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Sample records for ii viral fusion

  1. Viral membrane fusion

    PubMed Central

    Harrison, Stephen C.

    2015-01-01

    Membrane fusion is an essential step when enveloped viruses enter cells. Lipid bilayer fusion requires catalysis to overcome a high kinetic barrier; viral fusion proteins are the agents that fulfill this catalytic function. Despite a variety of molecular architectures, these proteins facilitate fusion by essentially the same generic mechanism. Stimulated by a signal associated with arrival at the cell to be infected (e.g., receptor or co-receptor binding, proton binding in an endosome), they undergo a series of conformational changes. A hydrophobic segment (a “fusion loop” or “fusion peptide”) engages the target-cell membrane and collapse of the bridging intermediate thus formed draws the two membranes (virus and cell) together. We know of three structural classes for viral fusion proteins. Structures for both pre- and postfusion conformations of illustrate the beginning and end points of a process that can be probed by single-virion measurements of fusion kinetics. PMID:25866377

  2. Viral membrane fusion

    SciTech Connect

    Harrison, Stephen C.

    2015-05-15

    Membrane fusion is an essential step when enveloped viruses enter cells. Lipid bilayer fusion requires catalysis to overcome a high kinetic barrier; viral fusion proteins are the agents that fulfill this catalytic function. Despite a variety of molecular architectures, these proteins facilitate fusion by essentially the same generic mechanism. Stimulated by a signal associated with arrival at the cell to be infected (e.g., receptor or co-receptor binding, proton binding in an endosome), they undergo a series of conformational changes. A hydrophobic segment (a “fusion loop” or “fusion peptide”) engages the target-cell membrane and collapse of the bridging intermediate thus formed draws the two membranes (virus and cell) together. We know of three structural classes for viral fusion proteins. Structures for both pre- and postfusion conformations of illustrate the beginning and end points of a process that can be probed by single-virion measurements of fusion kinetics. - Highlights: • Viral fusion proteins overcome the high energy barrier to lipid bilayer merger. • Different molecular structures but the same catalytic mechanism. • Review describes properties of three known fusion-protein structural classes. • Single-virion fusion experiments elucidate mechanism.

  3. Class III viral membrane fusion proteins

    PubMed Central

    Backovic, Marija

    2010-01-01

    SUMMARY Accumulating structural studies of viral fusion glycoproteins have revealed unanticipated structural relationships between unrelated virus families and allowed the grouping of these membrane fusogens into three distinct classes. Here we review the newly identified group of class III viral fusion proteins, whose members include fusion proteins from rhabdoviruses, herpesviruses and baculoviruses. While clearly related in structure, the class III viral fusion proteins exhibit distinct structural features in their architectures as well as in their membrane-interacting fusion loops, which are likely related to their virus-specific differences in cellular entry. Further study of the similarities and differences in the class III viral fusion glycoproteins may provide greater insights into protein:membrane interactions that are key to promoting efficient bilayer fusion during virus entry. PMID:19356922

  4. Neutron diffraction studies of viral fusion peptides

    NASA Astrophysics Data System (ADS)

    Bradshaw, Jeremy P.; J. M. Darkes, Malcolm; Katsaras, John; Epand, Richard M.

    2000-03-01

    Membrane fusion plays a vital role in a large and diverse number of essential biological processes. Despite this fact, the precise molecular events that occur during fusion are still not known. We are currently engaged on a study of membrane fusion as mediated by viral fusion peptides. These peptides are the N-terminal regions of certain viral envelope proteins that mediate the process of fusion between the viral envelope and the membranes of the host cell during the infection process. As part of this study, we have carried out neutron diffraction measurements at the ILL, BeNSC and Chalk River, on a range of viral fusion peptides. The peptides, from simian immunodeficiency virus (SIV), influenza A and feline leukaemia virus (FeLV), were incorporated into stacked phospholipid bilayers. Some of the peptides had been specifically deuterated at key amino acids. Lamellar diffraction data were collected and analysed to yield information on the peptide conformation, location and orientation relative to the bilayer.

  5. Broad-spectrum antivirals against viral fusion

    PubMed Central

    Vigant, Frederic; Santos, Nuno C.; Lee, Benhur

    2015-01-01

    Effective antivirals have been developed against specific viruses, such as HIV, Hepatitis C virus and influenza virus. This ‘one bug–one drug’ approach to antiviral drug development can be successful, but it may be inadequate for responding to an increasing diversity of viruses that cause significant diseases in humans. The majority of viral pathogens that cause emerging and re-emerging infectious diseases are membrane-enveloped viruses, which require the fusion of viral and cell membranes for virus entry. Therefore, antivirals that target the membrane fusion process represent new paradigms for broad-spectrum antiviral discovery. In this Review, we discuss the mechanisms responsible for the fusion between virus and cell membranes and explore how broad-spectrum antivirals target this process to prevent virus entry. PMID:26075364

  6. The three lives of viral fusion peptides

    PubMed Central

    Apellániz, Beatriz; Huarte, Nerea; Largo, Eneko; Nieva, José L.

