1,425 research outputs found

    Requirements for Human Respiratory Syncytial Virus Glycoproteins in Assembly and Egress from Infected Cells

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    Human respiratory syncytial virus (HRSV) is an enveloped RNA virus that assembles and buds from the plasma membrane of infected cells. The ribonucleoprotein complex (RNP) must associate with the viral matrix protein and glycoproteins to form newly infectious particles prior to budding. The viral proteins involved in HRSV assembly and egress are mostly unexplored. We investigated whether the glycoproteins of HRSV were involved in the late stages of viral replication by utilizing recombinant viruses where each individual glycoprotein gene was deleted and replaced with a reporter gene to maintain wild-type levels of gene expression. These engineered viruses allowed us to study the roles of the glycoproteins in assembly and budding in the context of infectious virus. Microscopy data showed that the F glycoprotein was involved in the localization of the glycoproteins with the other viral proteins at the plasma membrane. Biochemical analyses showed that deletion of the F and G proteins affected incorporation of the other viral proteins into budded virions. However, efficient viral release was unaffected by the deletion of any of the glycoproteins individually or in concert. These studies attribute a novel role to the F and G proteins in viral protein localization and assembly

    Transcriptional Termination Modulated by Nucleotides Outside the Characterized Gene End Sequence of Respiratory Syncytial Virus

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    AbstractThe genes of respiratory syncytial (RS) virus are transcribed sequentially by the viral RNA polymerase from a single 3â€Č-proximal promoter. Polyadenylation and termination are directed by a sequence at the end of each gene, after which the polymerase crosses an intergenic region and reinitiates at the start sequence of the next gene. The 10 viral genes have different gene end sequences and different termination efficiencies, which allow for regulation of gene expression, since termination of each gene is required for initiation of the downstream gene. RNA sequences within the previously characterized 13 nucleotide gene end, including a conserved sequence 3â€Č-UCAAU-5â€Č and a tract of U residues, are important for termination. In this study, two additional sequence elements outside of the 13 nucleotide gene end were found to modulate termination efficiency: the A residue upstream of the 3â€Č-UCAAU-5â€Č sequence, and the first nucleotide of the intergenic region when it follows a U4 tract

    Cells that express all five proteins of vesicular stomatitis virus from cloned cDNAs support replication, assembly, and budding of defective interfering particles

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    An alternative approach to structurefunction analysis of vesicular stomatitis virus (VSV) gene products and their interactions with one another during each phase of the viral life cycle is described. We showed previously by using the vaccinia viruslT7 RNA polymerase expression system that when cells expressing the nucleocapsid protein (N), the phosphoprotein (NS), and the large polymerase protein (L) of VSV were superinfected with defective interfering (DI) particles, rapid and efflicient replication and amplification of DI particle RNA occurred. Here, we demonstrate that all five VSV proteins can be expressed simultaneously when cells are cotransfected with plasmids containing the matrix protein (M) gene and the glycoprotein (G) gene of VSV in addition to plasmids containing the genes for the N, NS, and L proteins. When cells coexpressing all five VSV proteins were superinfected with DI particles, which because of their defectiveness are unable to express any viral proteins or to replicate, DI particle replication, assembly, and budding were observed and infectious DI particles were released into the culture fluids. Omission of either the M or G protein expression resulted in no DI particle budding. The vector-supported DI particles were similar in size and morphology to the authentic DI particles generated from cells coinfected with DI particles and helper VSV and their infectivity could be blocked by anti-VSV or anti-G antiserum. The successful replication, assembly, and budding of DI particles from cells expressing all five VSV proteins from cloned cDNAs provide a powerful approach for detailed structure-function analysis of the VSV gene products in each step of the replicative cycle of the virus

    Helical Virus Structure: The Case of the Rhabdovirus Bullet

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    Commentary on Ge, P.; Tsao, J.; Schein, S.; Green, T.J.; Luo, M.; Zhou, Z.H. Cryo-EM model of the bullet-shaped vesicular stomatitis virus. Science 2010, 327, 689–693

    Synthesis of Vesicular Stomatitis Virus Negative-Strand RNA In Vitro: Dependence on Viral Protein Synthesis

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    An in vitro system is described which supports the synthesis of vesicular stomatitis virus (VSV) negative-strand RNA. The major components of this system are (i) an mRNA-dependent rabbit reticulocyte lysate to carry out cell-free protein synthesis, (ii) the five VSV mRNAs to program VSV-specific protein synthesis, and (iii) nucleocapsids containing positive- and negative-strand genome-length RNA. The protein products synthesized in the system in response to addition of saturating amounts of the five VSV mRNA's included polypeptides which comigrated in acrylamide gels with the five VSV proteins. Approximately 200 pmol of protein per ml was synthesized during a 90-min reaction. The RNA products synthesized in the system included all five of the VSV mRNA's and, in addition, negative-strand, genome-sense RNA. All of the negative-strand RNA, which represented 2 to 5% of the total RNA product synthesized in vitro, banded in CsCl at the position of nucleocapsids. All of the mature mRNA's made in the system pelleted in CsCl. This technique allowed a clear separation of negative-strand product from the mRNA products and facilitated further analysis of the negative-strand product. The amount of negative-strand product produced in the system was shown to be a function of the amount of concurrent protein synthesis in the system. An increase in the level of protein synthesis led to an increase in the amount of negative-strand RNA synthesized, whereas inhibition of protein synthesis by cycloheximide resulted in a 70% inhibition of negative-strand synthesis. In contrast to the negative-strand RNA product, the amount of transcriptive product was decreased by 50% in the presence of maximum levels of viral protein synthesis. This inhibition was reversed by adding cycloheximide. Characterization of the negative-strand product by Northern blot analysis demonstrated that negative-strand product was being synthesized which hybridized to all five of the VSV mRNA's and, hence, that product representing all of the VSV cistrons was being made. This in vitro system offers an opportunity to study factors involved in the promotion of VSV genome replication as well as those responsible for the regulation of transcription

