological effects. Recent studies have shown that p38 mitogen-activated protein kinase (MAPK) activity is implicated in infection by and replication of viruses such as RSV and the influenza virus. Because berberine has previously been implicated in modulating the activity of p38 MAPK, its effects on RSV infection and RSV-mediated p38 MAPK activation were examined. Replication of RSV in epithelial cells was significantly reduced by treatment with berberine. Berberine treatment caused decrease in viral protein and mRNA syntheses. Similar to previously reported findings, RSV infection caused phosphorylation of p38 MAPK at a very early time point of infection, and phosphorylation was dramatically reduced by berberine treatment. In addition, production of interleukin-6 mRNA upon RSV infection was significantly suppressed by treatment with berberine, suggesting the anti-inflammatory role of berberine during RSV infection. Taken together, we showed that berberine, a natural compound already proven to be safe for human consumption, suppresses the replication of RSV. In addition, the current study suggests that inhibition of RSV-mediated early p38 MAPK activation, which has been implicated as an early step in viral infection, as a potential molecular mechanism.

  3. DBR1 siRNA inhibition of HIV-1 replication

    Directory of Open Access Journals (Sweden)

    Naidu Yathi

    2005-10-01

    Full Text Available Abstract Background HIV-1 and all retroviruses are related to retroelements of simpler organisms such as the yeast Ty elements. Recent work has suggested that the yeast retroelement Ty1 replicates via an unexpected RNA lariat intermediate in cDNA synthesis. The putative genomic RNA lariat intermediate is formed by a 2'-5' phosphodiester bond, like that found in pre-mRNA intron lariats and it facilitates the minus-strand template switch during cDNA synthesis. We hypothesized that HIV-1 might also form a genomic RNA lariat and therefore that siRNA-mediated inhibition of expression of the human RNA lariat de-branching enzyme (DBR1 expression would specifically inhibit HIV-1 replication. Results We designed three short interfering RNA (siRNA molecules targeting DBR1, which were capable of reducing DBR1 mRNA expression by 80% and did not significantly affect cell viability. We assessed HIV-1 replication in the presence of DBR1 siRNA and found that DBR1 knockdown led to decreases in viral cDNA and protein production. These effects could be reversed by cotransfection of a DBR1 cDNA indicating that the inhibition of HIV-1 replication was a specific effect of DBR1 underexpression. Conclusion These data suggest that DBR1 function may be needed to debranch a putative HIV-1 genomic RNA lariat prior to completion of reverse transcription.

  4. Distinct replicative and cytopathic characteristics of human immunodeficiency virus isolates.

    Science.gov (United States)

    Fenyö, E M; Morfeldt-Månson, L; Chiodi, F; Lind, B; von Gegerfelt, A; Albert, J; Olausson, E; Asjö, B

    1988-01-01

    According to their capacity to replicate in vitro, human immunodeficiency virus (HIV) isolates can be divided into two major groups, rapid/high and slow/low. Rapid/high viruses can easily be transmitted to a variety of cell lines of T-lymphoid (CEM, H9, and Jurkat) and monocytoid (U937) origin. In contrast, slow/low viruses replicate transiently, if at all, in these cell lines. Except for a few isolates, the great majority of slow/low viruses replicate in peripheral blood mononuclear cells and Jurkat-tatIII cells constitutively expressing the tatIII gene of HIV-1. The viruses able to replicate efficiently cause syncytium formation and are regularly isolated from immunodeficient patients. Poorly replicating HIV isolates, often obtained from individuals with no or mild disease, show syncytium formation and single-cell killing simultaneously or, with some isolates, cell killing only. Images PMID:2459416

  5. Involvement of the skin during bluetongue virus infection and replication in the ruminant host.

    Science.gov (United States)

    Darpel, Karin E; Monaghan, Paul; Simpson, Jennifer; Anthony, Simon J; Veronesi, Eva; Brooks, Harriet W; Elliott, Heather; Brownlie, Joe; Takamatsu, Haru-Hisa; Mellor, Philip S; Mertens, Peter Pc

    2012-04-30

    Bluetongue virus (BTV) is a double stranded (ds) RNA virus (genus Orbivirus; family Reoviridae), which is considered capable of infecting all species of domestic and wild ruminants, although clinical signs are seen mostly in sheep. BTV is arthropod-borne ("arbovirus") and able to productively infect and replicate in many different cell types of both insects and mammalian hosts. Although the organ and cellular tropism of BTV in ruminants has been the subject of several studies, many aspects of its pathogenesis are still poorly understood, partly because of inherent problems in distinguishing between "virus replication" and "virus presence".BTV replication and organ tropism were studied in a wide range of infected sheep tissues, by immuno-fluorescence-labeling of non-structural or structural proteins (NS2 or VP7 and core proteins, respectively) using confocal microscopy to distinguish between virus presence and replication. These results are compared to gross and microscopic pathological findings in selected organs from infected sheep. Replication was demonstrated in two major cell types: vascular endothelial cells, and agranular leukocytes which morphologically resemble lymphocytes, monocytes/macrophages and/or dendritic cells. Two organs (the skin and tonsils) were shown to support relatively high levels of BTV replication, although they have not previously been proposed as important replication sites during BTV infection. The high level of BTV replication in the skin is thought to be of major significance for the pathogenesis and transmission of BTV (via biting insects) and a refinement of our current model of BTV pathogenesis is discussed.

  6. RNA recombination in animal and plant viruses.

    OpenAIRE

    1992-01-01

    An increasing number of animal and plant viruses have been shown to undergo RNA-RNA recombination, which is defined as the exchange of genetic information between nonsegmented RNAs. Only some of these viruses have been shown to undergo recombination in experimental infection of tissue culture, animals, and plants. However, a survey of viral RNA structure and sequences suggests that many RNA viruses were derived form homologous or nonhomologous recombination between viruses or between viruses ...

  7. Vitamin D Potentiates the Inhibitory Effect of MicroRNA-130a in Hepatitis C Virus Replication Independent of Type I Interferon Signaling Pathway

    Directory of Open Access Journals (Sweden)

    Xiaoqiong Duan

    2015-01-01

    Full Text Available Calcitriol, the bioactive metabolite of vitamin D, was reported to inhibit HCV production in a synergistic fashion with interferon, a treatment in vitro. Our previous study established that miR-130a inhibits HCV replication by restoring the host innate immune response. We aimed to determine whether there is additive inhibitory effect of calcitriol and miR-130a on HCV replication. Here we showed that calcitriol potentiates the anti-HCV effect of miR-130a in both Con1b replicon and J6/JFH1 culture systems. Intriguingly, this potentiating effect of calcitriol on miR-130a was not through upregulating the expression of cellular miR-130a or through increasing the miR-130a-mediated IFNα/β production. All these findings may contribute to the development of novel anti-HCV therapeutic strategies although the antiviral mechanism needs to be further investigated.

  8. Activating Ras mutations fail to ensure efficient replication of adenovirus mutants lacking VA-RNA

    DEFF Research Database (Denmark)

    Schümann, Michael; Dobbelstein, Matthias

    2006-01-01

    Adenoviruses lacking their PKR-antagonizing VA RNAs replicate poorly in primary cells. It has been suggested that these virus recombinants still replicate efficiently in tumor cells with Ras mutations and might therefore be useful in tumor therapy. The ability of interferon-sensitive viruses...... to grow in Ras-mutant tumor cells is generally ascribed to a postulated inhibitory effect of mutant Ras on PKR. We have constructed a set of isogenic adenoviruses that lack either or both VA RNA species, and tested virus replication in a variety of cell species with different Ras status. In tendency, VA...... mutational status, upon infection with VA-less adenoviruses in the presence of interferon, but also upon addition of the PKR activator polyIC to cells. When comparing two isogenic cell lines that differ solely with regard to the presence or absence of mutant Ras, no difference was observed concerning...

  9. An siRNA screen for ATG protein depletion reveals the extent of the unconventional functions of the autophagy proteome in virus replication

    NARCIS (Netherlands)

    Mauthe, Mario; Langereis, Martijn; Jung, Jennifer; Zhou, Xingdong; Jones, Alex; Omta, Wienand; Tooze, Sharon A.; Stork, Bjoern; Paludan, Soren Riis; Ahola, Tero; Egan, Dave; Behrends, Christian; Mokry, Michal; de Haan, Cornelis; van Kuppeveld, Frank; Reggiori, Fulvio

    2016-01-01

    Autophagy is a catabolic process regulated by the orchestrated action of the autophagy-related (ATG) proteins. Recent work indicates that some of the ATG proteins also have autophagy-independent roles. Using an unbiased siRNA screen approach, we explored the extent of these unconventional functions

  10. Mutated primer binding sites interacting with different tRNAs allow efficient murine leukemia virus replication

    DEFF Research Database (Denmark)

    Lund, Anders Henrik; Duch, M; Lovmand, J

    1993-01-01

    can replicate by using various tRNA molecules as primers and propose primer binding site-tRNA primer interactions to be of major importance for tRNA primer selection. However, efficient primer selection does not require perfect Watson-Crick base pairing at all 18 positions of the primer binding site.......Two Akv murine leukemia virus-based retroviral vectors with primer binding sites matching tRNA(Gln-1) and tRNA(Lys-3) were constructed. The transduction efficiency of these mutated vectors was found to be comparable to that of a vector carrying the wild-type primer binding site matching t......RNA(Pro). Polymerase chain reaction amplification and sequence analysis of transduced proviruses confirmed the transfer of vectors with mutated primer binding sites and further showed that tRNA(Gln-2) may act efficiently in conjunction with the tRNA(Gln-1) primer binding site. We conclude that murine leukemia virus...

  11. Cutthroat trout virus as a surrogate in vitro infection model for testing inhibitors of hepatitis E virus replication

    Science.gov (United States)

    Debing, Yannick; Winton, James; Neyts, Johan; Dallmeier, Kai

    2013-01-01

    Hepatitis E virus (HEV) is one of the most important causes of acute hepatitis worldwide. Although most infections are self-limiting, mortality is particularly high in pregnant women. Chronic infections can occur in transplant and other immune-compromised patients. Successful treatment of chronic hepatitis E has been reported with ribavirin and pegylated interferon-alpha, however severe side effects were observed. We employed the cutthroat trout virus (CTV), a non-pathogenic fish virus with remarkable similarities to HEV, as a potential surrogate for HEV and established an antiviral assay against this virus using the Chinook salmon embryo (CHSE-214) cell line. Ribavirin and the respective trout interferon were found to efficiently inhibit CTV replication. Other known broad-spectrum inhibitors of RNA virus replication such as the nucleoside analog 2′-C-methylcytidine resulted only in a moderate antiviral activity. In its natural fish host, CTV levels largely fluctuate during the reproductive cycle with the virus detected mainly during spawning. We wondered whether this aspect of CTV infection may serve as a surrogate model for the peculiar pathogenesis of HEV in pregnant women. To that end the effect of three sex steroids on in vitro CTV replication was evaluated. Whereas progesterone resulted in marked inhibition of virus replication, testosterone and 17β-estradiol stimulated viral growth. Our data thus indicate that CTV may serve as a surrogate model for HEV, both for antiviral experiments and studies on the replication biology of the Hepeviridae.

  12. Influenza virus RNA polymerase: insights into the mechanisms of viral RNA synthesis

    Science.gov (United States)

    te Velthuis, Aartjan J.W.; Fodor, Ervin

    2016-01-01

    The genome of influenza viruses consists of multiple segments of single stranded negative-sense RNA. Each of these segments is bound by the heterotrimeric viral RNA-dependent RNA polymerase and multiple copies of nucleoprotein, forming viral ribonucleoprotein (vRNP) complexes. It is in the context of these vRNPs that the viral RNA polymerase carries out transcription of viral genes and replication of the viral RNA genome. In this Review, we discuss our current knowledge of the structure of the influenza virus RNA polymerase, how it carries out transcription and replication, and how its activities are modulated by viral and host factors. Furthermore, we discuss how advances in our understanding of polymerase function could help identifying new antiviral targets. PMID:27396566

  13. Effects of DNA replication on mRNA noise.

    Science.gov (United States)

    Peterson, Joseph R; Cole, John A; Fei, Jingyi; Ha, Taekjip; Luthey-Schulten, Zaida A

    2015-12-29

    There are several sources of fluctuations in gene expression. Here we study the effects of time-dependent DNA replication, itself a tightly controlled process, on noise in mRNA levels. Stochastic simulations of constitutive and regulated gene expression are used to analyze the time-averaged mean and variation in each case. The simulations demonstrate that to capture mRNA distributions correctly, chromosome replication must be realistically modeled. Slow relaxation of mRNA from the low copy number steady state before gene replication to the high steady state after replication is set by the transcript's half-life and contributes significantly to the shape of the mRNA distribution. Consequently both the intrinsic kinetics and the gene location play an important role in accounting for the mRNA average and variance. Exact analytic expressions for moments of the mRNA distributions that depend on the DNA copy number, gene location, cell doubling time, and the rates of transcription and degradation are derived for the case of constitutive expression and subsequently extended to provide approximate corrections for regulated expression and RNA polymerase variability. Comparisons of the simulated models and analytical expressions to experimentally measured mRNA distributions show that they better capture the physics of the system than previous theories.

  14. The Genomic Replication of the Crenarchaeal Virus SIRV2

    DEFF Research Database (Denmark)

    Martinez Alvarez, Laura

    of the crenarchaeal virus SIRV2, a model among archaeal viruses. SIRV2 was found to employ multiple replication mechanisms, with DNA synthesis starting by a strand-displacement mode that later derived in a rolling-circle replication from a circular intermediate. Interestingly, evidence for a secondary, bidirectional...... reinitiation events may partially explain the branched topology of the viral replication intermediates. We also analyzed the intracellular location of viral replication, showing the formation of viral peripheral replication centers in SIRV2-infected cells, where viral DNA synthesis and replication......-related proteins are concentrated. Our data indicates that the host DNA polymerase Dpo1 is also the viral replicative polymerase. Moreover, additional data suggests that other processes, such as translation, are also reorganized after infection. Based on our results, a model for the organization of viral...

  15. Roles for endocytic trafficking and phosphatidylinositol 4-kinase III alpha in hepatitis C virus replication.

    Science.gov (United States)

    Berger, Kristi L; Cooper, Jacob D; Heaton, Nicholas S; Yoon, Rosa; Oakland, Todd E; Jordan, Tristan X; Mateu, Guaniri; Grakoui, Arash; Randall, Glenn

    2009-05-05

    Hepatitis C virus (HCV) reorganizes cellular membranes to establish sites of replication. The required host pathways and the mechanism of cellular membrane reorganization are poorly characterized. Therefore, we interrogated a customized small interfering RNA (siRNA) library that targets 140 host membrane-trafficking genes to identify genes required for both HCV subgenomic replication and infectious virus production. We identified 7 host cofactors of viral replication, including Cdc42 and Rock2 (actin polymerization), EEA1 and Rab5A (early endosomes), Rab7L1, and PI3-kinase C2gamma and PI4-kinase IIIalpha (phospholipid metabolism). Studies of drug inhibitors indicate actin polymerization and phospholipid kinase activity are required for HCV replication. We found extensive co-localization of the HCV replicase markers NS5A and double-stranded RNA with Rab5A and partial co-localization with Rab7L1. PI4K-IIIalpha co-localized with NS5A and double-stranded RNA in addition to being present in detergent-resistant membranes containing NS5A. In a comparison of type II and type III PI4-kinases, PI4Ks were not required for HCV entry, and only PI4K-IIIalpha was required for HCV replication. Although PI4K-IIIalpha siRNAs decreased HCV replication and virus production by almost 100%, they had no effect on initial HCV RNA translation, suggesting that PI4K-IIIalpha functions at a posttranslational stage. Electron microscopy identified the presence of membranous webs, which are thought to be the site of HCV replication, in HCV-infected cells. Pretreatment with PI4K-IIIalpha siRNAs greatly reduced the accumulation of these membranous web structures in HCV-infected cells. We propose that PI4K-IIIalpha plays an essential role in membrane alterations leading to the formation of HCV replication complexes.

  16. RNA Viruses and RNAi: Quasispecies Implications for Viral Escape

    Directory of Open Access Journals (Sweden)

    John B. Presloid

    2015-06-01

    Full Text Available Due to high mutation rates, populations of RNA viruses exist as a collection of closely related mutants known as a quasispecies. A consequence of error-prone replication is the potential for rapid adaptation of RNA viruses when a selective pressure is applied, including host immune systems and antiviral drugs. RNA interference (RNAi acts to inhibit protein synthesis by targeting specific mRNAs for degradation and this process has been developed to target RNA viruses, exhibiting their potential as a therapeutic against infections. However, viruses containing mutations conferring resistance to RNAi were isolated in nearly all cases, underlining the problems of rapid viral evolution. Thus, while promising, the use of RNAi in treating or preventing viral diseases remains fraught with the typical complications that result from high specificity of the target, as seen in other antiviral regimens.

  17. Equine infectious anemia virus replication is upregulated during differentiation of blood monocytes from acutely infected horses.

    Science.gov (United States)

    Sellon, D C; Walker, K M; Russell, K E; Perry, S T; Covington, P; Fuller, F J

    1996-01-01

    Equine infectious anemia virus is a lentivirus that replicates in mature tissue macrophages of horses. Ponies were infected with equine infectious anemia virus. During febrile episodes, proviral DNA was detectable, but viral mRNA was not detectable. As cultured blood monocytes from these ponies differentiated into macrophages, viral expression was upregulated. In situ hybridization confirmed that viral transcription occurred in mature macrophages. PMID:8523576

  18. Requirement of cellular DDX3 for hepatitis C virus replication is unrelated to its interaction with the viral core protein.

    Science.gov (United States)

    Angus, Allan G N; Dalrymple, David; Boulant, Steeve; McGivern, David R; Clayton, Reginald F; Scott, Martin J; Adair, Richard; Graham, Susan; Owsianka, Ania M; Targett-Adams, Paul; Li, Kui; Wakita, Takaji; McLauchlan, John; Lemon, Stanley M; Patel, Arvind H

    2010-01-01

    The cellular DEAD-box protein DDX3 was recently shown to be essential for hepatitis C virus (HCV) replication. Prior to that, we had reported that HCV core binds to DDX3 in yeast-two hybrid and transient transfection assays. Here, we confirm by co-immunoprecipitation that this interaction occurs in cells replicating the JFH1 virus. Consistent with this result, immunofluorescence staining of infected cells revealed a dramatic redistribution of cytoplasmic DDX3 by core protein to the virus assembly sites around lipid droplets. Given this close association of DDX3 with core and lipid droplets, and its involvement in virus replication, we investigated the importance of this host factor in the virus life cycle. Mutagenesis studies located a single amino acid in the N-terminal domain of JFH1 core that when changed to alanine significantly abrogated this interaction. Surprisingly, this mutation did not alter infectious virus production and RNA replication, indicating that the core-DDX3 interaction is dispensable in the HCV life cycle. Consistent with previous studies, siRNA-led knockdown of DDX3 lowered virus production and RNA replication levels of both WT JFH1 and the mutant virus unable to bind DDX3. Thus, our study shows for the first time that the requirement of DDX3 for HCV replication is unrelated to its interaction with the viral core protein.

  19. Replicative intermediates of maize streak virus found during leaf development.

    Science.gov (United States)

    Erdmann, Julia B; Shepherd, Dionne N; Martin, Darren P; Varsani, Arvind; Rybicki, Edward P; Jeske, Holger

    2010-04-01

    Geminiviruses of the genera Begomovirus and Curtovirus utilize three replication modes: complementary-strand replication (CSR), rolling-circle replication (RCR) and recombination-dependent replication (RDR). Using two-dimensional gel electrophoresis, we now show for the first time that maize streak virus (MSV), the type member of the most divergent geminivirus genus, Mastrevirus, does the same. Although mastreviruses have fewer regulatory genes than other geminiviruses and uniquely express their replication-associated protein (Rep) from a spliced transcript, the replicative intermediates of CSR, RCR and RDR could be detected unequivocally within infected maize tissues. All replicative intermediates accumulated early and, to varying degrees, were already present in the shoot apex and leaves at different maturation stages. Relative to other replicative intermediates, those associated with RCR increased in prevalence during leaf maturation. Interestingly, in addition to RCR-associated DNA forms seen in other geminiviruses, MSV also apparently uses dimeric open circular DNA as a template for RCR.

  20. RNAi suppressor P19 can be broadly exploited for enhanced adenovirus replication and microRNA knockdown experiments.

    Science.gov (United States)

    Rauschhuber, Christina; Mueck-Haeusl, Martin; Zhang, Wenli; Nettelbeck, Dirk M; Ehrhardt, Anja

    2013-01-01

    RNA interference (RNAi) is a key regulator of various biological systems including viral infection. Within a virus life cycle gene products can be modulated by the RNA interference (RNAi) pathway which can crucially impact productive virus replication. Herein we explored the RNA interference suppressor protein P19 derived from a plant virus and we found that P19 enhanced adenovirus replication up to 100-fold. Critical factors responsible for this observation were overexpression of adenovirus encoded genes on mRNA and protein levels. To investigate the impact of this phenomenon on recombinant viruses, we exploited its feasibility for therapeutic and genomic applications. We found that P19 significantly increased recombinant adenovirus yields enabling up-scaling for preclinical and clinical studies. Moreover, adenoviruses possessed significantly higher oncolytic activity by expression of P19. Finally, we show that introducing a p19 expression cassette into high-capacity adenovirus provides a strategy to analyze RNAi knockdown in a tissue-specific manner.

  1. Screening and identification of virus-encoded RNA silencing suppressors.

    Science.gov (United States)

    Karjee, Sumona; Islam, Mohammad Nurul; Mukherjee, Sunil K

    2008-01-01

    RNA silencing, including RNA interference, is a novel method of gene regulation and one of the potent host-defense mechanisms against the viruses. In the course of evolution, the viruses have encoded proteins with the potential to suppress the host RNA silencing mechanism as a counterdefense strategy. The virus-encoded RNA silencing suppressors (RSSs) can serve as important biological tools to dissect the detailed RNA silencing pathways and also to evolve the antiviral strategies. Screening and identification of the RSSs are indeed of utmost significance in the field of plant biotechnology. We describe two Green Fluorescent Protein (GFP) reporter-based plant assay systems that rely on two different principles, namely reversal of silencing and enhancement of rolling circle replication (RCR) of geminiviral replicon. These proof-of-concept examples and assay systems could be used to screen various plant, animal, and insect viral ORFs for identification of the RSS activities.

  2. Phosphorylation of the viral coat protein regulates RNA virus infection

    Directory of Open Access Journals (Sweden)

    Hoover HS

    2016-11-01

    Full Text Available Haley S Hoover, C Cheng Kao Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN, USA Abstract: Coat proteins (CPs are the most abundant protein produced during a viral infection. CPs have been shown to regulate the infection processes of RNA viruses, including RNA replication and gene expression. The numerous activities of the CP in infection are likely to require regulation, possibly through posttranslational modifications. Protein posttranslational modifications are involved in signal transduction, expanding and regulating protein function, and responding to changes in the environment. Accumulating evidence suggests that phosphorylation of viral CPs is involved in the regulation of the viral infection process from enabling virion disassembly to regulation of viral protein synthesis and replication. CP phosphorylation also affects viral trafficking and virion assembly. This review focuses on the regulatory roles that phosphorylation of CPs has in the life cycle of viruses with RNA genomes. Keywords: viral capsid protein, posttranslational modification, phosphorylation, protein–RNA interaction

  3. Replication of a hepatitis C virus replicon clone in mouse cells

    Directory of Open Access Journals (Sweden)

    Chisari Francis V

    2006-10-01

    Full Text Available Abstract Background Hepatitis C Virus (HCV is a significant public health burden and small animal models are needed to study the pathology and immunobiology of the virus. In effort to develop experimental HCV mouse models, we screened a panel of HCV replicons to identify clones capable of replicating in mouse hepatocytes. Results We report the establishment of stable HCV replication in mouse hepatocyte and fibroblast cell lines using replicons derived from the JFH-1 genotype 2a consensus sequence. Viral RNA replication efficiency in mouse cells was comparable to that observed in human Huh-7 replicon cells, with negative-strand HCV RNA and the viral NS5A protein being readily detected by Northern and Western Blot analysis, respectively. Although HCV replication was established in the absence of adaptive mutations that might otherwise compromise the in vitro infectivity of the JFH-1 clone, no infectious virus was detected when the culture medium from full length HCV RNA replicating mouse cells was titrated on Huh-7 cells, suggesting that the mouse cells were unable to support production of infectious progeny viral particles. Consistent with an additional block in viral entry, infectious JFH-1 particles produced in Huh-7 cells were not able to establish detectable HCV RNA replication in naïve mouse cells. Conclusion Thus, this report expands the repertoire of HCV replication systems and possibly represents a step toward developing mouse models of HCV replication, but it also highlights that other species restrictions might continue to make the development of a purely murine HCV infectious model challenging.

  4. Integrative Functional Genomics of Hepatitis C Virus Infection Identifies Host Dependencies in Complete Viral Replication Cycle

    OpenAIRE

    Qisheng Li; Yong-Yuan Zhang; Stephan Chiu; Zongyi Hu; Keng-Hsin Lan; Helen Cha; Catherine Sodroski; Fang Zhang; Ching-Sheng Hsu; Emmanuel Thomas; T Jake Liang

    2014-01-01

    Recent functional genomics studies including genome-wide small interfering RNA (siRNA) screens demonstrated that hepatitis C virus (HCV) exploits an extensive network of host factors for productive infection and propagation. How these co-opted host functions interact with various steps of HCV replication cycle and exert pro- or antiviral effects on HCV infection remains largely undefined. Here we present an unbiased and systematic strategy to functionally interrogate HCV host dependencies unc...

  5. Crimean-Congo hemorrhagic fever virus-encoded ovarian tumor protease activity is dispensable for virus RNA polymerase function.

    Science.gov (United States)

    Bergeron, Eric; Albariño, César G; Khristova, Marina L; Nichol, Stuart T

    2010-01-01

    Crimean-Congo hemorrhagic fever virus (CCHFV) is a tick-borne virus (genus Nairovirus, family Bunyaviridae) associated with high case fatality disease outbreaks in regions of Africa, Europe, and Asia. The CCHFV genome consists of three negative-strand RNA segments, S, M, and L. The unusually large virus L polymerase protein and the need for biosafety level 4 (BSL-4) containment conditions for work with infectious virus have hampered the study of CCHFV replication. The L protein has an ovarian tumor (OTU) protease domain located in the N terminus, which has led to speculation that the protein may be autoproteolytically cleaved to generate the active virus L polymerase and additional functions. We report the successful development of efficient CCHFV helper virus-independent S, M, and L segment minigenome systems for analysis of virus RNA and protein features involved in replication. The virus RNA segment S, M, and L untranslated regions were found to be similar in support of replication of the respective minigenomes. In addition, the OTU domain located in the N terminus of the expressed virus L protein was shown to be a functional protease. However, no evidence of L protein autoproteolytic processing was found, and the OTU protease activity was dispensable for virus RNA replication. Finally, physiologically relevant doses of ribavirin inhibited CCHFV minigenome replication. These results demonstrated the utility of the minigenome system for use in BSL-2 laboratory settings to analyze CCHFV biology and in antiviral drug discovery programs for this important public health and bioterrorism threat.

  6. Replication-selective oncolytic viruses in the treatment of cancer.

    Science.gov (United States)

    Everts, Bart; van der Poel, Henk G

    2005-02-01

    In the search for novel strategies, oncolytic virotherapy has recently emerged as a viable approach to specifically kill tumor cells. Unlike conventional gene therapy, it uses replication competent viruses that are able to spread through tumor tissue by virtue of viral replication and concomitant cell lysis. Recent advances in molecular biology have allowed the design of several genetically modified viruses, such as adenovirus and herpes simplex virus that specifically replicate in, and kill tumor cells. On the other hand, viruses with intrinsic oncolytic capacity are also being evaluated for therapeutic purposes. In this review, an overview is given of the general mechanisms and genetic modifications by which these viruses achieve tumor cell-specific replication and antitumor efficacy. However, although generally the oncolytic efficacy of these approaches has been demonstrated in preclinical studies the therapeutic efficacy in clinical trails is still not optimal. Therefore, strategies are evaluated that could further enhance the oncolytic potential of conditionally replicating viruses. In this respect, the use of tumor-selective viruses in conjunction with other standard therapies seems most promising. However, still several hurdles regarding clinical limitations and safety issues should be overcome before this mode of therapy can become of clinical relevance.

  7. dsRNA interference on expression of a RNA-dependent RNA polymerase gene of Bombyx mori cytoplasmic polyhedrosis virus.

    Science.gov (United States)

    Pan, Zhong-Hua; Gao, Kun; Hou, Cheng-Xiang; Wu, Ping; Qin, Guang-Xing; Geng, Tao; Guo, Xi-Jie

    2015-07-01

    Bombyx mori cytoplasmic polyhedrosis virus (BmCPV) is one of the major viral pathogens in silkworm. Its infection often results in significant losses to sericulture. Studies have demonstrated that RNAi is one of the important anti-viral mechanisms in organisms. In this study, three dsRNAs targeting the RNA-dependent RNA polymerase (RDRP) gene of BmCPV were designed and synthesized with 2'-F modification to explore their interference effects on BmCPV replication in silkworm larvae. The results showed that injecting dsRNA in the dosage of 4-6 ng per mg body weight into the 5th instar larvae can interfere with the BmCPV-RDRP expression by 93% after virus infection and by 99.9% before virus infection. In addition, the expression of two viral structural protein genes (genome RNA segments 1 and 5) was also decreased with the decrease of RDRP expression, suggesting that RNAi interference of BmCPV-RDRP expression could affect viral replication. The study provides an effective method for investigating virus replication as well as the virus-host interactions in the silkworm larvae using dsRNA.

  8. Flock house virus replicates and expresses green fluorescent protein in mosquitoes.

    Science.gov (United States)

    Dasgupta, Ranjit; Cheng, Li-Lin; Bartholomay, Lyric C; Christensen, Bruce M

    2003-07-01

    Flock house virus (FHV) is a non-enveloped, positive-sense RNA virus of insect origin that belongs to the family Nodaviridae. FHV has been shown to overcome the kingdom barrier and to replicate in plants, insects, yeast and mammalian cells. Although of insect origin, FHV has not previously been shown to replicate in mosquitoes. We have tested FHV replication in vitro in C6/36 cells (derived from neonatal Aedes albopictus) and in vivo in four different genera of mosquitoes, Aedes, Culex, Anopheles and Armigeres. FHV replicated to high titres in C6/36 cells that had been subcloned to support maximum growth of FHV. When adult mosquitoes were orally fed or injected with the virus, FHV antigen was detected in various tissues and infectious virus was recovered. Vectors developed from an infectious cDNA clone of a defective-interfering RNA, derived from FHV genomic RNA2, expressed green fluorescent protein in Drosophila cells and adult mosquitoes. This demonstrates the potential of FHV-based vectors for expression of foreign genes in mosquitoes and possibly other insects.

  9. Evolution of mutational robustness in an RNA virus.

    Directory of Open Access Journals (Sweden)

    Rebecca Montville

    2005-11-01

    Full Text Available Mutational (genetic robustness is phenotypic constancy in the face of mutational changes to the genome. Robustness is critical to the understanding of evolution because phenotypically expressed genetic variation is the fuel of natural selection. Nonetheless, the evidence for adaptive evolution of mutational robustness in biological populations is controversial. Robustness should be selectively favored when mutation rates are high, a common feature of RNA viruses. However, selection for robustness may be relaxed under virus co-infection because complementation between virus genotypes can buffer mutational effects. We therefore hypothesized that selection for genetic robustness in viruses will be weakened with increasing frequency of co-infection. To test this idea, we used populations of RNA phage phi6 that were experimentally evolved at low and high levels of co-infection and subjected lineages of these viruses to mutation accumulation through population bottlenecking. The data demonstrate that viruses evolved under high co-infection show relatively greater mean magnitude and variance in the fitness changes generated by addition of random mutations, confirming our hypothesis that they experience weakened selection for robustness. Our study further suggests that co-infection of host cells may be advantageous to RNA viruses only in the short term. In addition, we observed higher mutation frequencies in the more robust viruses, indicating that evolution of robustness might foster less-accurate genome replication in RNA viruses.

  10. Early endonuclease-mediated evasion of RNA sensing ensures efficient coronavirus replication

    Science.gov (United States)

    Kindler, Eveline; Gil-Cruz, Cristina; Spanier, Julia; Li, Yize; Wilhelm, Jochen; Rabouw, Huib H.; Züst, Roland; Marti, Sabrina; Habjan, Matthias; Cervantes-Barragan, Luisa; Elliot, Ruth; Karl, Nadja; Gaughan, Christina; Silverman, Robert H.; Keller, Markus; Ludewig, Burkhard; Bergmann, Cornelia C.; Ziebuhr, John; Kalinke, Ulrich

    2017-01-01

    Coronaviruses are of veterinary and medical importance and include highly pathogenic zoonotic viruses, such as SARS-CoV and MERS-CoV. They are known to efficiently evade early innate immune responses, manifesting in almost negligible expression of type-I interferons (IFN-I). This evasion strategy suggests an evolutionary conserved viral function that has evolved to prevent RNA-based sensing of infection in vertebrate hosts. Here we show that the coronavirus endonuclease (EndoU) activity is key to prevent early induction of double-stranded RNA (dsRNA) host cell responses. Replication of EndoU-deficient coronaviruses is greatly attenuated in vivo and severely restricted in primary cells even during the early phase of the infection. In macrophages we found immediate induction of IFN-I expression and RNase L-mediated breakdown of ribosomal RNA. Accordingly, EndoU-deficient viruses can retain replication only in cells that are deficient in IFN-I expression or sensing, and in cells lacking both RNase L and PKR. Collectively our results demonstrate that the coronavirus EndoU efficiently prevents simultaneous activation of host cell dsRNA sensors, such as Mda5, OAS and PKR. The localization of the EndoU activity at the site of viral RNA synthesis–within the replicase complex—suggests that coronaviruses have evolved a viral RNA decay pathway to evade early innate and intrinsic antiviral host cell responses. PMID:28158275

  11. Inhibition of influenza virus replication by nitric oxide

    NARCIS (Netherlands)

    G.F. Rimmelzwaan (Guus); M.M.J.W. Baars (Marianne); P. de Lijster; R.A.M. Fouchier (Ron); A.D.M.E. Osterhaus (Albert)

    1999-01-01

    textabstractNitric oxide (NO) has been shown to contribute to the pathogenesis of influenza virus-induced pneumonia in mouse models. Here we show that replication of influenza A and B viruses in Mabin Darby canine kidney cells is severely impaired by the NO donor,

  12. Inhibitors of Nucleotidyltransferase Superfamily Enzymes Suppress Herpes Simplex Virus Replication

    OpenAIRE

    2014-01-01

    Herpesviruses are large double-stranded DNA viruses that cause serious human diseases. Herpesvirus DNA replication depends on multiple processes typically catalyzed by nucleotidyltransferase superfamily (NTS) enzymes. Therefore, we investigated whether inhibitors of NTS enzymes would suppress replication of herpes simplex virus 1 (HSV-1) and HSV-2. Eight of 42 NTS inhibitors suppressed HSV-1 and/or HSV-2 replication by >10-fold at 5 μM, with suppression at 50 μM reaching ∼1 million-fold. Five...

  13. Identification of a New Ribonucleoside Inhibitor of Ebola Virus Replication

    Directory of Open Access Journals (Sweden)

    Olivier Reynard

    2015-12-01

    Full Text Available The current outbreak of Ebola virus (EBOV in West Africa has claimed the lives of more than 15,000 people and highlights an urgent need for therapeutics capable of preventing virus replication. In this study we screened known nucleoside analogues for their ability to interfere with EBOV replication. Among them, the cytidine analogue β-d-N4-hydroxycytidine (NHC demonstrated potent inhibitory activities against EBOV replication and spread at non-cytotoxic concentrations. Thus, NHC constitutes an interesting candidate for the development of a suitable drug treatment against EBOV.

  14. Ultrastructural study of Mayaro virus replication in BHK-21 cells.

    Science.gov (United States)

    Mezencio, J M; de Souza, W; Fonseca, M E; Rebello, M A

    1990-01-01

    The replication of Mayaro virus in BHK-21 cells was studied by electron microscopy. The infected cells show an intense vacuolization and proliferation of membranous structures. At 5 h post-infection, precursor virus particles were seen in the cytoplasm of infected cells. Later, mature virus particles were found outside the cells and budding from the plasma membrane. Enveloped virus particles were also observed inside the vesicles and budding across their membrane. The release of virus particles into the extracellular space by exocytosis was also observed. In a later stage of the infection, inclusion bodies were sometimes present in the cytoplasm of infected cells. We conclude that in BHK-21 cells, budding from the plasma membrane is the main process of Mayaro virus maturation, and in this kind of cell replication differs significantly from that observed in Aedes albopictus cells.

  15. Inhibition of Mayaro virus replication by prostaglandin A(1) in Vero cells.

    Science.gov (United States)

    Burlandy, F M; Rebello, M A

    2001-01-01

    Prostaglandins exhibit antiviral activity against a wide variety of RNA and DNA viruses. In the present report, we describe the effect of cyclopentenone prostaglandin A(1) (PGA(1)) on Mayaro virus replication in Vero cells. Virus yield was significantly reduced at nontoxic concentrations which did not suppress DNA, RNA or protein synthesis in uninfected or infected cells. Antiviral action decreased if PGA(1) was added at later times after infection. In Mayaro virus-infected cells, PGA(1) inhibited the synthesis of virus proteins. This effect is accompanied by the induction of heat shock proteins (HSPs). Actinomycin D treatment not only inhibited the induction of HSPs but also partially prevented PGA(1) antiviral activity.

  16. Delayed IFN response differentiates replication of West Nile virus and Japanese encephalitis virus in human neuroblastoma and glioblastoma cells.

    Science.gov (United States)

    Takamatsu, Yuki; Uchida, Leo; Morita, Kouichi

    2015-08-01

    West Nile virus (WNV) and Japanese encephalitis virus (JEV) are important causes of human encephalitis cases, which result in a high mortality ratio and neurological sequelae after recovery. Understanding the mechanism of neuropathogenicity in these viral infections is important for the development of specific antiviral therapy. Here, we focused on human-derived neuronal and glial cells to understand the cellular responses against WNV and JEV infection. It was demonstrated that early IFN-β induction regulated virus replication in glioblastoma tbl98G cells, whereas delayed IFN-β induction resulted in efficient virus replication in neuroblastoma SK-N-SH cells. Moreover, the concealing of viral dsRNA in the intracellular membrane resulted in the delayed IFN response in SK-N-SH cells. These results, which showed different IFN responses between human neuronal and glial cells after WNV or JEV infection, are expected to contribute to our understanding of the molecular mechanisms for neuropathology in these viral infections.

  17. MicroRNA Regulation of Human Genes Essential for Influenza A (H7N9) Replication

    Science.gov (United States)

    Wolf, Stefan; Wu, Weilin; Jones, Cheryl; Perwitasari, Olivia; Mahalingam, Suresh; Tripp, Ralph A.

    2016-01-01

    Influenza A viruses are important pathogens of humans and animals. While seasonal influenza viruses infect humans every year, occasionally animal-origin viruses emerge to cause pandemics with significantly higher morbidity and mortality rates. In March 2013, the public health authorities of China reported three cases of laboratory confirmed human infection with avian influenza A (H7N9) virus, and subsequently there have been many cases reported across South East Asia and recently in North America. Most patients experience severe respiratory illness, and morbidity with mortality rates near 40%. No vaccine is currently available and the use of antivirals is complicated due the frequent emergence of drug resistant strains. Thus, there is an imminent need to identify new drug targets for therapeutic intervention. In the current study, a high-throughput screening (HTS) assay was performed using microRNA (miRNA) inhibitors to identify new host miRNA targets that reduce influenza H7N9 replication in human respiratory (A549) cells. Validation studies lead to a top hit, hsa-miR-664a-3p, that had potent antiviral effects in reducing H7N9 replication (TCID50 titers) by two logs. In silico pathway analysis revealed that this microRNA targeted the LIF and NEK7 genes with effects on pro-inflammatory factors. In follow up studies using siRNAs, anti-viral properties were shown for LIF. Furthermore, inhibition of hsa-miR-664a-3p also reduced virus replication of pandemic influenza A strains H1N1 and H3N2. PMID:27166678

  18. Interferon action on Mayaro virus replication.

    Science.gov (United States)

    Rebello, M C; Fonseca, M E; Marinho, J O; Rebello, M A

    1993-08-01

    Treatment of TC7 cells with interferon (IFN) drastically reduced the yield of infectious Mayaro virus under experimental conditions that virus attachment and penetration into the cells were not affected. In IFN-treated cells, synthesis of Mayaro virus proteins was inhibited and cellular protein synthesis was restored. This phenomenon is dependent on IFN concentration and multiplicity of infection. Electron microscopy of these cells revealed normal and anomalous viral particles inside cytoplasmic vacuoles. This suggests that IFN also interferes with Mayaro virus morphogenesis and inhibits the release of virions from cells.