    2014-01-01

    Fusion peptides comprise conserved hydrophobic domains absolutely required for the fusogenic activity of glycoproteins from divergent virus families. After 30 years of intensive research efforts, the structures and functions underlying their high degree of sequence conservation are not fully elucidated. The long-hydrophobic viral fusion peptide (VFP) sequences are structurally constrained to access three successive states after biogenesis. Firstly, the VFP sequence must fulfill the set of native interactions required for (meta) stable folding within the globular ectodomains of glycoprotein complexes. Secondly, at the onset of the fusion process, they get transferred into the target cell membrane and adopt specific conformations therein. According to commonly accepted mechanistic models, membrane-bound states of the VFP might promote the lipid bilayer remodeling required for virus-cell membrane merger. Finally, at least in some instances, several VFPs co-assemble with transmembrane anchors into membrane integral helical bundles, following a locking movement hypothetically coupled to fusion-pore expansion. Here we review different aspects of the three major states of the VFPs, including the functional assistance by other membrane-transferring glycoprotein regions, and discuss briefly their potential as targets for clinical intervention. PMID:24704587

  7. Concepts in viral pathogenesis II

    SciTech Connect

    Notkins, A.L.; Oldstone, M.B.A.

    1986-01-01

    This paper contains papers divided among 10 sections. The section titles are: Viral Structure and Function; Viral Constructs; Oncogenes, Transfection, and Differentiation; Viral Tropism and Entry into Cells; Immune Recognition of Viruses; Evolving Concepts in Viral Pathogenesis Illustrated by Selected Plant and Animal Models; Evolving Concepts in Viral Pathogenesis Illustrated by Selected Diseases in Humans; New Trends in Diagnosis and Epidemiology; and Vaccines and Antiviral Therapy.

  8. Structures and Mechanisms of Viral Membrane Fusion Proteins

    PubMed Central

    White, Judith M.; Delos, Sue E.; Brecher, Matthew; Schornberg, Kathryn

    2009-01-01

    Recent work has identified three distinct classes of viral membrane fusion proteins based on structural criteria. In addition, there are at least four distinct mechanisms by which viral fusion proteins can be triggered to undergo fusion-inducing conformational changes. Viral fusion proteins also contain different types of fusion peptides and vary in their reliance on accessory proteins. These differing features combine to yield a rich diversity of fusion proteins. Yet despite this staggering diversity, all characterized viral fusion proteins convert from a fusion-competent state (dimers or trimers, depending on the class) to a membrane-embedded homotrimeric prehairpin, and then to a trimer-of-hairpins that brings the fusion peptide, attached to the target membrane, and the transmembrane domain, attached to the viral membrane, into close proximity thereby facilitating the union of viral and target membranes. During these conformational conversions, the fusion proteins induce membranes to progress through stages of close apposition, hemifusion, and then the formation of small, and finally large, fusion pores. Clearly, highly divergent proteins have converged on the same overall strategy to mediate fusion, an essential step in the life cycle of every enveloped virus. PMID:18568847

  9. Reduction of Influenza Virus Envelope's Fusogenicity by Viral Fusion Inhibitors.

    PubMed

    Rowse, Michael; Qiu, Shihong; Tsao, Jun; Yamauchi, Yohei; Wang, Guoxin; Luo, Ming

    2016-01-01

    During cell entry of an enveloped virus, the viral membrane must be fused with the cellular membrane. The virus envelope has a unique structure consisting of viral proteins and a virus-specific lipid composition, whereas the host membrane has its own structure with host membrane proteins. Compound 136 was previously found to bind in close proximity to the viral envelope and inhibit influenza virus entry. We showed here that the 136-treated influenza virus still caused hemolysis. When liposomes were used as the target membrane for 136-treated viruses, aberrant fusion occurred; few liposomes fused per virion, and glycoproteins were not distributed evenly across fusion complexes. Additionally, large fusion aggregates did not form, and in some instances, neck-like structures were found. Based on previous results and hemolysis, fusion inhibition by 136 occurs post-scission but prior to lipid mixing. PMID:27622947

  10. Class II virus membrane fusion proteins

    SciTech Connect

    Kielian, Margaret . E-mail: kielian@aecom.yu.edu

    2006-01-05

    Enveloped animal viruses fuse their membrane with a host cell membrane, thus delivering the virus genetic material into the cytoplasm and initiating infection. This critical membrane fusion reaction is mediated by a virus transmembrane protein known as the fusion protein, which inserts its hydrophobic fusion peptide into the cell membrane and refolds to drive the fusion reaction. This review describes recent advances in our understanding of the structure and function of the class II fusion proteins of the alphaviruses and flaviviruses. Inhibition of the fusion protein refolding reaction confirms its importance in fusion and suggests new antiviral strategies for these medically important viruses.