    Optimasi Portofolio Resiko Menggunakan Model Markowitz MVO Dikaitkan dengan Keterbatasan Manusia dalam Memprediksi Masa Depan dalam Perspektif Al-Qur`an

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    Risk portfolio on modern finance has become increasingly technical, requiring the use of sophisticated mathematical tools in both research and practice. Since companies cannot insure themselves completely against risk, as human incompetence in predicting the future precisely that written in Al-Quran surah Luqman verse 34, they have to manage it to yield an optimal portfolio. The objective here is to minimize the variance among all portfolios, or alternatively, to maximize expected return among all portfolios that has at least a certain expected return. Furthermore, this study focuses on optimizing risk portfolio so called Markowitz MVO (Mean-Variance Optimization). Some theoretical frameworks for analysis are arithmetic mean, geometric mean, variance, covariance, linear programming, and quadratic programming. Moreover, finding a minimum variance portfolio produces a convex quadratic programming, that is minimizing the objective function ðð„with constraintsð ð ð„ „ ðandðŽð„ = ð. The outcome of this research is the solution of optimal risk portofolio in some investments that could be finished smoothly using MATLAB R2007b software together with its graphic analysis

    Search for new particles in events with energetic jets and large missing transverse momentum in proton-proton collisions at root s=13 TeV

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    A search is presented for new particles produced at the LHC in proton-proton collisions at root s = 13 TeV, using events with energetic jets and large missing transverse momentum. The analysis is based on a data sample corresponding to an integrated luminosity of 101 fb(-1), collected in 2017-2018 with the CMS detector. Machine learning techniques are used to define separate categories for events with narrow jets from initial-state radiation and events with large-radius jets consistent with a hadronic decay of a W or Z boson. A statistical combination is made with an earlier search based on a data sample of 36 fb(-1), collected in 2016. No significant excess of events is observed with respect to the standard model background expectation determined from control samples in data. The results are interpreted in terms of limits on the branching fraction of an invisible decay of the Higgs boson, as well as constraints on simplified models of dark matter, on first-generation scalar leptoquarks decaying to quarks and neutrinos, and on models with large extra dimensions. Several of the new limits, specifically for spin-1 dark matter mediators, pseudoscalar mediators, colored mediators, and leptoquarks, are the most restrictive to date.Peer reviewe

    Combined searches for the production of supersymmetric top quark partners in proton-proton collisions at root s=13 TeV

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    A combination of searches for top squark pair production using proton-proton collision data at a center-of-mass energy of 13 TeV at the CERN LHC, corresponding to an integrated luminosity of 137 fb(-1) collected by the CMS experiment, is presented. Signatures with at least 2 jets and large missing transverse momentum are categorized into events with 0, 1, or 2 leptons. New results for regions of parameter space where the kinematical properties of top squark pair production and top quark pair production are very similar are presented. Depending on themodel, the combined result excludes a top squarkmass up to 1325 GeV for amassless neutralino, and a neutralinomass up to 700 GeV for a top squarkmass of 1150 GeV. Top squarks with masses from 145 to 295 GeV, for neutralino masses from 0 to 100 GeV, with a mass difference between the top squark and the neutralino in a window of 30 GeV around the mass of the top quark, are excluded for the first time with CMS data. The results of theses searches are also interpreted in an alternative signal model of dark matter production via a spin-0 mediator in association with a top quark pair. Upper limits are set on the cross section for mediator particle masses of up to 420 GeV

    MUSiC : a model-unspecific search for new physics in proton-proton collisions at root s=13TeV

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    Results of the Model Unspecific Search in CMS (MUSiC), using proton-proton collision data recorded at the LHC at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb(-1), are presented. The MUSiC analysis searches for anomalies that could be signatures of physics beyond the standard model. The analysis is based on the comparison of observed data with the standard model prediction, as determined from simulation, in several hundred final states and multiple kinematic distributions. Events containing at least one electron or muon are classified based on their final state topology, and an automated search algorithm surveys the observed data for deviations from the prediction. The sensitivity of the search is validated using multiple methods. No significant deviations from the predictions have been observed. For a wide range of final state topologies, agreement is found between the data and the standard model simulation. This analysis complements dedicated search analyses by significantly expanding the range of final states covered using a model independent approach with the largest data set to date to probe phase space regions beyond the reach of previous general searches.Peer reviewe

    Measurement of prompt open-charm production cross sections in proton-proton collisions at root s=13 TeV

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    The production cross sections for prompt open-charm mesons in proton-proton collisions at a center-of-mass energy of 13TeV are reported. The measurement is performed using a data sample collected by the CMS experiment corresponding to an integrated luminosity of 29 nb(-1). The differential production cross sections of the D*(+/-), D-+/-, and D-0 ((D) over bar (0)) mesons are presented in ranges of transverse momentum and pseudorapidity 4 < p(T) < 100 GeV and vertical bar eta vertical bar < 2.1, respectively. The results are compared to several theoretical calculations and to previous measurements.Peer reviewe
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