  19. Influenza Virus Induces Inflammatory Response in Mouse Primary Cortical Neurons with Limited Viral Replication

    Directory of Open Access Journals (Sweden)

    Gefei Wang

    2016-01-01

    Full Text Available Unlike stereotypical neurotropic viruses, influenza A viruses have been detected in the brain tissues of human and animal models. To investigate the interaction between neurons and influenza A viruses, mouse cortical neurons were isolated, infected with human H1N1 influenza virus, and then examined for the production of various inflammatory molecules involved in immune response. We found that replication of the influenza virus in neurons was limited, although early viral transcription was not affected. Virus-induced neuron viability decreased at 6 h postinfection (p.i. but increased at 24 h p.i. depending upon the viral strain. Virus-induced apoptosis and cytopathy in primary cortical neurons were not apparent at 24 h p.i. The mRNA levels of inflammatory cytokines, chemokines, and type I interferons were upregulated at 6 h and 24 h p.i. These results indicate that the influenza virus induces inflammatory response in mouse primary cortical neurons with limited viral replication. The cytokines released in viral infection-induced neuroinflammation might play critical roles in influenza encephalopathy, rather than in viral replication-induced cytopathy.

  20. Inhibition of hepatitis C virus replication in vitro by xanthohumol, a natural product present in hops.

    Science.gov (United States)

    Lou, Sai; Zheng, Yi-Min; Liu, Shan-Lu; Qiu, Jianming; Han, Qunying; Li, Na; Zhu, Qianqian; Zhang, Pingping; Yang, Cuiling; Liu, Zhengwen

    2014-02-01

    Hepatitis C virus is a major cause of chronic liver disease worldwide. Xanthohumol, a prenylated flavonoid from hops, has various biological activities including an antiviral effect. It was previously characterized as a compound that inhibits bovine viral diarrhea virus, a surrogate model of hepatitis C virus. In the present work, xanthohumol was examined for its ability to inhibit hepatitis C virus replication in a cell culture system carrying replicating hepatitis C virus RNA replicon. 0.2 % DMSO and 500 units/mL interferon-alpha treatments were set as a negative and positive control, respectively. The inhibitory effect by xanthohumol was determined by the luciferase activity of the infected Huh7.5 cell lysates and the hepatitis C virus RNA levels in the culture. Xanthohumol at 3.53 µM significantly decreased the luciferase activity compared to the negative control (p Xanthohumol at 7.05 µM further decreased the luciferase activity compared to xanthohumol at 3.53 µM (p = 0.015). Xanthohumol at 7.05 µM or 14.11 µM achieved an inhibitory effect similar to that of interferon-alpha 2b (p > 0.05). Xanthohumol at 3.53 µM significantly reduced the hepatitis C virus RNA level compared to the negative control (p = 0.001). Although the results of xanthohumol at 7.05 µM had a higher variation, xanthohumol at the 7.05 µM and 14.11 µM decreased the hepatitis C virus RNA level to that achieved by interferon-alpha (p > 0.05). In conclusion, xanthohumol displays anti-hepatitis C virus activity in a cell culture system and may be potentially used as an alternative or complementary treatment against the hepatitis C virus.

  1. Simian Immunodeficiency Virus Disease Course Is Predicted by the Extent of Virus Replication during Primary Infection

    Science.gov (United States)

    Staprans, Silvija I.; Dailey, Peter J.; Rosenthal, Ann; Horton, Chris; Grant, Robert M.; Lerche, Nicholas; Feinberg, Mark B.

    1999-01-01

    To elucidate the relationship between early viral infection events and immunodeficiency virus disease progression, quantitative-competitive and branched-DNA methods of simian immunodeficiency virus (SIV) RNA quantitation were cross-validated and used to measure viremia following infection of rhesus macaques with the pathogenic SIVmac251 virus isolate. Excellent correlation between the methods suggests that both accurately approximate SIV copy number. Plasma viremia was evident 4 days postinfection, and rapid viral expansion led to peak viremia levels of 107 to 109 SIV RNA copies/ml by days 8 to 17. Limited resolution of primary viremia was accompanied by relatively short, though variable, times to the development of AIDS (81 to 630 days). The persistent high-level viremia observed following intravenous inoculation of SIVmac251 explains the aggressive disease course in this model. Survival analyses demonstrated that the disease course is established 8 to 17 days postinfection, when peak viremia is observed. The most significant predictor of disease progression was the extent of viral decline following peak viremia; larger decrements in viremia were associated with both lower steady-state viremia (P = 0.0005) and a reduced hazard of AIDS (P = 0.004). The data also unexpectedly suggested that following SIVmac251 infection, animals with the highest peak viremia were better able to control virus replication rather than more rapidly developing disease. Analysis of early viral replication dynamics should help define host responses that protect from disease progression and should provide quantitative measures to assess the extent to which protective responses may be induced by prophylactic vaccination. PMID:10233944

  2. Tombusviruses upregulate phospholipid biosynthesis via interaction between p33 replication protein and yeast lipid sensor proteins during virus replication in yeast

    Energy Technology Data Exchange (ETDEWEB)

    Barajas, Daniel; Xu, Kai; Sharma, Monika; Wu, Cheng-Yu; Nagy, Peter D., E-mail: pdnagy2@uky.edu

    2014-12-15

    Positive-stranded RNA viruses induce new membranous structures and promote membrane proliferation in infected cells to facilitate viral replication. In this paper, the authors show that a plant-infecting tombusvirus upregulates transcription of phospholipid biosynthesis genes, such as INO1, OPI3 and CHO1, and increases phospholipid levels in yeast model host. This is accomplished by the viral p33 replication protein, which interacts with Opi1p FFAT domain protein and Scs2p VAP protein. Opi1p and Scs2p are phospholipid sensor proteins and they repress the expression of phospholipid genes. Accordingly, deletion of OPI1 transcription repressor in yeast has a stimulatory effect on TBSV RNA accumulation and enhanced tombusvirus replicase activity in an in vitro assay. Altogether, the presented data convincingly demonstrate that de novo lipid biosynthesis is required for optimal TBSV replication. Overall, this work reveals that a (+)RNA virus reprograms the phospholipid biosynthesis pathway in a unique way to facilitate its replication in yeast cells. - Highlights: • Tombusvirus p33 replication protein interacts with FFAT-domain host protein. • Tombusvirus replication leads to upregulation of phospholipids. • Tombusvirus replication depends on de novo lipid synthesis. • Deletion of FFAT-domain host protein enhances TBSV replication. • TBSV rewires host phospholipid synthesis.

  3. Hydrogen peroxide thermochemical oscillator as driver for primordial RNA replication.

    Science.gov (United States)

    Ball, Rowena; Brindley, John

    2014-06-06

    This paper presents and tests a previously unrecognized mechanism for driving a replicating molecular system on the prebiotic earth. It is proposed that cell-free RNA replication in the primordial soup may have been driven by self-sustained oscillatory thermochemical reactions. To test this hypothesis, a well-characterized hydrogen peroxide oscillator was chosen as the driver and complementary RNA strands with known association and melting kinetics were used as the substrate. An open flow system model for the self-consistent, coupled evolution of the temperature and concentrations in a simple autocatalytic scheme is solved numerically, and it is shown that thermochemical cycling drives replication of the RNA strands. For the (justifiably realistic) values of parameters chosen for the simulated example system, the mean amount of replicant produced at steady state is 6.56 times the input amount, given a constant supply of substrate species. The spontaneous onset of sustained thermochemical oscillations via slowly drifting parameters is demonstrated, and a scheme is given for prebiotic production of complementary RNA strands on rock surfaces.

  4. Zinc finger antiviral protein inhibits coxsackievirus B3 virus replication and protects against viral myocarditis.

    Science.gov (United States)

    Li, Min; Yan, Kepeng; Wei, Lin; Yang, Jie; Lu, Chenyu; Xiong, Fei; Zheng, Chunfu; Xu, Wei

    2015-11-01

    The host Zinc finger antiviral protein (ZAP) has been reported exhibiting antiviral activity against positive-stranded RNA viruses (Togaviridae), negative-stranded RNA viruses (Filoviridae) and retroviruses (Retroviridae). However, whether ZAP restricts the infection of enterovirus and the development of enterovirus mediated disease remains unknown. Here, we reported the antiviral properties of ZAP against coxsackievirus B3 (CVB3), a single-stranded RNA virus of the Enterovirus genus within the Picornaviridae as a major causative agent of viral myocarditis (VMC). We found that the expression of ZAP was significantly induced after CVB3 infection in heart tissues of VMC mice. ZAP potently inhibited CVB3 replication in cells after infection, while overexpression of ZAP in mice significantly increased the resistance to CVB3 replication and viral myocarditis by significantly reducing cardiac inflammatory cytokine production. The ZAP-responsive elements (ZREs) were mapped to the 3'UTR and 5'UTR of viral RNA. Taken together, ZAP confers resistance to CVB3 infection via directly targeting viral RNA and protects mice from acute myocarditis by suppressing viral replication and cardiac inflammatory cytokine production. Our finding further expands ZAP's range of viral targets, and suggests ZAP as a potential therapeutic target for viral myocarditis caused by CVB3.

  5. Inhibition of BmNPV replication in Bombyx mori cell by dsRNA triggered RNA interference

    Institute of Scientific and Technical Information of China (English)

    XU Ying; ZHU Chenggang; JIN Yongfeng; ZHANG Yaozhou

    2004-01-01

    RNA interference (RNAi) causes degradation of targeted endogenous RNA in many diverse organisms, To investigate the effect of dsRNA on silkworm cells, we transfected three kinds of synthetic dsRNAs of 435 bp(Ap1), 300bp(Ape) and 399 bp(Au) in length against the various regions of BmNPV's DNA polymerase gene and DNA helicase gene,which are indispensable for viral replication in silkworm cells by TransMessengerTM transfection Reagent. Results indicated that in the experiment where silkworm cells were infected with wild-strain BmNPV of the three dsRNAs, Ap2 and AH can effectively suppress the replication of virus, but Ap1 had no effect on the inhibition of viral replication. Ap2 and Au can reduce the infective titer of BmNPV with a peak change of approximately 3-4 logs on day 4 post-infection.The results of reverse transcript polylnerase chain reaction (RT-PCR) and DNA dot blotting also indicated that the expression level of the two target genes and the quantity of viral DNA both distinctly decreased under the influence of Ap2 or Au. Furthermore, using fluorescence microscopy we analyzed the distribution patterns of dsRNA. Our studies revealed that a majority of dsRNA was localized in the nuclear periphery discontinuously after 24 h of transfection.

  6. RNA helicase DDX3: at the crossroad of viral replication and antiviral immunity.

    Science.gov (United States)

    Valiente-Echeverría, Fernando; Hermoso, Marcela A; Soto-Rifo, Ricardo

    2015-09-01

    Asp-Glu-Ala-Asp (DEAD)-box polypeptide 3, or DDX3, belongs to the DEAD-box family of ATP-dependent RNA helicases and is known to play different roles in RNA metabolism ranging from transcription to nuclear export, translation, and assembly of stress granules. In addition, there is growing evidence that DDX3 is a component of the innate immune response against viral infections. As such, DDX3 has been shown to play roles both upstream and downstream of I-kappa beta kinase ε (IKKε)/TANK-binding kinase 1, leading to IFN-β production. Interestingly, several RNA viruses, including human threats such as HIV-1 and hepatitis C virus, hijack DDX3 to accomplish various steps of their replication cycles. Thus, it seems that viruses have evolved to exploit DDX3's functions while threatening the innate immune response. Understanding this interesting dichotomy in DDX3 function will help us not only to improve our knowledge of virus-host interactions but also to develop novel antiviral drugs targeting the multifaceted roles of DDX3 in viral replication.

  7. Inhibitors of the interferon response enhance virus replication in vitro.

    Directory of Open Access Journals (Sweden)

    Claire E Stewart

    Full Text Available Virus replication efficiency is influenced by two conflicting factors, kinetics of the cellular interferon (IFN response and induction of an antiviral state versus speed of virus replication and virus-induced inhibition of the IFN response. Disablement of a virus's capacity to circumvent the IFN response enables both basic research and various practical applications. However, such IFN-sensitive viruses can be difficult to grow to high-titer in cells that produce and respond to IFN. The current default option for growing IFN-sensitive viruses is restricted to a limited selection of cell-lines (e.g. Vero cells that have lost their ability to produce IFN. This study demonstrates that supplementing tissue-culture medium with an IFN inhibitor provides a simple, effective and flexible approach to increase the growth of IFN-sensitive viruses in a cell-line of choice. We report that IFN inhibitors targeting components of the IFN response (TBK1, IKK2, JAK1 significantly increased virus replication. More specifically, the JAK1/2 inhibitor Ruxolitinib enhances the growth of viruses that are sensitive to IFN due to (i loss of function of the viral IFN antagonist (due to mutation or species-specific constraints or (ii mutations/host cell constraints that slow virus spread such that it can be controlled by the IFN response. This was demonstrated for a variety of viruses, including, viruses with disabled IFN antagonists that represent live-attenuated vaccine candidates (Respiratory Syncytial Virus (RSV, Influenza Virus, traditionally attenuated vaccine strains (Measles, Mumps and a slow-growing wild-type virus (RSV. In conclusion, supplementing tissue culture-medium with an IFN inhibitor to increase the growth of IFN-sensitive viruses in a cell-line of choice represents an approach, which is broadly applicable to research investigating the importance of the IFN response in controlling virus infections and has utility in a number of practical applications

  8. Analysis of RNA binding by the dengue virus NS5 RNA capping enzyme.

    Directory of Open Access Journals (Sweden)

    Brittney R Henderson

    Full Text Available Flaviviruses are small, capped positive sense RNA viruses that replicate in the cytoplasm of infected cells. Dengue virus and other related flaviviruses have evolved RNA capping enzymes to form the viral RNA cap structure that protects the viral genome and directs efficient viral polyprotein translation. The N-terminal domain of NS5 possesses the methyltransferase and guanylyltransferase activities necessary for forming mature RNA cap structures. The mechanism for flavivirus guanylyltransferase activity is currently unknown, and how the capping enzyme binds its diphosphorylated RNA substrate is important for deciphering how the flavivirus guanylyltransferase functions. In this report we examine how flavivirus NS5 N-terminal capping enzymes bind to the 5' end of the viral RNA using a fluorescence polarization-based RNA binding assay. We observed that the K(D for RNA binding is approximately 200 nM Dengue, Yellow Fever, and West Nile virus capping enzymes. Removal of one or both of the 5' phosphates reduces binding affinity, indicating that the terminal phosphates contribute significantly to binding. RNA binding affinity is negatively affected by the presence of GTP or ATP and positively affected by S-adensyl methoninine (SAM. Structural superpositioning of the dengue virus capping enzyme with the Vaccinia virus VP39 protein bound to RNA suggests how the flavivirus capping enzyme may bind RNA, and mutagenesis analysis of residues in the putative RNA binding site demonstrate that several basic residues are critical for RNA binding. Several mutants show differential binding to 5' di-, mono-, and un-phosphorylated RNAs. The mode of RNA binding appears similar to that found with other methyltransferase enzymes, and a discussion of diphosphorylated RNA binding is presented.

  9. Inhibition of avian tumor viruses by vector-based RNA interference

    Science.gov (United States)

    RNA interference (RNAi) has been shown to reduce the replication of certain animal viruses both in cell culture and in live animals. We developed RNAi-based anti-viral strategies against two important chicken pathogens: avian leukosis virus (ALV) and Marek’s Disease virus MDV). Entry plasmids conta...

  10. Intrathecal Humoral Immunity to Encephalitic RNA Viruses

    Directory of Open Access Journals (Sweden)

    Cornelia C. Bergmann

    2013-02-01

    Full Text Available The nervous system is the target for acute encephalitic viral infections, as well as a reservoir for persisting viruses. Intrathecal antibody (Ab synthesis is well documented in humans afflicted by infections associated with neurological complications, as well as the demyelinating disease, multiple sclerosis. This review focuses on the origin, recruitment, maintenance, and biological relevance of Ab-secreting cells (ASC found in the central nervous system (CNS following experimental neurotropic RNA virus infections. We will summarize evidence for a highly dynamic, evolving humoral response characterized by temporal alterations in B cell subsets, proliferation, and differentiation. Overall local Ab plays a beneficial role via complement-independent control of virus replication, although cross or self-reactive Ab to CNS antigens may contribute to immune-mediated pathogenesis during some infections. Importantly, protective Ab exert anti-viral activity not only by direct neutralization, but also by binding to cell surface-expressed viral glycoproteins. Ab engagement of viral glycoproteins blocks budding and mediates intracellular signaling leading to restored homeostatic and innate functions. The sustained Ab production by local ASC, as well as chemokines and cytokines associated with ASC recruitment and retention, are highlighted as critical components of immune control.

  11. Replication and pathogenicity of primer binding site mutants of SL3-3 murine leukemia viruses

    DEFF Research Database (Denmark)

    Lund, Anders Henrik; Schmidt, J; Luz, A

    1999-01-01

    delayed relative to that of the wild-type virus, molecular tumor analysis indicated that all the primer binding site-modified viruses induce T-cell lymphomas similar to those induced by the wild-type virus in terms of frequencies of genomic rearrangements within the T-cell receptor beta......) in undifferentiated embryonic cells. In this study we test whether SL3-3 MLV can replicate stably using tRNA primers other than the cognate tRNAPro and analyze the effect of altering the primer binding site sequence to match the 3' end of tRNA1Gln, tRNA3Lys, or tRNA1,2Arg in a mouse pathogenicity model. Contrary...... to findings from cell culture studies of primer binding site-modified human immunodeficiency virus type 1 and avian retroviruses, our findings were that SL3-3 MLV may stably and efficiently replicate with tRNA primers other than tRNAPro. Although lymphoma induction of the SL3-3 Lys3 mutant was significantly...

  12. The eIF4AIII RNA helicase is a critical determinant of human cytomegalovirus replication

    Energy Technology Data Exchange (ETDEWEB)

    Ziehr, Ben; Lenarcic, Erik; Cecil, Chad; Moorman, Nathaniel J., E-mail: nmoorman@med.unc.edu

    2016-02-15

    Human cytomegalovirus (HCMV) was recently shown to encode a large number of spliced mRNAs. While the nuclear export of unspliced viral transcripts has been extensively studied, the role of host mRNA export factors in HCMV mRNA trafficking remains poorly defined. We found that the eIF4AIII RNA helicase, a component of the exon junction complex, was necessary for efficient virus replication. Depletion of eIF4AIII limited viral DNA accumulation, export of viral mRNAs from the nucleus, and the production of progeny virus. However eIF4AIII was dispensable for the association of viral transcripts with ribosomes. We found that pateamine A, a natural compound that inhibits both eIF4AI/II and eIF4AIII, has potent antiviral activity and inhibits HCMV replication throughout the virus lytic cycle. Our results demonstrate that eIF4AIII is required for efficient HCMV replication, and suggest that eIF4A family helicases may be a new class of targets for the development of host-directed antiviral therapeutics. - Highlights: • The host eIF4AIII RNA helicase is required for efficient HCMV replication. • Depleting eIF4AIII inhibited the nuclear export of HCMV mRNAs. • HCMV mRNAs did not require eIF4AIII to associate with polyribosomes. • The eIF4A family helicases may be new targets for host-directed antiviral drugs.

  13. Efficient inhibition of HIV-1 replication by an artificial polycistronic miRNA construct

    Directory of Open Access Journals (Sweden)

    Zhang Tao

    2012-06-01

    Full Text Available Abstract Background RNA interference (RNAi has been used as a promising approach to inhibit human immunodeficiency virus type 1 (HIV-1 replication for both in vitro and in vivo animal models. However, HIV-1 escape mutants after RNAi treatment have been reported. Expressing multiple small interfering RNAs (siRNAs against conserved viral sequences can serve as a genetic barrier for viral escape, and optimization of the efficiency of this process was the aim of this study. Results An artificial polycistronic transcript driven by a CMV promoter was designed to inhibit HIV-1 replication. The artificial polycistronic transcript contained two pre-miR-30a backbones and one pre-miR-155 backbone, which are linked by a sequence derived from antisense RNA sequence targeting the HIV-1 env gene. Our results demonstrated that this artificial polycistronic transcript simultaneously expresses three anti-HIV siRNAs and efficiently inhibits HIV-1 replication. In addition, the biosafety of MT-4 cells expressing this polycistronic miRNA transcript was evaluated, and no apparent impacts on cell proliferation rate, interferon response, and interruption of native miRNA processing were observed. Conclusions The strategy described here to generate an artificial polycistronic transcript to inhibit viral replication provided an opportunity to select and optimize many factors to yield highly efficient constructs expressing multiple siRNAs against viral infection.

  14. Gene Knockdown of Venezuelan Equine Encephalitis Virus E2 Glycoprotein Using DNA-Directed RNA Interference

    Science.gov (United States)

    2006-12-01

    e _s~u~m mary - Introduction: Alphaviruses are a large family of RNA viruses that can cause acute infection resulting in arthritis and encephalitis...One of the important alphaviruses is the Venezuelan equine encephalitis virus. This virus has been linked to a number of outbreaks in both North and... replication of VEE virus in vitro. Bhogal, H.S., McLaws, L.J., and Jager, S.J. 2006. Gene Knockdown of Venezuelan Equine Encephalitis Virus E2

  15. A small yeast RNA inhibits HCV IRES mediated translation and inhibits replication of poliovirus in vivo

    Institute of Scientific and Technical Information of China (English)

    Xue-Song Liang; Jian-Qi Lian; Yong-Xing Zhou; Qing-He Nie; Chun-Qiu Hao

    2003-01-01

    AIM: To investigate the anti-virus infection activity of internal ribosome entry site (IRES) specific inhibitor RNA (IRNA).METHODS: IRNA eukaryotic vector pcRz-IRNA or mIRNA eukaryotic vector pcRz-mIRNA was tansfected into human hepatocarcinoma cells (HHCC), then selected with neomycin G418 for 4 to 8 weeks, and then infected with polio virus vaccinas line. The cytopethogenesis effect was investigated and the cell extract was collected. At last the polio virus titer of different cells was determined by plaque assay.RESULTS: Constitutive expression of IRNA was not detrimental to cell growth. HCV IRES-mediated capindependent translation was markedly inhibited in cells constitutively expressing IRNA compared to control hepatoma cells. However, cap-dependent translation was not significantly affected in these cell line. Additionally, HHCC cells constitutively expressing IRNA became refractory to infection of polio virus.CONCLUSION: IRES specific IRNA can inhibit HCV IRES mediated translation and poliovirus replication.

  16. Murine leukemia virus (MLV replication monitored with fluorescent proteins

    Directory of Open Access Journals (Sweden)

    Bittner Alexandra

    2004-12-01

    Full Text Available Abstract Background Cancer gene therapy will benefit from vectors that are able to replicate in tumor tissue and cause a bystander effect. Replication-competent murine leukemia virus (MLV has been described to have potential as cancer therapeutics, however, MLV infection does not cause a cytopathic effect in the infected cell and viral replication can only be studied by immunostaining or measurement of reverse transcriptase activity. Results We inserted the coding sequences for green fluorescent protein (GFP into the proline-rich region (PRR of the ecotropic envelope protein (Env and were able to fluorescently label MLV. This allowed us to directly monitor viral replication and attachment to target cells by flow cytometry. We used this method to study viral replication of recombinant MLVs and split viral genomes, which were generated by replacement of the MLV env gene with the red fluorescent protein (RFP and separately cloning GFP-Env into a retroviral vector. Co-transfection of both plasmids into target cells resulted in the generation of semi-replicative vectors, and the two color labeling allowed to determine the distribution of the individual genomes in the target cells and was indicative for the occurrence of recombination events. Conclusions Fluorescently labeled MLVs are excellent tools for the study of factors that influence viral replication and can be used to optimize MLV-based replication-competent viruses or vectors for gene therapy.

  17. Melon necrotic spot virus Replication Occurs in Association with Altered Mitochondria.

    Science.gov (United States)

    Gómez-Aix, Cristina; García-García, María; Aranda, Miguel A; Sánchez-Pina, María Amelia

    2015-04-01

    Melon necrotic spot virus (MNSV) (genus Carmovirus, family Tombusviridae) is a single-stranded, positive-sense RNA virus that has become an experimental model for the analysis of cell-to-cell virus movement and translation of uncapped viral RNAs, whereas little is known about its replication. Analysis of the cytopathology after MNSV infection showed the specific presence of modified organelles that resemble mitochondria. Immunolocalization of the glycine decarboxylase complex (GDC) P protein in these organelles confirmed their mitochondrial origin. In situ hybridization and immunolocalization experiments showed the specific localization of positive-sense viral RNA, capsid protein (CP), and double-stranded (ds)RNA in these organelles meaning that replication of the virus takes place in association with them. The three-dimensional reconstructions of the altered mitochondria showed the presence of large, interconnected, internal dilations which appeared to be linked to the outside cytoplasmic environment through pores and/or complex structures, and with lipid bodies. Transient expression of MNSV p29 revealed that its specific target is mitochondria. Our data document the extensive reorganization of host mitochondria induced by MNSV, which provides a protected environment to viral replication, and show that the MNSV p29 protein is the primary determinant of this effect in the host.

  18. Infidelity of SARS-CoV Nsp14-Exonuclease Mutant Virus Replication Is Revealed by Complete Genome Sequencing

    Science.gov (United States)

    Eckerle, Lance D.; Becker, Michelle M.; Halpin, Rebecca A.; Li, Kelvin; Venter, Eli; Lu, Xiaotao; Scherbakova, Sana; Graham, Rachel L.; Baric, Ralph S.; Stockwell, Timothy B.; Spiro, David J.; Denison, Mark R.

    2010-01-01

    Most RNA viruses lack the mechanisms to recognize and correct mutations that arise during genome replication, resulting in quasispecies diversity that is required for pathogenesis and adaptation. However, it is not known how viruses encoding large viral RNA genomes such as the Coronaviridae (26 to 32 kb) balance the requirements for genome stability and quasispecies diversity. Further, the limits of replication infidelity during replication of large RNA genomes and how decreased fidelity impacts virus fitness over time are not known. Our previous work demonstrated that genetic inactivation of the coronavirus exoribonuclease (ExoN) in nonstructural protein 14 (nsp14) of murine hepatitis virus results in a 15-fold decrease in replication fidelity. However, it is not known whether nsp14-ExoN is required for replication fidelity of all coronaviruses, nor the impact of decreased fidelity on genome diversity and fitness during replication and passage. We report here the engineering and recovery of nsp14-ExoN mutant viruses of severe acute respiratory syndrome coronavirus (SARS-CoV) that have stable growth defects and demonstrate a 21-fold increase in mutation frequency during replication in culture. Analysis of complete genome sequences from SARS-ExoN mutant viral clones revealed unique mutation sets in every genome examined from the same round of replication and a total of 100 unique mutations across the genome. Using novel bioinformatic tools and deep sequencing across the full-length genome following 10 population passages in vitro, we demonstrate retention of ExoN mutations and continued increased diversity and mutational load compared to wild-type SARS-CoV. The results define a novel genetic and bioinformatics model for introduction and identification of multi-allelic mutations in replication competent viruses that will be powerful tools for testing the effects of decreased fidelity and increased quasispecies diversity on viral replication, pathogenesis, and

  19. Increased Replicative Fitness Can Lead to Decreased Drug Sensitivity of Hepatitis C Virus

    Science.gov (United States)

    Sheldon, Julie; Beach, Nathan M.; Moreno, Elena; Gallego, Isabel; Piñeiro, David; Martínez-Salas, Encarnación; Gregori, Josep; Quer, Josep; Esteban, Juan Ignacio; Rice, Charles M.

    2014-01-01

    ABSTRACT Passage of hepatitis C virus (HCV) in human hepatoma cells resulted in populations that displayed partial resistance to alpha interferon (IFN-α), telaprevir, daclatasvir, cyclosporine, and ribavirin, despite no prior exposure to these drugs. Mutant spectrum analyses and kinetics of virus production in the absence and presence of drugs indicate that resistance is not due to the presence of drug resistance mutations in the mutant spectrum of the initial or passaged populations but to increased replicative fitness acquired during passage. Fitness increases did not alter host factors that lead to shutoff of general host cell protein synthesis and preferential translation of HCV RNA. The results imply that viral replicative fitness is a mechanism of multidrug resistance in HCV. IMPORTANCE Viral drug resistance is usually attributed to the presence of amino acid substitutions in the protein targeted by the drug. In the present study with HCV, we show that high viral replicative fitness can confer a general drug resistance phenotype to the virus. The results exclude the possibility that genomes with drug resistance mutations are responsible for the observed phenotype. The fact that replicative fitness can be a determinant of multidrug resistance may explain why the virus is less sensitive to drug treatments in prolonged chronic HCV infections that favor increases in replicative fitness. PMID:25122776

  20. The role of Vif oligomerization and RNA chaperone activity in HIV-1 replication.

    Science.gov (United States)

    Batisse, Julien; Guerrero, Santiago; Bernacchi, Serena; Sleiman, Dona; Gabus, Caroline; Darlix, Jean-Luc; Marquet, Roland; Tisné, Carine; Paillart, Jean-Christophe

    2012-11-01

    The viral infectivity factor (Vif) is essential for the productive infection and dissemination of HIV-1 in non-permissive cells that involve most natural HIV-1 target cells. Vif counteracts the packaging of two cellular cytidine deaminases named APOBEC3G (A3G) and A3F by diverse mechanisms including the recruitment of an E3 ubiquitin ligase complex and the proteasomal degradation of A3G/A3F, the inhibition of A3G mRNA translation or by a direct competition mechanism. In addition, Vif appears to be an active partner of the late steps of viral replication by participating in virus assembly and Gag processing, thus regulating the final stage of virion formation notably genomic RNA dimerization and by inhibiting the initiation of reverse transcription. Vif is a small pleiotropic protein with multiple domains, and recent studies highlighted the importance of Vif conformation and flexibility in counteracting A3G and in binding RNA. In this review, we will focus on the oligomerization and RNA chaperone properties of Vif and show that the intrinsic disordered nature of some Vif domains could play an important role in virus assembly and replication. Experimental evidence demonstrating the RNA chaperone activity of Vif will be presented.

  1. Reassortment in segmented RNA viruses: mechanisms and outcomes.

    Science.gov (United States)

    McDonald, Sarah M; Nelson, Martha I; Turner, Paul E; Patton, John T

    2016-07-01

    Segmented RNA viruses are widespread in nature and include important human, animal and plant pathogens, such as influenza viruses and rotaviruses. Although the origin of RNA virus genome segmentation remains elusive, a major consequence of this genome structure is the capacity for reassortment to occur during co-infection, whereby segments are exchanged among different viral strains. Therefore, reassortment can create viral progeny that contain genes that are derived from more than one parent, potentially conferring important fitness advantages or disadvantages to the progeny virus. However, for segmented RNA viruses that package their multiple genome segments into a single virion particle, reassortment also requires genetic compatibility between parental strains, which occurs in the form of conserved packaging signals, and the maintenance of RNA and protein interactions. In this Review, we discuss recent studies that examined the mechanisms and outcomes of reassortment for three well-studied viral families - Cystoviridae, Orthomyxoviridae and Reoviridae - and discuss how these findings provide new perspectives on the replication and evolution of segmented RNA viruses.

  2. Isolation and characterization of highly replicable hepatitis C virus genotype 1a strain HCV-RMT.

    Science.gov (United States)

    Arai, Masaaki; Tokunaga, Yuko; Takagi, Asako; Tobita, Yoshimi; Hirata, Yuichi; Ishida, Yuji; Tateno, Chise; Kohara, Michinori

    2013-01-01

    Multiple genotype 1a clones have been reported, including the very first hepatitis C virus (HCV) clone called H77. The replication ability of some of these clones has been confirmed in vitro and in vivo, although this ability is somehow compromised. We now report a newly isolated genotype 1a clone, designated HCV-RMT, which has the ability to replicate efficiently in patients, chimeric mice with humanized liver, and cultured cells. An authentic subgenomic replicon cell line was established from the HCV-RMT sequence with spontaneous introduction of three adaptive mutations, which were later confirmed to be responsible for efficient replication in HuH-7 cells as both subgenomic replicon RNA and viral genome RNA. Following transfection, the HCV-RMT RNA genome with three adaptive mutations was maintained for more than 2 months in HuH-7 cells. One clone selected from the transfected cells had a high copy number, and its supernatant could infect naïve HuH-7 cells. Direct injection of wild-type HCV-RMT RNA into the liver of chimeric mice with humanized liver resulted in vigorous replication, similar to inoculation with the parental patient's serum. A study of virus replication using HCV-RMT derivatives with various combinations of adaptive mutations revealed a clear inversely proportional relationship between in vitro and in vivo replication abilities. Thus, we suggest that HCV-RMT and its derivatives are important tools for HCV genotype 1a research and for determining the mechanism of HCV replication in vitro and in vivo.

  3. Isolation and characterization of highly replicable hepatitis C virus genotype 1a strain HCV-RMT.

    Directory of Open Access Journals (Sweden)

    Masaaki Arai

    Full Text Available Multiple genotype 1a clones have been reported, including the very first hepatitis C virus (HCV clone called H77. The replication ability of some of these clones has been confirmed in vitro and in vivo, although this ability is somehow compromised. We now report a newly isolated genotype 1a clone, designated HCV-RMT, which has the ability to replicate efficiently in patients, chimeric mice with humanized liver, and cultured cells. An authentic subgenomic replicon cell line was established from the HCV-RMT sequence with spontaneous introduction of three adaptive mutations, which were later confirmed to be responsible for efficient replication in HuH-7 cells as both subgenomic replicon RNA and viral genome RNA. Following transfection, the HCV-RMT RNA genome with three adaptive mutations was maintained for more than 2 months in HuH-7 cells. One clone selected from the transfected cells had a high copy number, and its supernatant could infect naïve HuH-7 cells. Direct injection of wild-type HCV-RMT RNA into the liver of chimeric mice with humanized liver resulted in vigorous replication, similar to inoculation with the parental patient's serum. A study of virus replication using HCV-RMT derivatives with various combinations of adaptive mutations revealed a clear inversely proportional relationship between in vitro and in vivo replication abilities. Thus, we suggest that HCV-RMT and its derivatives are important tools for HCV genotype 1a research and for determining the mechanism of HCV replication in vitro and in vivo.

  4. Inhibition of influenza A virus replication by rifampicin and selenocystamine

    Energy Technology Data Exchange (ETDEWEB)

    Hamzehei, M.; Ledinko, N.

    1980-01-01

    The effects of selenocystamine, an inhibitor of influenza virus RNA-dependent RNA polymerase in vitro activity, in the antibiotic rifampicin were studied on influenza A/PR/8/34 (HON1) infection in embryonated eggs. Both drugs completely inhibited hemagglutinating and infective virus yields when added at relatively early times postinfection. Maximal inhibition was produced by apparently noncytotoxic concentrations of 50 microgram of selenocystamine, or of 400 microgram of rifampicin, per egg.

  5. Application of hepatitis B virus replication mouse model

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    AIM:To evaluate the value of the hepatitis B virus(HBV) replication mouse model with regard to several aspects of the study of HBV biology.METHODS:To evaluate the HBV replication mouse model in detecting the efficacy of anti-HBV agents,the interferon inducer polyinosinic-polytidylin acid(polyIC) and nucleotide analogues adefovir and entecavir were administered to mice injected with wild type pHBV4.1,and the inhibiting effect of these agents on HBV DNA replication was evaluated.To identify the model's value ...

  6. Inhibition of brome mosaic virus (BMV) amplification in protoplasts from transgenic tobacco plants expressing replicable BMV RNAs.

    Science.gov (United States)

    Kaido, M; Mori, M; Mise, K; Okuno, T; Furusawa, I

    1995-11-01

    Transgenic tobacco plants (V123 plants) expressing a set of full-length brome mosaic virus (BMV) genomic RNAs from the cauliflower mosaic virus 35S promoter were produced. The accumulation level of BMV RNAs in V123 plant cells was approximately 1% of that in nontransgenic tobacco protoplasts inoculated with BMV RNAs. The level of BMV RNA in V123 protoplasts did not increase after inoculating the protoplasts with BMV RNAs, whereas V123 protoplasts supported the accumulation of cucumber mosaic virus (CMV) RNAs to a level similar to that in non-transgenic tobacco protoplasts after inoculation with CMV RNA. Such BMV-specific resistance was also observed in protoplasts from V12 plants expressing full-length BMV RNA1 and RNA2, both of which are required and sufficient for BMV RNA replication. On the other hand, protoplasts from M12 plants, expressing truncated BMV RNA1 and RNA2 in which the 3' 200 nucleotides required for BMV RNA replication were deleted, exhibited weaker resistance to infection with BMV RNA than V12 protoplasts, although the accumulation level of truncated BMV RNA1 and RNA2 in M12 protoplasts was higher than that of BMV RNA1 and RNA2 in V12 protoplasts. These results suggest that expression of BMV RNA replicons is involved in the induction of resistance, rather than high-level accumulation of BMV RNAs and/or their encoded proteins.

  7. The rhinovirus type 14 genome contains an internally located RNA structure that is required for viral replication.

    Science.gov (United States)

    McKnight, K L; Lemon, S M

    1998-12-01

    Cis-acting RNA signals are required for replication of positive-strand viruses such as the picornaviruses. Although these generally have been mapped to the 5' and/or 3' termini of the viral genome, RNAs derived from human rhinovirus type 14 are unable to replicate unless they contain an internal cis-acting replication element (cre) located within the genome segment encoding the capsid proteins. Here, we show that the essential cre sequence is 83-96 nt in length and located between nt 2318-2413 of the genome. Using dicistronic RNAs in which translation of the P1 and P2-P3 segments of the polyprotein were functionally dissociated, we further demonstrate that translation of the cre sequence is not required for RNA replication. Thus, although it is located within a protein-coding segment of the genome, the cre functions as an RNA entity. Computer folds suggested that cre sequences could form a stable structure in either positive- or minus-strand RNA. However, an analysis of mutant RNAs containing multiple covariant and non-covariant nucleotide substitutions within these putative structures demonstrated that only the predicted positive-strand structure is essential for efficient RNA replication. The absence of detectable minus-strand synthesis from RNAs that lack the cre suggests that the cre is required for initiation of minus-strand RNA synthesis. Since a lethal 3' noncoding region mutation could be partially rescued by a compensating mutation within the cre, the cre appears to participate in a long-range RNA-RNA interaction required for this process. These data provide novel insight into the mechanisms of replication of a positive-strand RNA virus, as they define the involvement of an internally located RNA structure in the recognition of viral RNA by the viral replicase complex. Since internally located RNA replication signals have been shown to exist in several other positive-strand RNA virus families, these observations are potentially relevant to a wide array of

  8. Role of the DIS hairpin in replication of human immunodeficiency virus type 1.

    Science.gov (United States)

    Berkhout, B; van Wamel, J L

    1996-10-01

    The virion-associated genome of human immunodeficiency virus type 1 consists of a noncovalently linked dimer of two identical, unspliced RNA molecules. A hairpin structure within the untranslated leader transcript is postulated to play a role in RNA dimerization through base pairing of the autocomplementary loop sequences. This hairpin motif with the palindromic loop sequence is referred to as the dimer initiation site (DIS), and the type of interaction is termed loop-loop kissing. Detailed phylogenetic analysis of the DIS motifs in different human and simian immunodeficiency viruses revealed conservation of the hairpin structure with a 6-mer palindrome in the loop, despite considerable sequence divergence. This finding supports the loop-loop kissing mechanism. To test this possibility, proviral genomes with mutations in the DIS palindrome were constructed. The appearance of infectious virus upon transfection into SupT1 T cells was delayed for the DIS mutants compared with that obtained by transfection of the wild-type provirus (pLAI), confirming that this RNA motif plays an important role in virus replication. Surprisingly, the RNA genome extracted from mutant virions was found to be fully dimeric and to have a normal thermal stability. These results indicate that the DIS motif is not essential for human immunodeficiency virus type 1 RNA dimerization and suggest that DIS base pairing does not contribute to the stability of the mature RNA dimer. Instead, we measured a reduction in the amount of viral RNA encapsidated in the mutant virions, suggesting a role of the DIS motif in RNA packaging. This result correlates with the idea that the processes of RNA dimerization and packaging are intrinsically linked, and we propose that DIS pairing is a prerequisite for RNA packaging.