  11. INITIAL SIZE AND DYNAMICS OF VIRAL FUSION PORES ARE A FUNCTION OF THE FUSION PROTEIN MEDIATING MEMBRANE FUSION

    PubMed Central

    Plonsky, I.; Kingsley, D. H.; Rashtian, A.; Blank, P.S.; Zimmerberg, J.

    2013-01-01

    To investigate the role of the fusogenic protein in the initial size and dynamics of the pore that widens to finalize membrane fusion, two different fusion proteins expressed in the same cell line were investigated: the major glycoprotein of baculovirus Autographa californica (GP64) and the hemaggluttinin of influenza X31 (HA). The host Sf9 cells expressing these viral proteins, irrespective of protein species, fused to human red blood cells (RBC) upon acidification of the medium. High time resolution electrophysiological study of fusion pore conductance revealed fundamental differences in a) the initial pore conductance (pores created by HA were smaller than those created by GP64), b) the ability of pores to flicker (only HA-mediated pores flickered), and c) the time required for pore formation (HA-mediated pores took much longer to form following acidification). Thus 1) HA and GP64 have divergent electrophysiological phenotypes even when they fuse identical membranes, and 2) fusion proteins play a crucial role in determining initial fusion pore characteristics. The structure of the initial fusion pore detected by electrical conductance measurements is sensitive to the nature of the fusion protein. PMID:18208404

  12. Influenza viral membrane fusion is sensitive to sterol concentration but surprisingly robust to sterol chemical identity

    PubMed Central

    Zawada, Katarzyna E.; Wrona, Dominik; Rawle, Robert J.; Kasson, Peter M.

    2016-01-01

    Influenza virions are enriched in cholesterol relative to the plasma membrane from which they bud. Previous work has shown that fusion between influenza virus and synthetic liposomes is sensitive to the amount of cholesterol in either the virus or the target membrane. Here, we test the chemical properties of cholesterol required to promote influenza fusion by replacing cholesterol with other sterols and assaying viral fusion kinetics. We find that influenza fusion with liposomes is surprisingly robust to sterol chemical identity, showing no significant dependence on sterol identity in target membranes for any of the sterols tested. In the viral membrane, lanosterol slowed fusion somewhat, while polar sterols produced a more pronounced slowing and inhibition of fusion. No other sterols tested showed a significant perturbation in fusion rates, including ones previously shown to alter membrane bending moduli or phase behavior. Although fusion rates depend on viral cholesterol, they thus do not require cholesterol’s ability to support liquid-liquid phase coexistence. Using electron cryo-microscopy, we further find that sterol-dependent changes to hemagglutinin spatial patterning in the viral membrane do not require liquid-liquid phase coexistence. We therefore speculate that local sterol-hemagglutinin interactions in the viral envelope may control the rate-limiting step of fusion. PMID:27431907

  13. Influenza viral membrane fusion is sensitive to sterol concentration but surprisingly robust to sterol chemical identity.

    PubMed

    Zawada, Katarzyna E; Wrona, Dominik; Rawle, Robert J; Kasson, Peter M

    2016-01-01

    Influenza virions are enriched in cholesterol relative to the plasma membrane from which they bud. Previous work has shown that fusion between influenza virus and synthetic liposomes is sensitive to the amount of cholesterol in either the virus or the target membrane. Here, we test the chemical properties of cholesterol required to promote influenza fusion by replacing cholesterol with other sterols and assaying viral fusion kinetics. We find that influenza fusion with liposomes is surprisingly robust to sterol chemical identity, showing no significant dependence on sterol identity in target membranes for any of the sterols tested. In the viral membrane, lanosterol slowed fusion somewhat, while polar sterols produced a more pronounced slowing and inhibition of fusion. No other sterols tested showed a significant perturbation in fusion rates, including ones previously shown to alter membrane bending moduli or phase behavior. Although fusion rates depend on viral cholesterol, they thus do not require cholesterol's ability to support liquid-liquid phase coexistence. Using electron cryo-microscopy, we further find that sterol-dependent changes to hemagglutinin spatial patterning in the viral membrane do not require liquid-liquid phase coexistence. We therefore speculate that local sterol-hemagglutinin interactions in the viral envelope may control the rate-limiting step of fusion. PMID:27431907

  14. Premature Activation of the Paramyxovirus Fusion Protein before Target Cell Attachment with Corruption of the Viral Fusion Machinery*

    PubMed Central

    Farzan, Shohreh F.; Palermo, Laura M.; Yokoyama, Christine C.; Orefice, Gianmarco; Fornabaio, Micaela; Sarkar, Aurijit; Kellogg, Glen E.; Greengard, Olga; Porotto, Matteo; Moscona, Anne

    2011-01-01

    Paramyxoviruses, including the childhood pathogen human parainfluenza virus type 3, enter host cells by fusion of the viral and target cell membranes. This fusion results from the concerted action of its two envelope glycoproteins, the hemagglutinin-neuraminidase (HN) and the fusion protein (F). The receptor-bound HN triggers F to undergo conformational changes that render it competent to mediate fusion of the viral and cellular membranes. We proposed that, if the fusion process could be activated prematurely before the virion reaches the target host cell, infection could be prevented. We identified a small molecule that inhibits paramyxovirus entry into target cells and prevents infection. We show here that this compound works by an interaction with HN that results in F-activation prior to receptor binding. The fusion process is thereby prematurely activated, preventing fusion of the viral membrane with target cells and precluding viral entry. This first evidence that activation of a paramyxovirus F can be specifically induced before the virus contacts its target cell suggests a new strategy with broad implications for the design of antiviral agents. PMID:21799008

  15. Dynamic Viral Glycoprotein Machines: Approaches for Probing Transient States That Drive Membrane Fusion

    PubMed Central

    Garcia, Natalie K.; Lee, Kelly K.

    2016-01-01

    The fusion glycoproteins that decorate the surface of enveloped viruses undergo dramatic conformational changes in the course of engaging with target cells through receptor interactions and during cell entry. These refolding events ultimately drive the fusion of viral and cellular membranes leading to delivery of the genetic cargo. While well-established methods for structure determination such as X-ray crystallography have provided detailed structures of fusion proteins in the pre- and post-fusion fusion states, to understand mechanistically how these fusion glycoproteins perform their structural calisthenics and drive membrane fusion requires new analytical approaches that enable dynamic intermediate states to be probed. Methods including structural mass spectrometry, small-angle X-ray scattering, and electron microscopy have begun to provide new insight into pathways of conformational change and fusion protein function. In combination, the approaches provide a significantly richer portrait of viral fusion glycoprotein structural variation and fusion activation as well as inhibition by neutralizing agents. Here recent studies that highlight the utility of these complementary approaches will be reviewed with a focus on the well-characterized influenza virus hemagglutinin fusion glycoprotein system. PMID:26761026

  16. Dynamic Viral Glycoprotein Machines: Approaches for Probing Transient States That Drive Membrane Fusion.

    PubMed

    Garcia, Natalie K; Lee, Kelly K

    2016-01-01

    The fusion glycoproteins that decorate the surface of enveloped viruses undergo dramatic conformational changes in the course of engaging with target cells through receptor interactions and during cell entry. These refolding events ultimately drive the fusion of viral and cellular membranes leading to delivery of the genetic cargo. While well-established methods for structure determination such as X-ray crystallography have provided detailed structures of fusion proteins in the pre- and post-fusion fusion states, to understand mechanistically how these fusion glycoproteins perform their structural calisthenics and drive membrane fusion requires new analytical approaches that enable dynamic intermediate states to be probed. Methods including structural mass spectrometry, small-angle X-ray scattering, and electron microscopy have begun to provide new insight into pathways of conformational change and fusion protein function. In combination, the approaches provide a significantly richer portrait of viral fusion glycoprotein structural variation and fusion activation as well as inhibition by neutralizing agents. Here recent studies that highlight the utility of these complementary approaches will be reviewed with a focus on the well-characterized influenza virus hemagglutinin fusion glycoprotein system. PMID:26761026

  17. Roles of the Putative Integrin-Binding Motif of the Human Metapneumovirus Fusion (F) Protein in Cell-Cell Fusion, Viral Infectivity, and Pathogenesis

    PubMed Central

    Wei, Yongwei; Zhang, Yu; Cai, Hui; Mirza, Anne M.; Iorio, Ronald M.; Peeples, Mark E.; Niewiesk, Stefan