  9. Hepatitis C virus replicates in peripheral blood mononuclear cells of patients with occult hepatitis C virus infection

    Science.gov (United States)

    Castillo, I; Rodríguez-Iñigo, E; Bartolomé, J; de Lucas, S; Ortíz-Movilla, N; López-Alcorocho, J M; Pardo, M; Carreño, V

    2005-01-01

    Background: Occult hepatitis C virus (HCV) infection is characterised by the presence of HCV-RNA in the liver in the absence of anti-HCV, and serum viral RNA. Up to 70% of these patients also have HCV-RNA in peripheral blood mononuclear cells (PBMC) but it is not known if HCV is replicating in these cells. Aim: We studied possible HCV replication in PBMC of 18 patients with an occult HCV infection who were selected on the basis of HCV-RNA positivity in PBMC. Methods: Detection of HCV-RNA positive and negative strands in PBMC was done by strand specific reverse transcriptase-polymerase chain reaction (RT-PCR) and by in situ hybridisation. Results: The presence of HCV-RNA positive strand in PBMC was confirmed in all patients by strand specific RT-PCR and by in situ hybridisation. Mean percentage of PBMC which had the HCV-RNA positive strand was 3.3% (95% confidence interval (CI) 2.1–4.4) The HCV-RNA negative strand was found in the PBMC of 11/18 (61%) patients by strand specific RT-PCR and confirmed by in situ hybridisation, and the percentage of PBMC harbouring the HCV-RNA negative strand was 3.1% (95% CI 0.8–5.5). There was a significant correlation (p = 0.001, r = 0.84) between the percentage of PBMC with the HCV-RNA positive strand and that of PBMC with the HCV-RNA negative strand. Conclusion: HCV replicates in the PBMC of patients with occult HCV infection and thus, although these patients do not have serum HCV-RNA, they could be potentially infectious. PMID:15831916

  10. Strategies underlying RNA silencing suppression by negative strand RNA viruses

    NARCIS (Netherlands)

    Hemmes, J.C.

    2007-01-01

    The research described in this thesis focused on the strategies of negative strand RNA viruses to counteract antiviral RNA silencing. In plants and insects, RNA silencing has been shown to act as a sequence specific antiviral defence mechanism that is characterised by the processing of double strand

  11. Strategies underlying RNA silencing suppression by negative strand RNA viruses

    NARCIS (Netherlands)

    Hemmes, J.C.

    2007-01-01

    The research described in this thesis focused on the strategies of negative strand RNA viruses to counteract antiviral RNA silencing. In plants and insects, RNA silencing has been shown to act as a sequence specific antiviral defence mechanism that is characterised by the processing of double strand

  12. A Functional Role of Fibroblast Growth Factor Receptor 1 (FGFR1 in the Suppression of Influenza A Virus Replication.

    Directory of Open Access Journals (Sweden)

    Xin Liu

    Full Text Available Influenza A virus causes annual epidemics and occasional pandemics in humans. Here, we investigated four members of the fibroblast growth factor receptor (FGFR family; FGFR1 to 4, and examined their expression patterns in human lung epithelial cells A549 with influenza A virus infection. We identified a functional role of FGFR1 in influenza A/Puerto Rico/8/1934 (PR8 and A/Anhui/01/2005 (H5N1 virus replication. Our results showed that FGFR1 silencing by siRNA interference promoted influenza A/PR8 and H5N1 virus replication in A549 cells, while lentivirus-mediated exogenous FGFR1 expression significantly suppressed influenza A virus replication; however, FGFR4 did not have the same effects. Moreover, FGFR1 phosphorylation levels were downregulated in A549 cells by influenza A virus infection, while the repression of FGFR1 kinase using PD173074, a potent and selective FGFR1 inhibitor, could enhance virus replication. Furthermore, we found that FGFR1 inhibits influenza virus internalization, but not binding, during viral entry. These results suggested that FGFR1 specifically antagonizes influenza A virus replication, probably by blocking viral entry.

  13. Rubella Virus Replication and Links to Teratogenicity

    OpenAIRE

    Lee, Jia-Yee; Bowden, D. Scott

    2000-01-01

    Rubella virus (RV) is the causative agent of the disease known more popularly as German measles. Rubella is predominantly a childhood disease and is endemic throughout the world. Natural infections of rubella occur only in humans and are generally mild. Complications of rubella infection, most commonly polyarthralgia in adult women, do exist; occasionally more serious sequelae occur. However, the primary public health concern of RV infection is its teratogenicity. RV infection of women during...

  14. Construction of self-replicating subgenomic dengue virus 4 (DENV4) replicon.

    Science.gov (United States)

    Alcaraz-Estrada, Sofia L; Del Angel, Rosa; Padmanabhan, Radhakrishnan

    2014-01-01

    Dengue virus serotypes 1-4 are members of mosquito-borne flavivirus genus of Flaviviridae family that encode one long open reading frame (ORF) that is translated to a polyprotein. Both host and virally encoded proteases function in the processing of the polyprotein by co-translational and posttranslational mechanisms to yield 10 mature proteins prior to viral RNA replication. To study cis- and trans-acting factors involved in viral RNA replication, many groups [1-8] have constructed cDNAs encoding West Nile virus (WNV), DENV, or yellow fever virus reporter replicon RNAs. The replicon plasmids constructed in our laboratory for WNV [9] and the DENV4 replicon described here are arranged in the order of 5'-untranslated region (UTR), the N-terminal coding sequence of capsid (C), Renilla luciferase (Rluc) reporter gene with a translation termination codon, and an internal ribosome entry site (IRES) element from encephalomyocarditis virus (EMCV) for cap-independent translation of the downstream ORF that codes for a polyprotein precursor, CterE-NS1-NS2A-NS2B-NS3-NS4A-NS4B-NS5, followed by the 3'-UTR. In the second DENV4 replicon, the Rluc gene is fused sequentially downstream to the 20 amino acid (aa) FMDV 2A protease coding sequence, neomycin resistance gene (Neo(r)), a termination codon, and the EMCV leader followed by the same polyprotein coding sequence and 3'-UTR as in the first replicon. The first replicon is useful to study by transient transfection experiments the cis-acting elements and trans-acting factors involved in viral RNA replication. The second DENV4 replicon is used to establish a stable monkey kidney (Vero) cell line by transfection of replicon RNA and selection in the presence of the G418, an analog of neomycin. This replicon is useful for screening and identifying antiviral compounds that are potential inhibitors of viral replication.

  15. Enhanced inhibition of Avian leukosis virus subgroup J replication by multi-target miRNAs

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    Meng Qing-Wen

    2011-12-01

    Full Text Available Abstract Background Avian leukosis virus (ALV is a major infectious disease that impacts the poultry industry worldwide. Despite intensive efforts, no effective vaccine has been developed against ALV because of mutations that lead to resistant forms. Therefore, there is a dire need to develop antiviral agents for the treatment of ALV infections and RNA interference (RNAi is considered an effective antiviral strategy. Results In this study, the avian leukosis virus subgroup J (ALV-J proviral genome, including the gag genes, were treated as targets for RNAi. Four pairs of miRNA sequences were designed and synthesized that targeted different regions of the gag gene. The screened target (i.e., the gag genes was shown to effectively suppress the replication of ALV-J by 19.0-77.3%. To avoid the generation of escape variants during virus infection, expression vectors of multi-target miRNAs were constructed using the multi-target serial strategy (against different regions of the gag, pol, and env genes. Multi-target miRNAs were shown to play a synergistic role in the inhibition of ALV-J replication, with an inhibition efficiency of viral replication ranging from 85.0-91.2%. Conclusion The strategy of multi-target miRNAs might be an effective method for inhibiting ALV replication and the acquisition of resistant mutations.

  16. Detecting RNA viruses in living mammalian cells by fluorescence microscopy.

    Science.gov (United States)

    Sivaraman, Divya; Biswas, Payal; Cella, Lakshmi N; Yates, Marylynn V; Chen, Wilfred

    2011-07-01

    Traditional methods that rely on viral isolation and culture techniques continue to be the gold standards used for detection of infectious viral particles. However, new techniques that rely on visualization of live cells can shed light on understanding virus-host interaction for early stage detection and potential drug discovery. Live-cell imaging techniques that incorporate fluorescent probes into viral components provide opportunities for understanding mRNA expression, interaction, and virus movement and localization. Other viral replication events inside a host cell can be exploited for non-invasive detection, such as single-virus tracking, which does not inhibit viral infectivity or cellular function. This review highlights some of the recent advances made using these novel approaches for visualization of viral entry and replication in live cells. Copyright © 2011 Elsevier Ltd. All rights reserved.

  17. The eukaryotic elongation factor 1A is critical for genome replication of the paramyxovirus respiratory syncytial virus.

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    Ting Wei

    Full Text Available The eukaryotic translation factor eEF1A assists replication of many RNA viruses by various mechanisms. Here we show that down-regulation of eEF1A restricts the expression of viral genomic RNA and the release of infectious virus, demonstrating a biological requirement for eEF1A in the respiratory syncytial virus (RSV life cycle. The key proteins in the replicase/transcriptase complex of RSV; the nucleocapsid (N protein, phosphoprotein (P and matrix (M protein, all associate with eEF1A in RSV infected cells, although N is the strongest binding partner. Using individually expressed proteins, N, but not P or M bound to eEF1A. This study demonstrates a novel interaction between eEF1A and the RSV replication complex, through binding to N protein, to facilitate genomic RNA synthesis and virus production.

  18. Defining Hsp70 Subnetworks in Dengue Virus Replication Reveals Key Vulnerability in Flavivirus Infection.

    Science.gov (United States)

    Taguwa, Shuhei; Maringer, Kevin; Li, Xiaokai; Bernal-Rubio, Dabeiba; Rauch, Jennifer N; Gestwicki, Jason E; Andino, Raul; Fernandez-Sesma, Ana; Frydman, Judith

    2015-11-19

    Viral protein homeostasis depends entirely on the machinery of the infected cell. Accordingly, viruses can illuminate the interplay between cellular proteostasis components and their distinct substrates. Here, we define how the Hsp70 chaperone network mediates the dengue virus life cycle. Cytosolic Hsp70 isoforms are required at distinct steps of the viral cycle, including entry, RNA replication, and virion biogenesis. Hsp70 function at each step is specified by nine distinct DNAJ cofactors. Of these, DnaJB11 relocalizes to virus-induced replication complexes to promote RNA synthesis, while DnaJB6 associates with capsid protein and facilitates virion biogenesis. Importantly, an allosteric Hsp70 inhibitor, JG40, potently blocks infection of different dengue serotypes in human primary blood cells without eliciting viral resistance or exerting toxicity to the host cells. JG40 also blocks replication of other medically-important flaviviruses including yellow fever, West Nile and Japanese encephalitis viruses. Thus, targeting host Hsp70 subnetworks provides a path for broad-spectrum antivirals.

  19. Cellular DDX3 regulates Japanese encephalitis virus replication by interacting with viral un-translated regions.

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    Li, Chen; Ge, Ling-ling; Li, Peng-peng; Wang, Yue; Dai, Juan-juan; Sun, Ming-xia; Huang, Li; Shen, Zhi-qiang; Hu, Xiao-chun; Ishag, Hassan; Mao, Xiang

    2014-01-20

    Japanese encephalitis virus is one of the most common causes for epidemic viral encephalitis in humans and animals. Herein we demonstrated that cellular helicase DDX3 is involved in JEV replication. DDX3 knockdown inhibits JEV replication. The helicase activity of DDX3 is crucial for JEV replication. GST-pulldown and co-immunoprecipitation experiments demonstrated that DDX3 could interact with JEV non-structural proteins 3 and 5. Co-immunoprecipitation and confocal microscopy analysis confirmed that DDX3 interacts and colocalizes with these viral proteins and viral RNA during the infection. We determined that DDX3 binds to JEV 5' and 3' un-translated regions. We used a JEV-replicon system to demonstrate that DDX3 positively regulates viral RNA translation, which might affect viral RNA replication at the late stage of virus infection. Collectively, we identified that DDX3 is necessary for JEV infection, suggesting that DDX3 might be a novel target to design new antiviral agents against JEV or other flavivirus infections.

  20. Mutations in Encephalomyocarditis Virus 3A Protein Uncouple the Dependency of Genome Replication on Host Factors Phosphatidylinositol 4-Kinase IIIα and Oxysterol-Binding Protein

    NARCIS (Netherlands)

    Dorobantu, Cristina M; Albulescu, Lucian; Lyoo, Heyrhyoung; van Kampen, Mirjam; De Francesco, Raffaele; Lohmann, Volker; Harak, Christian; van der Schaar, Hilde M; Strating, Jeroen R P M; Gorbalenya, Alexander E; van Kuppeveld, Frank J M

    2016-01-01

    Positive-strand RNA [(+)RNA] viruses are true masters of reprogramming host lipid trafficking and synthesis to support virus genome replication. Via their membrane-associated 3A protein, picornaviruses of the genus Enterovirus (e.g., poliovirus, coxsackievirus, and rhinovirus) subvert Golgi

  1. VP40 Octamers Are Essential for Ebola Virus Replication

    Science.gov (United States)

    Hoenen, Thomas; Volchkov, Viktor; Kolesnikova, Larissa; Mittler, Eva; Timmins, Joanna; Ottmann, Michelle; Reynard, Olivier; Becker, Stephan; Weissenhorn, Winfried

    2005-01-01

    Matrix protein VP40 of Ebola virus is essential for virus assembly and budding. Monomeric VP40 can oligomerize in vitro into RNA binding octamers, and the crystal structure of octameric VP40 has revealed that residues Phe125 and Arg134 are the most important residues for the coordination of a short single-stranded RNA. Here we show that full-length wild-type VP40 octamers bind RNA upon HEK 293 cell expression. While the Phe125-to-Ala mutation resulted in reduced RNA binding, the Arg134-to-Ala mutation completely abolished RNA binding and thus octamer formation. The absence of octamer formation, however, does not affect virus-like particle (VLP) formation, as the VLPs generated from the expression of wild-type VP40 and mutated VP40 in HEK 293 cells showed similar morphology and abundance and no significant difference in size. These results strongly indicate that octameric VP40 is dispensable for VLP formation. The cellular localization of mutant VP40 was different from that of wild-type VP40. While wild-type VP40 was present in small patches predominantly at the plasma membrane, the octamer-negative mutants were found in larger aggregates at the periphery of the cell and in the perinuclear region. We next introduced the Arg134-to-Ala and/or the Phe125-to-Ala mutation into the Ebola virus genome. Recombinant wild-type virus and virus expressing the VP40 Phe125-to-Ala mutation were both rescued. In contrast, no recombinant virus expressing the VP40 Arg134-to-Ala mutation could be recovered. These results suggest that RNA binding of VP40 and therefore octamer formation are essential for the Ebola virus life cycle. PMID:15650213

  2. Regulation of Human Adenovirus Replication by RNA Interference.

    Science.gov (United States)

    Nikitenko, N A; Speiseder, T; Lam, E; Rubtsov, P M; Tonaeva, Kh D; Borzenok, S A; Dobner, T; Prassolov, V S

    2015-01-01

    Adenoviruses cause a wide variety of human infectious diseases. Adenoviral conjunctivitis and epidemic keratoconjunctivitis are commonly associated with human species D adenoviruses. Currently, there is no sufficient or appropriate treatment to counteract these adenovirus infections. Thus, there is an urgent need for new etiology-directed therapies with selective activity against human adenoviruses. To address this problem, the adenoviral early genes E1A and E2B (viral DNA polymerase) seem to be promising targets. Here, we propose an effective approach to downregulate the replication of human species D adenoviruses by means of RNA interference. We generated E1A expressing model cell lines enabling fast evaluation of the RNA interference potential. Small interfering RNAs complementary to the E1A mRNA sequences of human species D adenoviruses mediate significant suppression of the E1A expression in model cells. Furthermore, we observed a strong downregulation of replication of human adenoviruses type D8 and D37 by small hairpin RNAs complementary to the E1A or E2B mRNA sequences in primary human limbal cells. We believe that our results will contribute to the development of efficient anti-adenoviral therapy.

  3. MicroRNA-141 Targets Sirt1 and Inhibits Autophagy to Reduce HBV Replication.

    Science.gov (United States)

    Yang, Ying; Liu, Yanning; Xue, Jihua; Yang, Zhenggang; Shi, Yu; Shi, Yixian; Lou, Guohua; Wu, Shanshan; Qi, Jinjin; Liu, Weixia; Chen, Zhi; Wang, Jing

    2017-01-01

    About 400 million individuals are chronically infected with hepatitis B virus, at high risk of developing liver cirrhosis and hepatocellular carcinoma. Recent studies have demonstrated an interaction between hepatitis B virus replication and autophagy activity of hepatocytes. In the present study, we aimed to investigate the role of miR-141 in regulating autophagy and hepatitis B virus replication. The expression of HBV-DNA, miR-141 and Sirt1 mRNA was determined by quantitative real-time PCR analysis. The expression of HBsAg and HBeAg was determined by ELISA. Western blotting was performed to detect protein expression. The LC3 puncta was determined by immunofluorescence. To test whether miR-141 directly regulate the expression level of Sirt1 mRNA, dual-luciferase reporter gene assay was performed. In vitro studies showed that miR-141 mimic inhibited the autophagic response, hepatitis B virus and the expression of Sirt1 in hepatocytes. And transfection with miR-141 inhibitor enhanced autophagic response and Sirt1 expression. The autophagy induced by overexpression of Sirt1 was inhibited by miR-141 mimic. In addition, miR-141 mimic also decreased the expression of Sirt1 mRNA. Sirt1 was predicted as a potential miR-141 target by bioinformatic analysis of its 3'-UTR, and confirmed by luciferase reporter assays which analyzing the interaction of miR-141 with the wild- type or the mutated Sirt1 3'-UTR. We have therefore demonstrated a role of miR-141 in regulating autophagy-mediated hepatitis B virus inhibition by targeting Sirt1, and may provide potential targets for drug development. © 2017 The Author(s) Published by S. Karger AG, Basel.

  4. MicroRNA-141 Targets Sirt1 and Inhibits Autophagy to Reduce HBV Replication

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    Ying Yang

    2017-01-01

    Full Text Available Background/Aims: About 400 million individuals are chronically infected with hepatitis B virus, at high risk of developing liver cirrhosis and hepatocellular carcinoma. Recent studies have demonstrated an interaction between hepatitis B virus replication and autophagy activity of hepatocytes. In the present study, we aimed to investigate the role of miR-141 in regulating autophagy and hepatitis B virus replication. Methods: The expression of HBV-DNA, miR-141 and Sirt1 mRNA was determined by quantitative real-time PCR analysis. The expression of HBsAg and HBeAg was determined by ELISA. Western blotting was performed to detect protein expression. The LC3 puncta was determined by immunofluorescence. To test whether miR-141 directly regulate the expression level of Sirt1 mRNA, dual-luciferase reporter gene assay was performed. Results: In vitro studies showed that miR-141 mimic inhibited the autophagic response, hepatitis B virus and the expression of Sirt1 in hepatocytes. And transfection with miR-141 inhibitor enhanced autophagic response and Sirt1 expression. The autophagy induced by overexpression of Sirt1 was inhibited by miR-141 mimic. In addition, miR-141 mimic also decreased the expression of Sirt1 mRNA. Sirt1 was predicted as a potential miR-141 target by bioinformatic analysis of its 3'-UTR, and confirmed by luciferase reporter assays which analyzing the interaction of miR-141 with the wild- type or the mutated Sirt1 3’-UTR. Conclusion: We have therefore demonstrated a role of miR-141 in regulating autophagy-mediated hepatitis B virus inhibition by targeting Sirt1, and may provide potential targets for drug development.

  5. Dengue virus type 2 infections of Aedes aegypti are modulated by the mosquito's RNA interference pathway.

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    Irma Sánchez-Vargas

    2009-02-01

    Full Text Available A number of studies have shown that both innate and adaptive immune defense mechanisms greatly influence the course of human dengue virus (DENV infections, but little is known about the innate immune response of the mosquito vector Aedes aegypti to arbovirus infection. We present evidence here that a major component of the mosquito innate immune response, RNA interference (RNAi, is an important modulator of mosquito infections. The RNAi response is triggered by double-stranded RNA (dsRNA, which occurs in the cytoplasm as a result of positive-sense RNA virus infection, leading to production of small interfering RNAs (siRNAs. These siRNAs are instrumental in degradation of viral mRNA with sequence homology to the dsRNA trigger and thereby inhibition of virus replication. We show that although dengue virus type 2 (DENV2 infection of Ae. aegypti cultured cells and oral infection of adult mosquitoes generated dsRNA and production of DENV2-specific siRNAs, virus replication and release of infectious virus persisted, suggesting viral circumvention of RNAi. We also show that DENV2 does not completely evade RNAi, since impairing the pathway by silencing expression of dcr2, r2d2, or ago2, genes encoding important sensor and effector proteins in the RNAi pathway, increased virus replication in the vector and decreased the extrinsic incubation period required for virus transmission. Our findings indicate a major role for RNAi as a determinant of DENV transmission by Ae. aegypti.

  6. Genome rearrangement affects RNA virus adaptability on prostate cancer cells

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    Kendra ePesko

    2015-04-01

    Full Text Available Gene order is often highly conserved within taxonomic groups, such that organisms with rearranged genomes tend to be less fit than wildtype gene orders, and suggesting natural selection favors genome architectures that maximize fitness. But it is unclear whether rearranged genomes hinder adaptability: capacity to evolutionarily improve in a new environment. Negative-sense nonsegmented RNA viruses (order Mononegavirales have specific genome architecture: 3′ UTR – core protein genes – envelope protein genes – RNA-dependent RNA-polymerase gene – 5′ UTR. To test how genome architecture affects RNA virus evolution, we examined vesicular stomatitis virus (VSV variants with the nucleocapsid (N gene moved sequentially downstream in the genome. Because RNA polymerase stuttering in VSV replication causes greater mRNA production in upstream genes, N-gene translocation towards the 5’ end leads to stepwise decreases in N transcription, viral replication and progeny production, and also impacts the activation of type 1 interferon mediated antiviral responses. We evolved VSV gene-order variants in two prostate cancer cell lines: LNCap cells deficient in innate immune response to viral infection, and PC3 cells that mount an IFN stimulated anti-viral response to infection. We observed that gene order affects phenotypic adaptability (reproductive growth; viral suppression of immune function, especially on PC3 cells that strongly select against virus infection. Overall, populations derived from the least-fit ancestor (most-altered N position architecture adapted fastest, consistent with theory predicting populations with low initial fitness should improve faster in evolutionary time. Also, we observed correlated responses to selection, where viruses improved across both hosts, rather than suffer fitness trade-offs on unselected hosts. Whole genomics revealed multiple mutations in evolved variants, some of which were conserved across selective

  7. Discovery of replicating circular RNAs by RNA-seq and computational algorithms.

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    Zhixiang Zhang

    2014-12-01

    Full Text Available Replicating circular RNAs are independent plant pathogens known as viroids, or act to modulate the pathogenesis of plant and animal viruses as their satellite RNAs. The rate of discovery of these subviral pathogens was low over the past 40 years because the classical approaches are technical demanding and time-consuming. We previously described an approach for homology-independent discovery of replicating circular RNAs by analysing the total small RNA populations from samples of diseased tissues with a computational program known as progressive filtering of overlapping small RNAs (PFOR. However, PFOR written in PERL language is extremely slow and is unable to discover those subviral pathogens that do not trigger in vivo accumulation of extensively overlapping small RNAs. Moreover, PFOR is yet to identify a new viroid capable of initiating independent infection. Here we report the development of PFOR2 that adopted parallel programming in the C++ language and was 3 to 8 times faster than PFOR. A new computational program was further developed and incorporated into PFOR2 to allow the identification of circular RNAs by deep sequencing of long RNAs instead of small RNAs. PFOR2 analysis of the small RNA libraries from grapevine and apple plants led to the discovery of Grapevine latent viroid (GLVd and Apple hammerhead viroid-like RNA (AHVd-like RNA, respectively. GLVd was proposed as a new species in the genus Apscaviroid, because it contained the typical structural elements found in this group of viroids and initiated independent infection in grapevine seedlings. AHVd-like RNA encoded a biologically active hammerhead ribozyme in both polarities, and was not specifically associated with any of the viruses found in apple plants. We propose that these computational algorithms have the potential to discover novel circular RNAs in plants, invertebrates and vertebrates regardless of whether they replicate and/or induce the in vivo accumulation of small

  8. Discovery of replicating circular RNAs by RNA-seq and computational algorithms.

    Science.gov (United States)

    Zhang, Zhixiang; Qi, Shuishui; Tang, Nan; Zhang, Xinxin; Chen, Shanshan; Zhu, Pengfei; Ma, Lin; Cheng, Jinping; Xu, Yun; Lu, Meiguang; Wang, Hongqing; Ding, Shou-Wei; Li, Shifang; Wu, Qingfa

    2014-12-01

    Replicating circular RNAs are independent plant pathogens known as viroids, or act to modulate the pathogenesis of plant and animal viruses as their satellite RNAs. The rate of discovery of these subviral pathogens was low over the past 40 years because the classical approaches are technical demanding and time-consuming. We previously described an approach for homology-independent discovery of replicating circular RNAs by analysing the total small RNA populations from samples of diseased tissues with a computational program known as progressive filtering of overlapping small RNAs (PFOR). However, PFOR written in PERL language is extremely slow and is unable to discover those subviral pathogens that do not trigger in vivo accumulation of extensively overlapping small RNAs. Moreover, PFOR is yet to identify a new viroid capable of initiating independent infection. Here we report the development of PFOR2 that adopted parallel programming in the C++ language and was 3 to 8 times faster than PFOR. A new computational program was further developed and incorporated into PFOR2 to allow the identification of circular RNAs by deep sequencing of long RNAs instead of small RNAs. PFOR2 analysis of the small RNA libraries from grapevine and apple plants led to the discovery of Grapevine latent viroid (GLVd) and Apple hammerhead viroid-like RNA (AHVd-like RNA), respectively. GLVd was proposed as a new species in the genus Apscaviroid, because it contained the typical structural elements found in this group of viroids and initiated independent infection in grapevine seedlings. AHVd-like RNA encoded a biologically active hammerhead ribozyme in both polarities, and was not specifically associated with any of the viruses found in apple plants. We propose that these computational algorithms have the potential to discover novel circular RNAs in plants, invertebrates and vertebrates regardless of whether they replicate and/or induce the in vivo accumulation of small RNAs.

  9. Discovery of replicating circular RNAs by RNA-seq and computational algorithms.

    Directory of Open Access Journals (Sweden)

    Zhixiang Zhang

    2014-12-01

    Full Text Available Replicating circular RNAs are independent plant pathogens known as viroids, or act to modulate the pathogenesis of plant and animal viruses as their satellite RNAs. The rate of discovery of these subviral pathogens was low over the past 40 years because the classical approaches are technical demanding and time-consuming. We previously described an approach for homology-independent discovery of replicating circular RNAs by analysing the total small RNA populations from samples of diseased tissues with a computational program known as progressive filtering of overlapping small RNAs (PFOR. However, PFOR written in PERL language is extremely slow and is unable to discover those subviral pathogens that do not trigger in vivo accumulation of extensively overlapping small RNAs. Moreover, PFOR is yet to identify a new viroid capable of initiating independent infection. Here we report the development of PFOR2 that adopted parallel programming in the C++ language and was 3 to 8 times faster than PFOR. A new computational program was further developed and incorporated into PFOR2 to allow the identification of circular RNAs by deep sequencing of long RNAs instead of small RNAs. PFOR2 analysis of the small RNA libraries from grapevine and apple plants led to the discovery of Grapevine latent viroid (GLVd and Apple hammerhead viroid-like RNA (AHVd-like RNA, respectively. GLVd was proposed as a new species in the genus Apscaviroid, because it contained the typical structural elements found in this group of viroids and initiated independent infection in grapevine seedlings. AHVd-like RNA encoded a biologically active hammerhead ribozyme in both polarities, and was not specifically associated with any of the viruses found in apple plants. We propose that these computational algorithms have the potential to discover novel circular RNAs in plants, invertebrates and vertebrates regardless of whether they replicate and/or induce the in vivo accumulation of small

  10. Dinucleotide composition in animal RNA viruses is shaped more by virus family than host species.

    Science.gov (United States)

    Di Giallonardo, Francesca; Schlub, Timothy E; Shi, Mang; Holmes, Edward C

    2017-02-01

    Viruses use the cellular machinery of their hosts for replication. It has therefore been proposed that the nucleotide and dinucleotide composition of viruses should match that of their host species. If upheld, it may then be possible to use dinucleotide composition to predict the true host species of viruses sampled in metagenomic surveys. However, it is also clear that different taxonomic groups of viruses tend to have distinctive patterns of dinucleotide composition that may be independent of host species. To determine the relative strength of the effect of host versus virus family in shaping dinucleotide composition we performed a comparative analysis of 20 RNA virus families from 15 host groupings, spanning two animal phyla and more than 900 virus species. In particular, we determined the odds ratios for the 16 possible dinucleotides and performed a discriminant analysis to evaluate the capability of virus dinucleotide composition to predict the correct virus family or host taxon from which it was isolated. Notably, while 81% of the data analyzed here were predicted to the correct virus family, only 62% of these data were predicted to their correct subphylum/class host, and a mere 32% to their correct mammalian order. Similarly, dinucleotide composition has a weak predictive power for different hosts within individual virus families. We therefore conclude that dinucleotide composition is generally uniform within a virus family but less well reflects that of its host species. This has obvious implications for attempts to accurately predict host species from virus genome sequences alone.

  11. Initiation of RNA Polymerization and Polymerase Encapsidation by a Small dsRNA Virus.

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    Aaron M Collier

    2016-04-01

    Full Text Available During the replication cycle of double-stranded (ds RNA viruses, the viral RNA-dependent RNA polymerase (RdRP replicates and transcribes the viral genome from within the viral capsid. How the RdRP molecules are packaged within the virion and how they function within the confines of an intact capsid are intriguing questions with answers that most likely vary across the different dsRNA virus families. In this study, we have determined a 2.4 Å resolution structure of an RdRP from the human picobirnavirus (hPBV. In addition to the conserved polymerase fold, the hPBV RdRP possesses a highly flexible 24 amino acid loop structure located near the C-terminus of the protein that is inserted into its active site. In vitro RNA polymerization assays and site-directed mutagenesis showed that: (1 the hPBV RdRP is fully active using both ssRNA and dsRNA templates; (2 the insertion loop likely functions as an assembly platform for the priming nucleotide to allow de novo initiation; (3 RNA transcription by the hPBV RdRP proceeds in a semi-conservative manner; and (4 the preference of virus-specific RNA during transcription is dictated by the lower melting temperature associated with the terminal sequences. Co-expression of the hPBV RdRP and the capsid protein (CP indicated that, under the conditions used, the RdRP could not be incorporated into the recombinant capsids in the absence of the viral genome. Additionally, the hPBV RdRP exhibited higher affinity towards the conserved 5'-terminal sequence of the viral RNA, suggesting that the RdRP molecules may be encapsidated through their specific binding to the viral RNAs during assembly.

  12. Wolbachia Blocks Viral Genome Replication Early in Infection without a Transcriptional Response by the Endosymbiont or Host Small RNA Pathways.

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    Stephanie M Rainey

    2016-04-01

    Full Text Available The intracellular endosymbiotic bacterium Wolbachia can protect insects against viral infection, and is being introduced into mosquito populations in the wild to block the transmission of arboviruses that infect humans and are a major public health concern. To investigate the mechanisms underlying this antiviral protection, we have developed a new model system combining Wolbachia-infected Drosophila melanogaster cell culture with the model mosquito-borne Semliki Forest virus (SFV; Togaviridae, Alphavirus. Wolbachia provides strong antiviral protection rapidly after infection, suggesting that an early stage post-infection is being blocked. Wolbachia does appear to have major effects on events distinct from entry, assembly or exit as it inhibits the replication of an SFV replicon transfected into the cells. Furthermore, it causes a far greater reduction in the expression of proteins from the 3' open reading frame than the 5' non-structural protein open reading frame, indicating that it is blocking the replication of viral RNA. Further to this separation of the replicase proteins and viral RNA in transreplication assays shows that uncoupling of viral RNA and replicase proteins does not overcome Wolbachia's antiviral activity. This further suggests that replicative processes are disrupted, such as translation or replication, by Wolbachia infection. This may occur by Wolbachia mounting an active antiviral response, but the virus did not cause any transcriptional response by the bacterium, suggesting that this is not the case. Host microRNAs (miRNAs have been implicated in protection, but again we found that host cell miRNA expression was unaffected by the bacterium and neither do our findings suggest any involvement of the antiviral siRNA pathway. We conclude that Wolbachia may directly interfere with early events in virus replication such as translation of incoming viral RNA or RNA transcription, and this likely involves an intrinsic (as opposed to

  13. Wolbachia Blocks Viral Genome Replication Early in Infection without a Transcriptional Response by the Endosymbiont or Host Small RNA Pathways.

    Science.gov (United States)

    Rainey, Stephanie M; Martinez, Julien; McFarlane, Melanie; Juneja, Punita; Sarkies, Peter; Lulla, Aleksei; Schnettler, Esther; Varjak, Margus; Merits, Andres; Miska, Eric A; Jiggins, Francis M; Kohl, Alain

    2016-04-01

    The intracellular endosymbiotic bacterium Wolbachia can protect insects against viral infection, and is being introduced into mosquito populations in the wild to block the transmission of arboviruses that infect humans and are a major public health concern. To investigate the mechanisms underlying this antiviral protection, we have developed a new model system combining Wolbachia-infected Drosophila melanogaster cell culture with the model mosquito-borne Semliki Forest virus (SFV; Togaviridae, Alphavirus). Wolbachia provides strong antiviral protection rapidly after infection, suggesting that an early stage post-infection is being blocked. Wolbachia does appear to have major effects on events distinct from entry, assembly or exit as it inhibits the replication of an SFV replicon transfected into the cells. Furthermore, it causes a far greater reduction in the expression of proteins from the 3' open reading frame than the 5' non-structural protein open reading frame, indicating that it is blocking the replication of viral RNA. Further to this separation of the replicase proteins and viral RNA in transreplication assays shows that uncoupling of viral RNA and replicase proteins does not overcome Wolbachia's antiviral activity. This further suggests that replicative processes are disrupted, such as translation or replication, by Wolbachia infection. This may occur by Wolbachia mounting an active antiviral response, but the virus did not cause any transcriptional response by the bacterium, suggesting that this is not the case. Host microRNAs (miRNAs) have been implicated in protection, but again we found that host cell miRNA expression was unaffected by the bacterium and neither do our findings suggest any involvement of the antiviral siRNA pathway. We conclude that Wolbachia may directly interfere with early events in virus replication such as translation of incoming viral RNA or RNA transcription, and this likely involves an intrinsic (as opposed to an induced

  14. RNA-dependent RNA polymerase 6 delays accumulation and precludes meristem invasion of a viroid that replicates in the nucleus.

    Science.gov (United States)

    Di Serio, Francesco; Martínez de Alba, Angel-Emilio; Navarro, Beatriz; Gisel, Andreas; Flores, Ricardo

    2010-03-01

    The detection of viroid-derived small RNAs (vd-sRNAs) similar to the small interfering RNAs (siRNAs, 21 to 24 nucleotides [nt]) in plants infected by nuclear-replicating members of the family Pospiviroidae (type species, Potato spindle tuber viroid [PSTVd]) indicates that they are inducers and targets of the RNA-silencing machinery of their hosts. RNA-dependent RNA polymerase 6 (RDR6) catalyzes an amplification circuit producing the double-stranded precursors of secondary siRNAs. Recently, the role of RDR6 in restricting systemic spread of certain RNA viruses and precluding their invasion of the apical growing tip has been documented using RDR6-silenced Nicotiana benthamiana (NbRDR6i) plants. Here we show that RDR6 is also engaged in regulating PSTVd levels: accumulation of PSTVd genomic RNA was increased in NbRDR6i plants with respect to the wild-type controls (Nbwt) early in infection, whereas this difference decreased or disappeared in later infection stages. Moreover, in situ hybridization revealed that RDR6 is involved in restricting PSTVd access in floral and vegetative meristems, thus providing firm genetic evidence for an antiviroid RNA silencing mechanism. RNA gel blot hybridization and deep sequencing showed in wt and RDR6i backgrounds that PSTVd sRNAs (i) accumulate to levels paralleling their genomic RNA, (ii) display similar patterns with prevailing 22- or 21-nt plus-strand species, and (iii) adopt strand-specific hot spot profiles along the genomic RNA. Therefore, the surveillance mechanism restraining entry of some RNA viruses into meristems likely also controls PSTVd access in N. benthamiana. Unexpectedly, deep sequencing also disclosed in NbRDR6i plants a profile of RDR6-derived siRNA dominated by 21-nt plus-strand species mapping within a narrow window of the hairpin RNA stem expressed transgenically for silencing RDR6, indicating that minus-strand siRNAs silencing the NbRDR6 mRNA represent a minor fraction of the total siRNA population.

  15. Inhibition of infectious pancreatic necrosis virus replication by atlantic salmon Mx1 protein.

    Science.gov (United States)

    Larsen, Rannveig; Røkenes, Torunn P; Robertsen, Børre

    2004-08-01

    Mx proteins form a family of interferon (IFN)-induced GTPases with potent antiviral activity against various single-stranded RNA viruses in mammals and chickens. In fish, alpha/beta IFN has been reported to inhibit the replication of infectious pancreatic necrosis virus (IPNV), but the mode of action has not been elucidated. A correlation between the inhibition of IPNV and Mx protein expression has, however, been observed. To examine whether Atlantic salmon Mx1 protein (ASMx1) possesses antiviral activity against IPNV, CHSE-214 cells constitutively expressing ASMx1 were established. ASMx1 appeared to be localized in the cytoplasm. The ASMx1-expressing clone selected showed a severely reduced IPNV-induced cytopathic effect, which was confirmed by a 500-fold reduction in virus yield. The antiviral activity against IPNV was further confirmed by the inhibition of virus protein synthesis and the reduced accumulation of virus transcripts. The present work further adds to the body of evidence which suggests that antiviral activity is a major functional role of vertebrate Mx proteins. Moreover, the list of viruses inhibited by Mx proteins is extended to include double-stranded RNA viruses.

  16. Transfection of RNA from organ samples of infected animals represents a highly sensitive method for virus detection and recovery of classical swine fever virus.

    Directory of Open Access Journals (Sweden)

    Denise Meyer

    Full Text Available Translation and replication of positive stranded RNA viruses are directly initiated in the cellular cytoplasm after uncoating of the viral genome. Accordingly, infectious virus can be generated by transfection of RNA genomes into susceptible cells. In the present study, efficiency of conventional virus isolation after inoculation of cells with infectious sample material was compared to virus recovery after transfection of total RNA derived from organ samples of pigs infected with Classical swine fever virus (CSFV. Compared to the conventional method of virus isolation applied in three different porcine cell lines used in routine diagnosis of CSF, RNA transfection showed a similar efficiency for virus rescue. For two samples, recovery of infectious virus was only possible by RNA transfection, but not by the classical approach of virus isolation. Therefore, RNA transfection represents a valuable alternative to conventional virus isolation in particular when virus isolation is not possible, sample material is not suitable for virus isolation or when infectious material is not available. To estimate the potential risk of RNA prepared from sample material for infection of pigs, five domestic pigs were oronasally inoculated with RNA that was tested positive for virus rescue after RNA transfection. This exposure did not result in viral infection or clinical disease of the animals. In consequence, shipment of CSFV RNA can be regarded as a safe alternative to transportation of infectious virus and thereby facilitates the exchange of virus isolates among authorized laboratories with appropriate containment facilities.