    2014-01-01

    ABSTRACT Human metapneumovirus (hMPV) is a relatively recently identified paramyxovirus that causes acute upper and lower respiratory tract infection. Entry of hMPV is unusual among the paramyxoviruses, in that fusion is accomplished by the fusion (F) protein without the attachment glycoprotein (G protein). It has been suggested that hMPV F protein utilizes integrin αvβ1 as a cellular receptor. Consistent with this, the F proteins of all known hMPV strains possess an integrin-binding motif (329RGD331). The role of this motif in viral entry, infectivity, and pathogenesis is poorly understood. Here, we show that α5β1 and αv integrins are essential for cell-cell fusion and hMPV infection. Mutational analysis found that residues R329 and G330 in the 329RGD331 motif are essential for cell-cell fusion, whereas mutations at D331 did not significantly impact fusion activity. Furthermore, fusion-defective RGD mutations were either lethal to the virus or resulted in recombinant hMPVs that had defects in viral replication in cell culture. In cotton rats, recombinant hMPV with the R329K mutation in the F protein (rhMPV-R329K) and rhMPV-D331A exhibited significant defects in viral replication in nasal turbinates and lungs. Importantly, inoculation of cotton rats with these mutants triggered a high level of neutralizing antibodies and protected against hMPV challenge. Taken together, our data indicate that (i) α5β1 and αv integrins are essential for cell-cell fusion and viral replication, (ii) the first two residues in the RGD motif are essential for fusion activity, and (iii) inhibition of the interaction of the integrin-RGD motif may serve as a new target to rationally attenuate hMPV for the development of live attenuated vaccines. IMPORTANCE Human metapneumovirus (hMPV) is one of the major causative agents of acute respiratory disease in humans. Currently, there is no vaccine or antiviral drug for hMPV. hMPV enters host cells via a unique mechanism, in that viral

  18. RTNS-II fusion materials irradiation facility

    SciTech Connect

    Heikkinen, D.W.; Tuckerman, D.B.; Davis, J.C.; Massoletti, D.J.; Short, D.W.

    1986-01-01

    The Rotating Target Neutron Source (RTNS-II) facility provides an intense source of 14-MeV neutrons for the fusion energy programs of Japan and the United States. Each of the two identical accelerator-based neutron sources is capable of providing source strengths in excess of 3 x 10/sup 13/ n/s using deuteron beam currents up to 150 mA. The present status of the facility, as well as the various upgrade options, will be described in detail.

  19. Disentangling Viral Membrane Fusion from Receptor Binding Using Synthetic DNA-Lipid Conjugates.

    PubMed

    Rawle, Robert J; Boxer, Steven G; Kasson, Peter M

    2016-07-12

    Enveloped viruses must bind to a receptor on the host membrane to initiate infection. Membrane fusion is subsequently initiated by a conformational change in the viral fusion protein, triggered by receptor binding, an environmental change, or both. Here, we present a strategy to disentangle the two processes of receptor binding and fusion using synthetic DNA-lipid conjugates to bind enveloped viruses to target membranes in the absence of receptor. This permits direct testing of whether receptor engagement affects the fusion mechanism as well as a comparison of fusion behavior across viruses with different receptor binding specificities. We demonstrate this approach by binding X-31 influenza virus to target vesicles and measuring the rates of individual pH-triggered lipid mixing events using fluorescence microscopy. Influenza lipid mixing kinetics are found to be independent of receptor binding, supporting the common yet previously unproven assumption that receptor binding does not produce any clustering or spatial rearrangement of viral hemagglutinin, which affects the rate-limiting step of pH-triggered fusion. This DNA-lipid tethering strategy should also allow the study of viruses where challenging receptor reconstitution has previously prevented single-virus fusion experiments. PMID:27410740

  20. Fusion Power Demonstrations I and II

    SciTech Connect

    Doggett, J.N.

    1985-01-01

    In this report we present a summary of the first phase of the Fusion Power Demonstration (FPD) design study. During this first phase, we investigated two configurations, performed detailed studies of major components, and identified and examined critical issues. In addition to these design specific studies, we also assembled a mirror-systems computer code to help optimize future device designs. The two configurations that we have studied are based on the MARS magnet configuration and are labeled FPD-I and FPD-II. The FPD-I configuration employs the same magnet set used in the FY83 FPD study, whereas the FPD-II magnets are a new, much smaller set chosen to help reduce the capital cost of the system. As part of the FPD study, we also identified and explored issues critical to the construction of an Engineering Test Reactor (ETR). These issues involve subsystems or components, which because of their cost or state of technology can have a significant impact on our ability to meet FPD's mission requirements on the assumed schedule. General Dynamics and Grumman Aerospace studied two of these systems, the high-field choke coil and the halo pump/direct converter, in great detail and their findings are presented in this report.

  1. Viral fusion protein transmembrane domain adopts β-strand structure to facilitate membrane topological changes for virus–cell fusion

    PubMed Central

    Yao, Hongwei; Lee, Michelle W.; Waring, Alan J.; Wong, Gerard C. L.; Hong, Mei

    2015-01-01

    The C-terminal transmembrane domain (TMD) of viral fusion proteins such as HIV gp41 and influenza hemagglutinin (HA) is traditionally viewed as a passive α-helical anchor of the protein to the virus envelope during its merger with the cell membrane. The conformation, dynamics, and lipid interaction of these fusion protein TMDs have so far eluded high-resolution structure characterization because of their highly hydrophobic nature. Using magic-angle-spinning solid-state NMR spectroscopy, we show that the TMD of the parainfluenza virus 5 (PIV5) fusion protein adopts lipid-dependent conformations and interactions with the membrane and water. In phosphatidylcholine (PC) and phosphatidylglycerol (PG) membranes, the TMD is predominantly α-helical, but in phosphatidylethanolamine (PE) membranes, the TMD changes significantly to the β-strand conformation. Measured order parameters indicate that the strand segments are immobilized and thus oligomerized. 31P NMR spectra and small-angle X-ray scattering (SAXS) data show that this β-strand–rich conformation converts the PE membrane to a bicontinuous cubic phase, which is rich in negative Gaussian curvature that is characteristic of hemifusion intermediates and fusion pores. 1H-31P 2D correlation spectra and 2H spectra show that the PE membrane with or without the TMD is much less hydrated than PC and PG membranes, suggesting that the TMD works with the natural dehydration tendency of PE to facilitate membrane merger. These results suggest a new viral-fusion model in which the TMD actively promotes membrane topological changes during fusion using the β-strand as the fusogenic conformation. PMID:26283363

  2. Phosphorylation of Nonmuscle myosin II-A regulatory light chain resists Sendai virus fusion with host cells

    PubMed Central

    Das, Provas; Saha, Shekhar; Chandra, Sunandini; Das, Alakesh; Dey, Sumit K.; Das, Mahua R.; Sen, Shamik; Sarkar, Debi P.; Jana, Siddhartha S.

    2015-01-01

    Enveloped viruses enter host cells through membrane fusion and the cells in turn alter their shape to accommodate components of the virus. However, the role of nonmuscle myosin II of the actomyosin complex of host cells in membrane fusion is yet to be understood. Herein, we show that both (−) blebbistatin, a specific inhibitor of nonmuscle myosin II (NMII) and small interfering RNA markedly augment fusion of Sendai virus (SeV), with chinese hamster ovary cells and human hepatocarcinoma cells. Inhibition of RLC phosphorylation using inhibitors against ROCK, but not PKC and MRCK, or overexpression of phospho-dead mutant of RLC enhances membrane fusion. SeV infection increases cellular stiffness and myosin light chain phosphorylation at two hour post infection. Taken together, the present investigation strongly indicates that Rho-ROCK-NMII contractility signaling pathway may provide a physical barrier to host cells against viral fusion. PMID:25993465

  3. Phosphorylation of Nonmuscle myosin II-A regulatory light chain resists Sendai virus fusion with host cells.

    PubMed

    Das, Provas; Saha, Shekhar; Chandra, Sunandini; Das, Alakesh; Dey, Sumit K; Das, Mahua R; Sen, Shamik; Sarkar, Debi P; Jana, Siddhartha S

    2015-01-01

    Enveloped viruses enter host cells through membrane fusion and the cells in turn alter their shape to accommodate components of the virus. However, the role of nonmuscle myosin II of the actomyosin complex of host cells in membrane fusion is yet to be understood. Herein, we show that both (-) blebbistatin, a specific inhibitor of nonmuscle myosin II (NMII) and small interfering RNA markedly augment fusion of Sendai virus (SeV), with chinese hamster ovary cells and human hepatocarcinoma cells. Inhibition of RLC phosphorylation using inhibitors against ROCK, but not PKC and MRCK, or overexpression of phospho-dead mutant of RLC enhances membrane fusion. SeV infection increases cellular stiffness and myosin light chain phosphorylation at two hour post infection. Taken together, the present investigation strongly indicates that Rho-ROCK-NMII contractility signaling pathway may provide a physical barrier to host cells against viral fusion. PMID:25993465

  4. Productive infection of human immunodeficiency virus type 1 in dendritic cells requires fusion-mediated viral entry

    SciTech Connect

    Janas, Alicia M.; Dong, Chunsheng; Wang Jianhua; Wu Li

    2008-06-05

    Human immunodeficiency virus type 1 (HIV-1) enters dendritic cells (DCs) through endocytosis and viral receptor-mediated fusion. Although endocytosis-mediated HIV-1 entry can generate productive infection in certain cell types, including human monocyte-derived macrophages, productive HIV-1 infection in DCs appears to be dependent on fusion-mediated viral entry. It remains to be defined whether endocytosed HIV-1 in DCs can initiate productive infection. Using HIV-1 infection and cellular fractionation assays to measure productive viral infection and entry, here we show that HIV-1 enters monocyte-derived DCs predominately through endocytosis; however, endocytosed HIV-1 cannot initiate productive HIV-1 infection in DCs. In contrast, productive HIV-1 infection in DCs requires fusion-mediated viral entry. Together, these results provide functional evidence in understanding HIV-1 cis-infection of DCs, suggesting that different pathways of HIV-1 entry into DCs determine the outcome of viral infection.

  5. Sendai virus-erythrocyte membrane interaction: quantitative and kinetic analysis of viral binding, dissociation, and fusion.