  17. Variable Inhibition of Zika Virus Replication by Different Wolbachia Strains in Mosquito Cell Cultures.

    Science.gov (United States)

    Schultz, Michaela J; Isern, Sharon; Michael, Scott F; Corley, Ronald B; Connor, John H; Frydman, Horacio M

    2017-07-15

    Mosquito-borne arboviruses are a major source of human disease. One strategy to reduce arbovirus disease is to reduce the mosquito's ability to transmit virus. Mosquito infection with the bacterial endosymbiont Wolbachia pipientis wMel is a novel strategy to reduce Aedes mosquito competency for flavivirus infection. However, experiments investigating cyclic environmental temperatures have shown a reduction in maternal transmission of wMel, potentially weakening the integration of this strain into a mosquito population relative to that of other Wolbachia strains. Consequently, it is important to investigate additional Wolbachia strains. All Zika virus (ZIKV) suppression studies are limited to the wMel Wolbachia strain. Here we show ZIKV inhibition by two different Wolbachia strains: wAlbB (isolated from Aedes albopictus mosquitoes) and wStri (isolated from the planthopper Laodelphax striatellus) in mosquito cells. Wolbachia strain wStri inhibited ZIKV most effectively. Single-cycle infection experiments showed that ZIKV RNA replication and nonstructural protein 5 translation were reduced below the limits of detection in wStri-containing cells, demonstrating early inhibition of virus replication. ZIKV replication was rescued when Wolbachia was inhibited with a bacteriostatic antibiotic. We observed a partial rescue of ZIKV growth when Wolbachia-infected cells were supplemented with cholesterol-lipid concentrate, suggesting competition for nutrients as one of the possible mechanisms of Wolbachia inhibition of ZIKV. Our data show that wAlbB and wStri infection causes inhibition of ZIKV, making them attractive candidates for further in vitro mechanistic and in vivo studies and future vector-centered approaches to limit ZIKV infection and spread.IMPORTANCE Zika virus (ZIKV) has swiftly spread throughout most of the Western Hemisphere. This is due in large part to its replication in and spread by a mosquito vector host. There is an urgent need for approaches that limit

  18. Hepatitis Delta Virus: Replication Strategy and Upcoming Therapeutic Options for a Neglected Human Pathogen

    Science.gov (United States)

    Lempp, Florian A.; Urban, Stephan

    2017-01-01

    The human Hepatitis Delta Virus (HDV) is unique among all viral pathogens. Encoding only one protein (Hepatitis Delta Antigen; HDAg) within its viroid-like self-complementary RNA, HDV constitutes the smallest known virus in the animal kingdom. To disseminate in its host, HDV depends on a helper virus, the human Hepatitis B virus (HBV), which provides the envelope proteins required for HDV assembly. HDV affects an estimated 15–20 million out of the 240 million chronic HBV-carriers and disperses unequally in disparate geographical regions of the world. The disease it causes (chronic Hepatitis D) presents as the most severe form of viral hepatitis, leading to accelerated progression of liver dysfunction including cirrhosis and hepatocellular carcinoma and a high mortality rate. The lack of approved drugs interfering with specific steps of HDV replication poses a high burden for gaining insights into the molecular biology of the virus and, consequently, the development of specific novel medications that resiliently control HDV replication or, in the best case, functionally cure HDV infection or HBV/HDV co-infection. This review summarizes our current knowledge of HBV molecular biology, presents an update on novel cell culture and animal models to study the virus and provides updates on the clinical development of the three developmental drugs Lonafarnib, REP2139-Ca and Myrcludex B. PMID:28677645

  19. Function and Structural Organization of the Replication Protein of Bamboo mosaic virus

    Science.gov (United States)

    Meng, Menghsiao; Lee, Cheng-Cheng

    2017-01-01

    The genus Potexvirus is one of the eight genera belonging to the family Alphaflexiviridae according to the Virus Taxonomy 2015 released by International Committee on Taxonomy of Viruses (www.ictvonline.org/index.asp). Currently, the genus contains 35 known species including many agricultural important viruses, e.g., Potato virus X (PVX). Members of this genus are characterized by flexuous, filamentous virions of 13 nm in diameter and 470–580 nm in length. A potexvirus has a monopartite positive-strand RNA genome, encoding five open-reading frames (ORFs), with a cap structure at the 5′ end and a poly(A) tail at the 3′ end. Besides PVX, Bamboo mosaic virus (BaMV) is another potexvirus that has received intensive attention due to the wealth of knowledge on the molecular biology of the virus. In this review, we discuss the enzymatic activities associated with each of the functional domains of the BaMV replication protein, a 155-kDa polypeptide encoded by ORF1. The unique cap formation mechanism, which may be conserved across the alphavirus superfamily, is particularly addressed. The recently identified interactions between the replication protein and the plant host factors are also described.

  20. Mapping vaccinia virus DNA replication origins at nucleotide level by deep sequencing.

    Science.gov (United States)

    Senkevich, Tatiana G; Bruno, Daniel; Martens, Craig; Porcella, Stephen F; Wolf, Yuri I; Moss, Bernard

    2015-09-01

    Poxviruses reproduce in the host cytoplasm and encode most or all of the enzymes and factors needed for expression and synthesis of their double-stranded DNA genomes. Nevertheless, the mode of poxvirus DNA replication and the nature and location of the replication origins remain unknown. A current but unsubstantiated model posits only leading strand synthesis starting at a nick near one covalently closed end of the genome and continuing around the other end to generate a concatemer that is subsequently resolved into unit genomes. The existence of specific origins has been questioned because any plasmid can replicate in cells infected by vaccinia virus (VACV), the prototype poxvirus. We applied directional deep sequencing of short single-stranded DNA fragments enriched for RNA-primed nascent strands isolated from the cytoplasm of VACV-infected cells to pinpoint replication origins. The origins were identified as the switching points of the fragment directions, which correspond to the transition from continuous to discontinuous DNA synthesis. Origins containing a prominent initiation point mapped to a sequence within the hairpin loop at one end of the VACV genome and to the same sequence within the concatemeric junction of replication intermediates. These findings support a model for poxvirus genome replication that involves leading and lagging strand synthesis and is consistent with the requirements for primase and ligase activities as well as earlier electron microscopic and biochemical studies implicating a replication origin at the end of the VACV genome.

  1. Role for RNA: DNA hybrids in origin-independent replication priming in a eukaryotic system

    OpenAIRE

    Stuckey, Ruth; García Rodriguez, Néstor; Aguilera López, Andrés; Wellinger, Ralf Erik

    2015-01-01

    DNA replication initiates at defined replication origins along eukaryotic chromosomes, ensuring complete genome duplication within a single S-phase. A key feature of replication origins is their ability to control the onset of DNA synthesis mediated by DNA polymerase-α and its intrinsic RNA primase activity. Here, we describe a novel origin-independent replication process that is mediated by transcription. RNA polymerase I transcription constraints lead to persistent RNA:DNA hybrids (R-loops)...

  2. Effect of Wolbachia on replication of West Nile virus in a mosquito cell line and adult mosquitoes.

    Science.gov (United States)

    Hussain, Mazhar; Lu, Guangjin; Torres, Shessy; Edmonds, Judith H; Kay, Brian H; Khromykh, Alexander A; Asgari, Sassan

    2013-01-01

    Wolbachia as an endosymbiont is widespread in insects and other arthropods and is best known for reproductive manipulations of the host. Recently, it has been shown that wMelpop and wMel strains of Wolbachia inhibit the replication of several RNA viruses, including dengue virus, and other vector-borne pathogens (e.g., Plasmodium and filarial nematodes) in mosquitoes, providing an alternative approach to limit the transmission of vector-borne pathogens. In this study, we tested the effect of Wolbachia on the replication of West Nile Virus (WNV). Surprisingly, accumulation of the genomic RNA of WNV for all three strains of WNV tested (New York 99, Kunjin, and New South Wales) was enhanced in Wolbachia-infected Aedes aegypti cells (Aag2). However, the amount of secreted virus was significantly reduced in the presence of Wolbachia. Intrathoracic injections showed that replication of WNV in A. aegypti mosquitoes infected with wMel strain of Wolbachia was not inhibited, whereas wMelPop strain of Wolbachia significantly reduced the replication of WNV in mosquitoes. Further, when wMelPop mosquitoes were orally fed with WNV, virus infection, transmission, and dissemination rates were very low in Wolbachia-free mosquitoes and were completely inhibited in the presence of Wolbachia. The results suggest that (i) despite the enhancement of viral genomic RNA replication in the Wolbachia-infected cell line the production of secreted virus was significantly inhibited, (ii) the antiviral effect in intrathoracically infected mosquitoes depends on the strain of Wolbachia, and (iii) replication of the virus in orally fed mosquitoes was completely inhibited in wMelPop strain of Wolbachia.

  3. RAB1A promotes Vaccinia virus replication by facilitating the production of intracellular enveloped virions

    Energy Technology Data Exchange (ETDEWEB)

    Pechenick Jowers, Tali; Featherstone, Rebecca J.; Reynolds, Danielle K.; Brown, Helen K. [The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Roslin, Midlothian EH25 9RG, Scotland (United Kingdom); James, John; Prescott, Alan [Division of Cell Signalling and Immunology, College of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland (United Kingdom); Haga, Ismar R. [The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Roslin, Midlothian EH25 9RG, Scotland (United Kingdom); Beard, Philippa M., E-mail: pip.beard@roslin.ed.ac.uk [The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Roslin, Midlothian EH25 9RG, Scotland (United Kingdom)

    2015-01-15

    Vaccinia virus (VACV) is a large double-stranded DNA virus with a complex cytoplasmic replication cycle that exploits numerous cellular proteins. This work characterises the role of a proviral cellular protein, the small GTPase RAB1A, in VACV replication. Using siRNA, we identified RAB1A as required for the production of extracellular enveloped virions (EEVs), but not intracellular mature virions (IMVs). Immunofluorescence and electron microscopy further refined the role of RAB1A as facilitating the wrapping of IMVs to become intracellular enveloped virions (IEVs). This is consistent with the known function of RAB1A in maintenance of ER to Golgi transport. VACV can therefore be added to the growing list of viruses which require RAB1A for optimal replication, highlighting this protein as a broadly proviral host factor. - Highlights: • Characterisation of the role of the small GTPase RAB1A in VACV replication. • RAB1A is not required for production of the primary virion form (IMV). • RAB1A is required for production of processed virion forms (IEVs, CEVs and EEVs). • Consistent with known role of RAB1A in ER to Golgi transport.

  4. Exogenous IFN-alpha administration reduces influenza A virus replication in the lower respiratory tract of rhesus macaques.

    Directory of Open Access Journals (Sweden)

    Shannon R Matzinger

    Full Text Available To determine the role of innate immune responses in controlling influenza A virus replication, rhesus macaques (RM were administered pegylated IFN-alpha prior to virus challenge. Systemic and mucosal pegylated IFN-alpha administration induced expression of the interferon-stimulated genes (ISG MxA and OAS in the airways. RM treated with IFN-alpha 24 hours prior to influenza virus challenge had significantly lower peak vRNA levels in the trachea compared to untreated animals. In addition to blunting viral replication, IFN-alpha treatment minimized the weight loss and spike in body temperature after influenza infection of RM. These results confirm the importance of IFN-alpha induced innate immune responses in the rapid control of influenza A virus replication in primates.

  5. The cell biology of Tobacco mosaic virus replication and movement.

    Science.gov (United States)

    Liu, Chengke; Nelson, Richard S

    2013-01-01

    Successful systemic infection of a plant by Tobacco mosaic virus (TMV) requires three processes that repeat over time: initial establishment and accumulation in invaded cells, intercellular movement, and systemic transport. Accumulation and intercellular movement of TMV necessarily involves intracellular transport by complexes containing virus and host proteins and virus RNA during a dynamic process that can be visualized. Multiple membranes appear to assist TMV accumulation, while membranes, microfilaments and microtubules appear to assist TMV movement. Here we review cell biological studies that describe TMV-membrane, -cytoskeleton, and -other host protein interactions which influence virus accumulation and movement in leaves and callus tissue. The importance of understanding the developmental phase of the infection in relationship to the observed virus-membrane or -host protein interaction is emphasized. Utilizing the latest observations of TMV-membrane and -host protein interactions within our evolving understanding of the infection ontogeny, a model for TMV accumulation and intracellular spread in a cell biological context is provided.

  6. Are there any subgenomic forms of hepatitis C virus RNA in the liver?

    Science.gov (United States)

    Quadri, R; Negro, F

    2001-01-01

    Hepatitis C virus has a single stranded positive RNA genoma. Although believed to replicate via semi-conservative transcription of a negative-stranded, genomic-length RNA intermediate, detailed steps of its replicative cycle are unknown. To quantify some of intrahepatic hepatitis C virus RNA forms, as inferred from comparison with replication of other members of the Flaviviridae family. Genomic and negative-stranded hepatitis C virus RNA were semi-quantitated by strand-specific reverse transcriptase-polymerase chain reaction at both their 5' and 3' ends in liver of 10 patients with recurrent hepatitis C after liver transplantation. Our data are consistent with the existence of hitherto unrecognized, very large amounts (up to approximately 10,000 fold the amount of the replication intermediate proper) of subgenomic hepatitis C virus RNAs of genomic polarity, starting in the 5' untranslated region, of unknown length. Similarly, subgenomic RNAs of negative polarity, starting in the 3' untranslated region, may also be produced, albeit to a less extent. We found no correlation between the amount of these forms and any clinical, histological or virological feature. However, the number of subgenomic RNA molecules of negative polarity tended to be inversely correlated with viraemia (r = 0.7, p = 0.058), suggesting their possible role in controlling rate of virion production. Hepatitis C virus replication results in transcription of huge amounts of subgenomic RNAs both of genomic and negative polarity, which may either regulate translation of excess structural antigens of hepatitis C virus, or play the role of defective RNAs interfering with viral replication. A revised model of hepatitis C virus RNA replication is proposed.

  7. Genetic recombination in plant-infecting messenger-sense RNA viruses: overview and research perspectives

    Directory of Open Access Journals (Sweden)

    Jozef Julian Bujarski

    2013-03-01

    Full Text Available RNA recombination is one of the driving forces of genetic variability in (+-strand RNA viruses. Various types of RNA-RNA crossovers were described including crosses between the same or different viral RNAs or between viral and cellular RNAs. Likewise, a variety of molecular mechanisms are known to support RNA recombination, such as replicative events (based on internal or end-to-end replicase switchings along with nonreplicative joining among RNA fragments of viral and/or cellular origin. Such mechanisms as RNA decay or RNA interference are responsible for RNA fragmentation and trans-esterification reactions which are likely accountable for ligation of RNA fragments. Numerous host factors were found to affect the profiles of viral RNA recombinants and significant differences in recombination frequency were observed among various RNA viruses. Comparative analyses of viral sequences allowed for the development of evolutionary models in order to explain adaptive phenotypic changes and co-evolving sites. Many questions remain to be answered by forthcoming RNA recombination research. (i How various factors modulate the ability of viral replicase to switch templates, (ii What is the intracellular location of RNA-RNA template switchings, (iii Mechanisms and factors responsible for non-replicative RNA recombination, (iv Mechanisms of integration of RNA viral sequences with cellular genomic DNA, and (v What is the role of RNA splicing and ribozyme activity. From an evolutionary stand point, it is not known how RNA viruses parasitize new host species via recombination, nor is it obvious what the contribution of RNA recombination is among other RNA modification pathways. We do not understand why the frequency of RNA recombination varies so much among RNA viruses and the status of RNA recombination as a form of sex is not well documented.

  8. Autophagy sustains the replication of porcine reproductive and respiratory virus in host cells

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Qinghao; Qin, Yixian; Zhou, Lei; Kou, Qiuwen; Guo, Xin; Ge, Xinna [Key Laboratory of Animal Epidemiology and Zoonosis of Ministry of Agriculture, College of Veterinary Medicine and State Key Laboratory of Agribiotechnology, China Agricultural University, Beijing (China); Yang, Hanchun, E-mail: yanghanchun1@cau.edu.cn [Key Laboratory of Animal Epidemiology and Zoonosis of Ministry of Agriculture, College of Veterinary Medicine and State Key Laboratory of Agribiotechnology, China Agricultural University, Beijing (China); Hu, Hongbo, E-mail: hongbo@cau.edu.cn [College of Food Science and Nutritional Engineering, China Agricultural University, Beijing (China)

    2012-08-01

    In this study, we confirmed the autophagy induced by porcine reproductive and respiratory syndrome virus (PRRSV) in permissive cells and investigated the role of autophagy in the replication of PRRSV. We first demonstrated that PRRSV infection significantly results in the increased double-membrane vesicles, the accumulation of LC3 fluorescence puncta, and the raised ratio of LC3-II/{beta}-actin, in MARC-145 cells. Then we discovered that induction of autophagy by rapamycin significantly enhances the viral titers of PRRSV, while inhibition of autophagy by 3-MA and silencing of LC3 gene by siRNA reduces the yield of PRRSV. The results showed functional autolysosomes can be formed after PRRSV infection and the autophagosome-lysosome-fusion inhibitor decreases the virus titers. We also examined the induction of autophagy by PRRSV infection in pulmonary alveolar macrophages. These findings indicate that autophagy induced by PRRSV infection plays a role in sustaining the replication of PRRSV in host cells.

  9. Fujinami sarcoma virus: An avian RNA tumor virus with a unique transforming gene

    Science.gov (United States)

    Lee, Wen-Hwa; Bister, Klaus; Pawson, Anthony; Robins, Terry; Moscovici, Carlo; Duesberg, Peter H.

    1980-01-01

    The oncogenic properties and RNA of the Fujinami avian sarcoma virus (FSV) and the protein it encodes were investigated and compared to those of other avian tumor viruses with sarcomagenic properties such as Rous sarcoma virus and the acute leukemia viruses MC29 and erythroblastosis virus. Cloned stocks of FSV caused sarcomas in all chickens inoculated and were found to contain a 4.5-kilobase (kb) and an 8.5-kb RNA species. The 4.5-kb RNA was identified as the genome of defective FSV because it was absent from nondefective FSV-associated helper virus and because the titer of focus-forming units increased with the ratio of 4.5-kb to 8.5-kb RNA in virus preparations. This is, then, the smallest known tumor virus RNA with a transforming function. Comparisons with other viral RNAs, based on oligonucleotide mapping and molecular hybridization, indicated that 4.5-kb FSV RNA contains a 5′ gag gene-related sequence of 1 kb, an internal specific sequence of about 3 kb that is unrelated to Rous sarcoma virus, MC29, and erythroblastosis virus, and a 3′-terminal sequence of about 0.5 kb related to the conserved C region of avian tumor viruses. The lack of some or all nucleotide sequences of the essential virion genes, gag, pol, and env, and the isolation of FSV-transformed nonproducer cell clones indicated that FSV is replication defective. A 140,000-dalton, gag-related non-structural protein was found in FSV-transformed producer and nonproducer cells and was translated in vitro from full-length FSV RNA. This protein is expected to have a transforming function both because its intracellular concentration showed a positive correlation with the percentage of transformed cells in a culture and because FSV is unlikely to code for major additional proteins since the genetic complexities of FSV RNA and the FSV protein are almost the same. It is concluded that the transforming onc gene of FSV is distinct from that of Rous sarcoma virus and other avian tumor viruses with

  10. Efficient inhibition of hepatitis B virus replication by hepatitis delta virus ribozymes delivered by targeting retrovirus

    Directory of Open Access Journals (Sweden)

    Chen Long-Hua

    2010-03-01

    Full Text Available Abstract Background Hepatitis delta virus (HDV ribozyme is an attractive molecular tool that can specifically recognize and catalyze the self-cleavage of the viral RNA phosphodiester backbone. However, a major obstacle in the medical application of the HDV ribozyme is the lack of specificity in the delivery of the ribozyme to defined target cells. Results The objective of this study was to determine whether retroviral vectors can deliver the HDV ribozyme into the target cells and to elucidate whether HDV ribozyme plays a role in hepatitis B virus (HBV replication. In our study, the transduction of helper-free pseudotyped retrovirus, which showed a broad host range, in human hepatoma cells was performed under 2 conditions, that is, in the presence of polymerized human serum albumin (pHSA and in the absence of pHSA. The transduction ability in the presence of pHSA was higher than in the absence of pHSA. Moreover, HBsAg and HBeAg levels after transductions with pHSA were significantly lower than those in the absence of pHSA, thus indicating that the recombinant retrovirus had HBV-specific cleavage activity and targeted HepG2215 cells. Conclusions These data suggest that this system provides a new approach for targeting hepatocytes and has a great potential in gene therapy for HBV infection.

  11. A Tat-conjugated Peptide Nucleic Acid Tat-PNA-DR Inhibits Hepatitis B Virus Replication In Vitro and In Vivo by Targeting LTR Direct Repeats of HBV RNA

    Directory of Open Access Journals (Sweden)

    Zhengyang Zeng

    2016-01-01

    Full Text Available Hepatitis B virus (HBV infection is a major cause of chronic active hepatitis, cirrhosis, and primary hepatocellular carcinoma, all of which are severe threats to human health. However, current clinical therapies for HBV are limited by potential side effects, toxicity, and drug-resistance. In this study, a cell-penetrating peptide-conjugated peptide nucleic acid (PNA, Tat-PNA-DR, was designed to target the direct repeat (DR sequences of HBV. Tat-PNA-DR effectively inhibited HBV replication in HepG2.2.15 cells. Its anti-HBV effect relied on the binding of Tat-PNA-DR to the DR, whereby it suppressed the translation of hepatitis B e antigen (HBeAg, HBsAg, HBV core, hepatitis B virus x protein, and HBV reverse transcriptase (RT and the reverse transcription of the HBV genome. Furthermore, Tat-PNA-DR administered by intravenous injection efficiently cleared HBeAg and HBsAg in an acute hepatitis B mouse model. Importantly, it induced an 80% decline in HBV DNA in mouse serum, which was similar to the effect of the widely used clinical drug Lamivudine (3TC. Additionally, a long-term hydrodynamics HBV mouse model also demonstrated Tat-PNA-DR's antiviral effect. Interestingly, Tat-PNA-DR displayed low cytotoxicity, low mouse acute toxicity, low immunogenicity, and high serum stability. These data indicate that Tat-PNA-DR is a unique PNA and a promising drug candidate against HBV.

  12. Sites of replication of bovine respiratory syncytial virus in naturally infected calves as determined by in situ hybridization

    DEFF Research Database (Denmark)

    Viuff, B.; Uttenthal, Åse; Tegtmeier, C.

    1996-01-01

    Replication of bovine respiratory syncytial virus (BRSV) was studied in three naturally infected calves by in situ hybridization using strand-specific RNA probes. One of the calves was a 5-month-old Friesian, the other two calves were a 3-month-old and a 2-week-old Jersey. Two Jersey calves, 3 mo...

  13. Modifications of the 3 '-UTR stem-loop of infectious bursal disease virus are allowed without influencing replication or virulence

    NARCIS (Netherlands)

    Boot, H.J.; Pritz-Verschuren, S.B.E.

    2004-01-01

    Many questions regarding the initiation of replication and translation of the segmented, double-stranded RNA genome of infectious bursal disease virus (IBDV) remain to be solved. Computer analysis shows that the non-polyadenylated extreme 3'-untranslated regions (UTRs) of the coding strand of both g

  14. Silver nanoparticles impair Peste des petits ruminants virus replication.

    Science.gov (United States)

    Khandelwal, Nitin; Kaur, Gurpreet; Chaubey, Kundan Kumar; Singh, Pushpendra; Sharma, Shalini; Tiwari, Archana; Singh, Shoor Vir; Kumar, Naveen

    2014-09-22

    In the present study, we evaluated the antiviral efficacy of the silver nanoparticles (SNPs) against Peste des petits ruminants virus (PPRV), a prototype Morbillivirus. The leaf extract of the Argemone maxicana was used as a reducing agent for biological synthesis of the SNPs from silver nitrate. The SNPs were characterized using UV-vis absorption spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM). The TEM analysis revealed particle size of 5-30 nm and the XRD analysis revealed their characteristic silver structure. The treatment of Vero cells with the SNPs at a noncytotoxic concentration significantly inhibited PPRV replication in vitro. The time-course and virus step-specific assays showed that the SNPs impair PPRV replication at the level of virus entry. The TEM analysis showed that the SNPs interact with the virion surface as well with the virion core. However, this interaction has no direct virucidal effect, instead exerts a blocking effect on viral entry into the target cells. This is the first documented evidence indicating that the SNPs are capable of inhibiting a Morbillivirus replication in vitro. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Hepatitis G virus genomic RNA is pathogenic to Macaca mulatta

    Institute of Scientific and Technical Information of China (English)

    Hao Ren; Fen-Lu Zhu; Ming-Mei Cao; Xin-Yu Wen; Ping Zhao; Zhong-Tian Qi

    2005-01-01

    AIM: To explore the pathogenicity and infectivity of hepatitis G virus (HGV) by observing replication and expression of the virus, as well as the serological and histological changes of Macaca mulatta infected with HGV genomic RNA or HGV RNA-positive serum.METHODS: Full-length HGV cDNA clone (HGVqz) was constructed and proved to be infectious, from which HGV genomic RNA was transcribed in vitro. Macaca mulatta BY1 was intra-hepatically inoculated with HGV genomic RNA, HGV RNA-positive serum from BY1 was intravenously inoculated into Macaca mulatta BM1, and then BB1 was infected with serum from BM1. Serum and liver tissue were taken regularly, and checked with RT-PCR, in situ hybridization and other immunological, serological,histological assays.RESULTS: Serum HGV RNA was detectable in all the 3Macaca mulattas, serological and histological examinations showed the experimental animals had slightly elevated alanine transaminase (ALT) and developed HGV viremia during the infectious period. The histology, immunohistochemistry, and in situ hybridization in liver tissues of the inoculated animals demonstrated a very mild hepatitis with HGV antigen expression in cytoplasm of hepatocytes.RT-PCR and quantitative PCR results showed that HGV could replicate in liver.CONCLUSION: The genomic RNA from full-length HGV cDNA is infectious to the Macaca mulatta and can cause mild hepatitis. HGV RNA-positive serum, from HGV RNA inoculated Macaca mulatta, is infectious to other Macaca mulattas. Macaca mulatta is susceptible to the inoculated HGV, and therefore can be used as an experimental animal model for the studies of HGV infection and pathogenesis.

  16. A new stochastic model for subgenomic hepatitis C virus replication considers drug resistant mutants.

    Directory of Open Access Journals (Sweden)

    Nikita V Ivanisenko

    Full Text Available As an RNA virus, hepatitis C virus (HCV is able to rapidly acquire drug resistance, and for this reason the design of effective anti-HCV drugs is a real challenge. The HCV subgenomic replicon-containing cells are widely used for experimental studies of the HCV genome replication mechanisms, for drug testing in vitro and in studies of HCV drug resistance. The NS3/4A protease is essential for virus replication and, therefore, it is one of the most attractive targets for developing specific antiviral agents against HCV. We have developed a stochastic model of subgenomic HCV replicon replication, in which the emergence and selection of drug resistant mutant viral RNAs in replicon cells is taken into account. Incorporation into the model of key NS3 protease mutations leading to resistance to BILN-2061 (A156T, D168V, R155Q, VX-950 (A156S, A156T, T54A and SCH 503034 (A156T, A156S, T54A inhibitors allows us to describe the long term dynamics of the viral RNA suppression for various inhibitor concentrations. We theoretically showed that the observable difference between the viral RNA kinetics for different inhibitor concentrations can be explained by differences in the replication rate and inhibitor sensitivity of the mutant RNAs. The pre-existing mutants of the NS3 protease contribute more significantly to appearance of new resistant mutants during treatment with inhibitors than wild-type replicon. The model can be used to interpret the results of anti-HCV drug testing on replicon systems, as well as to estimate the efficacy of potential drugs and predict optimal schemes of their usage.

  17. Visualization of the structures of the hepatitis C virus replication complex

    Energy Technology Data Exchange (ETDEWEB)

    Chan, Shih-Ching [Graduate Institute of Molecular and Cellular Biology, Tzu Chi University, Hualien, Taiwan (China); Lo, Shih-Yen [Graduate Institute of Medical Biotechnology, Tzu Chi University, Hualien, Taiwan (China); Graduate Institute of Medical Sciences, Tzu Chi University, Hualien, Taiwan (China); Liou, Je-Wen [Graduate Institute of Medical Sciences, Tzu Chi University, Hualien, Taiwan (China); Department of Biochemistry, Tzu Chi University, Hualien, Taiwan (China); Lin, Min-Ching [Graduate Institute of Medical Biotechnology, Tzu Chi University, Hualien, Taiwan (China); Syu, Ciao-Ling [Graduate Institute of Medical Sciences, Tzu Chi University, Hualien, Taiwan (China); Lai, Meng-Jiun; Chen, Yi- Cheng [Graduate Institute of Medical Biotechnology, Tzu Chi University, Hualien, Taiwan (China); Li, Hui-Chun, E-mail: huichun@mail.tcu.edu.tw [Graduate Institute of Molecular and Cellular Biology, Tzu Chi University, Hualien, Taiwan (China); Graduate Institute of Medical Sciences, Tzu Chi University, Hualien, Taiwan (China); Department of Biochemistry, Tzu Chi University, Hualien, Taiwan (China)

    2011-01-07

    Research highlights: {yields} Lipid rafts are known to play an important role in virus entry and virus assembly of many viruses. {yields} However, HCV is the first example of the association of lipid raft with viral RNA replication. {yields} Our results in this manuscript demonstrate that purified HCV RCs with associated lipid raft membrane appeared as distinct particles of around 0.7 um under EM and AFM. {yields} Knockdown of proteins associated with lipid raft suppressed the HCV replication and reduced the number of these particles. {yields} To our knowledge, structures of HCV RCs were demonstrated at its first time in this manuscript. -- Abstract: Hepatitis C viral RNA synthesis has been demonstrated to occur on a lipid raft membrane structure. Lipid raft membrane fraction purified by membrane flotation analysis was observed using transmission electron microscopy and atomic force microscopy. Particles around 0.7 um in size were found in lipid raft membrane fraction purified from hepatitis C virus (HCV) replicon but not their parental HuH7 cells. HCV NS5A protein was associated with these specialized particles. After several cycles of freezing-thawing, these particles would fuse into larger sizes up to 10 um. Knockdown of seven proteins associated with lipid raft (VAPA, COPG, RAB18, COMT, CDC42, DPP4, and KDELR2) of HCV replicon cells reduced the observed number of these particles and suppressed the HCV replication. Results in this study indicated that HCV replication complexes with associated lipid raft membrane form distinct particle structures of around 0.7 um as observed from transmission electron microscopy and atomic force microscopy.

  18. Silencing E1A mRNA by RNA interference inhibits adenovirus replication.

    Science.gov (United States)

    Chung, Y-S; Kim, M-K; Lee, W-J; Kang, C

    2007-01-01

    The adenovirus family contains 51 human serotypes, and most human adenoviruses cause widespread respiratory tract infections. Adenovirus infections can result in severe complications in some cases, such as in adenovirus type 11 infection in immunocompromised patients. However, effective treatment methods for adenovirus infections are currently unavailable. This prompted the search for antiviral agents effective against adenovirus infections. In the present study, adenovirus E1A was targeted by RNA interference (RNAi) using synthetic small interfering RNAs (siRNAs) in an attempt to inhibit viral replication, since adenovirus E1A proteins are known to be involved in the transcriptional activation of the viral and cellular genes necessary for controlling the cell cycle and viral replication. The results indicated that the siRNAs effectively reduced the amount of adenovirus E1A mRNA and the levels of replicative intermediates. Additionally, siRNA-mediated gene silencing inhibited adenovirus replication by suppressing the E1A mRNA. These results suggest that the RNAi-mediated targeting of adenovirus E1A may have a potentially therapeutic effect in controlling adenovirus infections.

  19. The capsid-coding region hairpin element (cHP) is a critical determinant of dengue virus and West Nile virus RNA synthesis.

    Science.gov (United States)

    Clyde, Karen; Barrera, Julio; Harris, Eva

    2008-09-30

    Dengue virus (DENV) and West Nile virus (WNV) are members of the Flavivirus genus of positive-strand RNA viruses. RNA sequences and structures, primarily in the untranslated regions, have been shown to modulate flaviviral gene expression and genome replication. Previously, we demonstrated that a structure in the DENV coding region (cHP) enhances translation start codon selection and is required for viral replication. Here we further characterize the role of the cHP in the DENV life cycle. We demonstrate that the cHP is required for efficient viral RNA synthesis in a sequence-independent manner. Viruses with a disrupted cHP are rescued by a spontaneous compensatory mutation that restabilizes the structure. Furthermore, the cHP, which is predicted to be conserved among arthropod-borne flaviviruses, is required for WNV replication. We propose that the cHP is a multifunctional determinant of flavivirus replication, functioning in both translation and RNA synthesis.

  20. MicroRNA-mediated suppression of oncolytic adenovirus replication in human liver.

    Science.gov (United States)

    Ylösmäki, Erkko; Lavilla-Alonso, Sergio; Jäämaa, Sari; Vähä-Koskela, Markus; af Hällström, Taija; Hemminki, Akseli; Arola, Johanna; Mäkisalo, Heikki; Saksela, Kalle

    2013-01-01

    MicroRNAs (miRNAs) are important and ubiquitous regulators of gene expression that can suppress their target genes by translational inhibition as well as mRNA destruction. Cell type-specific miRNA expression patterns have been successfully exploited for targeting the expression of experimental and therapeutic gene constructs, for example to reduce pathogenic effects of cancer virotherapy in normal tissues. In order to avoid liver damage associated with systemic or intrahepatic delivery of oncolytic adenoviruses we have introduced the concept of suppressing adenovirus replication in hepatic cells by inserting target elements for the liver-specific miR122 into the viral genome. Here we show using ex vivo cultured tissue specimens that six perfectly complementary miR122 target sites in the 3' untranslated region of the viral E1A gene are sufficient in the absence of any other genetic modifications to prevent productive replication of serotype 5 adenovirus (Ad5) in normal human liver. This modification did not compromise the replicative capacity of the modified virus in cancer tissue derived from a colon carcinoma liver metastasis or its oncolytic potency in a human lung cancer xenograft mouse model. Unlike wild-type Ad5, the modified virus did not result in increased serum levels of liver enzymes in infected mice. These results provide a strong preclinical proof of concept for the use of miR122 target sites for reducing the risk of liver damage caused by oncolytic adenoviruses, and suggest that ectopic miR122 target elements should be considered as an additional safety measure included in any therapeutic virus or viral vector posing potential hazard to the liver.

  1. MicroRNA-mediated suppression of oncolytic adenovirus replication in human liver.

    Directory of Open Access Journals (Sweden)

    Erkko Ylösmäki

    Full Text Available MicroRNAs (miRNAs are important and ubiquitous regulators of gene expression that can suppress their target genes by translational inhibition as well as mRNA destruction. Cell type-specific miRNA expression patterns have been successfully exploited for targeting the expression of experimental and therapeutic gene constructs, for example to reduce pathogenic effects of cancer virotherapy in normal tissues. In order to avoid liver damage associated with systemic or intrahepatic delivery of oncolytic adenoviruses we have introduced the concept of suppressing adenovirus replication in hepatic cells by inserting target elements for the liver-specific miR122 into the viral genome. Here we show using ex vivo cultured tissue specimens that six perfectly complementary miR122 target sites in the 3' untranslated region of the viral E1A gene are sufficient in the absence of any other genetic modifications to prevent productive replication of serotype 5 adenovirus (Ad5 in normal human liver. This modification did not compromise the replicative capacity of the modified virus in cancer tissue derived from a colon carcinoma liver metastasis or its oncolytic potency in a human lung cancer xenograft mouse model. Unlike wild-type Ad5, the modified virus did not result in increased serum levels of liver enzymes in infected mice. These results provide a strong preclinical proof of concept for the use of miR122 target sites for reducing the risk of liver damage caused by oncolytic adenoviruses, and suggest that ectopic miR122 target elements should be considered as an additional safety measure included in any therapeutic virus or viral vector posing potential hazard to the liver.

  2. Functional RNA during Zika virus infection

    NARCIS (Netherlands)

    Göertz, Giel P.; Abbo, Sandra R.; Fros, Jelke J.; Pijlman, Gorben P.

    2017-01-01

    Zika virus (ZIKV; family Flaviviridae; genus Flavivirus) is a pathogenic mosquito-borne RNA virus that currently threatens human health in the Americas, large parts of Asia and occasionally elsewhere in the world. ZIKV infection is often asymptomatic but can cause severe symptoms including

  3. Cell Transformation by RNA Viruses: An Overview

    Directory of Open Access Journals (Sweden)

    Hung Fan

    2011-06-01

    Full Text Available Studies of oncogenic viruses have made seminal contributions to the molecular biology of cancer. Key discoveries include the identification of viral oncogenes and cellular proto-oncogenes, elucidation of signal transduction pathways, and identification of tumor suppressor genes. The origins of cancer virology began almost exactly one hundred years ago with the discovery of avian sarcoma and acute leukemia viruses—RNA-containing viruses of the retrovirus family. The study of animal cancer viruses accelerated beginning in the late 1960s and early 1970s, with the discovery of DNA viruses that could transform cells in culture, and the development of quantitative assays for transformation by DNA and RNA-containing tumor viruses. The discovery of reverse transcriptase in retroviruses in 1970 also greatly accelerated research on these viruses. Indeed RNA and DNA tumor viruses led the way in cancer molecular biology during this era before molecular cloning. It was possible to physically purify virus particles and generate specific hybridization probes for viral DNA and RNA at a time when it was not possible to analyze cellular genes in the same manner. [...

  4. Cytoskeletal Requirements for Hepatitis C Virus (HCV) RNA Synthesis in the HCV Replicon Cell Culture System

    OpenAIRE

    Bost, Anne G.; Venable, Daryl; Liu, Lifei; Heinz, Beverly A.

    2003-01-01

    Hepatitis C virus (HCV) induces microtubule aggregates in infected hepatocytes. To determine if cytoskeletal elements are important for HCV RNA synthesis, we examined the effect of cytoskeleton inhibitors on HCV replicon transcription in Huh7 cells. The data demonstrate that HCV replication complex-mediated RNA synthesis requires microtubule and actin polymerization.

  5. Cytoskeletal requirements for hepatitis C virus (HCV) RNA synthesis in the HCV replicon cell culture system.

    Science.gov (United States)

    Bost, Anne G; Venable, Daryl; Liu, Lifei; Heinz, Beverly A

    2003-04-01

    Hepatitis C virus (HCV) induces microtubule aggregates in infected hepatocytes. To determine if cytoskeletal elements are important for HCV RNA synthesis, we examined the effect of cytoskeleton inhibitors on HCV replicon transcription in Huh7 cells. The data demonstrate that HCV replication complex-mediated RNA synthesis requires microtubule and actin polymerization.

  6. Hepatitis B virus-3p-siRNA inhibits hepatitis B virus replication and activates interferon-βexpression in mice%乙型肝炎病毒-三磷酸-小干扰核糖核酸抑制小鼠乙型肝炎病毒复制并激活β干扰素的表达

    Institute of Scientific and Technical Information of China (English)

    邢雅玲; 陈晓娟; 闫飞; 杜鹃; 周勇; 王学军; 陈忠斌

    2014-01-01

    Objective To observe the activation of anti-viral innate immune response of type Ⅰinterferon and inhibition of hepatitis B virus (HBV)genome replication in mice by HBV-3p-siRNA. Methods HBV-3p-siRNA was designed by targeting specific sequence of HBV S/P mRNA and was generated by in vitro transcription.Negative control siRNA (NC-siRNA)and non-modified HBV-siRNA were used as control groups.Blood samples were collected from tail vein of mice and the model of HBV-infected mice were established by hydrodynamic injection.Forty mice were divided into 4 groups with 10 in each group.The model group was only injected with pGL3.0-HBV1 .2 copy plasmid.The negative control group received peritoneal injection of NC-siRNA.HBV-siRNA group received peritoneal injection of HBV-siRNA and HBV-3p-siRNA group received peritoneal injection of HBV-3p-siRNA.The interferon-β(IFN-β)and hepatitis B surface antigen (HBsAg)in serum were detected by enzyme linked immunosorbent assay (ELISA).The copies of HBV DNA were assessed by fluore scence quantitative polymerase chain reaction (PCR ).The statistical difference between groups was determined using One way-ANOVA analysis by LSD or Dunnett T3.Results Serum level of IFN-β was (12.37±5 .32)pg/mL in model group,(22.61 ±6.29 )pg/mL in negative control group,(26.40±5 .39)pg/mL in HBV-siRNA group and (68.37± 21 .00 ) pg/mL in HBV-3p-siRNA group.The secretions of IFN-β into serum were significantly enhanced by HBV-siRNA and HBV-3p-siRNA compared with model group (F =23.988 and 46.523,respectively,both P <0.01).Serum level of HBsAg was (2 864.86±907.11 )ng/mL in model group,(2 198.86±456.89 )ng/mL in negative control group,(1 049.71 ± 396.28 )ng/mL in HBV-siRNA group and (640.86±383.08)ng/mL in HBV-3p-siRNA group.The expressions of HBsAg were inhibited by HBV-3p-siRNA and HBV-siRNA compared with model group (F = 23.537 and 39.144, respectively;P =0.025 and 0.010,respectively).Serum level of HBV DNA was (2.54 ×104 ±1 .46 × 104 )copy

  7. Meganuclease-mediated virus self-cleavage facilitates tumor-specific virus replication.

    Science.gov (United States)

    Gürlevik, Engin; Schache, Peter; Goez, Anneliese; Kloos, Arnold; Woller, Norman; Armbrecht, Nina; Manns, Michael P; Kubicka, Stefan; Kühnel, Florian

    2013-09-01

    Meganucleases can specifically cleave long DNA sequence motifs, a feature that makes them an ideal tool for gene engineering in living cells. In a proof-of-concept study, we investigated the use of the meganuclease I-Sce I for targeted virus self-disruption to generate high-specific oncolytic viruses. For this purpose, we provided oncolytic adenoviruses with a molecular circuit that selectively responds to p53 activation by expression of I-Sce I subsequently leading to self-disruption of the viral DNA via heterologous I-Sce I recognition sites within the virus genome. We observed that virus replication and cell lysis was effectively impaired in p53-normal cells, but not in p53-dysfunctional tumor cells. I-Sce I activity led to effective intracellular processing of viral DNA as confirmed by detection of specific cleavage products. Virus disruption did not interfere with E1A levels indicating that reduction of functional virus genomes was the predominant cause for conditional replication. Consequently, tumor-specific replication was further enhanced when E1A expression was additionally inhibited by targeted transcriptional repression. Finally, we demonstrated p53-dependent oncolysis by I-Sce I-expressing viruses in vitro and in vivo, and demonstrated effective inhibition of tumor growth. In summary, meganuclease-mediated virus cleavage represents a promising approach to provide oncolytic viruses with attractive safety profiles.

  8. Crystal structure of Zika virus NS5 RNA-dependent RNA polymerase

    Science.gov (United States)

    Godoy, Andre S.; Lima, Gustavo M. A.; Oliveira, Ketllyn I. Z.; Torres, Naiara U.; Maluf, Fernando V.; Guido, Rafael V. C.; Oliva, Glaucius

    2017-01-01

    The current Zika virus (ZIKV) outbreak became a global health threat of complex epidemiology and devastating neurological impacts, therefore requiring urgent efforts towards the development of novel efficacious and safe antiviral drugs. Due to its central role in RNA viral replication, the non-structural protein 5 (NS5) RNA-dependent RNA-polymerase (RdRp) is a prime target for drug discovery. Here we describe the crystal structure of the recombinant ZIKV NS5 RdRp domain at 1.9 Å resolution as a platform for structure-based drug design strategy. The overall structure is similar to other flaviviral homologues. However, the priming loop target site, which is suitable for non-nucleoside polymerase inhibitor design, shows significant differences in comparison with the dengue virus structures, including a tighter pocket and a modified local charge distribution. PMID:28345596

  9. RNAi-based inhibition of infectious myonecrosis virus replication in Pacific white shrimp Litopenaeus vannamei.

    Science.gov (United States)

    Feijó, Rubens Galdino; Maggioni, Rodrigo; Cunha Martins, Pedro Carlos; de Abreu, Keuly Ladislau; Oliveira-Neto, João Mafaldo; Guertler, Cristhiane; Justino, Emily Bruna; Perazzolo, Luciane Maria; Marins, Luis Fernando

    2015-05-21

    Disease in Pacific white shrimp Litopenaeus vannamei caused by the infectious myonecrosis virus (IMNV) causes significant socioeconomic impacts in infection-prone shrimp aquaculture regions. The use of synthetic dsRNA to activate an RNA interference (RNAi) response is being explored as a means of disease prophylaxis in farmed shrimp. Here, survival was tracked in L. vannamei injected with long synthetic dsRNAs targeted to IMNV open reading frame (ORF) 1a, ORF1b, and ORF2 genome regions prior to injection challenge with IMNV, and real-time RT-PCR was used to track the progress of IMNV infection and mRNA expression levels of the host genes sid1, dicer2, and argonaute2. Injection of dsRNAs targeting the ORF1a and ORF1b genes but not the ORF2 gene strongly inhibited IMNV replication over a 3 wk period following IMNV challenge, and resulted in 90 and 83% shrimp survival, respectively. Host gene mRNA expression data indicated that the Sid1 protein, which forms a transmembrane channel involved in cellular import/export of dsRNA, increased in abundance most significantly in shrimp groups that were most highly protected by virus-specific dsRNA injection. Subclinical IMNV infections present in the experimental L. vannamei used increased markedly in the 2 d between injection of any of the 4 virus-specific or non-specific dsRNAs tested and IMNV challenge. While handling and injection stress are implicated in increasing IMNV replication levels, the underlying molecular factors that may have been involved remain to be elucidated.

  10. Generation of influenza A viruses as live but replication-incompetent virus vaccines.

    Science.gov (United States)

    Si, Longlong; Xu, Huan; Zhou, Xueying; Zhang, Ziwei; Tian, Zhenyu; Wang, Yan; Wu, Yiming; Zhang, Bo; Niu, Zhenlan; Zhang, Chuanling; Fu, Ge; Xiao, Sulong; Xia, Qing; Zhang, Lihe; Zhou, Demin

    2016-12-02

    The conversion of life-threatening viruses into live but avirulent vaccines represents a revolution in vaccinology. In a proof-of-principle study, we expanded the genetic code of the genome of influenza A virus via a transgenic cell line containing orthogonal translation machinery. This generated premature termination codon (PTC)-harboring viruses that exerted full infectivity but were replication-incompetent in conventional cells. Genome-wide optimization of the sites for incorporation of multiple PTCs resulted in highly reproductive and genetically stable progeny viruses in transgenic cells. In mouse, ferret, and guinea pig models, vaccination with PTC viruses elicited robust humoral, mucosal, and T cell-mediated immunity against antigenically distinct influenza viruses and even neutralized existing infecting strains. The methods presented here may become a general approach for generating live virus vaccines that can be adapted to almost any virus. Copyright © 2016, American Association for the Advancement of Science.

  11. Tumor viruses and replicative immortality--avoiding the telomere hurdle.

    Science.gov (United States)

    Chen, Xinsong; Kamranvar, Siamak Akbari; Masucci, Maria G

    2014-06-01

    Tumor viruses promote cell proliferation in order to gain access to an environment suitable for persistence and replication. The expression of viral products that promote growth transformation is often accompanied by the induction of multiple signs of telomere dysfunction, including telomere shortening, damage of telomeric DNA and chromosome instability. Long-term survival and progression to full malignancy require the bypassing of senescence programs that are triggered by the damaged telomeres. Here we review different strategies by which tumor viruses interfere with telomere homeostasis during cell transformation. This frequently involves the activation of telomerase, which assures both the integrity and functionality of telomeres. In addition, recent evidence suggests that oncogenic viruses may activate a recombination-based mechanism for telomere elongation known as Alternative Lengthening of Telomeres (ALT). This error-prone strategy promotes genomic instability and could play an important role in viral oncogenesis. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. Determination of the minimal amount of Tat activity required for human immunodeficiency virus type 1 replication.

    Science.gov (United States)

    Verhoef, K; Koper, M; Berkhout, B

    1997-10-27

    The Tat protein of human immunodeficiency virus type 1 (HIV-1) is a potent trans-activator of transcription from the viral LTR promoter. Previous mutagenesis studies have identified domains within Tat responsible for binding to its TAR RNA target and for transcriptional activation. The minimal Tat activation domain is composed of the N-terminal 48 residues, and mutational analyses identified a cluster of critical cysteines. The importance of four highly conserved aromatic amino acids within the activation domain has not been thoroughly investigated. We have systematically substituted these aromatic residues (Y26, F32, F38, Y47) of the HIV-1 LAI Tat protein with other aromatic residues (conservative mutation) or alanine (nonconservative mutation). The activity of the mutant Tat constructs was measured in different cell lines by transfection with a LTR-CAT reporter plasmid. The range of transcriptional activities measured for this set of Tat mutants allowed careful assessment of the level of Tat activity required for optimal viral replication. To test this, the mutant Tat genes were introduced into the pLAI infectious molecular clone and tested for their effect on virus replication in a T-cell line. We found that a twofold reduction in Tat activity already affects viral replication, and no virus replication was measured for Tat mutants with less than 15% activity. This strict correlation between Tat activity and viral replication demonstrates the importance of the Tat function to viral fitness. Interestingly, a less pronounced replication defect was observed in primary cell types. This finding may correlate with the frequent detection of proviruses with Tat-inactivating mutations in clinical samples. Copyright 1997 Academic Press.

  13. Replication-competent infectious hepatitis B virus vectors carrying substantially sized transgenes by redesigned viral polymerase translation.

    Directory of Open Access Journals (Sweden)

    Zihua Wang

    Full Text Available Viral vectors are engineered virus variants able to deliver nonviral genetic information into cells, usually by the same routes as the parental viruses. For several virus families, replication-competent vectors carrying reporter genes have become invaluable tools for easy and quantitative monitoring of replication and infection, and thus also for identifying antivirals and virus susceptible cells. For hepatitis B virus (HBV, a small enveloped DNA virus causing B-type hepatitis, such vectors are not available because insertions into its tiny 3.2 kb genome almost inevitably affect essential replication elements. HBV replicates by reverse transcription of the pregenomic (pg RNA which is also required as bicistronic mRNA for the capsid (core protein and the reverse transcriptase (Pol; their open reading frames (ORFs overlap by some 150 basepairs. Translation of the downstream Pol ORF does not involve a conventional internal ribosome entry site (IRES. We reasoned that duplicating the overlap region and providing artificial IRES control for translation of both Pol and an in-between inserted transgene might yield a functional tricistronic pgRNA, without interfering with envelope protein expression. As IRESs we used a 22 nucleotide element termed Rbm3 IRES to minimize genome size increase. Model plasmids confirmed its activity even in tricistronic arrangements. Analogous plasmids for complete HBV genomes carrying 399 bp and 720 bp transgenes for blasticidin resistance (BsdR and humanized Renilla green fluorescent protein (hrGFP produced core and envelope proteins like wild-type HBV; while the hrGFP vector replicated poorly, the BsdR vector generated around 40% as much replicative DNA as wild-type HBV. Both vectors, however, formed enveloped virions which were infectious for HBV-susceptible HepaRG cells. Because numerous reporter and effector genes with sizes of around 500 bp or less are available, the new HBV vectors should become highly useful tools to

  14. Prolactin Regulatory Element Binding Protein Is Involved in Hepatitis C Virus Replication by Interaction with NS4B

    Science.gov (United States)

    Kong, Lingbao; Fujimoto, Akira; Nakamura, Mariko; Aoyagi, Haruyo; Matsuda, Mami; Watashi, Koichi; Suzuki, Ryosuke; Arita, Minetaro; Yamagoe, Satoshi; Dohmae, Naoshi; Suzuki, Takehiro; Sakamaki, Yuriko; Ichinose, Shizuko; Suzuki, Tetsuro; Wakita, Takaji

    2016-01-01

    ABSTRACT It has been proposed that the hepatitis C virus (HCV) NS4B protein triggers the membranous HCV replication compartment, but the underlying molecular mechanism is not fully understood. Here, we screened for NS4B-associated membrane proteins by tandem affinity purification and proteome analysis and identified 202 host proteins. Subsequent screening of replicon cells with small interfering RNA identified prolactin regulatory element binding (PREB) to be a novel HCV host cofactor. The interaction between PREB and NS4B was confirmed by immunoprecipitation, immunofluorescence, and proximity ligation assays. PREB colocalized with double-stranded RNA and the newly synthesized HCV RNA labeled with bromouridine triphosphate in HCV replicon cells. Furthermore, PREB shifted to detergent-resistant membranes (DRMs), where HCV replication complexes reside, in the presence of NS4B expression in Huh7 cells. However, a PREB mutant lacking the NS4B-binding region (PREBd3) could not colocalize with double-stranded RNA and did not shift to the DRM in the presence of NS4B. These results indicate that PREB locates at the HCV replication complex by interacting with NS4B. PREB silencing inhibited the formation of the membranous HCV replication compartment and increased the protease and nuclease sensitivity of HCV replicase proteins and RNA in DRMs, respectively. Collectively, these data indicate that PREB promotes HCV RNA replication by participating in the formation of the membranous replication compartment and by maintaining its proper structure by interacting with NS4B. Furthermore, PREB was induced by HCV infection in vitro and in vivo. Our findings provide new insights into HCV host cofactors. IMPORTANCE The hepatitis C virus (HCV) protein NS4B can induce alteration of the endoplasmic reticulum and the formation of a membranous web structure, which provides a platform for the HCV replication complex. The molecular mechanism by which NS4B induces the membranous HCV replication

  15. Inhibitory effect of mycophenolic acid on the replication of infectious pancreatic necrosis virus and viral hemorrhagic septicemia virus.

    Science.gov (United States)

    Marroquí, Laura; Estepa, Amparo; Perez, Luis

    2008-12-01

    Infectious pancreatic necrosis virus (IPNV) and viral hemorrhagic septicemia virus (VHSV) remain two of the most important pathogens of farmed trout worldwide. Mycophenolic acid (MPA) is an inhibitor of cellular inosine monophosphate dehydrogenase (IMPDH), an enzyme that catalyzes an essential step in the biosynthesis of GTP. In this report, the antiviral activity of MPA against IPNV and VHSV in cell culture was assessed. Cell viability, virus yield, protein and RNA synthesis determinations were used to evaluate the inhibitory effect of MPA. MPA caused a dose-dependent inhibition of IPNV and VHSV replication. It was found that MPA had a particularly potent effect against IPNV, inhibiting the production of infectious virus more than 10(5)-fold. MPA was also highly effective in preventing viral protein synthesis. Quantitative real-time RT-PCR was used to measure viral RNA in cells infected by IPNV or VHSV to evaluate the inhibitory capacity of MPA as well as to compare MPA to the established antiviral drug ribavirin. MPA showed a good efficacy in decreasing accumulation of viral RNA at low concentrations. Finally, time of addition and wash out experiments suggested that MPA may have a dual mechanism of action, targeting both a cell and a viral function. This study provides evidence that MPA can function as a broad-spectrum antiviral drug for use in therapy of rainbow trout diseases.

  16. Permissiveness of human hepatocellular carcinoma cell lines for hepatitis C virus entry and replication.

    Science.gov (United States)

    Coto-Llerena, Mairene; Koutsoudakis, George; Boix, Loreto; López-Oliva, Juan Manuel; Caro-Pérez, Noelia; Fernández-Carrillo, Carlos; González, Patricia; Gastaminza, Pablo; Bruix, Jordi; Forns, Xavier; Pérez-Del-Pulgar, Sofía

    2017-07-24

    Hepatitis C virus (HCV) is a globally prevalent pathogen and is associated with high death rates and morbidity. Since its discovery in 1989, HCV research has been impeded by the lack of a robust infectious cell culture system and thus in vitro studies on diverse genetic backgrounds are hampered because of the limited number of hepatoma cell lines which are able to support different aspects of the HCV life cycle. In the current study, we sought to expand the limited number of permissive cells capable of supporting the diverse phases of the HCV life cycle. Initially, we screened a panel of new hepatoma-derived cell lines, designated BCLC-1, -2, -3, -4, -5, -6, -9 and -10 cells, for their ability to express essential HCV receptors and subsequently to support HCV entry by using the well-characterized HCV pseudoparticle system (HCVpp). Apart from BCLC-9, all BCLC cell lines were permissive for HCVpp infection. Next, BCLC cells were subjected to short- and long-term HCV RNA replication studies using HCV subgenomic replicons. Interestingly, only BCLC-1, -5 and -9 cells, supported short-term HCV RNA replication, but the latter were excluded from further studies since they were refractory for HCV entry. BCLC-1, -5 were able to support long-term HCV replication too; yet BCLC-5 cells supported the highest long-term HCV RNA replication levels. Furthermore, cured BCLC-5 clones from HCV subgenomic replicon, showed increased permissiveness for HCV RNA replication. Strikingly, we were unable to detect endogenous BCLC-5 miR122 expression - an important HCV host factor- and as expected, the exogenous expression of miR122 in BCLC-5 cells increased their permissiveness for HCV RNA replication. However, this cell line was unable to produce HCV infectious particles despite ectopic expression of apolipoprotein E, which in other hepatoma cell lines has been shown to be sufficient to enable the HCV secretion process, suggesting a lack of other host cellular factor(s) and/or the presence of

  17. Properties and use of novel replication-competent vectors based on Semliki Forest virus

    Directory of Open Access Journals (Sweden)

    Lulla Valeria

    2009-03-01

    Full Text Available Abstract Background Semliki Forest virus (SFV has a positive strand RNA genome and infects different cells of vertebrates and invertebrates. The 5' two-thirds of the genome encodes non-structural proteins that are required for virus replication and synthesis of subgenomic (SG mRNA for structural proteins. SG-mRNA is generated by internal initiation at the SG-promoter that is located at the complementary minus-strand template. Different types of expression systems including replication-competent vectors, which represent alphavirus genomes with inserted expression units, have been developed. The replication-competent vectors represent useful tools for studying alphaviruses and have potential therapeutic applications. In both cases, the properties of the vector, such as its genetic stability and expression level of the protein of interest, are important. Results We analysed 14 candidates of replication-competent vectors based on the genome of an SFV4 isolate that contained a duplicated SG promoter or an internal ribosomal entry site (IRES-element controlled marker gene. It was found that the IRES elements and the minimal -21 to +5 SG promoter were non-functional in the context of these vectors. The efficient SG promoters contained at least 26 residues upstream of the start site of SG mRNA. The insertion site of the SG promoter and its length affected the genetic stability of the vectors, which was always higher when the SG promoter was inserted downstream of the coding region for structural proteins. The stability also depended on the conditions used for vector propagation. A procedure based on the in vitro transcription of ligation products was used for generation of replication-competent vector-based expression libraries that contained hundreds of thousands of different genomes, and maintained genetic diversity and the ability to express inserted genes over five passages in cell culture. Conclusion The properties of replication-competent vectors

  18. Integrative functional genomics of hepatitis C virus infection identifies host dependencies in complete viral replication cycle.

    Science.gov (United States)

    Li, Qisheng; Zhang, Yong-Yuan; Chiu, Stephan; Hu, Zongyi; Lan, Keng-Hsin; Cha, Helen; Sodroski, Catherine; Zhang, Fang; Hsu, Ching-Sheng; Thomas, Emmanuel; Liang, T Jake

    2014-05-01

    Recent functional genomics studies including genome-wide small interfering RNA (siRNA) screens demonstrated that hepatitis C virus (HCV) exploits an extensive network of host factors for productive infection and propagation. How these co-opted host functions interact with various steps of HCV replication cycle and exert pro- or antiviral effects on HCV infection remains largely undefined. Here we present an unbiased and systematic strategy to functionally interrogate HCV host dependencies uncovered from our previous infectious HCV (HCVcc) siRNA screen. Applying functional genomics approaches and various in vitro HCV model systems, including HCV pseudoparticles (HCVpp), single-cycle infectious particles (HCVsc), subgenomic replicons, and HCV cell culture systems (HCVcc), we identified and characterized novel host factors or pathways required for each individual step of the HCV replication cycle. Particularly, we uncovered multiple HCV entry factors, including E-cadherin, choline kinase α, NADPH oxidase CYBA, Rho GTPase RAC1 and SMAD family member 6. We also demonstrated that guanine nucleotide binding protein GNB2L1, E2 ubiquitin-conjugating enzyme UBE2J1, and 39 other host factors are required for HCV RNA replication, while the deubiquitinating enzyme USP11 and multiple other cellular genes are specifically involved in HCV IRES-mediated translation. Families of antiviral factors that target HCV replication or translation were also identified. In addition, various virologic assays validated that 66 host factors are involved in HCV assembly or secretion. These genes included insulin-degrading enzyme (IDE), a proviral factor, and N-Myc down regulated Gene 1 (NDRG1), an antiviral factor. Bioinformatics meta-analyses of our results integrated with literature mining of previously published HCV host factors allows the construction of an extensive roadmap of cellular networks and pathways involved in the complete HCV replication cycle. This comprehensive study of HCV host

  19. Integrative functional genomics of hepatitis C virus infection identifies host dependencies in complete viral replication cycle.

    Directory of Open Access Journals (Sweden)

    Qisheng Li

    2014-05-01

    Full Text Available Recent functional genomics studies including genome-wide small interfering RNA (siRNA screens demonstrated that hepatitis C virus (HCV exploits an extensive network of host factors for productive infection and propagation. How these co-opted host functions interact with various steps of HCV replication cycle and exert pro- or antiviral effects on HCV infection remains largely undefined. Here we present an unbiased and systematic strategy to functionally interrogate HCV host dependencies uncovered from our previous infectious HCV (HCVcc siRNA screen. Applying functional genomics approaches and various in vitro HCV model systems, including HCV pseudoparticles (HCVpp, single-cycle infectious particles (HCVsc, subgenomic replicons, and HCV cell culture systems (HCVcc, we identified and characterized novel host factors or pathways required for each individual step of the HCV replication cycle. Particularly, we uncovered multiple HCV entry factors, including E-cadherin, choline kinase α, NADPH oxidase CYBA, Rho GTPase RAC1 and SMAD family member 6. We also demonstrated that guanine nucleotide binding protein GNB2L1, E2 ubiquitin-conjugating enzyme UBE2J1, and 39 other host factors are required for HCV RNA replication, while the deubiquitinating enzyme USP11 and multiple other cellular genes are specifically involved in HCV IRES-mediated translation. Families of antiviral factors that target HCV replication or translation were also identified. In addition, various virologic assays validated that 66 host factors are involved in HCV assembly or secretion. These genes included insulin-degrading enzyme (IDE, a proviral factor, and N-Myc down regulated Gene 1 (NDRG1, an antiviral factor. Bioinformatics meta-analyses of our results integrated with literature mining of previously published HCV host factors allows the construction of an extensive roadmap of cellular networks and pathways involved in the complete HCV replication cycle. This comprehensive study

  20. Temporal SILAC-based quantitative proteomics identifies host factors involved in chikungunya virus replication.

    Science.gov (United States)

    Treffers, Emmely E; Tas, Ali; Scholte, Florine E M; Van, Myrthe N; Heemskerk, Matthias T; de Ru, Arnoud H; Snijder, Eric J; van Hemert, Martijn J; van Veelen, Peter A

    2015-07-01

    Chikungunya virus (CHIKV) is an arthropod-borne reemerging human pathogen that generally causes a severe persisting arthritis. Since 2005, the virus has infected millions of people during outbreaks in Africa, Indian Ocean Islands, Asia, and South/Central America. Many steps of the replication and expression of CHIKV's 12-kb RNA genome are highly dependent on cellular factors, which thus constitute potential therapeutic targets. SILAC and LC-MS/MS were used to define the temporal dynamics of the cellular response to infection. Using samples harvested at 8, 10, and 12 h postinfection, over 4700 proteins were identified and per time point 2800-3500 proteins could be quantified in both biological replicates. At 8, 10, and 12 h postinfection, 13, 38, and 106 proteins, respectively, were differentially expressed. The majority of these proteins showed decreased abundance. Most subunits of the RNA polymerase II complex were progressively degraded, which likely contributes to the transcriptional host shut-off observed during CHIKV infection. Overexpression of four proteins that were significantly downregulated (Rho family GTPase 3 (Rnd3), DEAD box helicase 56 (DDX56), polo-like kinase 1 (Plk1), and ubiquitin-conjugating enzyme E2C (UbcH10) reduced susceptibility of cells to CHIKV infection, suggesting that infection-induced downregulation of these proteins is beneficial for CHIKV replication. All MS data have been deposited in the ProteomeXchange with identifier PXD001330 (http://proteomecentral.proteomexchange.org/dataset/PXD001330).

  1. A Vicilin-Like Seed Storage Protein, PAP85, Is Involved in Tobacco Mosaic Virus Replication

    Science.gov (United States)

    Chen, Cheng-En; Yeh, Kuo-Chen; Wu, Shu-Hsing; Wang, Hsiang-Iu

    2013-01-01

    One striking feature of viruses with RNA genomes is the modification of the host membrane structure during early infection. This process requires both virus- and host-encoded proteins; however, the host factors involved and their role in this process remain largely unknown. On infection with Tobacco mosaic virus (TMV), a positive-strand RNA virus, the filamentous and tubular endoplasmic reticulum (ER) converts to aggregations at the early stage and returns to filamentous at the late infectious stage, termed the ER transition. Also, membrane- or vesicle-packaged viral replication complexes (VRCs) are induced early during infection. We used microarray assays to screen the Arabidopsis thaliana gene(s) responding to infection with TMV in the initial infection stage and identified an Arabidopsis gene, PAP85 (annotated as a vicilin-like seed storage protein), with upregulated expression during 0.5 to 6 h of TMV infection. TMV accumulation was reduced in pap85-RNA interference (RNAi) Arabidopsis and restored to wild-type levels when PAP85 was overexpressed in pap85-RNAi Arabidopsis. We did not observe the ER transition in TMV-infected PAP85-knockdown Arabidopsis protoplasts. In addition, TMV accumulation was reduced in PAP85-knockdown protoplasts. VRC accumulation was reduced, but not significantly (P = 0.06), in PAP85-knockdown protoplasts. Coexpression of PAP85 and the TMV main replicase (P126), but not their expression alone in Arabidopsis protoplasts, could induce ER aggregations. PMID:23576511

  2. Expression of bovine Mx1 protein inhibits the replication of foot-and-mouth disease virus in BHK-21 cells.

    Science.gov (United States)

    Cai, K J; Meng, Q L; Qiao, J; Huang, J; Zhang, Z C; Wang, G C; Wang, J W; Chen, C F

    2013-01-01

    Mx proteins belonging to the dynamin superfamily of large GTPases inhibit replication of a wide range of RNA viruses. In this study, we examined whether bovine Mx1 protein could interfere with the replication of foot-and-mouth disease virus (FMDV). For this purpose we established cloned BHK-21 cells expressing bovine Mx1 protein (BM1 cells) and infected them with FMDV serotype O. Cloned BHK-21 cells expressing neomycin resistance instead of Mx1 protein (BH1 cells) and original BHK-21 cells served as negative controls. The results showed that the expression of bovine Mx1 protein reduced viral yields by 90% and levels of viral VP1 mRNA by 60%. These findings correlated with a significant reduction of viral antigen detectable in infected cells by immunofluorescent assay. These results demonstrate that bovine Mx1 protein interferes with the replication of FMDV.

  3. siRNAs targeting PB2 and NP genes potentially inhibit replication of Highly Pathogenic H5N1 Avian Influenza Virus.

    Science.gov (United States)

    Behera, Padmanava; Nagarajan, Shanmugasundaram; Murugkar, Harshad V; Kalaiyarasu, Semmannan; Prakash, Anil; Gothalwal, Ragini; Dubey, Shiv Chandra; Kulkarni, Diwakar D; Tosh, Chakradhar

    2015-06-01

    Highly Pathogenic Avian Influenza (HPAI) H5N1 virus is a threat to animal and public health worldwide. Till date, the H5N1 virus has claimed 402 human lives, with a mortality rate of 58 percent and has caused the death or culling of millions of poultry since 2003. In this study, we have designed three siRNAs (PB2-2235, PB2-479 and NP-865) targeting PB2 and NP genes of avian influenza virus and evaluated their potential, measured by hemagglutination (HA), plaque reduction and Real time RT-PCR assay, in inhibiting H5N1 virus (A/chicken/Navapur/7972/2006) replication in MDCK cells. The siRNAs caused 8- to 16-fold reduction in virus HA titers at 24 h after challenged with 100TCID50 of virus. Among these siRNAs, PB2-2235 offered the highest inhibition of virus replication with 16-fold reduction in virus HA titer, 80 percent reduction in viral plaque counts and 94 percent inhibition in expression of specific RNA at 24 h. The other two siRNAs had 68-73 percent and 87-88 percent reduction in viral plaque counts and RNA copy number, respectively. The effect of siRNA on H5N1 virus replication continued till 48h (maximum observation period). These findings suggest that PB2-2235 could efficiently inhibit HPAI H5N1 virus replication.

  4. siRNAs targeting PB2 and NP genes potentially inhibit replication of Highly Pathogenic H5N1 Avian Influenza Virus

    Indian Academy of Sciences (India)

    Padmanava Behera; Shanmugasundaram Nagarajan; Harshad V Murugkar; Semmannan Kalaiyarasu; Anil Prakash; Ragini Gothalwal; Shiv Chandra Dubey; Diwakar D Kulkarni; Chakradhar Tosh

    2015-06-01

    Highly Pathogenic Avian Influenza (HPAI) H5N1 virus is a threat to animal and public health worldwide. Till date, the H5N1 virus has claimed 402 human lives, with a mortality rate of 58% and has caused the death or culling of millions of poultry since 2003. In this study, we have designed three siRNAs (PB2-2235, PB2-479 and NP-865) targeting PB2 and NP genes of avian influenza virus and evaluated their potential, measured by hemagglutination (HA), plaque reduction and Real time RT-PCR assay, in inhibiting H5N1 virus (A/chicken/Navapur/7972/2006) replication in MDCK cells. The siRNAs caused 8- to 16-fold reduction in virus HA titers at 24 h after challenged with 100TCID50 of virus. Among these siRNAs, PB2-2235 offered the highest inhibition of virus replication with 16-fold reduction in virus HA titer, 80% reduction in viral plaque counts and 94% inhibition in expression of specific RNA at 24 h. The other two siRNAs had 68–73% and 87–88% reduction in viral plaque counts and RNA copy number, respectively. The effect of siRNA on H5N1 virus replication continued till 48h (maximum observation period). These findings suggest that PB2-2235 could efficiently inhibit HPAI H5N1 virus replication.

  5. Human keratinocytes restrict chikungunya virus replication at a post-fusion step

    Energy Technology Data Exchange (ETDEWEB)

    Bernard, Eric [Centre d' étude d’agents Pathogènes et Biotechnologies pour la Santé, CPBS CNRS- UMR5236/UM1/UM2, Montpellier (France); Hamel, Rodolphe [Laboratoire Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution, Contrôle, UMR 5290 CNRS/IRD/UM1, Montpellier (France); Neyret, Aymeric [Centre d' étude d’agents Pathogènes et Biotechnologies pour la Santé, CPBS CNRS- UMR5236/UM1/UM2, Montpellier (France); Ekchariyawat, Peeraya [Laboratoire Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution, Contrôle, UMR 5290 CNRS/IRD/UM1, Montpellier (France); Molès, Jean-Pierre [INSERM U1058, UM1, CHU Montpellier (France); Simmons, Graham [Blood Systems Research Institute, San Francisco, CA 94118 (United States); Chazal, Nathalie [Centre d' étude d’agents Pathogènes et Biotechnologies pour la Santé, CPBS CNRS- UMR5236/UM1/UM2, Montpellier (France); Desprès, Philippe [Unité Interactions Moléculaires Flavivirus-Hôtes, Institut Pasteur, Paris (France); and others

    2015-02-15

    Transmission of chikungunya virus (CHIKV) to humans is initiated by puncture of the skin by a blood-feeding Aedes mosquito. Despite the growing knowledge accumulated on CHIKV, the interplay between skin cells and CHIKV following inoculation still remains unclear. In this study we questioned the behavior of human keratinocytes, the predominant cell population in the skin, following viral challenge. We report that CHIKV rapidly elicits an innate immune response in these cells leading to the enhanced transcription of type I/II and type III interferon genes. Concomitantly, we show that despite viral particles internalization into Rab5-positive endosomes and efficient fusion of virus and cell membranes, keratinocytes poorly replicate CHIKV as attested by absence of nonstructural proteins and genomic RNA synthesis. Accordingly, human keratinocytes behave as an antiviral defense against CHIKV infection rather than as a primary targets for initial replication. This picture significantly differs from that reported for Dengue and West Nile mosquito-borne viruses. - Highlights: • Human keratinocytes support endocytosis of CHIKV and fusion of viral membranes. • CHIKV replication is blocked at a post entry step in these cells. • Infection upregulates type-I, –II and –III IFN genes expression. • Keratinocytes behave as immune sentinels against CHIKV.

  6. Rad51 and Rad52 are involved in homologous recombination of replicating herpes simplex virus DNA.

    Directory of Open Access Journals (Sweden)

    Ka-Wei Tang

    Full Text Available Replication of herpes simplex virus 1 is coupled to recombination, but the molecular mechanisms underlying this process are poorly characterized. The role of Rad51 and Rad52 recombinases in viral recombination was examined in human fibroblast cells 1BR.3.N (wild type and in GM16097 with replication defects caused by mutations in DNA ligase I. Intermolecular recombination between viruses, tsS and tsK, harboring genetic markers gave rise to ∼17% recombinants in both cell lines. Knock-down of Rad51 and Rad52 by siRNA reduced production of recombinants to 11% and 5%, respectively, in wild type cells and to 3% and 5%, respectively, in GM16097 cells. The results indicate a specific role for Rad51 and Rad52 in recombination of replicating herpes simplex virus 1 DNA. Mixed infections using clinical isolates with restriction enzyme polymorphisms in the US4 and US7 genes revealed recombination frequencies of 0.7%/kbp in wild type cells and 4%/kbp in GM16097 cells. Finally, tandem repeats in the US7 gene remained stable upon serial passage, indicating a high fidelity of recombination in infected cells.

  7. Critical role of Dengue Virus NS1 protein in viral replication

    Institute of Scientific and Technical Information of China (English)

    Jingjing Fan; Yi Liu; Zhiming Yuan

    2014-01-01

    Dengue virus (DENV) nonstructural protein 1 (NS1) is a highly conserved 46-kDa protein that contains 2 glycosylation sites (Asn-130 and Asn-207) and 12 conserved cysteine (Cys) residues. Here, we performed site-directed mutagenesis to generate systematic mutants of viral strain TSV01. The results of the subsequent analysis showed that an alanine substitution at the second N-linked glycan Asn-207 in NS1 delayed viral RNA synthesis, reduced virus plaque size, and weakened the cytopathic effect. Three mutants at Cys sites (Cys-4, Cys-55, Cys-291) and a C-terminal deletion (ΔC) mutant signiifcantly impaired RNA synthesis, and consequently abolished viral growth, whereas alanine mutations at Asn-130 and Glu-173 resulted in phenotypes that were similar to the wild-type (WT) virus. Further analysis showed that the Asn-207 mutation slightly delayed viral replication. These results suggest that the three conserved disulifde bonds and the second N-linked glycan in NS1 are required for DENV-2 replication.

  8. Inhibition of hepatitis C virus protein expression by RNA interference.

    Science.gov (United States)

    Sen, Adrish; Steele, Robert; Ghosh, Asish K; Basu, Arnab; Ray, Ranjit; Ray, Ratna B

    2003-10-01

    Hepatitis C virus (HCV) is a serious human pathogen and an estimated 170 million people are infected worldwide. Current therapeutic regimens have shown limited efficacy against selected genotypes of the virus. The phenomenon of RNA interference can be used to selectively block homologous genes post-transcriptionally, and has revolutionized approaches to study gene function. In this report, we have demonstrated that small interfering RNAs (siRNAs) targeted against NS5A of HCV genotype 1a specifically inhibit NS5A RNA and protein expression in a human hepatoma (HepG2) cell line. Expression of endogenous alpha-actin and the ds-RNA activated serine/threonine kinase-PKR were unaltered, demonstrating that the inhibitory effect observed from siRNA was specific to the HCV NS5A protein. We next examined whether siRNA directed against NS5A could inhibit core protein expression, the first gene product synthesized in virus infected cells due to its localization at the 5' end of the HCV polyprotein. For this purpose, a full-length cDNA clone from HCV (H77, genotype 1a) was used, and results indicated that the introduction of NS5A targeted siRNA resulted in an inhibition of NS5A and core protein expression. Moreover, we observed that this siRNA effectively inhibited NS5A mediated activation of the IL-8 promoter. Taken together, our results demonstrated that siRNA was effective in inhibiting HCV protein expression, and may have therapeutic potential to limit HCV replication in chronically infected patients.

  9. Structural organization of poliovirus RNA replication is mediated by viral proteins of the P2 genomic region

    Energy Technology Data Exchange (ETDEWEB)

    Bienz, K.; Egger, D.; Troxler, M.; Pasamontes, L. (Univ. of Basel (Switzerland))

    1990-03-01

    Transcriptionally active replication complexes bound to smooth membrane vesicles were isolated from poliovirus-infected cells. In electron microscopic, negatively stained preparations, the replication complex appeared as an irregularly shaped, oblong structure attached to several virus-induced vesicles of a rosettelike arrangement. Electron microscopic immunocytochemistry of such preparations demonstrated that the poliovirus replication complex contains the proteins coded by the P2 genomic region (P2 proteins) in a membrane-associated form. In addition, the P2 proteins are also associated with viral RNA, and they can be cross-linked to viral RNA by UV irradiation. Guanidine hydrochloride prevented the P2 proteins from becoming membrane bound but did not change their association with viral RNA. The findings allow the conclusion that the protein 2C or 2C-containing precursor(s) is responsible for the attachment of the viral RNA to the vesicular membrane and for the spatial organization of the replication complex necessary for its proper functioning in viral transcription. A model for the structure of the viral replication complex and for the function of the 2C-containing P2 protein(s) and the vesicular membranes is proposed.

  10. RNA genetics

    Energy Technology Data Exchange (ETDEWEB)

    Domingo, E. (Instituto de Biologia Molecular, Facultad de Ciencias, Universidad Autonoma de Madrid, Canto Blanco, Madrid (ES)); Holland, J.J. (California Univ., San Diego, La Jolla, CA (USA). Dept. of Biology); Ahlquist, P. (Wisconsin Univ., Madison, WI (USA). Dept. of Plant Pathology)

    1988-01-01

    This book contains the proceedings on RNA genetics: RNA-directed virus replication Volume 1. Topics covered include: Replication of the poliovirus genome; Influenza viral RNA transcription and replication; and Relication of the reoviridal: Information derived from gene cloning and expression.

  11. Alfalfa mosaic virus replicase proteins, P1 and P2, localize to the tonoplast in the presence of virus RNA

    Energy Technology Data Exchange (ETDEWEB)

    Ibrahim, Amr [Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907 (United States); Present address: Genomics Facility, Agricultural Genetic Engineering Research Institute, Agricultural Research Center, Giza 12619 (Egypt); Hutchens, Heather M. [Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907 (United States); Howard Berg, R. [Integrated Microscopy Facility, Donald Danforth Plant Science Center, Saint Louis, MO 63132 (United States); Sue Loesch-Fries, L., E-mail: loeschfr@purdue.edu [Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907 (United States)

    2012-11-25

    To identify the virus components important for assembly of the Alfalfa mosaic virus replicase complex, we used live cell imaging of Arabidopsis thaliana protoplasts that expressed various virus cDNAs encoding native and GFP-fusion proteins of P1 and P2 replicase proteins and full-length virus RNAs. Expression of P1-GFP alone resulted in fluorescent vesicle-like bodies in the cytoplasm that colocalized with FM4-64, an endocytic marker, and RFP-AtVSR2, RabF2a/Rha1-mCherry, and RabF2b/Ara7-mCherry, all of which localize to multivesicular bodies (MVBs), which are also called prevacuolar compartments, that mediate traffic to the lytic vacuole. GFP-P2 was driven from the cytosol to MVBs when expressed with P1 indicating that P1 recruited GFP-P2. P1-GFP localized on the tonoplast, which surrounds the vacuole, in the presence of infectious virus RNA, replication competent RNA2, or P2 and replication competent RNA1 or RNA3. This suggests that a functional replication complex containing P1, P2, and a full-length AMV RNA assembles on MVBs to traffic to the tonoplast.