    PubMed

    Hoekstra, D; Klappe, K

    1986-04-01

    A kinetic and quantitative analysis of the binding and fusion of Sendai virus with erythrocyte membranes was performed by using a membrane fusion assay based on the relief of fluorescence self-quenching. At 37 degrees C, the process of virus association displayed a half time of 2.5 min; at 4 degrees C, the half time was 3.0 min. The fraction of the viral dose which became cell associated was independent of the incubation temperature and increased with increasing target membrane concentration. On the average, one erythrocyte ghost can accommodate ca. 1,200 Sendai virus particles. The stability of viral attachment was sensitive to a shift in temperature: a fraction of the virions (ca. 30%), attached at 4 degrees C, rapidly (half time, ca. 2.5 min) eluted from the cell surface at 37 degrees C, irrespective of the presence of free virus in the medium. The elution can be attributed to a spontaneous, temperature-induced release, rather than to viral neuraminidase activity. Competition experiments with nonlabeled virus revealed that viruses destined to fuse do not exchange with free particles in the medium but rather bind in a rapid and irreversible manner. The fusion rate of Sendai virus was affected by the density of the virus particles on the cell surface and became restrained when more than 170 virus particles were attached per ghost. In principle, all virus particles added displayed fusion activity. However, at high virus-to-ghost ratios, only a fraction actually fused, indicating that a limited number of fusion sites exist on the erythrocyte membrane. We estimate that ca. 180 virus particles maximally can fuse with one erythrocyte ghost. PMID:3005662

  6. The β-Lactamase Assay: Harnessing a FRET Biosensor to Analyse Viral Fusion Mechanisms.

    PubMed

    Jones, Daniel M; Padilla-Parra, Sergi

    2016-01-01

    The β-lactamase (BlaM) assay was first revealed in 1998 and was demonstrated to be a robust Förster resonance energy transfer (FRET)-based reporter system that was compatible with a range of commonly-used cell lines. Today, the BlaM assay is available commercially as a kit and can be utilised readily and inexpensively for an array of experimental procedures that require a fluorescence-based readout. One frequent application of the BlaM assay is the measurement of viral fusion-the moment at which the genetic material harboured within virus particles is released into the cytosol following successful entry. The flexibility of the system permits evaluation of not only total fusion levels, but also the kinetics of fusion. However, significant variation exists in the scientific literature regarding the methodology by which the assay is applied to viral fusion analysis, making comparison between results difficult. In this review we draw attention to the disparity of these methodologies and examine the advantages and disadvantages of each approach. Successful strategies shown to render viruses compatible with BlaM-based analyses are also discussed. PMID:27347948

  7. Click labeling of unnatural sugars metabolically incorporated into viral envelope glycoproteins enables visualization of single particle fusion.

    PubMed

    Oum, Yoon Hyeun; Desai, Tanay M; Marin, Mariana; Melikyan, Gregory B

    2016-07-01

    Enveloped viruses infect target cells by fusing their membrane with cellular membrane through a process that is mediated by specialized viral glycoproteins. The inefficient and highly asynchronous nature of viral fusion complicates studies of virus entry on a population level. Single virus imaging in living cells has become an important tool for delineating the entry pathways and for mechanistic studies of viral fusion. We have previously demonstrated that incorporation of fluorescent labels into the viral membrane and trapping fluorescent proteins in the virus interior enables the visualization of single virus fusion in living cells. Here, we implement a new approach to non-invasively label the viral membrane glycoproteins through metabolic incorporation of unnatural sugars followed by click-reaction with organic fluorescent dyes. This approach allows for efficient labeling of diverse viral fusion glycoproteins on the surface of HIV pseudoviruses. Incorporation of a content marker into surface-labeled viral particles enables sensitive detection of single virus fusion with live cells. PMID:27033181

  8. The β-Lactamase Assay: Harnessing a FRET Biosensor to Analyse Viral Fusion Mechanisms

    PubMed Central

    Jones, Daniel M.; Padilla-Parra, Sergi

    2016-01-01

    The β-lactamase (BlaM) assay was first revealed in 1998 and was demonstrated to be a robust Förster resonance energy transfer (FRET)-based reporter system that was compatible with a range of commonly-used cell lines. Today, the BlaM assay is available commercially as a kit and can be utilised readily and inexpensively for an array of experimental procedures that require a fluorescence-based readout. One frequent application of the BlaM assay is the measurement of viral fusion—the moment at which the genetic material harboured within virus particles is released into the cytosol following successful entry. The flexibility of the system permits evaluation of not only total fusion levels, but also the kinetics of fusion. However, significant variation exists in the scientific literature regarding the methodology by which the assay is applied to viral fusion analysis, making comparison between results difficult. In this review we draw attention to the disparity of these methodologies and examine the advantages and disadvantages of each approach. Successful strategies shown to render viruses compatible with BlaM-based analyses are also discussed. PMID:27347948