  12. Both foot-and-mouth disease virus and bovine viral diarrhea virus replication are inhibited by Mx1 protein originated from porcine.

    Science.gov (United States)

    Shi, Huijun; Fu, Qiang; Ren, Yan; Wang, Dawei; Qiao, Jun; Wang, Pengyan; Zhang, Hui; Chen, Chuangfu

    2015-01-01

    Mx1 protein is I type interferons (IFNs)-induced 76-kDa guanosine triphosphatases (GTPases) that belong to the dynamin superfamily of large GTPases. Mx1 proteins have attracted attention because some display antiviral activity against pathogenic RNA and DNA viruses. Meanwhile, Mx1 gene generally exists in organisms or cells of mammalian, fish and chicken. Blocking a wide range of RNA virus replication by inhibiting nuclear viral mRNA synthesis is a unique property of Mx1 protein. In order to investigate a novel prevention measure against foot-and-mouth disease virus (FMDV) and bovine viral diarrhea virus (BVDV), which frequently break out in Xinjiang Uygur Autonomous Region of China, we investigated the effects of porcine Mx1 protein on FMDV and BVDV replication by measuring viral reverse transcriptase activity at various time intervals. In our study, Mx1 protein was overexpressed in BHK-21 and MDBK cells mediated by lentivirus prior to infect with FMDV and BVDV. FMDV and BVDV replication levels were monitored by quantitative real-Time PCR. The results showed porcine Mx1 overexpression significantly inhibited both FMDV and BVDV replication within 12 and 36 hours post-infection (pi). The finding may provide a new therapeutic approach for preventing from FDMV and BVDV infection.

  13. A Cytoplasmic RNA Virus Alters the Function of the Cell Splicing Protein SRSF2.

    Science.gov (United States)

    Rivera-Serrano, Efraín E; Fritch, Ethan J; Scholl, Elizabeth H; Sherry, Barbara

    2017-04-01

    To replicate efficiently, viruses must create favorable cell conditions and overcome cell antiviral responses. We previously reported that the reovirus protein μ2 from strain T1L, but not strain T3D, represses one antiviral response: alpha/beta interferon signaling. We report here that T1L, but not T3D, μ2 localizes to nuclear speckles, where it forms a complex with the mRNA splicing factor SRSF2 and alters its subnuclear localization. Reovirus replicates in cytoplasmic viral factories, and there is no evidence that reovirus genomic or messenger RNAs are spliced, suggesting that T1L μ2 might target splicing of cell RNAs. Indeed, RNA sequencing revealed that reovirus T1L, but not T3D, infection alters the splicing of transcripts for host genes involved in mRNA posttranscriptional modifications. Moreover, depletion of SRSF2 enhanced reovirus replication and cytopathic effect, suggesting that T1L μ2 modulation of splicing benefits the virus. This provides the first report of viral antagonism of the splicing factor SRSF2 and identifies the viral protein that determines strain-specific differences in cell RNA splicing.IMPORTANCE Efficient viral replication requires that the virus create favorable cell conditions. Many viruses accomplish this by repressing specific antiviral responses. We demonstrate here that some mammalian reoviruses, RNA viruses that replicate strictly in the cytoplasm, express a protein variant that localizes to nuclear speckles, where it targets a cell mRNA splicing factor. Infection with a reovirus strain that targets this splicing factor alters splicing of cell mRNAs involved in the maturation of many other cell mRNAs. Depletion of this cell splicing factor enhances reovirus replication and cytopathic effect. Our results provide the first evidence of viral antagonism of this splicing factor and suggest that downstream consequences to the cell are global and benefit the virus. Copyright © 2017 American Society for Microbiology.

  14. Effect of monensin on Mayaro virus replication in monkey kidney and Aedes albopictus cells.

    Science.gov (United States)

    De Campos, R M; Ferreira, D F; Da Veiga, V F; Rebello, M A; Rebello, M C S

    2003-01-01

    The effect of a cationic ionophore, monensin, on the replication of Mayaro virus in monkey kidney TC7 and Aedes albopictus cells has been studied. Treatment of these cells with 1 micromol/l monensin during infection did not affect the virus protein synthesis but inhibited severely the virus replication. Electron microscopy of the cells infected with Mayaro virus and treated with monensin revealed that the morphogenesis of Mayaro virus was impaired in TC7 but not in A. albopictus cells.

  15. The Lsm1-7-Pat1 complex promotes viral RNA translation and replication by differential mechanisms.

    Science.gov (United States)

    Jungfleisch, Jennifer; Chowdhury, Ashis; Alves-Rodrigues, Isabel; Tharun, Sundaresan; Díez, Juana

    2015-08-01

    The Lsm1-7-Pat1 complex binds to the 3' end of cellular mRNAs and promotes 3' end protection and 5'-3' decay. Interestingly, this complex also specifically binds to cis-acting regulatory sequences of viral positive-strand RNA genomes promoting their translation and subsequent recruitment from translation to replication. Yet, how the Lsm1-7-Pat1 complex regulates these two processes remains elusive. Here, we show that Lsm1-7-Pat1 complex acts differentially in these processes. By using a collection of well-characterized lsm1 mutant alleles and a system that allows the replication of Brome mosaic virus (BMV) in yeast we show that the Lsm1-7-Pat1 complex integrity is essential for both, translation and recruitment. However, the intrinsic RNA-binding ability of the complex is only required for translation. Consistent with an RNA-binding-independent function of the Lsm1-7-Pat1 complex on BMV RNA recruitment, we show that the BMV 1a protein, the sole viral protein required for recruitment, interacts with this complex in an RNA-independent manner. Together, these results support a model wherein Lsm1-7-Pat1 complex binds consecutively to BMV RNA regulatory sequences and the 1a protein to promote viral RNA translation and later recruitment out of the host translation machinery to the viral replication complexes.

  16. Trigocherrierin A, a potent inhibitor of chikungunya virus replication.

    Science.gov (United States)

    Bourjot, Mélanie; Leyssen, Pieter; Neyts, Johan; Dumontet, Vincent; Litaudon, Marc

    2014-03-24

    Trigocherrierin A (1) and trigocherriolide E (2), two new daphnane diterpenoid orthoesters (DDOs), and six chlorinated analogues, trigocherrins A, B, F and trigocherriolides A-C, were isolated from the leaves of Trigonostemon cherrieri. Their structures were identified by mass spectrometry, extensive one- and two-dimensional NMR spectroscopy and through comparison with data reported in the literature. These compounds are potent and selective inhibitors of chikungunya virus (CHIKV) replication. Among the DDOs isolated, compound 1 exhibited the strongest anti-CHIKV activity (EC₅₀ = 0.6 ± 0.1 µM, SI = 71.7).

  17. Trigocherrierin A, a Potent Inhibitor of Chikungunya Virus Replication

    Directory of Open Access Journals (Sweden)

    Mélanie Bourjot

    2014-03-01

    Full Text Available Trigocherrierin A (1 and trigocherriolide E (2, two new daphnane diterpenoid orthoesters (DDOs, and six chlorinated analogues, trigocherrins A, B, F and trigocherriolides A–C, were isolated from the leaves of Trigonostemon cherrieri. Their structures were identified by mass spectrometry, extensive one- and two-dimensional NMR spectroscopy and through comparison with data reported in the literature. These compounds are potent and selective inhibitors of chikungunya virus (CHIKV replication. Among the DDOs isolated, compound 1 exhibited the strongest anti-CHIKV activity (EC50 = 0.6 ± 0.1 µM, SI = 71.7.

  18. Nucleolin interacts with the feline calicivirus 3' untranslated region and the protease-polymerase NS6 and NS7 proteins, playing a role in virus replication.

    Science.gov (United States)

    Cancio-Lonches, Clotilde; Yocupicio-Monroy, Martha; Sandoval-Jaime, Carlos; Galvan-Mendoza, Iván; Ureña, Luis; Vashist, Surender; Goodfellow, Ian; Salas-Benito, Juan; Gutiérrez-Escolano, Ana Lorena

    2011-08-01

    Cellular proteins play many important roles during the life cycle of all viruses. Specifically, host cell nucleic acid-binding proteins interact with viral components of positive-stranded RNA viruses and regulate viral translation, as well as RNA replication. Here, we report that nucleolin, a ubiquitous multifunctional nucleolar shuttling phosphoprotein, interacts with the Norwalk virus and feline calicivirus (FCV) genomic 3' untranslated regions (UTRs). Nucleolin can also form a complex in vitro with recombinant Norwalk virus NS6 and -7 (NS6/7) and can be copurified with the analogous protein from feline calicivirus (p76 or NS6/7) from infected feline kidney cells. Nucleolin RNA levels or protein were not modified during FCV infection; however, as a consequence of the infection, nucleolin was seen to relocalize from the nucleoli to the nucleoplasm, as well as to the perinuclear area where it colocalizes with the feline calicivirus NS6/7 protein. In addition, antibodies to nucleolin were able to precipitate viral RNA from feline calicivirus-infected cells, indicating a direct or indirect association of nucleolin with the viral RNA during virus replication. Small interfering RNA (siRNA)-mediated knockdown of nucleolin resulted in a reduction of the cytopathic effect and virus yield in CrFK cells. Taken together, these results demonstrate that nucleolin is a nucleolar component that interacts with viral RNA and NS6/7 and is required for feline calicivirus replication.

  19. Nucleolin Interacts with the Feline Calicivirus 3′ Untranslated Region and the Protease-Polymerase NS6 and NS7 Proteins, Playing a Role in Virus Replication

    Science.gov (United States)

    Cancio-Lonches, Clotilde; Yocupicio-Monroy, Martha; Sandoval-Jaime, Carlos; Galvan-Mendoza, Iván; Ureña, Luis; Vashist, Surender; Goodfellow, Ian; Salas-Benito, Juan; Gutiérrez-Escolano, Ana Lorena

    2011-01-01

    Cellular proteins play many important roles during the life cycle of all viruses. Specifically, host cell nucleic acid-binding proteins interact with viral components of positive-stranded RNA viruses and regulate viral translation, as well as RNA replication. Here, we report that nucleolin, a ubiquitous multifunctional nucleolar shuttling phosphoprotein, interacts with the Norwalk virus and feline calicivirus (FCV) genomic 3′ untranslated regions (UTRs). Nucleolin can also form a complex in vitro with recombinant Norwalk virus NS6 and -7 (NS6/7) and can be copurified with the analogous protein from feline calicivirus (p76 or NS6/7) from infected feline kidney cells. Nucleolin RNA levels or protein were not modified during FCV infection; however, as a consequence of the infection, nucleolin was seen to relocalize from the nucleoli to the nucleoplasm, as well as to the perinuclear area where it colocalizes with the feline calicivirus NS6/7 protein. In addition, antibodies to nucleolin were able to precipitate viral RNA from feline calicivirus-infected cells, indicating a direct or indirect association of nucleolin with the viral RNA during virus replication. Small interfering RNA (siRNA)-mediated knockdown of nucleolin resulted in a reduction of the cytopathic effect and virus yield in CrFK cells. Taken together, these results demonstrate that nucleolin is a nucleolar component that interacts with viral RNA and NS6/7 and is required for feline calicivirus replication. PMID:21680514

  20. RNA families in Epstein–Barr virus

    Science.gov (United States)

    Moss, Walter N; Lee, Nara; Pimienta, Genaro; Steitz, Joan A

    2014-01-01

    Epstein–Barr virus (EBV) is a tumorigenic human γ-herpesvirus, which produces several known structured RNAs with functional importance: two are implicated in latency maintenance and tumorigenic phenotypes, EBER1 and EBER2; a viral small nucleolar RNA (v-snoRNA1) that may generate a small regulatory RNA; and an internal ribosomal entry site in the EBNA1 mRNA. A recent bioinformatics and RNA-Seq study of EBV identified two novel EBV non-coding (nc)RNAs with evolutionary conservation in lymphocryptoviruses and likely functional importance. Both RNAs are transcribed from a repetitive region of the EBV genome (the W repeats) during a highly oncogenic type of viral latency. One novel ncRNA can form a massive (586 nt) hairpin, while the other RNA is generated from a short (81 nt) intron and is found in high abundance in EBV-infected cells. PMID:24441309

  1. RNA families in Epstein-Barr virus.

    Science.gov (United States)

    Moss, Walter N; Lee, Nara; Pimienta, Genaro; Steitz, Joan A

    2014-01-01

    Epstein-Barr virus (EBV) is a tumorigenic human γ-herpesvirus, which produces several known structured RNAs with functional importance: two are implicated in latency maintenance and tumorigenic phenotypes, EBER1 and EBER2; a viral small nucleolar RNA (v-snoRNA1) that may generate a small regulatory RNA; and an internal ribosomal entry site in the EBNA1 mRNA. A recent bioinformatics and RNA-Seq study of EBV identified two novel EBV non-coding (nc)RNAs with evolutionary conservation in lymphocryptoviruses and likely functional importance. Both RNAs are transcribed from a repetitive region of the EBV genome (the W repeats) during a highly oncogenic type of viral latency. One novel ncRNA can form a massive (586 nt) hairpin, while the other RNA is generated from a short (81 nt) intron and is found in high abundance in EBV-infected cells.

  2. Antisense oligonucleotide inhibition of hepatitis C virus genotype 4 replication in HepG2 cells

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    Omran Moataza H

    2006-06-01

    Full Text Available Abstract Background Hepatitis C (HCV viral infection is a serious medical problem in Egypt and it has a devastating impact on the Egyptian economy. It is estimated that over 15% of Egyptians are infected by the virus and thus finding a cure for this disease is of utmost importance. Current therapies for hepatitis C virus (HCV genotype 4 with interferon/ribavirin have not been successful and thus the development of alternative therapy for this genotype is disparately needed. Results Although previous studies utilizing viral subgenomic or full cDNA fragments linked to reporter genes transfected into adhered cells or in a cell free system showed promise, demonstration of efficient viral replication was lacking. Thus, we utilized HepG2 cells infected with native HCV RNA genomes in a replication competent system and used antisense phosphorothioate Oligonucleotides (S-ODN against stem loop IIId and the AUG translation start site of the viral polyprotein precursor to monitor viral replication. We were able to show complete arrest of intracellular replication of HCV-4 at 1 uM S-ODN, thus providing a proof of concept for the potential antiviral activity of S-ODN on native genomic replication of HCV genotype 4. Conclusion We have successfully demonstrated that by using two S-ODNs [(S-ODN1 (nt 326–348 and S-ODN-2 (nt 264–282], we were able to completely inhibit viral replication in culture, thus confirming earlier reports on subgenomic constructs and suggesting a potential therapeutic value in HCV type 4.

  3. Virus-derived transgenes expressing hairpin RNA give immunity to Tobacco mosaic virus and Cucumber mosaic virus

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    Liu Yong

    2011-01-01

    Full Text Available Abstract Background An effective method for obtaining resistant transgenic plants is to induce RNA silencing by expressing virus-derived dsRNA in plants and this method has been successfully implemented for the generation of different plant lines resistant to many plant viruses. Results Inverted repeats of the partial Tobacco mosaic virus (TMV movement protein (MP gene and the partial Cucumber mosaic virus (CMV replication protein (Rep gene were introduced into the plant expression vector and the recombinant plasmids were transformed into Agrobacterium tumefaciens. Agrobacterium-mediated transformation was carried out and three transgenic tobacco lines (MP16-17-3, MP16-17-29 and MP16-17-58 immune to TMV infection and three transgenic tobacco lines (Rep15-1-1, Rep15-1-7 and Rep15-1-32 immune to CMV infection were obtained. Virus inoculation assays showed that the resistance of these transgenic plants could inherit and keep stable in T4 progeny. The low temperature (15℃ did not influence the resistance of transgenic plants. There was no significant correlation between the resistance and the copy number of the transgene. CMV infection could not break the resistance to TMV in the transgenic tobacco plants expressing TMV hairpin MP RNA. Conclusions We have demonstrated that transgenic tobacco plants expressed partial TMV movement gene and partial CMV replicase gene in the form of an intermolecular intron-hairpin RNA exhibited complete resistance to TMV or CMV infection.

  4. Hepatitis B virus replication in damaged endothelial tissues of patients with extrahepatic disease.

    Science.gov (United States)

    Mason, Andrew; Theal, Jeremy; Bain, Vince; Adams, Elizabeth; Perrillo, Robert

    2005-04-01

    Hepatitis B virus (HBV) infection may be complicated by extrahepatic manifestations such as polyarteritis nodosa (PAN), glomerulonephritis, polymyositis, and dermatitis, but the etiology of these processes is not yet clear. HBV replication has been demonstrated in a variety of extrahepatic tissues and cell types, but the possible pathogenetic role of extrahepatic HBV replication has not been fully explored in patients with extrahepatic manifestations of HBV infection. In this case series, immunohistochemistry and in situ hybridization studies were performed on extrahepatic tissues from one HBsAg-positive patient with PAN and another HBsAg-positive patient with polymyositis, using HBsAg-seronegative control subjects with the same vasculitic disorders as controls. Tissue samples from the two study patients had detectable HBV RNA, replicative intermediates of HBV DNA, as well as HBsAg and HBcAg localized to vascular endothelium. In contrast, HBsAg-negative control patients had no tissue reactivity. Our results suggest that patients with HBV-related extrahepatic disease have evidence of viral replication in damaged extrahepatic endothelial tissues. While further studies would be required to support a hypothesis of causality, these findings suggest a role for both immune complex deposition and viral replication within diseased endothelial tissue in the pathogenesis of these poorly understood extrahepatic disorders.

  5. A 5'-proximal Stem-loop Structure of 5' Untranslated Region of Porcine Reproductive and Respiratory Syndrome Virus Genome Is Key for Virus Replication

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    Li Yanhua

    2011-04-01

    Full Text Available Abstract Background It has been well documented that the 5' untranslated region (5' UTR of many positive-stranded RNA viruses contain key cis-acting regulatory sequences, as well as high-order structural elements. Little is known for such regulatory elements controlling porcine arterivirus replication. We investigated the roles of a conserved stem-loop 2 (SL2 that resides in the 5'UTR of the genome of a type II porcine reproductive and respiratory syndrome virus (PRRSV. Results We provided genetic evidences demonstrating that 1 the SL2 in type II PRRSV 5' UTR, N-SL2, could be structurally and functionally substituted by its counterpart in type I PRRSV, E-SL2; 2 the functionality of N-SL2 was dependent upon the G-C rich stem structure, while the ternary-loop size was irrelevant to RNA synthesis; 3 serial deletions showed that the stem integrity of N-SL2 was crucial for subgenomic mRNA synthesis; and 4 when extensive base-pairs in the stem region was deleted, an alternative N-SL2-like structure with different sequence was utilized for virus replication. Conclusion Taken together, we concluded that the phylogenetically conserved SL2 in the 5' UTR was crucial for PRRSV virus replication, subgenomic mRNA synthesis in particular.

  6. A Functional Role for ADAM10 in Human Immunodeficiency Virus Type-1 Replication

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    Rubin Donald H

    2011-05-01

    Full Text Available Abstract Background Gene trap insertional mutagenesis was used as a high-throughput approach to discover cellular genes participating in viral infection by screening libraries of cells selected for survival from lytic infection with a variety of viruses. Cells harboring a disrupted ADAM10 (A Disintegrin and Metalloprotease 10 allele survived reovirus infection, and subsequently ADAM10 was shown by RNA interference to be important for replication of HIV-1. Results Silencing ADAM10 expression with small interfering RNA (siRNA 48 hours before infection significantly inhibited HIV-1 replication in primary human monocyte-derived macrophages and in CD4+ cell lines. In agreement, ADAM10 over-expression significantly increased HIV-1 replication. ADAM10 down-regulation did not inhibit viral reverse transcription, indicating that viral entry and uncoating are also independent of ADAM10 expression. Integration of HIV-1 cDNA was reduced in ADAM10 down-regulated cells; however, concomitant 2-LTR circle formation was not detected, suggesting that HIV-1 does not enter the nucleus. Further, ADAM10 silencing inhibited downstream reporter gene expression and viral protein translation. Interestingly, we found that while the metalloprotease domain of ADAM10 is not required for HIV-1 replication, ADAM15 and γ-secretase (which proteolytically release the extracellular and intracellular domains of ADAM10 from the plasma membrane, respectively do support productive infection. Conclusions We propose that ADAM10 facilitates replication at the level of nuclear trafficking. Collectively, our data support a model whereby ADAM10 is cleaved by ADAM15 and γ-secretase and that the ADAM10 intracellular domain directly facilitates HIV-1 nuclear trafficking. Thus, ADAM10 represents a novel cellular target class for development of antiretroviral drugs.

  7. Effects of adeno-associated virus on adenovirus replication and gene expression during coinfection.

    Science.gov (United States)

    Timpe, Jennifer M; Verrill, Kristin C; Trempe, James P

    2006-08-01

    Adeno-associated virus (AAV) is a nonpathogenic parvovirus that requires adenovirus (Ad) or another helper virus for a fully permissive infection. AAV-mediated inhibition of Ad is well documented, yet many details of this interaction remain unclear. In this study, we observed a maximum 50-fold decrease in infectious virus production and a 10- to 40-fold reduction in Ad DNA synthesis during coinfections with AAV. With the exception of the E3 gene, AAV decreased all steady-state Ad mRNA levels at 24 h postinfection (hpi) in a dose-dependent manner. However, not all transcription units were affected equally. E4 and late transcription were the most strongly inhibited, and E1A and E2A were the least affected. The temporal effects of AAV on Ad mRNA transcript levels also varied among the Ad genes. Ad protein expression paralleled mRNA levels at 24 hpi, suggesting that coinfecting AAV does not exert substantial effects on translation. In plasmid transfection assays, Rep78 protein most effectively limited Ad amplification, while Rep40 had no effect. Since E2a and E4 proteins are essential for efficient Ad DNA amplification, we examined the relationship between reduced E2A and E4 expression and decreased DNA amplification. Transfected Rep78 did not reduce E2A and E4 transcript levels prior to DNA replication. Also, AAV-induced inhibition of E2A and E4 mRNA production did not occur in the presence of hydroxyurea. It is therefore unlikely that decreased early gene expression is solely responsible for AAV's suppression of Ad DNA replication. Our results suggest that AAV amplification and/or Rep gene expression inhibits Ad DNA synthesis.

  8. The Ebola virus VP35 protein is a suppressor of RNA silencing.

    Science.gov (United States)

    Haasnoot, Joost; de Vries, Walter; Geutjes, Ernst-Jan; Prins, Marcel; de Haan, Peter; Berkhout, Ben

    2007-06-01

    RNA silencing or interference (RNAi) is a gene regulation mechanism in eukaryotes that controls cell differentiation and developmental processes via expression of microRNAs. RNAi also serves as an innate antiviral defence response in plants, nematodes, and insects. This antiviral response is triggered by virus-specific double-stranded RNA molecules (dsRNAs) that are produced during infection. To overcome antiviral RNAi responses, many plant and insect viruses encode RNA silencing suppressors (RSSs) that enable them to replicate at higher titers. Recently, several human viruses were shown to encode RSSs, suggesting that RNAi also serves as an innate defence response in mammals. Here, we demonstrate that the Ebola virus VP35 protein is a suppressor of RNAi in mammalian cells and that its RSS activity is functionally equivalent to that of the HIV-1 Tat protein. We show that VP35 can replace HIV-1 Tat and thereby support the replication of a Tat-minus HIV-1 variant. The VP35 dsRNA-binding domain is required for this RSS activity. Vaccinia virus E3L protein and influenza A virus NS1 protein are also capable of replacing the HIV-1 Tat RSS function. These findings support the hypothesis that RNAi is part of the innate antiviral response in mammalian cells. Moreover, the results indicate that RSSs play a critical role in mammalian virus replication.

  9. The Ebola virus VP35 protein is a suppressor of RNA silencing.

    Directory of Open Access Journals (Sweden)

    Joost Haasnoot

    2007-06-01

    Full Text Available RNA silencing or interference (RNAi is a gene regulation mechanism in eukaryotes that controls cell differentiation and developmental processes via expression of microRNAs. RNAi also serves as an innate antiviral defence response in plants, nematodes, and insects. This antiviral response is triggered by virus-specific double-stranded RNA molecules (dsRNAs that are produced during infection. To overcome antiviral RNAi responses, many plant and insect viruses encode RNA silencing suppressors (RSSs that enable them to replicate at higher titers. Recently, several human viruses were shown to encode RSSs, suggesting that RNAi also serves as an innate defence response in mammals. Here, we demonstrate that the Ebola virus VP35 protein is a suppressor of RNAi in mammalian cells and that its RSS activity is functionally equivalent to that of the HIV-1 Tat protein. We show that VP35 can replace HIV-1 Tat and thereby support the replication of a Tat-minus HIV-1 variant. The VP35 dsRNA-binding domain is required for this RSS activity. Vaccinia virus E3L protein and influenza A virus NS1 protein are also capable of replacing the HIV-1 Tat RSS function. These findings support the hypothesis that RNAi is part of the innate antiviral response in mammalian cells. Moreover, the results indicate that RSSs play a critical role in mammalian virus replication.

  10. The R35 residue of the influenza A virus NS1 protein has minimal effects on nuclear localization but alters virus replication through disrupting protein dimerization

    Energy Technology Data Exchange (ETDEWEB)

    Lalime, Erin N.; Pekosz, Andrew, E-mail: apekosz@jhsph.edu

    2014-06-15

    The influenza A virus NS1 protein has a nuclear localization sequence (NLS) in the amino terminal region. This NLS overlaps sequences that are important for RNA binding as well as protein dimerization. To assess the significance of the NS1 NLS on influenza virus replication, the NLS amino acids were individually mutated to alanines and recombinant viruses encoding these mutations were rescued. Viruses containing NS1 proteins with mutations at R37, R38 and K41 displayed minimal changes in replication or NS1 protein nuclear localization. Recombinant viruses encoding NS1 R35A were not recovered but viruses containing second site mutations at position D39 in addition to the R35A mutation were isolated. The mutations at position 39 were shown to partially restore NS1 protein dimerization but had minimal effects on nuclear localization. These data indicate that the amino acids in the NS1 NLS region play a more important role in protein dimerization compared to nuclear localization. - Highlights: • Mutations were introduced into influenza NS1 NLS1. • NS1 R37A, R38A, K41A viruses had minimal changes in replication and NS1 localization. • Viruses from NS1 R35A rescue all contained additional mutations at D39. • NS1 R35A D39X mutations recover dimerization lost in NS1 R35A mutations. • These results reaffirm the importance of dimerization for NS1 protein function.

  11. RNA polymerase activity of Ustilago maydis virus

    Energy Technology Data Exchange (ETDEWEB)

    Yie, S.W.

    1986-01-01

    Ustilago maydis virus has an RNA polymerase enzyme which is associated with virion capsids. In the presence of Mg/sup 2 +/ ion and ribonucleotide triphosphate, the enzyme catalyzes the in vitro synthesis of mRNA by using dsRNA as a template. The products of the UmV RNA polymerase were both ssRNA and dsRNA. The dsRNA was determined by characteristic mobilities in gel electrophoresis, lack of sensitivity to RNase, and specific hybridization tests. The ssRNAs were identified by elution from a CF-11 column and by their RNase sensitivity. On the basis of the size of ssRNAs, it was concluded that partial transcripts were produced from H dsRNA segments, and full length transcripts were produced from M and L dsRNA segments. The following observations indicates that transcription occurs by strand displacement; (1) Only the positive strand of M2 dsRNA was labeled by the in vitro reaction. (2) The M2 dsRNA which had been labeled with /sup 32/''P-UTP in vitro could be chased from dsRNA with unlabeled UTP. The transcription products of three UmV strains were compared, and the overall pattern of transcription was very similar among them.

  12. Influenza virus mRNA trafficking through host nuclear speckles.

    Science.gov (United States)

    Mor, Amir; White, Alexander; Zhang, Ke; Thompson, Matthew; Esparza, Matthew; Muñoz-Moreno, Raquel; Koide, Kazunori; Lynch, Kristen W; García-Sastre, Adolfo; Fontoura, Beatriz M A

    2016-05-27

    Influenza A virus is a human pathogen with a genome composed of eight viral RNA segments that replicate in the nucleus. Two viral mRNAs are alternatively spliced. The unspliced M1 mRNA is translated into the matrix M1 protein, while the ion channel M2 protein is generated after alternative splicing. These proteins are critical mediators of viral trafficking and budding. We show that the influenza virus uses nuclear speckles to promote post-transcriptional splicing of its M1 mRNA. We assign previously unknown roles for the viral NS1 protein and cellular factors to an intranuclear trafficking pathway that targets the viral M1 mRNA to nuclear speckles, mediates splicing at these nuclear bodies and exports the spliced M2 mRNA from the nucleus. Given that nuclear speckles are storage sites for splicing factors, which leave these sites to splice cellular pre-mRNAs at transcribing genes, we reveal a functional subversion of nuclear speckles to promote viral gene expression.

  13. From Cells to Virus Particles: Quantitative Methods to Monitor RNA Packaging

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    Mireia Ferrer

    2016-08-01

    Full Text Available In cells, positive strand RNA viruses, such as Retroviridae, must selectively recognize their full-length RNA genome among abundant cellular RNAs to assemble and release particles. How viruses coordinate the intracellular trafficking of both RNA and protein components to the assembly sites of infectious particles at the cell surface remains a long-standing question. The mechanisms ensuring packaging of genomic RNA are essential for viral infectivity. Since RNA packaging impacts on several essential functions of retroviral replication such as RNA dimerization, translation and recombination events, there are many studies that require the determination of RNA packaging efficiency and/or RNA packaging ability. Studies of RNA encapsidation rely upon techniques for the identification and quantification of RNA species packaged by the virus. This review focuses on the different approaches available to monitor RNA packaging: Northern blot analysis, ribonuclease protection assay and quantitative reverse transcriptase-coupled polymerase chain reaction as well as the most recent RNA imaging and sequencing technologies. Advantages, disadvantages and limitations of these approaches will be discussed in order to help the investigator to choose the most appropriate technique. Although the review was written with the prototypic simple murine leukemia virus (MLV and complex human immunodeficiency virus type 1 (HIV-1 in mind, the techniques were described in order to benefit to a larger community.

  14. The cell biology of Tobacco mosaic virus replication and movement

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    Chengke eLiu

    2013-02-01

    Full Text Available Successful systemic infection of a plant by Tobacco mosaic virus (TMV requires three processes that repeat over time: initial establishment and accumulation in invaded cells, intercellular movement and systemic transport. Accumulation and intercellular movement of TMV necessarily involves intracellular transport by complexes containing virus and host proteins and virus RNA during a dynamic process that can be visualized. Multiple membranes appear to assist TMV accumulation, while membranes, microfilaments and microtubules appear to assist TMV movement. Here we review cell biological studies that describe TMV-membrane, -cytoskeleton and -other host protein interactions which influence virus accumulation and movement in leaves and callus tissue. The importance of understanding the developmental phase of the infection in relationship to the observed virus-membrane or -host protein interaction is emphasized. Utilizing the latest observations of TMV-membrane and -host protein interactions within our evolving understanding of the infection ontogeny, a model for TMV accumulation and intracellular spread in a cell biological context is provided.

  15. Identification of novel positive-strand RNA viruses by metagenomic analysis of archaea-dominated Yellowstone hot springs.

    Science.gov (United States)

    Bolduc, Benjamin; Shaughnessy, Daniel P; Wolf, Yuri I; Koonin, Eugene V; Roberto, Francisco F; Young, Mark

    2012-05-01

    There are no known RNA viruses that infect Archaea. Filling this gap in our knowledge of viruses will enhance our understanding of the relationships between RNA viruses from the three domains of cellular life and, in particular, could shed light on the origin of the enormous diversity of RNA viruses infecting eukaryotes. We describe here the identification of novel RNA viral genome segments from high-temperature acidic hot springs in Yellowstone National Park in the United States. These hot springs harbor low-complexity cellular communities dominated by several species of hyperthermophilic Archaea. A viral metagenomics approach was taken to assemble segments of these RNA virus genomes from viral populations isolated directly from hot spring samples. Analysis of these RNA metagenomes demonstrated unique gene content that is not generally related to known RNA viruses of Bacteria and Eukarya. However, genes for RNA-dependent RNA polymerase (RdRp), a hallmark of positive-strand RNA viruses, were identified in two contigs. One of these contigs is approximately 5,600 nucleotides in length and encodes a polyprotein that also contains a region homologous to the capsid protein of nodaviruses, tetraviruses, and birnaviruses. Phylogenetic analyses of the RdRps encoded in these contigs indicate that the putative archaeal viruses form a unique group that is distinct from the RdRps of RNA viruses of Eukarya and Bacteria. Collectively, our findings suggest the existence of novel positive-strand RNA viruses that probably replicate in hyperthermophilic archaeal hosts and are highly divergent from RNA viruses that infect eukaryotes and even more distant from known bacterial RNA viruses. These positive-strand RNA viruses might be direct ancestors of RNA viruses of eukaryotes.

  16. Association of Hepatitis C Virus Replication Complexes with Microtubules and Actin Filaments Is Dependent on the Interaction of NS3 and NS5A▿

    OpenAIRE

    Lai, Chao-Kuen; Jeng, King-Song; Machida, Keigo; Lai, Michael M. C.

    2008-01-01

    The hepatitis C virus (HCV) RNA replication complex (RC), which is composed of viral nonstructural (NS) proteins and host cellular proteins, replicates the viral RNA genome in association with intracellular membranes. Two viral NS proteins, NS3 and NS5A, are essential elements of the RC. Here, by using immunoprecipitation and fluorescence resonance energy transfer assays, we demonstrated that NS3 and NS5A interact with tubulin and actin. Furthermore, immunofluorescence microscopy and electron...

  17. Analysis of IAV Replication and Co-infection Dynamics by a Versatile RNA Viral Genome Labeling Method

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    Dan Dou

    2017-07-01

    Full Text Available Genome delivery to the proper cellular compartment for transcription and replication is a primary goal of viruses. However, methods for analyzing viral genome localization and differentiating genomes with high identity are lacking, making it difficult to investigate entry-related processes and co-examine heterogeneous RNA viral populations. Here, we present an RNA labeling approach for single-cell analysis of RNA viral replication and co-infection dynamics in situ, which uses the versatility of padlock probes. We applied this method to identify influenza A virus (IAV infections in cells and lung tissue with single-nucleotide specificity and to classify entry and replication stages by gene segment localization. Extending the classification strategy to co-infections of IAVs with single-nucleotide variations, we found that the dependence on intracellular trafficking places a time restriction on secondary co-infections necessary for genome reassortment. Altogether, these data demonstrate how RNA viral genome labeling can help dissect entry and co-infections.

  18. Characterization of RyDEN (C19orf66 as an Interferon-Stimulated Cellular Inhibitor against Dengue Virus Replication.

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    Youichi Suzuki

    2016-01-01

    Full Text Available Dengue virus (DENV is one of the most important arthropod-borne pathogens that cause life-threatening diseases in humans. However, no vaccine or specific antiviral is available for dengue. As seen in other RNA viruses, the innate immune system plays a key role in controlling DENV infection and disease outcome. Although the interferon (IFN response, which is central to host protective immunity, has been reported to limit DENV replication, the molecular details of how DENV infection is modulated by IFN treatment are elusive. In this study, by employing a gain-of-function screen using a type I IFN-treated cell-derived cDNA library, we identified a previously uncharacterized gene, C19orf66, as an IFN-stimulated gene (ISG that inhibits DENV replication, which we named Repressor of yield of DENV (RyDEN. Overexpression and gene knockdown experiments revealed that expression of RyDEN confers resistance to all serotypes of DENV in human cells. RyDEN expression also limited the replication of hepatitis C virus, Kunjin virus, Chikungunya virus, herpes simplex virus type 1, and human adenovirus. Importantly, RyDEN was considered to be a crucial effector molecule in the IFN-mediated anti-DENV response. When affinity purification-mass spectrometry analysis was performed, RyDEN was revealed to form a complex with cellular mRNA-binding proteins, poly(A-binding protein cytoplasmic 1 (PABPC1, and La motif-related protein 1 (LARP1. Interestingly, PABPC1 and LARP1 were found to be positive modulators of DENV replication. Since RyDEN influenced intracellular events on DENV replication and, suppression of protein synthesis from DENV-based reporter construct RNA was also observed in RyDEN-expressing cells, our data suggest that RyDEN is likely to interfere with the translation of DENV via interaction with viral RNA and cellular mRNA-binding proteins, resulting in the inhibition of virus replication in infected cells.

  19. Characterization of RyDEN (C19orf66) as an Interferon-Stimulated Cellular Inhibitor against Dengue Virus Replication.

    Science.gov (United States)

    Suzuki, Youichi; Chin, Wei-Xin; Han, Qi'En; Ichiyama, Koji; Lee, Ching Hua; Eyo, Zhi Wen; Ebina, Hirotaka; Takahashi, Hirotaka; Takahashi, Chikako; Tan, Beng Hui; Hishiki, Takayuki; Ohba, Kenji; Matsuyama, Toshifumi; Koyanagi, Yoshio; Tan, Yee-Joo; Sawasaki, Tatsuya; Chu, Justin Jang Hann; Vasudevan, Subhash G; Sano, Kouichi; Yamamoto, Naoki

    2016-01-01

    Dengue virus (DENV) is one of the most important arthropod-borne pathogens that cause life-threatening diseases in humans. However, no vaccine or specific antiviral is available for dengue. As seen in other RNA viruses, the innate immune system plays a key role in controlling DENV infection and disease outcome. Although the interferon (IFN) response, which is central to host protective immunity, has been reported to limit DENV replication, the molecular details of how DENV infection is modulated by IFN treatment are elusive. In this study, by employing a gain-of-function screen using a type I IFN-treated cell-derived cDNA library, we identified a previously uncharacterized gene, C19orf66, as an IFN-stimulated gene (ISG) that inhibits DENV replication, which we named Repressor of yield of DENV (RyDEN). Overexpression and gene knockdown experiments revealed that expression of RyDEN confers resistance to all serotypes of DENV in human cells. RyDEN expression also limited the replication of hepatitis C virus, Kunjin virus, Chikungunya virus, herpes simplex virus type 1, and human adenovirus. Importantly, RyDEN was considered to be a crucial effector molecule in the IFN-mediated anti-DENV response. When affinity purification-mass spectrometry analysis was performed, RyDEN was revealed to form a complex with cellular mRNA-binding proteins, poly(A)-binding protein cytoplasmic 1 (PABPC1), and La motif-related protein 1 (LARP1). Interestingly, PABPC1 and LARP1 were found to be positive modulators of DENV replication. Since RyDEN influenced intracellular events on DENV replication and, suppression of protein synthesis from DENV-based reporter construct RNA was also observed in RyDEN-expressing cells, our data suggest that RyDEN is likely to interfere with the translation of DENV via interaction with viral RNA and cellular mRNA-binding proteins, resulting in the inhibition of virus replication in infected cells.

  20. Partial deletion of stem-loop 2 in the 3' untranslated region of foot-and-mouth disease virus identifies a region that is dispensable for virus replication.

    Science.gov (United States)

    Biswal, Jitendra K; Subramaniam, Saravanan; Ranjan, Rajeev; Pattnaik, Bramhadev

    2016-08-01

    The 3' untranslated region (3' UTR) of the foot-and-mouth disease virus (FMDV) genome plays an essential role in virus replication, but the properties of the 3' UTR are not completely defined. In order to determine the role of different regions of the 3' UTR in FMDV replication, we conducted site-directed mutagenesis of the 3' UTR of FMDV serotype O IND R2/1975 using a cDNA clone. Through independent serial deletions in various regions of the 3' UTR, we demonstrated that deletion of nucleotides between the stem-loop (SL) structures and in the beginning and the end regions of the SL2 structure could be lethal for FMDV replication. However, a block deletion of 20 nucleotides (nt 60 to 79) in the middle of SL2 did not affect the viability of FMDV in cultured cells. Characterisation of the deletion mutant virus (O(R2/1975-Δ3'UTR 60-79)) revealed no significant difference in growth kinetics or RNA replication ability compared to the parental virus. However, the mutant virus produced slightly larger plaques when compared to the parental virus. This is the first description of a dispensable 20-nucleotide region in SL2 of the FMDV 3' UTR.

  1. Staufen1 promotes HCV replication by inhibiting protein kinase R and transporting viral RNA to the site of translation and replication in the cells

    Science.gov (United States)

    Dixit, Updesh; Pandey, Ashutosh K.; Mishra, Priya; Sengupta, Amitabha; Pandey, Virendra N.

    2016-01-01

    Persistent hepatitis C virus (HCV) infection leads to chronic hepatitis C (CHC), which often progresses to liver cirrhosis (LC) and hepatocellular carcinoma (HCC). The molecular mechanisms that establish CHC and cause its subsequent development into LC and HCC are poorly understood. We have identified a cytoplasmic double-stranded RNA binding protein, Stau1, which is crucial for HCV replication. In this study, Stau1 specifically interacted with the variable-stem-loop region in the 3′ NTR and domain IIId of the HCV-IRES in the 5′ NTR, and promoted HCV replication and translation. Stau1 coimmunoprecipitates HCV NS5B and a cell factor, protein kinase R (PKR), which is critical for interferon-induced cellular antiviral and antiproliferative responses. Like Stau1, PKR displayed binding specificity to domain IIId of HCV-IRES. Stau1 binds to PKR and strongly inhibits PKR-autophosphorylation. We demonstrated that the transport of HCV RNA on the polysomes is Stau1-dependent, being mainly localized in the monosome fractions when Stau1 is downregulated and exclusively localized in the polysomes when Stau1 is overexpressed. Our findings suggest that HCV may appropriate Stau1 to its advantage to prevent PKR-mediated inhibition of eIF2α, which is required for the synthesis of HCV proteins for translocation of viral RNA genome to the polysomes for efficient translation and replication. PMID:27106056

  2. Dengue virus type 2: replication and tropisms in orally infected Aedes aegypti mosquitoes.

    Science.gov (United States)

    Salazar, Ma Isabel; Richardson, Jason H; Sánchez-Vargas, Irma; Olson, Ken E; Beaty, Barry J

    2007-01-30

    To be transmitted by its mosquito vector, dengue virus (DENV) must infect midgut epithelial cells, replicate and disseminate into the hemocoel, and finally infect the salivary glands, which is essential for transmission. The extrinsic incubation period (EIP) is very relevant epidemiologically and is the time required from the ingestion of virus until it can be transmitted to the next vertebrate host. The EIP is conditioned by the kinetics and tropisms of virus replication in its vector. Here we document the virogenesis of DENV-2 in newly-colonized Aedes aegypti mosquitoes from Chetumal, Mexico in order to understand better the effect of vector-virus interactions on dengue transmission. After ingestion of DENV-2, midgut infections in Chetumal mosquitoes were characterized by a peak in virus titers between 7 and 10 days post-infection (dpi). The amount of viral antigen and viral titers in the midgut then declined, but viral RNA levels remained stable. The presence of DENV-2 antigen in the trachea was positively correlated with virus dissemination from the midgut. DENV-2 antigen was found in salivary gland tissue in more than a third of mosquitoes at 4 dpi. Unlike in the midgut, the amount of viral antigen (as well as the percent of infected salivary glands) increased with time. DENV-2 antigen also accumulated and increased in neural tissue throughout the EIP. DENV-2 antigen was detected in multiple tissues of the vector, but unlike some other arboviruses, was not detected in muscle. Our results suggest that the EIP of DENV-2 in its vector may be shorter that the previously reported and that the tracheal system may facilitate DENV-2 dissemination from the midgut. Mosquito organs (e.g. midgut, neural tissue, and salivary glands) differed in their response to DENV-2 infection.

  3. Dengue virus type 2: replication and tropisms in orally infected Aedes aegypti mosquitoes

    Directory of Open Access Journals (Sweden)

    Olson Ken E

    2007-01-01

    Full Text Available Abstract Background To be transmitted by its mosquito vector, dengue virus (DENV must infect midgut epithelial cells, replicate and disseminate into the hemocoel, and finally infect the salivary glands, which is essential for transmission. The extrinsic incubation period (EIP is very relevant epidemiologically and is the time required from the ingestion of virus until it can be transmitted to the next vertebrate host. The EIP is conditioned by the kinetics and tropisms of virus replication in its vector. Here we document the virogenesis of DENV-2 in newly-colonized Aedes aegypti mosquitoes from Chetumal, Mexico in order to understand better the effect of vector-virus interactions on dengue transmission. Results After ingestion of DENV-2, midgut infections in Chetumal mosquitoes were characterized by a peak in virus titers between 7 and 10 days post-infection (dpi. The amount of viral antigen and viral titers in the midgut then declined, but viral RNA levels remained stable. The presence of DENV-2 antigen in the trachea was positively correlated with virus dissemination from the midgut. DENV-2 antigen was found in salivary gland tissue in more than a third of mosquitoes at 4 dpi. Unlike in the midgut, the amount of viral antigen (as well as the percent of infected salivary glands increased with time. DENV-2 antigen also accumulated and increased in neural tissue throughout the EIP. DENV-2 antigen was detected in multiple tissues of the vector, but unlike some other arboviruses, was not detected in muscle. Conclusion Our results suggest that the EIP of DENV-2 in its vector may be shorter that the previously reported and that the tracheal system may facilitate DENV-2 dissemination from the midgut. Mosquito organs (e.g. midgut, neural tissue, and salivary glands differed in their response to DENV-2 infection.

  4. Unusual loop-sequence flexibility of the proximal RNA replication element in EMCV

    NARCIS (Netherlands)

    Zoll, J.; Hahn, M.M.; Gielen, P.R.; Heus, H.A.; Melchers, W.J.G.; Kuppeveld, F.J.M. van

    2011-01-01

    Picornaviruses contain stable RNA structures at the 5' and 3' ends of the RNA genome, OriL and OriR involved in viral RNA replication. The OriL RNA element found at the 5' end of the enterovirus genome folds into a cloverleaf-like configuration. In vivo SELEX experiments revealed that functioning of

  5. Autophagy Activated by Bluetongue Virus Infection Plays a Positive Role in Its Replication

    Directory of Open Access Journals (Sweden)

    Shuang Lv

    2015-08-01

    Full Text Available Bluetongue virus (BTV is an important pathogen of wild and domestic ruminants. Despite extensive study in recent decades, the interplay between BTV and host cells is not clearly understood. Autophagy as a cellular adaptive response plays a part in many viral infections. In our study, we found that BTV1 infection triggers the complete autophagic process in host cells, as demonstrated by the appearance of obvious double-membrane autophagosome-like vesicles, GFP-LC3 dots accumulation, the conversion of LC3-I to LC3-II and increased levels of autophagic flux in BSR cells (baby hamster kidney cell clones and primary lamb lingual epithelial cells upon BTV1 infection. Moreover, the results of a UV-inactivated BTV1 infection assay suggested that the induction of autophagy was dependent on BTV1 replication. Therefore, we investigated the role of autophagy in BTV1 replication. The inhibition of autophagy by pharmacological inhibitors (3-MA, CQ and RNA interference (siBeclin1 significantly decreased viral protein synthesis and virus yields. In contrast, treating BSR cells with rapamycin, an inducer of autophagy, promoted viral protein expression and the production of infectious BTV1. These findings lead us to conclude that autophagy is activated by BTV1 and contributes to its replication, and provide novel insights into BTV-host interactions.

  6. Autophagy Activated by Bluetongue Virus Infection Plays a Positive Role in Its Replication.

    Science.gov (United States)

    Lv, Shuang; Xu, Qingyuan; Sun, Encheng; Yang, Tao; Li, Junping; Feng, Yufei; Zhang, Qin; Wang, Haixiu; Zhang, Jikai; Wu, Donglai

    2015-08-01

    Bluetongue virus (BTV) is an important pathogen of wild and domestic ruminants. Despite extensive study in recent decades, the interplay between BTV and host cells is not clearly understood. Autophagy as a cellular adaptive response plays a part in many viral infections. In our study, we found that BTV1 infection triggers the complete autophagic process in host cells, as demonstrated by the appearance of obvious double-membrane autophagosome-like vesicles, GFP-LC3 dots accumulation, the conversion of LC3-I to LC3-II and increased levels of autophagic flux in BSR cells (baby hamster kidney cell clones) and primary lamb lingual epithelial cells upon BTV1 infection. Moreover, the results of a UV-inactivated BTV1 infection assay suggested that the induction of autophagy was dependent on BTV1 replication. Therefore, we investigated the role of autophagy in BTV1 replication. The inhibition of autophagy by pharmacological inhibitors (3-MA, CQ) and RNA interference (siBeclin1) significantly decreased viral protein synthesis and virus yields. In contrast, treating BSR cells with rapamycin, an inducer of autophagy, promoted viral protein expression and the production of infectious BTV1. These findings lead us to conclude that autophagy is activated by BTV1 and contributes to its replication, and provide novel insights into BTV-host interactions.

  7. Infectious Progeny of 2009 A (H1N1) Influenza Virus Replicated in and Released from Human Neutrophils.

    Science.gov (United States)

    Zhang, Zhang; Huang, Tao; Yu, Feiyuan; Liu, Xingmu; Zhao, Conghui; Chen, Xueling; Kelvin, David J; Gu, Jiang

    2015-12-07

    Various reports have indicated that a number of viruses could infect neutrophils, but the multiplication of viruses in neutrophils was abortive. Based on our previous finding that avian influenza viral RNA and proteins were present in the nucleus of infected human neutrophils in vivo, we investigated the possibility of 2009 A (H1N1) influenza viral synthesis in infected neutrophils and possible release of infectious progeny from host cells. In this study we found that human neutrophils in vitro without detectable level of sialic acid expression could be infected by this virus strain. We also show that the infected neutrophils can not only synthesize 2009 A (H1N1) viral mRNA and proteins, but also produce infectious progeny. These findings suggest that infectious progeny of 2009 A (H1N1) influenza virus could be replicated in and released from human neutrophils with possible clinical implications.

  8. Borna disease virus phosphoprotein modulates epigenetic signaling in neurons to control viral replication.

    Science.gov (United States)

    Bonnaud, Emilie M; Szelechowski, Marion; Bétourné, Alexandre; Foret, Charlotte; Thouard, Anne; Gonzalez-Dunia, Daniel; Malnou, Cécile E

    2015-06-01

    Understanding the modalities of interaction of neurotropic viruses with their target cells represents a major challenge that may improve our knowledge of many human neurological disorders for which viral origin is suspected. Borna disease virus (BDV) represents an ideal model to analyze the molecular mechanisms of viral persistence in neurons and its consequences for neuronal homeostasis. It is now established that BDV ensures its long-term maintenance in infected cells through a stable interaction of viral components with the host cell chromatin, in particular, with core histones. This has led to our hypothesis that such an interaction may trigger epigenetic changes in the host cell. Here, we focused on histone acetylation, which plays key roles in epigenetic regulation of gene expression, notably for neurons. We performed a comparative analysis of histone acetylation patterns of neurons infected or not infected by BDV, which revealed that infection decreases histone acetylation on selected lysine residues. We showed that the BDV phosphoprotein (P) is responsible for these perturbations, even when it is expressed alone independently of the viral context, and that this action depends on its phosphorylation by protein kinase C. We also demonstrated that BDV P inhibits cellular histone acetyltransferase activities. Finally, by pharmacologically manipulating cellular acetylation levels, we observed that inhibiting cellular acetyl transferases reduces viral replication in cell culture. Our findings reveal that manipulation of cellular epigenetics by BDV could be a means to modulate viral replication and thus illustrate a fascinating example of virus-host cell interaction. Persistent DNA viruses often subvert the mechanisms that regulate cellular chromatin dynamics, thereby benefitting from the resulting epigenetic changes to create a favorable milieu for their latent and persistent states. Here, we reasoned that Borna disease virus (BDV), the only RNA virus known to

  9. Hijacking of host calreticulin is required for the white spot syndrome virus replication cycle.

    Science.gov (United States)

    Watthanasurorot, Apiruck; Guo, Enen; Tharntada, Sirinit; Lo, Chu-Fang; Söderhäll, Kenneth; Söderhäll, Irene

    2014-07-01

    We have previously shown that multifunctional calreticulin (CRT), which resides in the endoplasmic reticulum (ER) and is involved in ER-associated protein processing, responds to infection with white spot syndrome virus (WSSV) by increasing mRNA and protein expression and by forming a complex with gC1qR and thereby delaying apoptosis. Here, we show that CRT can directly interact with WSSV structural proteins, including VP15 and VP28, during an early stage of virus infection. The binding of VP28 with CRT does not promote WSSV entry, and CRT-VP15 interaction was detected in the viral genome in virally infected host cells and thus may have an effect on WSSV replication. Moreover, CRT was detected in the viral envelope of purified WSSV virions. CRT was also found to be of high importance for proper oligomerization of the viral structural proteins VP26 and VP28, and when CRT glycosylation was blocked with tunicamycin, a significant decrease in both viral replication and assembly was detected. Together, these findings suggest that CRT confers several advantages to WSSV, from the initial steps of WSSV infection to the assembly of virions. Therefore, CRT is required as a "vital factor" and is hijacked by WSSV for its replication cycle. Importance: White spot syndrome virus (WSSV) is a double-stranded DNA virus and the cause of a serious disease in a wide range of crustaceans that often leads to high mortality rates. We have previously shown that the protein calreticulin (CRT), which resides in the endoplasmic reticulum (ER) of the cell, is important in the host response to the virus. In this report, we show that the virus uses this host protein to enter the cell and to make the host produce new viral structural proteins. Through its interaction with two viral proteins, the virus "hijacks" host calreticulin and uses it for its own needs. These findings provide new insight into the interaction between a large DNA virus and the host protein CRT and may help in understanding

  10. Studies on the effects of persistent RNA priming on DNA replication and genomic stability

    OpenAIRE

    Stuckey, Ruth

    2014-01-01

    [EN]: DNA replication and transcription take place on the same DNA template, and the correct interplay between these processes ensures faithful genome duplication. DNA replication must be highly coordinated with other cell cycle events, such as segregation of fully replicated DNA in order to maintain genomic integrity. Transcription generates RNA:DNA hybrids, transient intermediate structures that are degraded by the ribonuclease H (RNaseH) class of enzymes. RNA:DNA hybrids can form R-loops, ...

  11. Studies on the effects of persistent RNA priming on DNA replication and genomic stability

    OpenAIRE

    Stuckey, Ruth

    2014-01-01

    [EN]: DNA replication and transcription take place on the same DNA template, and the correct interplay between these processes ensures faithful genome duplication. DNA replication must be highly coordinated with other cell cycle events, such as segregation of fully replicated DNA in order to maintain genomic integrity. Transcription generates RNA:DNA hybrids, transient intermediate structures that are degraded by the ribonuclease H (RNaseH) class of enzymes. RNA:DNA hybrids can form R-loops, ...

  12. Transiently Expressed Short Hairpin RNA Targeting 126 kDa Protein of Tobacco Mosaic Virus Interferes with Virus Infection

    Institute of Scientific and Technical Information of China (English)

    Ming-Min ZHAO; De-Rong AN; Jian ZHAO; Guang-Hua HUANG; Zu-Hua HE; Jiang-Ye CHEN

    2006-01-01

    RNA interference (RNAi) silences gene expression by guiding mRNA degradation in asequence-specific fashion. Small interfering RNA (siRNA), an intermediate of the RNAi pathway, has been shown to be very effective in inhibiting virus infection in mammalian cells and cultured plant cells. Here, we report that Agrobacterium tumefaciens-mediated transient expression of short hairpin RNA (shRNA) could inhibit tobacco mosaic virus (TMV) RNA accumulation by targeting the gene encoding the replication-associated 126 kDa protein in intact plant tissue. Our results indicate that transiently expressed shRNA efficiently interfered with TMV infection. The interference observed is sequence-specific, and time- and site-dependent.Transiently expressed shRNA corresponding to the TMV 126 kDa protein gene did not inhibit cucumber mosaic virus (CMV), an unrelated tobamovirus. In order to interfere with TMV accumulation in tobacco leaves, it is essential for the shRNA constructs to be infiltrated into the same leaves as TMV inoculation. Our results support the view that RNAi opens the door for novel therapeutic procedures against virus diseases.We propose that a combination of the RNAi technique and Agrobacterium-mediated transient expression could be employed as a potent antiviral treatment in plants.

  13. A self-perpetuating repressive state of a viral replication protein blocks superinfection by the same virus

    Science.gov (United States)

    Zhang, Xiao-Feng; Sun, Rong; Guo, Qin; Zhang, Shaoyan; Li, Dawei

    2017-01-01

    Diverse animal and plant viruses block the re-infection of host cells by the same or highly similar viruses through superinfection exclusion (SIE), a widely observed, yet poorly understood phenomenon. Here we demonstrate that SIE of turnip crinkle virus (TCV) is exclusively determined by p28, one of the two replication proteins encoded by this virus. p28 expressed from a TCV replicon exerts strong SIE to a different TCV replicon. Transiently expressed p28, delivered simultaneously with, or ahead of, a TCV replicon, largely recapitulates this repressive activity. Interestingly, p28-mediated SIE is dramatically enhanced by C-terminally fused epitope tags or fluorescent proteins, but weakened by N-terminal modifications, and it inversely correlates with the ability of p28 to complement the replication of a p28-defective TCV replicon. Strikingly, p28 in SIE-positive cells forms large, mobile punctate inclusions that trans-aggregate a non-coalescing, SIE-defective, yet replication-competent p28 mutant. These results support a model postulating that TCV SIE is caused by the formation of multimeric p28 complexes capable of intercepting fresh p28 monomers translated from superinfector genomes, thereby abolishing superinfector replication. This model could prove to be applicable to other RNA viruses, and offer novel targets for antiviral therapy. PMID:28267773

  14. PKR Activation Favors Infectious Pancreatic Necrosis Virus Replication in Infected Cells

    Directory of Open Access Journals (Sweden)

    Amr A.A. Gamil

    2016-06-01

    Full Text Available The double-stranded RNA-activated protein kinase R (PKR is a Type I interferon (IFN stimulated gene that has important biological and immunological functions. In viral infections, in general, PKR inhibits or promotes viral replication, but PKR-IPNV interaction has not been previously studied. We investigated the involvement of PKR during infectious pancreatic necrosis virus (IPNV infection using a custom-made rabbit antiserum and the PKR inhibitor C16. Reactivity of the antiserum to PKR in CHSE-214 cells was confirmed after IFNα treatment giving an increased protein level. IPNV infection alone did not give increased PKR levels by Western blot, while pre-treatment with PKR inhibitor before IPNV infection gave decreased eukaryotic initiation factor 2-alpha (eIF2α phosphorylation. This suggests that PKR, despite not being upregulated, is involved in eIF2α phosphorylation during IPNV infection. PKR inhibitor pre-treatment resulted in decreased virus titers, extra- and intracellularly, concomitant with reduction of cells with compromised membranes in IPNV-permissive cell lines. These findings suggest that IPNV uses PKR activation to promote virus replication in infected cells.

  15. miR-124 attenuates Japanese encephalitis virus replication by targeting DNM2.

    Science.gov (United States)

    Yang, Songbai; Pei, Yue; Li, Xinyun; Zhao, Shuhong; Zhu, Mengjin; Zhao, Ayong

    2016-06-21

    Japanese encephalitis virus (JEV) is a mosquito-borne flavivirus that causes acute viral encephalitis in humans. Pigs are important amplifier hosts of JEV. Emerging evidence indicates that host microRNAs (miRNAs) play key roles in modulating viral infection and pathogenesis. However, mechanistic studies delineating the roles of miRNAs in regulating host-JEV interactions remain scarce. In this study, we demonstrated that miR-124 inhibited JEV replication in porcine kidney epithelial PK15 cells. Furthermore, using bioinformatics tools, we identified dynamin2 (DNM2), a GTPase responsible for vesicle scission, as a target of miR-124. Small interfering RNA (siRNA) depletion studies inicated that dynamin2 was required for efficient JEV replication. We also demonstrated that upregulation of miR-124 expression corresponded to decreased expression of its target, DNM2, in the JEV-infected PK15 cells. Overall, these results suggest the importance of miR-124 in modulating JEV replication and provide a scientific basis for using cellular miRNAs in anti-JEV therapies.

  16. Characterization of Aedes aegypti innate-immune pathways that limit Chikungunya virus replication.

    Directory of Open Access Journals (Sweden)

    Melanie McFarlane

    2014-07-01

    Full Text Available Replication of arboviruses in their arthropod vectors is controlled by innate immune responses. The RNA sequence-specific break down mechanism, RNA interference (RNAi, has been shown to be an important innate antiviral response in mosquitoes. In addition, immune signaling pathways have been reported to mediate arbovirus infections in mosquitoes; namely the JAK/STAT, immune deficiency (IMD and Toll pathways. Very little is known about these pathways in response to chikungunya virus (CHIKV infection, a mosquito-borne alphavirus (Togaviridae transmitted by aedine species to humans resulting in a febrile and arthralgic disease. In this study, the contribution of several innate immune responses to control CHIKV replication was investigated. In vitro experiments identified the RNAi pathway as a key antiviral pathway. CHIKV was shown to repress the activity of the Toll signaling pathway in vitro but neither JAK/STAT, IMD nor Toll pathways were found to mediate antiviral activities. In vivo data further confirmed our in vitro identification of the vital role of RNAi in antiviral defence. Taken together these results indicate a complex interaction between CHIKV replication and mosquito innate immune responses and demonstrate similarities as well as differences in the control of alphaviruses and other arboviruses by mosquito immune pathways.

  17. Beneficial Effects of Population Bottlenecks in an RNA Virus Evolving at Increased Error Rate

    OpenAIRE

    Cases-González, Clara E.; Arribas, María; Domingo, Esteban; Lázaro, Ester

    2008-01-01

    RNA viruses replicate their genomes with a very high error rate and constitute highly heterogeneous mutant distributions similar to the molecular quasispecies introduced to explain the evolution of prebiotic replicators. The genetic information included in a quasispecies can only be faithfully transmitted below a critical error rate. When the error threshold is crossed, the population structure disorganizes, and it is substituted by a randomly distributed mutant spectrum. For viral quasispeci...

  18. HERP Binds TBK1 To Activate Innate Immunity and Repress Virus Replication in Response to Endoplasmic Reticulum Stress.

    Science.gov (United States)

    Ge, Maolin; Luo, Zhen; Qiao, Zhi; Zhou, Yao; Cheng, Xin; Geng, Qibin; Cai, Yanyan; Wan, Pin; Xiong, Ying; Liu, Fang; Wu, Kailang; Liu, Yingle; Wu, Jianguo

    2017-09-27

    Host innate immunity is crucial for cellular responses against viral infection sensed by distinct pattern recognition receptors and endoplasmic reticulum (ER) stress. Enterovirus 71 (EV71) is a causative agent of hand, foot, and mouth disease and neurological diseases. However, the exact mechanism underlying the link between ER stress induced by EV71 infection and host innate immunity is largely unknown. In this study, we demonstrated that EV71 infection induces the homocysteine-induced ER protein (HERP), a modulator of the ER stress response which is dependent on the participation of MAVS. Virus-induced HERP subsequently stimulates host innate immunity to repress viral replication by promoting type-I IFNs (IFN-α and IFN-β) and type-III IFN (IFN-λ1) expression. Through interacting with TANK-binding kinase 1, HERP amplifies the MAVS signaling and facilitates the phosphorylation and nuclear translocation of IFN regulatory factor 3 and NF-κB to enhance the expression of IFNs, which leads to a broad inhibition of the replication of RNA viruses, including EV71, Sendai virus, influenza A virus, and vesicular stomatitis virus. Therefore, we demonstrated that HERP plays an important role in the regulation of host innate immunity in response to ER stress during the infection of RNA viruses. These findings provide new insights into the mechanism underlying the replication of RNA viruses and the production of IFNs, and also demonstrate a new role of HERP in the regulation of host innate immunity in response to viral infection. Copyright © 2017 by The American Association of Immunologists, Inc.

  19. Mutation rates among RNA viruses

    OpenAIRE

    Drake, John W.; Holland, John J.

    1999-01-01

    The rate of spontaneous mutation is a key parameter in modeling the genetic structure and evolution of populations. The impact of the accumulated load of mutations and the consequences of increasing the mutation rate are important in assessing the genetic health of populations. Mutation frequencies are among the more directly measurable population parameters, although the information needed to convert them into mutation rates is often lacking. A previous analysis of mutation rates in RNA viru...

  20. Rapid screening of RNA silencing suppressors by using a recombinant virus derived from beet necrotic yellow vein virus.

    Science.gov (United States)

    Guilley, H; Bortolamiol, D; Jonard, G; Bouzoubaa, S; Ziegler-Graff, V

    2009-10-01

    To counteract plant defence mechanisms, plant viruses have evolved to encode RNA silencing suppressor (RSS) proteins. These proteins can be identified by a range of silencing suppressor assays. Here, we describe a simple method using beet necrotic yellow vein virus (BNYVV) that allows a rapid screening of RSS activity. The viral inoculum consisted of BNYVV RNA1, which encodes proteins involved in viral replication, and two BNYVV-derived replicons: rep3-P30, which expresses the movement protein P30 of tobacco mosaic virus, and rep5-X, which allows the expression of a putative RSS (X). This approach has been validated through the use of several known RSSs. Two potential candidates have been tested and we show that, in our system, the P13 protein of burdock mottle virus displays RSS activity while the P0 protein of cereal yellow dwarf virus-RPV does not.

  1. Stimulation of Vesicular Stomatitis Virus in vitro RNA Synthesis by Microtubule-Associated Proteins

    Science.gov (United States)

    Hill, Virginia M.; Harmon, Shirley A.; Summers, Donald F.

    1986-08-01

    Microtubule-associated proteins purified from bovine brains stimulated the in vitro transcription and replication reactions of vesicular stomatitis virus. The products of these reactions were intact messenger or genome-sized RNA species. A preparation from HeLa cells containing tubulin and microtubule-associated proteins also stimulated vesicular stomatitis virus transcription in vitro. This observation is in accord with previous studies, which suggested that a host cell factor was involved with the function of the vesicular stomatitis virus RNA polymerase, and others that indicated that several animal viruses displayed an association with host cell cytoskeletal elements during their replication cycles. We show evidence in this report of a host cell protein that seems to have a functional role in interacting with the virion polymerase.

  2. Hepatitis B virus and microRNAs: Complex interactions affecting hepatitis B virus replication and hepatitis B virus-associated diseases.

    Science.gov (United States)

    Lamontagne, Jason; Steel, Laura F; Bouchard, Michael J

    2015-06-28

    Chronic infection with the hepatitis B virus (HBV) is the leading risk factor for the development of hepatocellular carcinoma (HCC). With nearly 750000 deaths yearly, hepatocellular carcinoma is the second highest cause of cancer-related death in the world. Unfortunately, the molecular mechanisms that contribute to the development of HBV-associated HCC remain incompletely understood. Recently, microRNAs (miRNAs), a family of small non-coding RNAs that play a role primarily in post-transcriptional gene regulation, have been recognized as important regulators of cellular homeostasis, and altered regulation of miRNA expression has been suggested to play a significant role in virus-associated diseases and the development of many cancers. With this in mind, many groups have begun to investigate the relationship between miRNAs and HBV replication and HBV-associated disease. Multiple findings suggest that some miRNAs, such as miR-122, and miR-125 and miR-199 family members, are playing a role in HBV replication and HBV-associated disease, including the development of HBV-associated HCC. In this review, we discuss the current state of our understanding of the relationship between HBV and miRNAs, including how HBV affects cellular miRNAs, how these miRNAs impact HBV replication, and the relationship between HBV-mediated miRNA regulation and HCC development. We also address the impact of challenges in studying HBV, such as the lack of an effective model system for infectivity and a reliance on transformed cell lines, on our understanding of the relationship between HBV and miRNAs, and propose potential applications of miRNA-related techniques that could enhance our understanding of the role miRNAs play in HBV replication and HBV-associated disease, ultimately leading to new therapeutic options and improved patient outcomes.

  3. Inhibition of hepatitis B virus replication by APOBEC3G in vitro and in vivo

    Institute of Scientific and Technical Information of China (English)

    Yan-Chang Lei; Dong-Liang Yang; You-Hua Hao; Zheng-Mao Zhang; Yong-Jun Tian; Bao-Ju Wang; Yan Yang; Xi-Ping Zhao; Meng-Ji Lu; Fei-Li Gong

    2006-01-01

    AIM: To investigate the effect of APOBEC3G mediated antiviral activity against hepatitis B virus (HBV) in cell cultures and replication competent HBV vector-based mouse model.METHODS: The mammalian hepatoma cells Huh7 and HepG2 were cotransfected with various amounts of CMV-driven expression vector encoding APOBEC3G and replication competent 1.3 fold over-length HBV. Levels of HBsAg and HBeAg in the media of the transfected cells were determined by ELISA. The expression of HBcAg in transfected cells was detected by western blot. HBV DNA and RNA from intracellular core particles were examined by Northern and Southern blot analyses. To assess activity of the APOBEC3G in vivo, an HBV vector-based model was used in which APOBEC3G and the HBV vector were co-delivered via high-volume tail vein injection.Levels of HBsAg and HBV DNA in the sera of mice as well as HBV core-associated RNA in the liver of mice were determined by ELISA and quantitative PCR analysis respectively.RESULTS: There was a dose dependent decrease in the levels of intracellular core-associated HBV DNA and extracellular production of HBsAg and HBeAg. The levels of intracellular core-associated viral RNA also decreased,but the expression of HBcAg in transfected cells showed almost no change. Consistent with in vitro results,levels of HBsAg in the sera of mice were dramatically decreased. More than 1.5 log10 decrease in levels of serum HBV DNA and liver HBV RNA were observed in the APOBEC3G-treated groups compared with the control groups.CONCLUSION: These findings indicate that APOBEC3G could suppress HBV replication and antigen expression both in vivo and in vitro, promising an advance in treatment of HBV infection.

  4. Short hairpin-looped oligodeoxynucleotides reduce hepatitis C virus replication

    Directory of Open Access Journals (Sweden)

    Broecker Felix

    2012-07-01

    Full Text Available Abstract Background Persistent infection with hepatitis C virus (HCV is a leading cause of chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma. Standard therapy consists of a combination of interferon-alpha and ribavirin, but many patients respond poorly, especially those infected with HCV genotypes 1 and 4. Furthermore, standard therapy is associated with severe side-effects. Thus, alternative therapeutic approaches against HCV are needed. Findings Here, we studied the effect of a new class of antiviral agents against HCV, short, partially double-stranded oligodeoxynucleotides (ODNs, on viral replication. We targeted the 5’ nontranslated region (5’ NTR of the HCV genome that has previously been shown as effective target for small interfering RNAs (siRNAs in vitro. One of the investigated ODNs, ODN 320, significantly and efficiently reduced replication of HCV replicons in a sequence-, time- and dose-dependent manner. ODN 320 targets a genomic region highly conserved among different HCV genotypes and might thus be able to inhibit a broad range of genotypes and subtypes. Conclusions ODNs provide an additional approach for inhibition of HCV, might be superior to siRNAs in terms of stability and cellular delivery, and suitable against HCV resistant to standard therapy. This study underlines the potential of partially double-stranded ODNs as antiviral agents.

  5. Sphingosine kinase 2 is a chikungunya virus host factor co-localized with the viral replication complex.

    Science.gov (United States)

    Reid, St Patrick; Tritsch, Sarah R; Kota, Krishna; Chiang, Chih-Yuan; Dong, Lian; Kenny, Tara; Brueggemann, Ernest E; Ward, Michael D; Cazares, Lisa H; Bavari, Sina

    2015-10-01

    Chikungunya virus (CHIKV) is a re-emerging alphavirus which causes severe and prolonged arthralgic febrile illness. The recent global spread of the virus and lack of approved therapeutic options makes it imperative to gain greater insight into the molecular mechanisms underlying CHIKV pathogenesis, in particular host factors recruited by the virus. In the current study, we identify sphingosine kinase 2 (SK2) as a CHIKV host factor co-localized with the viral replication complex (VRC) during infection. SK2 was demonstrated to co-localize with viral RNA and nonstructural proteins. Targeted impairment of SK2 expression or function significantly inhibited CHIKV infection. Furthermore, affinity purification-mass spectrometry studies revealed that SK2 associates with a number of proteins involved in cellular gene expression specifically during viral infection, suggesting a role in replication. Collectively these results identify SK2 as a novel CHIKV host factor.

  6. Adaptation and Diversification of an RNA Replication System under Initiation- or Termination-Impaired Translational Conditions.

    Science.gov (United States)

    Mizuuchi, Ryo; Ichihashi, Norikazu; Yomo, Tetsuya

    2016-07-01

    Adaptation to various environments is a remarkable characteristic of life. Is this limited to extant complex living organisms, or is it also possible for a simpler self-replication system to adapt? In this study, we addressed this question by using a translation-coupled RNA replication system that comprised a reconstituted translation system and an RNA "genome" that encoded a replicase gene. We performed RNA replication reactions under four conditions, under which different components of translation were partly inhibited. We found that replication efficiency increased with the number of rounds of replication under all the tested conditions. The types of dominant mutations differed depending on the condition, thus indicating that this simple system adapted to different environments in different ways. This suggests that even a primitive self-replication system composed of a small number of genes on the early earth could have had the ability to adapt to various environments.

  7. Versatile Trans-Replication Systems for Chikungunya Virus Allow Functional Analysis and Tagging of Every Replicase Protein.

    Directory of Open Access Journals (Sweden)

    Age Utt

    Full Text Available Chikungunya virus (CHIKV; genus Alphavirus, family Togaviridae has recently caused several major outbreaks affecting millions of people. There are no licensed vaccines or antivirals, and the knowledge of the molecular biology of CHIKV, crucial for development of efficient antiviral strategies, remains fragmentary. CHIKV has a 12 kb positive-strand RNA genome, which is translated to yield a nonstructural (ns or replicase polyprotein. CHIKV structural proteins are expressed from a subgenomic RNA synthesized in infected cells. Here we have developed CHIKV trans-replication systems, where replicase expression and RNA replication are uncoupled. Bacteriophage T7 RNA polymerase or cellular RNA polymerase II were used for production of mRNAs for CHIKV ns polyprotein and template RNAs, which are recognized by CHIKV replicase and encode for reporter proteins. CHIKV replicase efficiently amplified such RNA templates and synthesized large amounts of subgenomic RNA in several cell lines. This system was used to create tagged versions of ns proteins including nsP1 fused with enhanced green fluorescent protein and nsP4 with an immunological tag. Analysis of these constructs and a matching set of replicon vectors revealed that the replicases containing tagged ns proteins were functional and maintained their subcellular localizations. When cells were co-transfected with constructs expressing template RNA and wild type or tagged versions of CHIKV replicases, formation of characteristic replicase complexes (spherules was observed. Analysis of mutations associated with noncytotoxic phenotype in CHIKV replicons showed that a low level of RNA replication is not a pre-requisite for reduced cytotoxicity. The CHIKV trans-replicase does not suffer from genetic instability and represents an efficient, sensitive and reliable tool for studies of different aspects of CHIKV RNA replication process.

  8. Versatile Trans-Replication Systems for Chikungunya Virus Allow Functional Analysis and Tagging of Every Replicase Protein.

    Science.gov (United States)

    Utt, Age; Quirin, Tania; Saul, Sirle; Hellström, Kirsi; Ahola, Tero; Merits, Andres

    2016-01-01

    Chikungunya virus (CHIKV; genus Alphavirus, family Togaviridae) has recently caused several major outbreaks affecting millions of people. There are no licensed vaccines or antivirals, and the knowledge of the molecular biology of CHIKV, crucial for development of efficient antiviral strategies, remains fragmentary. CHIKV has a 12 kb positive-strand RNA genome, which is translated to yield a nonstructural (ns) or replicase polyprotein. CHIKV structural proteins are expressed from a subgenomic RNA synthesized in infected cells. Here we have developed CHIKV trans-replication systems, where replicase expression and RNA replication are uncoupled. Bacteriophage T7 RNA polymerase or cellular RNA polymerase II were used for production of mRNAs for CHIKV ns polyprotein and template RNAs, which are recognized by CHIKV replicase and encode for reporter proteins. CHIKV replicase efficiently amplified such RNA templates and synthesized large amounts of subgenomic RNA in several cell lines. This system was used to create tagged versions of ns proteins including nsP1 fused with enhanced green fluorescent protein and nsP4 with an immunological tag. Analysis of these constructs and a matching set of replicon vectors revealed that the replicases containing tagged ns proteins were functional and maintained their subcellular localizations. When cells were co-transfected with constructs expressing template RNA and wild type or tagged versions of CHIKV replicases, formation of characteristic replicase complexes (spherules) was observed. Analysis of mutations associated with noncytotoxic phenotype in CHIKV replicons showed that a low level of RNA replication is not a pre-requisite for reduced cytotoxicity. The CHIKV trans-replicase does not suffer from genetic instability and represents an efficient, sensitive and reliable tool for studies of different aspects of CHIKV RNA replication process.

  9. Enhancement of internal ribosome entry site-mediated translation and replication of hepatitis C virus by PD98059.

    Science.gov (United States)

    Murata, Takayuki; Hijikata, Makoto; Shimotohno, Kunitada

    2005-09-15

    Translation initiation of hepatitis C virus (HCV) occurs in an internal ribosome entry site (IRES)-dependent manner. We found that HCV IRES-dependent protein synthesis is enhanced by PD98059, an inhibitor of the extracellular signal-regulated kinase (ERK) signaling pathway, while cellular cap-dependent translation was relatively unaffected by the compound. Treatment of cells with PD98059 allowed for robust HCV replication following cellular incubation with HCV-positive serum. Though the molecular mechanism underlying IRES enhancement remains elusive, PD98059 is a potent accelerator of HCV RNA replication.

  10. Virus-Like Particles That Can Deliver Proteins and RNA | NCI Technology Transfer Center | TTC

    Science.gov (United States)

    The present invention describes novel virus-like particles (VLPs) that are capable of binding to and replicating within a target mammalian cell, including human cells. The claimed VLPs are safer than viral delivery because they are incapable of re-infecting target cells. The National Cancer Institute's Protein Expression Laboratory seeks parties interested in licensing the novel delivery of RNA to mammalian cells using virus-like particles.

  11. CD8+ Lymphocytes Can Control HIV Infection in vitro by Suppressing Virus Replication

    Science.gov (United States)

    Walker, Christopher M.; Moody, Dewey J.; Stites, Daniel P.; Levy, Jay A.

    1986-12-01

    Lymphocytes bearing the CD8 marker were shown to suppress replication of human immunodeficiency virus (HIV) in peripheral blood mononuclear cells. The effect was dose-dependent and most apparent with autologous lymphocytes; it did not appear to be mediated by a cytotoxic response. This suppression of HIV replication could be demonstrated by the addition of CD8+ cells at the initiation of virus production as well as after several weeks of virus replication by cultured cells. The observations suggest a potential approach to therapy in which autologous CD8 lymphocytes could be administered to individuals to inhibit HIV replication and perhaps progression of disease.

  12. Cellular DNA ligase I is recruited to cytoplasmic vaccinia virus factories and masks the role of the vaccinia ligase in viral DNA replication.

    Science.gov (United States)

    Paran, Nir; De Silva, Frank S; Senkevich, Tatiana G; Moss, Bernard

    2009-12-17

    Vaccinia virus (VACV) encodes DNA polymerase and additional proteins that enable cytoplasmic replication. We confirmed the ability of VACV DNA ligase mutants to replicate and tested the hypothesis that cellular ligases compensate for loss of viral gene expression. RNA silencing of human DNA ligase I expression and a small molecule inhibitor of human DNA ligase I [corrected] severely reduced replication of viral DNA in cells infected with VACV ligase-deficient mutants, indicating that the cellular enzyme plays a complementary role. Replication of ligase-deficient VACV was greatly reduced and delayed in resting primary cells, correlating with initial low levels of ligase I and subsequent viral induction and localization of ligase I in virus factories. These studies indicate that DNA ligation is essential for poxvirus replication and explain the ability of ligase deletion mutants to replicate in dividing cells but exhibit decreased pathogenicity in mice. Encoding its own ligase might allow VACV to "jump-start" DNA synthesis.

  13. RNA virus attenuation by codon pair deoptimisation is an artefact of increases in CpG/UpA dinucleotide frequencies.

    Science.gov (United States)

    Tulloch, Fiona; Atkinson, Nicky J; Evans, David J; Ryan, Martin D; Simmonds, Peter

    2014-12-09

    Mutating RNA virus genomes to alter codon pair (CP) frequencies and reduce translation efficiency has been advocated as a method to generate safe, attenuated virus vaccines. However, selection for disfavoured CPs leads to unintended increases in CpG and UpA dinucleotide frequencies that also attenuate replication. We designed and phenotypically characterised mutants of the picornavirus, echovirus 7, in which these parameters were independently varied to determine which most influenced virus replication. CpG and UpA dinucleotide frequencies primarily influenced virus replication ability while no fitness differences were observed between mutants with different CP usage where dinucleotide frequencies were kept constant. Contrastingly, translation efficiency was unaffected by either CP usage or dinucleotide frequencies. This mechanistic insight is critical for future rational design of live virus vaccines and their safety evaluation; attenuation is mediated through enhanced innate immune responses to viruses with elevated CpG/UpA dinucleotide frequencies rather the viruses themselves being intrinsically defective.

  14. Novel benzoxazole inhibitor of dengue virus replication that targets the NS3 helicase.

    Science.gov (United States)

    Byrd, Chelsea M; Grosenbach, Douglas W; Berhanu, Aklile; Dai, Dongcheng; Jones, Kevin F; Cardwell, Kara B; Schneider, Christine; Yang, Guang; Tyavanagimatt, Shanthakumar; Harver, Chris; Wineinger, Kristin A; Page, Jessica; Stavale, Eric; Stone, Melialani A; Fuller, Kathleen P; Lovejoy, Candace; Leeds, Janet M; Hruby, Dennis E; Jordan, Robert

    2013-04-01

    Dengue virus (DENV) is the predominant mosquito-borne viral pathogen that infects humans with an estimated 50 to 100 million infections per year worldwide. Over the past 50 years, the incidence of dengue disease has increased dramatically and the virus is now endemic in more than 100 countries. Moreover, multiple serotypes of DENV are now found in the same geographic region, increasing the likelihood of more severe forms of disease. Despite extensive research, there are still no approved vaccines or therapeutics commercially available to treat DENV infection. Here we report the results of a high-throughput screen of a chemical compound library using a whole-virus assay that identified a novel small-molecule inhibitor of DENV, ST-610, that potently and selectively inhibits all four serotypes of DENV replication in vitro. Sequence analysis of drug-resistant virus isolates has identified a single point mutation, A263T, in the NS3 helicase domain that confers resistance to this compound. ST-610 inhibits DENV NS3 helicase RNA unwinding activity in a molecular-beacon-based helicase assay but does not inhibit nucleoside triphosphatase activity based on a malachite green ATPase assay. ST-610 is nonmutagenic, is well tolerated (nontoxic) in mice, and has shown efficacy in a sublethal murine model of DENV infection with the ability to significantly reduce viremia and viral load compared to vehicle controls.

  15. Imaging of the alphavirus capsid protein during virus replication.

    Science.gov (United States)

    Zheng, Yan; Kielian, Margaret

    2013-09-01

    Alphaviruses are enveloped viruses with highly organized structures. The nucleocapsid (NC) core contains a capsid protein lattice enclosing the plus-sense RNA genome, and it is surrounded by a lipid bilayer containing a lattice of the E1 and E2 envelope glycoproteins. Capsid protein is synthesized in the cytoplasm and particle budding occurs at the plasma membrane (PM), but the traffic and assembly of viral components and the exit of virions from host cells are not well understood. To visualize the dynamics of capsid protein during infection, we developed a Sindbis virus infectious clone tagged with a tetracysteine motif. Tagged capsid protein could be fluorescently labeled with biarsenical dyes in living cells without effects on virus growth, morphology, or protein distribution. Live cell imaging and colocalization experiments defined distinct groups of capsid foci in infected cells. We observed highly motile internal puncta that colocalized with E2 protein, which may represent the transport machinery that capsid protein uses to reach the PM. Capsid was also found in larger nonmotile internal structures that colocalized with cellular G3BP and viral nsP3. Thus, capsid may play an unforeseen role in these previously observed G3BP-positive foci, such as regulation of cellular stress granules. Capsid puncta were also observed at the PM. These puncta colocalized with E2 and recruited newly synthesized capsid protein; thus, they may be sites of virus assembly and egress. Together, our studies provide the first dynamic views of the alphavirus capsid protein in living cells and a system to define detailed mechanisms during alphavirus infection.

  16. ER stress, autophagy, and RNA viruses

    Directory of Open Access Journals (Sweden)

    Jia-Rong eJheng

    2014-08-01

    Full Text Available Endoplasmic reticulum (ER stress is a general term for representing the pathway by which various stimuli affect ER functions. ER stress induces the evolutionarily conserved signaling pathways, called the unfolded protein response (UPR, which compromises the stimulus and then determines whether the cell survives or dies. In recent years, ongoing research has suggested that these pathways may be linked to the autophagic response, which plays a key role in the cell’s response to various stressors. Autophagy performs a self-digestion function, and its activation protects cells against certain pathogens. However, the link between the UPR and autophagy may be more complicated. These two systems may act dependently, or the induction of one system may interfere with the other. Experimental studies have found that different viruses modulate these mechanisms to allow them to escape the host immune response or, worse, to exploit the host’s defense to their advantage; thus, this topic is a critical area in antiviral research. In this review, we summarize the current knowledge about how RNA viruses, including influenza virus, poliovirus, coxsackievirus, enterovirus 71, Japanese encephalitis virus, hepatitis C virus, and dengue virus, regulate these processes. We also discuss recent discoveries and how these will produce novel strategies for antiviral treatment.

  17. Cell Type-Dependent RNA Recombination Frequency in the Japanese Encephalitis Virus

    Directory of Open Access Journals (Sweden)

    Wei-Wei Chiang

    2014-01-01

    Full Text Available Japanese encephalitis virus (JEV is one of approximately 70 flaviviruses, frequently causing symptoms involving the central nervous system. Mutations of its genomic RNA frequently occur during viral replication, which is believed to be a force contributing to viral evolution. Nevertheless, accumulating evidences show that some JEV strains may have actually arisen from RNA recombination between genetically different populations of the virus. We have demonstrated that RNA recombination in JEV occurs unequally in different cell types. In the present study, viral RNA fragments transfected into as well as viral RNAs synthesized in mosquito cells were shown not to be stable, especially in the early phase of infection possibly via cleavage by exoribonuclease. Such cleaved small RNA fragments may be further degraded through an RNA interference pathway triggered by viral double-stranded RNA during replication in mosquito cells, resulting in a lower frequency of RNA recombination in mosquito cells compared to that which occurs in mammalian cells. In fact, adjustment of viral RNA to an appropriately lower level in mosquito cells prevents overgrowth of the virus and is beneficial for cells to survive the infection. Our findings may also account for the slower evolution of arboviruses as reported previously.

  18. Cell type-dependent RNA recombination frequency in the Japanese encephalitis virus.

    Science.gov (United States)

    Chiang, Wei-Wei; Chuang, Ching-Kai; Chao, Mei; Chen, Wei-June

    2014-01-01

    Japanese encephalitis virus (JEV) is one of approximately 70 flaviviruses, frequently causing symptoms involving the central nervous system. Mutations of its genomic RNA frequently occur during viral replication, which is believed to be a force contributing to viral evolution. Nevertheless, accumulating evidences show that some JEV strains may have actually arisen from RNA recombination between genetically different populations of the virus. We have demonstrated that RNA recombination in JEV occurs unequally in different cell types. In the present study, viral RNA fragments transfected into as well as viral RNAs synthesized in mosquito cells were shown not to be stable, especially in the early phase of infection possibly via cleavage by exoribonuclease. Such cleaved small RNA fragments may be further degraded through an RNA interference pathway triggered by viral double-stranded RNA during replication in mosquito cells, resulting in a lower frequency of RNA recombination in mosquito cells compared to that which occurs in mammalian cells. In fact, adjustment of viral RNA to an appropriately lower level in mosquito cells prevents overgrowth of the virus and is beneficial for cells to survive the infection. Our findings may also account for the slower evolution of arboviruses as reported previously.

  19. A dimeric Rep protein initiates replication of a linear archaeal virus genome: implications for the Rep mechanism and viral replication

    DEFF Research Database (Denmark)

    Oke, Muse; Kerou, Melina; Liu, Huanting

    2011-01-01

    that a protein encoded in the 34-kbp genome of the rudivirus SIRV1 is a member of the replication initiator (Rep) superfamily of proteins, which initiate rolling-circle replication (RCR) of diverse viruses and plasmids. We show that SIRV Rep nicks the viral hairpin terminus, forming a covalent adduct between...... positioned active sites, each with a single tyrosine residue, work in tandem to catalyze DNA nicking and joining. We propose a novel mechanism for rudivirus DNA replication, incorporating the first known example of a Rep protein that is not linked to RCR. The implications for Rep protein function and viral...

  20. Potent Inhibition of HIV-1 Reverse Transcriptase and Replication by Nonpseudoknot, "UCAA-motif" RNA Aptamers.

    Science.gov (United States)

    Whatley, Angela S; Ditzler, Mark A; Lange, Margaret J; Biondi, Elisa; Sawyer, Andrew W; Chang, Jonathan L; Franken, Joshua D; Burke, Donald H

    2013-02-05

    RNA aptamers that bind the reverse transcriptase (RT) of human immunodeficiency virus (HIV) compete with nucleic acid primer/template for access to RT, inhibit RT enzymatic activity in vitro, and suppress viral replication when expressed in human cells. Numerous pseudoknot aptamers have been identified by sequence analysis, but relatively few have been confirmed experimentally. In this work, a screen of nearly 100 full-length and >60 truncated aptamer transcripts established the predictive value of the F1Pk and F2Pk pseudoknot signature motifs. The screen also identified a new, nonpseudoknot motif with a conserved unpaired UCAA element. High-throughput sequence (HTS) analysis identified 181 clusters capable of forming this novel element. Comparative sequence analysis, enzymatic probing and RT inhibition by aptamer variants established the essential requirements of the motif, which include two conserved base pairs (AC/GU) on the 5' side of the unpaired UCAA. Aptamers in this family inhibit RT in primer extension assays with IC(50) values in the low nmol/l range, and they suppress viral replication with a potency that is comparable with that of previously studied aptamers. All three known anti-RT aptamer families (pseudoknots, the UCAA element, and the recently described "(6/5)AL" motif) are therefore suitable for developing aptamer-based antiviral gene therapies.Molecular Therapy - Nucleic Acids (2013) 2, e71; doi:10.1038/mtna.2012.62; published online 5 February 2013.

  1. Influenza virus targets the mRNA export machinery and the nuclear pore complex.

    Science.gov (United States)

    Satterly, Neal; Tsai, Pei-Ling; van Deursen, Jan; Nussenzveig, Daniel R; Wang, Yaming; Faria, Paula A; Levay, Agata; Levy, David E; Fontoura, Beatriz M A

    2007-02-01

    The NS1 protein of influenza A virus is a major virulence factor that is essential for pathogenesis. NS1 functions to impair innate and adaptive immunity by inhibiting host signal transduction and gene expression, but its mechanisms of action remain to be fully elucidated. We show here that NS1 forms an inhibitory complex with NXF1/TAP, p15/NXT, Rae1/mrnp41, and E1B-AP5, which are key constituents of the mRNA export machinery that interact with both mRNAs and nucleoporins to direct mRNAs through the nuclear pore complex. Increased levels of NXF1, p15, or Rae1 revert the mRNA export blockage induced by NS1. Furthermore, influenza virus down-regulates Nup98, a nucleoporin that is a docking site for mRNA export factors. Reduced expression of these mRNA export factors renders cells highly permissive to influenza virus replication, demonstrating that proper levels of key constituents of the mRNA export machinery protect against influenza virus replication. Because Nup98 and Rae1 are induced by interferons, down-regulation of this pathway is likely a viral strategy to promote viral replication. These findings demonstrate previously undescribed influenza-mediated viral-host interactions and provide insights into potential molecular therapies that may interfere with influenza infection.

  2. Suppression of feline calicivirus replication using small interfering RNA targeted to its polymerase gene.

    Science.gov (United States)

    Taharaguchi, Satoshi; Matsuhiro, Takahisa; Harima, Hayato; Sato, Atsuko; Ohe, Kyoko; Sakai, Sachi; Takahashi, Toshikazu; Hara, Motonobu

    2012-06-01

    Feline calicivirus (FCV) is a pathogenic microorganism that causes upper respiratory diseases in cats. Recently, an FCV infection with a high mortality rate has been confirmed, and there is need to develop a treatment for cases of acute infection. We evaluated whether the replication of FCV could be prevented by RNA interference. For this study, we designed an siRNA targeted to the polymerase region of the strain FCV-B isolated from a cat that died after exhibiting neurological symptoms. Cells transfected with siR-pol dose-dependently suppressed the replication of FCV-B. siR-pol suppressed its replication by suppressing the target viral RNA.

  3. Simian varicella virus open reading frame 63/70 expression is required for efficient virus replication in culture

    Science.gov (United States)

    Brazeau, Elizabeth; Wellish, Mary; Kaufer, Benedict B.; Tischer, B. Karsten; Gray, Wayne; Zhou, Fuchun; Osterrieder, Nikolaus; Hanlon, Teri; Golive, Anjani; Hall, Travis; Nair, Sreekala; Owens, Gregory P.; Mueller, Niklaus H.; Cohrs, Randall J.; Pugazhenthi, Subbiah; Gilden, Don

    2011-01-01

    Simian varicella virus (SVV) open reading frame (ORF) 63, duplicated in the virus genome as ORF 70, is homologous to varicella zoster virus ORF 63/70. Transfection of bacterial artificial chromosome clones containing the wild-type SVV genome and mutants with stop codons in ORF 70, in both ORFs 63 and 70 and the repaired virus DNA sequences into Vero cells produced a cytopathic effect (CPE). The onset of CPE was much slower with the double-mutant transfectants (10 days vs. 3 days) and plaques were smaller. While SVV ORF 63 is not required for replication in culture, its expression leads to robust virus replication. PMID:21479719

  4. Variation in RNA virus mutation rates across host cells.

    Directory of Open Access Journals (Sweden)

    Marine Combe

    2014-01-01

    Full Text Available It is well established that RNA viruses exhibit higher rates of spontaneous mutation than DNA viruses and microorganisms. However, their mutation rates vary amply, from 10(-6 to 10(-4 substitutions per nucleotide per round of copying (s/n/r and the causes of this variability remain poorly understood. In addition to differences in intrinsic fidelity or error correction capability, viral mutation rates may be dependent on host factors. Here, we assessed the effect of the cellular environment on the rate of spontaneous mutation of the vesicular stomatitis virus (VSV, which has a broad host range and cell tropism. Luria-Delbrück fluctuation tests and sequencing showed that VSV mutated similarly in baby hamster kidney, murine embryonic fibroblasts, colon cancer, and neuroblastoma cells (approx. 10(-5 s/n/r. Cell immortalization through p53 inactivation and oxygen levels (1-21% did not have a significant impact on viral replication fidelity. This shows that previously published mutation rates can be considered reliable despite being based on a narrow and artificial set of laboratory conditions. Interestingly, we also found that VSV mutated approximately four times more slowly in various insect cells compared with mammalian cells. This may contribute to explaining the relatively slow evolution of VSV and other arthropod-borne viruses in nature.

  5. Brome mosaic virus Infection of Rice Results in Decreased Accumulation of RNA1.

    Science.gov (United States)

    Kitayama, Masahiko; Hoover, Haley; Middleton, Stefani; Kao, C Cheng

    2015-05-01

    Brome mosaic virus (BMV) (the Russian strain) infects monocot plants and has been studied extensively in barley and wheat. Here, we report BMV can systemically infect rice (Oryza sativa var. japonica), including cultivars in which the genomes have been determined. The BMV capsid protein can be found throughout the inoculated plants. However, infection in rice exhibits delayed symptom expression or no symptoms when compared with wheat (Triticum aestivum). The sequences of BMV RNAs isolated from rice did not reveal any nucleotide changes in RNA1 or RNA2, while RNA3 had only one synonymous nucleotide change from the inoculum sequence. Preparations of purified BMV virions contained RNA1 at a significantly reduced level relative to the other two RNAs. Analysis of BMV RNA replication in rice revealed that minus-strand RNA1 was replicated at a reduced rate when compared with RNA2. Thus, rice appears to either inhibit RNA1 replication or lacks a sufficient amount of a factor needed to support efficient RNA1 replication.

  6. The V protein of canine distemper virus is required for virus replication in human epithelial cells.

    Directory of Open Access Journals (Sweden)

    Noriyuki Otsuki

    Full Text Available Canine distemper virus (CDV becomes able to use human receptors through a single amino acid substitution in the H protein. In addition, CDV strains possessing an intact C protein replicate well in human epithelial H358 cells. The present study showed that CDV strain 007Lm, which was isolated from lymph node tissue of a dog with distemper, failed to replicate in H358 cells, although it possessed an intact C protein. Sequence analyses suggested that a cysteine-to-tyrosine substitution at position 267 of the V protein caused this growth defect. Analyses using H358 cells constitutively expressing the CDV V protein showed that the V protein with a cysteine, but not that with a tyrosine, at this position effectively blocked the interferon-stimulated signal transduction pathway, and supported virus replication of 007Lm in H358 cells. Thus, the V protein as well as the C protein appears to be functional and essential for CDV replication in human epithelial cells.

  7. Epstein-Barr virus stimulates torque teno virus replication: a possible relationship to multiple sclerosis.

    Directory of Open Access Journals (Sweden)

    Silvia S Borkosky

    Full Text Available Viral infections have been implicated in the pathogenesis of multiple sclerosis. Epstein-Barr virus (EBV has frequently been investigated as a possible candidate and torque teno virus (TTV has also been discussed in this context. Nevertheless, mechanistic aspects remain unresolved. We report viral replication, as measured by genome amplification, as well as quantitative PCR of two TTV-HD14 isolates isolated from multiple sclerosis brain in a series of EBV-positive and -negative lymphoblastoid and Burkitt's lymphoma cell lines. Our results demonstrate the replication of both transfected TTV genomes up to day 21 post transfection in all the evaluated cell lines. Quantitative amplification indicates statistically significant enhanced TTV replication in the EBV-positive cell lines, including the EBV-converted BJAB line, in comparison to the EBV-negative Burkitt's lymphoma cell line BJAB. This suggests a helper effect of EBV infections in the replication of TTV. The present study provides information on a possible interaction of EBV and TTV in the etiology and progression of multiple sclerosis.

  8. Virucidal activity of Colombian Lippia essential oils on dengue virus replication in vitro

    OpenAIRE

    Raquel Elvira Ocazionez; Rocio Meneses; Flor Ángela Torres; Elena Stashenko

    2010-01-01

    The inhibitory effect of Lippia alba and Lippia citriodora essential oils on dengue virus serotypes replication in vitro was investigated. The cytotoxicity (CC50) was evaluated by the MTT assay and the mode of viral inhibitory effect was investigated with a plaque reduction assay. The virus was treated with the essential oil for 2 h at 37ºC before cell adsorption and experiments were conducted to evaluate inhibition of untreated-virus replication in the presence of oil. Antiviral activity was...

  9. The proteasomal Rpn11 metalloprotease suppresses tombusvirus RNA recombination and promotes viral replication via facilitating assembly of the viral replicase complex.

    Science.gov (United States)

    Prasanth, K Reddisiva; Barajas, Daniel; Nagy, Peter D

    2015-03-01

    RNA viruses co-opt a large number of cellular proteins that affect virus replication and, in some cases, viral genetic recombination. RNA recombination helps viruses in an evolutionary arms race with the host's antiviral responses and adaptation of viruses to new hosts. Tombusviruses and a yeast model host are used to identify cellular factors affecting RNA virus replication and RNA recombination. In this study, we have examined the role of the conserved Rpn11p metalloprotease subunit of the proteasome, which couples deubiquitination and degradation of proteasome substrates, in tombusvirus replication and recombination in Saccharomyces cerevisiae and plants. Depletion or mutations of Rpn11p lead to the rapid formation of viral RNA recombinants in combination with reduced levels of viral RNA replication in yeast or in vitro based on cell extracts. Rpn11p interacts with the viral replication proteins and is recruited to the viral replicase complex (VRC). Analysis of the multifunctional Rpn11p has revealed that the primary role of Rpn11p is to act as a "matchmaker" that brings the viral p92(pol) replication protein and the DDX3-like Ded1p/RH20 DEAD box helicases into VRCs. Overexpression of Ded1p can complement the defect observed in rpn11 mutant yeast by reducing TBSV recombination. This suggests that Rpn11p can suppress tombusvirus recombination via facilitating the recruitment of the cellular Ded1p helicase, which is a strong suppressor of viral recombination, into VRCs. Overall, this work demonstrates that the co-opted Rpn11p, which is involved in the assembly of the functional proteasome, also functions in the proper assembly of the tombusvirus VRCs. RNA viruses evolve rapidly due to genetic changes based on mutations and RNA recombination. Viral genetic recombination helps viruses in an evolutionary arms race with the host's antiviral responses and facilitates adaptation of viruses to new hosts. Cellular factors affect viral RNA recombination, although the role

  10. Replication of Tomato Yellow Leaf Curl Virus in Its Whitefly Vector, Bemisia tabaci.

    Science.gov (United States)

    Pakkianathan, Britto Cathrin; Kontsedalov, Svetlana; Lebedev, Galina; Mahadav, Assaf; Zeidan, Muhammad; Czosnek, Henryk; Ghanim, Murad

    2015-10-01

    Tomato yellow leaf curl virus (TYLCV) is a begomovirus transmitted exclusively by the whitefly Bemisia tabaci in a persistent, circulative manner. Replication of TYLCV in its vector remains controversial, and thus far, the virus has been considered to be nonpropagative. Following 8 h of acquisition on TYLCV-infected tomato plants or purified virions and then transfer to non-TYLCV-host cotton plants, the amounts of virus inside whitefly adults significantly increased (>2-fold) during the first few days and then continuously decreased, as measured by the amounts of genes on both virus DNA strands. Reported alterations in insect immune and defense responses upon virus retention led us to hypothesize a role for the immune response in suppressing virus replication. After virus acquisition, stress conditions were imposed on whiteflies, and the levels of three viral gene sequences were measured over time. When whiteflies were exposed to TYLCV and treatment with two different pesticides, the virus levels continuously increased. Upon exposure to heat stress, the virus levels gradually decreased, without any initial accumulation. Switching of whiteflies between pesticide, heat stress, and control treatments caused fluctuating increases and decreases in virus levels. Fluorescence in situ hybridization analysis confirmed these results and showed virus signals inside midgut epithelial cell nuclei. Combining the pesticide and heat treatments with virus acquisition had significant effects on fecundity. Altogether, our results demonstrate for the first time that a single-stranded DNA plant virus can replicate in its hemipteran vector. Plant viruses in agricultural crops are of great concern worldwide. Many of them are transmitted from infected to healthy plants by insects. Persistently transmitted viruses often have a complex association with their vectors; however, most are believed not to replicate within these vectors. Such replication is important, as it contributes to the

  11. Primary Human Placental Trophoblasts are Permissive for Zika Virus (ZIKV) Replication

    Science.gov (United States)

    Aagaard, Kjersti M.; Lahon, Anismrita; Suter, Melissa A.; Arya, Ravi P.; Seferovic, Maxim D.; Vogt, Megan B.; Hu, Min; Stossi, Fabio; Mancini, Michael A.; Harris, R. Alan; Kahr, Maike; Eppes, Catherine; Rac, Martha; Belfort, Michael A.; Park, Chun Shik; Lacorazza, Daniel; Rico-Hesse, Rebecca

    2017-01-01

    Zika virus (ZIKV) is an emerging mosquito-borne (Aedes genus) arbovirus of the Flaviviridae family. Although ZIKV has been predominately associated with a mild or asymptomatic dengue-like disease, its appearance in the Americas has been accompanied by a multi-fold increase in reported incidence of fetal microcephaly and brain malformations. The source and mode of vertical transmission from mother to fetus is presumptively transplacental, although a causal link explaining the interval delay between maternal symptoms and observed fetal malformations following infection has been missing. In this study, we show that primary human placental trophoblasts from non-exposed donors (n = 20) can be infected by primary passage ZIKV-FLR isolate, and uniquely allowed for ZIKV viral RNA replication when compared to dengue virus (DENV). Consistent with their being permissive for ZIKV infection, primary trophoblasts expressed multiple putative ZIKV cell entry receptors, and cellular function and differentiation were preserved. These findings suggest that ZIKV-FLR strain can replicate in human placental trophoblasts without host cell destruction, thereby serving as a likely permissive reservoir and portal of fetal transmission with risk of latent microcephaly and malformations. PMID:28128342

  12. Cellular RNA binding proteins NS1-BP and hnRNP K regulate influenza A virus RNA splicing.

    Science.gov (United States)

    Tsai, Pei-Ling; Chiou, Ni-Ting; Kuss, Sharon; García-Sastre, Adolfo; Lynch, Kristen W; Fontoura, Beatriz M A

    2013-01-01

    Influenza A virus is a major human pathogen with a genome comprised of eight single-strand, negative-sense, RNA segments. Two viral RNA segments, NS1 and M, undergo alternative splicing and yield several proteins including NS1, NS2, M1 and M2 proteins. However, the mechanisms or players involved in splicing of these viral RNA segments have not been fully studied. Here, by investigating the interacting partners and function of the cellular protein NS1-binding protein (NS1-BP), we revealed novel players in the splicing of the M1 segment. Using a proteomics approach, we identified a complex of RNA binding proteins containing NS1-BP and heterogeneous nuclear ribonucleoproteins (hnRNPs), among which are hnRNPs involved in host pre-mRNA splicing. We found that low levels of NS1-BP specifically impaired proper alternative splicing of the viral M1 mRNA segment to yield the M2 mRNA without affecting splicing of mRNA3, M4, or the NS mRNA segments. Further biochemical analysis by formaldehyde and UV cross-linking demonstrated that NS1-BP did not interact directly with viral M1 mRNA but its interacting partners, hnRNPs A1, K, L, and M, directly bound M1 mRNA. Among these hnRNPs, we identified hnRNP K as a major mediator of M1 mRNA splicing. The M1 mRNA segment generates the matrix protein M1 and the M2 ion channel, which are essential proteins involved in viral trafficking, release into the cytoplasm, and budding. Thus, reduction of NS1-BP and/or hnRNP K levels altered M2/M1 mRNA and protein ratios, decreasing M2 levels and inhibiting virus replication. Thus, NS1-BP-hnRNPK complex is a key mediator of influenza A virus gene expression.

  13. Inhibition of Mayaro virus replication by cerulenin in Aedes albopictus cells.

    Science.gov (United States)

    Pereira, H S; Rebello, M A

    1998-12-01

    The antibiotic cerulenin, an inhibitor of lipid synthesis, was shown to suppress Mayaro virus replication in Aedes albopictus cells at non-cytotoxic doses. Cerulenin blocked the incorporation of [3H]glycerol into lipids when present at any time post infection (p.i.). Cerulenin added at the beginning of infection inhibited the synthesis of virus proteins. However, when this antibiotic was added at later stages of infection, it had only a mild effect on the virus protein synthesis. The possibility that cerulenin acts by blocking an initial step in the Mayaro virus replication after virus entry and before late viral translation is discussed.

  14. In vitro transcription of Sonchus yellow net virus RNA by a virus-associated RNA-dependent RNA polymerase.

    NARCIS (Netherlands)

    Flore, P.H.

    1986-01-01

    The aim of the investigation presented in this thesis was to elucidate the nature of the RNA- dependent RNA polymerase, thought to be associated with Sonchus yellow net virus (SYNV), a rhabdovirus infecting plants. This research was initiated to shed light on the transcription activity in rhabdoviru

  15. Evolutionary dynamics of RNA-like replicator systems: A bioinformatic approach to the origin of life.

    Science.gov (United States)

    Takeuchi, Nobuto; Hogeweg, Paulien

    2012-09-01

    We review computational studies on prebiotic evolution, focusing on informatic processes in RNA-like replicator systems. In particular, we consider the following processes: the maintenance of information by replicators with and without interactions, the acquisition of information by replicators having a complex genotype-phenotype map, the generation of information by replicators having a complex genotype-phenotype-interaction map, and the storage of information by replicators serving as dedicated templates. Focusing on these informatic aspects, we review studies on quasi-species, error threshold, RNA-folding genotype-phenotype map, hypercycle, multilevel selection (including spatial self-organization, classical group selection, and compartmentalization), and the origin of DNA-like replicators. In conclusion, we pose a future question for theoretical studies on the origin of life.

  16. A replication-deficient rabies virus vaccine expressing Ebola virus glycoprotein is highly attenuated for neurovirulence

    Energy Technology Data Exchange (ETDEWEB)

    Papaneri, Amy B. [Emerging Viral Pathogens Section, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Fort Detrick, MD 21702 (United States); Wirblich, Christoph [Department of Microbiology and Immunology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, PA 19107 (United States); Cann, Jennifer A.; Cooper, Kurt [Integrated Research Facility, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Fort Detrick MD, 21702 (United States); Jahrling, Peter B. [Emerging Viral Pathogens Section, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Fort Detrick, MD 21702 (United States); Integrated Research Facility, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Fort Detrick MD, 21702 (United States); Schnell, Matthias J., E-mail: matthias.schnell@jefferson.edu [Department of Microbiology and Immunology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, PA 19107 (United States); Jefferson Vaccine Center, Jefferson Medical College, Thomas Jefferson University, Philadelphia, PA 19107 (United States); Blaney, Joseph E., E-mail: jblaney@niaid.nih.gov [Emerging Viral Pathogens Section, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Fort Detrick, MD 21702 (United States)

    2012-12-05

    We are developing inactivated and live-attenuated rabies virus (RABV) vaccines expressing Ebola virus (EBOV) glycoprotein for use in humans and endangered wildlife, respectively. Here, we further characterize the pathogenesis of the live-attenuated RABV/EBOV vaccine candidates in mice in an effort to define their growth properties and potential for safety. RABV vaccines expressing GP (RV-GP) or a replication-deficient derivative with a deletion of the RABV G gene (RV{Delta}G-GP) are both avirulent after intracerebral inoculation of adult mice. Furthermore, RV{Delta}G-GP is completely avirulent upon intracerebral inoculation of suckling mice unlike parental RABV vaccine or RV-GP. Analysis of RV{Delta}G-GP in the brain by quantitative PCR, determination of virus titer, and immunohistochemistry indicated greatly restricted virus replication. In summary, our findings indicate that RV-GP retains the attenuation phenotype of the live-attenuated RABV vaccine, and RV{Delta}G-GP would appear to be an even safer alternative for use in wildlife or consideration for human use.

  17. Structural protein VP2 of African horse sickness virus is not essential for virus replication in vitro

    NARCIS (Netherlands)

    Gennip, van René G.P.; Water, van de Sandra G.P.; Potgieter, Christiaan A.; Rijn, van Piet A.

    2017-01-01

    The Reoviridae family consists of nonenveloped multilayered viruses with a double-stranded RNA genome consisting of 9 to 12 genome segments. The Orbivirus genus of the Reoviridae family contains African horse sickness virus (AHSV), bluetongue virus, and epizootic hemorrhagic disease virus, which

  18. Differential association with cellular substructures of pseudorabies virus DNA during early and late phases of replication

    Energy Technology Data Exchange (ETDEWEB)

    Ben-Porat, T.; Veach, R.A.; Blankenship, M.L.; Kaplan, A.S.

    1984-12-01

    Pseudorabies virus DNA synthesis can be divided into two phases, early and late, which can be distinguished from each other on the basis of the structures of the replicating DNA. The two types of replicating virus DNA can also be distinguished from each other on the basis of the cellular substructures with which each is associated. Analysis by electron microscopic autoradiography showed that during the first round of replication, nascent virus DNA was found in the vicinity of the nuclear membrane; during later rounds of replication the nascent virus DNA was located centrally within the nucleus. The degree of association of virus DNA synthesized at early and late phases with the nuclear matrix fractions also differed; a larger proportion of late than of early nascent virus DNA was associated with this fraction. While nascent cellular DNA only was associated in significant amounts with the nuclear matrix fraction, a large part (up to 40%) of all the virus DNA remained associated with this fraction. However, no retention of specific virus proteins in this fraction was observed. Except for two virus proteins, which were preferentially extracted from the nuclear matrix, approximately 20% of all virus proteins remained in the nuclear matrix fraction. The large proportion of virus DNA associated with the nuclear fraction indicated that virus DNA may be intimately associated with some proteins.

  19. Rapid molecular detection of Lujo virus RNA.

    Science.gov (United States)

    Atkinson, Barry; Chamberlain, John; Dowall, Stuart D; Cook, Nicola; Bruce, Christine; Hewson, Roger

    2014-01-01

    Lujo virus is an emerging arenavirus circulating in Southern Africa. Although to date there has only been a single outbreak of the novel haemorrhagic disease resulting from human infection with this virus, the case-fatality rate of exposed individuals, including nosocomial transmission, was 80%. The ability to identify viral haemorrhagic fevers accurately, especially those capable of nosocomial transmission, is of critical importance. Timely identification of these diseases allow medical professionals to isolate patients and implement barrier nursing techniques in order to prevent onward transmission of the virus. While rapid diagnostic methods are published for most viral haemorrhagic fevers, at present there are no such virus specific protocols for Lujo haemorrhagic fever. This report details the first set of diagnostic molecular assays designed to identify Lujo viral RNA rapidly, and demonstrates the potential functionality of these assays for use in the clinical setting. Although these assays have been designed and validated against a solitary isolate of Lujo virus, this represents the entirety of strains detected to date, and offer quick, cheap and easy methods for use in diagnostic laboratories.

  20. Redistribution of Endosomal Membranes to the African Swine Fever Virus Replication Site

    Directory of Open Access Journals (Sweden)

    Miguel Ángel Cuesta-Geijo

    2017-06-01

    Full Text Available African swine fever virus (ASFV infection causes endosomal reorganization. Here, we show that the virus causes endosomal congregation close to the nucleus as the infection progresses, which is necessary to build a compact viral replication organelle. ASFV enters the cell by the endosomal pathway and reaches multivesicular late endosomes. Upon uncoating and fusion, the virus should exit to the cytosol to start replication. ASFV remodels endosomal traffic and redistributes endosomal membranes to the viral replication site. Virus replication also depends on endosomal membrane phosphoinositides (PtdIns synthesized by PIKfyve. Endosomes could act as platforms providing membranes and PtdIns, necessary for ASFV replication. Our study has revealed that ASFV reorganizes endosome dynamics, in order to ensure a productive infection.

  1. Direct Inhibition of Cellular Fatty Acid Synthase Impairs Replication of Respiratory Syncytial Virus and Other Respiratory Viruses.

    Directory of Open Access Journals (Sweden)

    Yamini M Ohol

    Full Text Available Fatty acid synthase (FASN catalyzes the de novo synthesis of palmitate, a fatty acid utilized for synthesis of more complex fatty acids, plasma membrane structure, and post-translational palmitoylation of host and viral proteins. We have developed a potent inhibitor of FASN (TVB-3166 that reduces the production of respiratory syncytial virus (RSV progeny in vitro from infected human lung epithelial cells (A549 and in vivo from mice challenged intranasally with RSV. Addition of TVB-3166 to the culture medium of RSV-infected A549 cells reduces viral spread without inducing cytopathic effects. The antiviral effect of the FASN inhibitor is a direct consequence of reducing de novo palmitate synthesis; similar doses are required for both antiviral activity and inhibition of palmitate production, and the addition of exogenous palmitate to TVB-3166-treated cells restores RSV production. TVB-3166 has minimal effect on RSV entry but significantly reduces viral RNA replication, protein levels, viral particle formation and infectivity of released viral particles. TVB-3166 substantially impacts viral replication, reducing production of infectious progeny 250-fold. In vivo, oral administration of TVB-3166 to RSV-A (Long-infected BALB/c mice on normal chow, starting either on the day of infection or one day post-infection, reduces RSV lung titers 21-fold and 9-fold respectively. Further, TVB-3166 also inhibits the production of RSV B, human parainfluenza 3 (PIV3, and human rhinovirus 16 (HRV16 progeny from A549, HEp2 and HeLa cells respectively. Thus, inhibition of FASN and palmitate synthesis by TVB-3166 significantly reduces RSV progeny both in vitro and in vivo and has broad-spectrum activity against other respiratory viruses. FASN inhibition may alter the composition of regions of the host cell membrane where RSV assembly or replication occurs, or change the membrane composition of RSV progeny particles, decreasing their infectivity.

  2. Respiratory Syncytial Virus Induces Host RNA Stress Granules To Facilitate Viral Replication▿

    Science.gov (United States)

    Lindquist, Michael E.; Lifland, Aaron W.; Utley, Thomas J.; Santangelo, Philip J.; Crowe, James E.

    2010-01-01

    Mammalian cell cytoplasmic RNA stress granules are induced during various conditions of stress and are strongly associated with regulation of host mRNA translation. Several viruses induce stress granules during the course of infection, but the exact function of these structures during virus replication is not well understood. In this study, we showed that respiratory syncytial virus (RSV) induced host stress granules in epithelial cells during the course of infection. We also showed that stress granules are distinct from cytoplasmic viral inclusion bodies and that the RNA binding protein HuR, normally found in stress granules, also localized to viral inclusion bodies during infection. Interestingly, we demonstrated that infected cells containing stress granules also contained more RSV protein than infected cells that did not form inclusion bodies. To address the role of stress granule formation in RSV infection, we generated a stable epithelial cell line with reduced expression of the Ras-GAP SH3 domain-binding protein (G3BP) that displayed an inhibited stress granule response. Surprisingly, RSV replication was impaired in these cells compared to its replication in cells with intact G3BP expression. In contrast, knockdown of HuR by RNA interference did not affect stress granule formation or RSV replication. Finally, using RNA probes specific for RSV genomic RNA, we found that viral RNA predominantly localized to viral inclusion bodies but a small percentage also interacted with stress granules during infection. These results suggest that RSV induces a host stress granule response and preferentially replicates in host cells that have committed to a stress response. PMID:20844027

  3. A crystal structure of the Dengue virus NS5 protein reveals a novel inter-domain interface essential for protein flexibility and virus replication.

    Directory of Open Access Journals (Sweden)

    Yongqian Zhao

    2015-03-01

    Full Text Available Flavivirus RNA replication occurs within a replication complex (RC that assembles on ER membranes and comprises both non-structural (NS viral proteins and host cofactors. As the largest protein component within the flavivirus RC, NS5 plays key enzymatic roles through its N-terminal methyltransferase (MTase and C-terminal RNA-dependent-RNA polymerase (RdRp domains, and constitutes a major target for antivirals. We determined a crystal structure of the full-length NS5 protein from Dengue virus serotype 3 (DENV3 at a resolution of 2.3 Å in the presence of bound SAH and GTP. Although the overall molecular shape of NS5 from DENV3 resembles that of NS5 from Japanese Encephalitis Virus (JEV, the relative orientation between the MTase and RdRp domains differs between the two structures, providing direct evidence for the existence of a set of discrete stable molecular conformations that may be required for its function. While the inter-domain region is mostly disordered in NS5 from JEV, the NS5 structure from DENV3 reveals a well-ordered linker region comprising a short 310 helix that may act as a swivel. Solution Hydrogen/Deuterium Exchange Mass Spectrometry (HDX-MS analysis reveals an increased mobility of the thumb subdomain of RdRp in the context of the full length NS5 protein which correlates well with the analysis of the crystallographic temperature factors. Site-directed mutagenesis targeting the mostly polar interface between the MTase and RdRp do