  9. Viral Membrane Fusion and Nucleocapsid Delivery into the Cytoplasm are Distinct Events in Some Flaviviruses

    PubMed Central

    Nour, Adel M.; Li, Yue; Wolenski, Joseph; Modis, Yorgo

    2013-01-01

    Flaviviruses deliver their genome into the cell by fusing the viral lipid membrane to an endosomal membrane. The sequence and kinetics of the steps required for nucleocapsid delivery into the cytoplasm remain unclear. Here we dissect the cell entry pathway of virions and virus-like particles from two flaviviruses using single-particle tracking in live cells, a biochemical membrane fusion assay and virus infectivity assays. We show that the virus particles fuse with a small endosomal compartment in which the nucleocapsid remains trapped for several minutes. Endosomal maturation inhibitors inhibit infectivity but not membrane fusion. We propose a flavivirus cell entry mechanism in which the virus particles fuse preferentially with small endosomal carrier vesicles and depend on back-fusion of the vesicles with the late endosomal membrane to deliver the nucleocapsid into the cytoplasm. Virus entry modulates intracellular calcium release and phosphatidylinositol-3-phosphate kinase signaling. Moreover, the broadly cross-reactive therapeutic antibody scFv11 binds to virus-like particles and inhibits fusion. PMID:24039574

  10. Crystal Structures of Beta- and Gammaretrovirus Fusion Proteins Reveal a Role for Electrostatic Stapling in Viral Entry

    PubMed Central

    Aydin, Halil; Cook, Jonathan D.

    2014-01-01

    Membrane fusion is a key step in the life cycle of all envelope viruses, but this process is energetically unfavorable; the transmembrane fusion subunit (TM) of the virion-attached glycoprotein actively catalyzes the membrane merger process. Retroviral glycoproteins are the prototypical system to study pH-independent viral entry. In this study, we determined crystal structures of extramembrane regions of the TMs from Mason-Pfizer monkey virus (MPMV) and xenotropic murine leukemia virus-related virus (XMRV) at 1.7-Å and 2.2-Å resolution, respectively. The structures are comprised of a trimer of hairpins that is characteristic of class I viral fusion proteins and now completes a structural library of retroviral fusion proteins. Our results allowed us to identify a series of intra- and interchain electrostatic interactions in the heptad repeat and chain reversal regions. Mutagenesis reveals that charge-neutralizing salt bridge mutations significantly destabilize the postfusion six-helix bundle and abrogate retroviral infection, demonstrating that electrostatic stapling of the fusion subunit is essential for viral entry. Our data indicate that salt bridges are a major stabilizing force on the MPMV and XMRV retroviral TMs and likely provide the key energetics for viral and host membrane fusion. PMID:24131724

  11. A fusion DNA vaccine that targets antigen-presenting cells increases protection from viral challenge

    NASA Astrophysics Data System (ADS)

    Deliyannis, Georgia; Boyle, Jefferey S.; Brady, Jamie L.; Brown, Lorena E.; Lew, Andrew M.

    2000-06-01

    Improving the immunological potency, particularly the Ab response, is a serious hurdle for the protective efficacy and hence broad application of DNA vaccines. We examined the immunogenicity and protective efficacy of a hemagglutinin-based influenza DNA vaccine that was targeted to antigen-presenting cells (APCs) by fusion to CTLA4. The targeted vaccine was shown to induce an accelerated and increased Ab response (as compared with those receiving the nontargeted control) that was predominated by IgG1 and recognized conformationally dependent viral epitopes. Moreover, mice receiving the APC-targeted DNA vaccine had significantly reduced viral titers (100-fold) after a nonlethal virus challenge. The increased protective efficacy was most likely because of increased Ab responses, as cytotoxic T lymphocyte responses were not enhanced. Targeting was demonstrated by direct binding studies of CTLA4 fusion proteins to the cognate ligand (B7; expressed on APCs in vivo). In addition, a targeted protein was detected at 4-fold higher levels in draining lymph nodes within 2-24 h of administration. Therefore, this study demonstrates that targeting DNA-encoded antigen to APCs results in enhanced immunity and strongly suggests that this approach may be useful in improving the protective efficacy of DNA vaccines.

  12. A fusion DNA vaccine that targets antigen-presenting cells increases protection from viral challenge

    PubMed Central

    Deliyannis, Georgia; Boyle, Jefferey S.; Brady, Jamie L.; Brown, Lorena E.; Lew, Andrew M.

    2000-01-01

    Improving the immunological potency, particularly the Ab response, is a serious hurdle for the protective efficacy and hence broad application of DNA vaccines. We examined the immunogenicity and protective efficacy of a hemagglutinin-based influenza DNA vaccine that was targeted to antigen-presenting cells (APCs) by fusion to CTLA4. The targeted vaccine was shown to induce an accelerated and increased Ab response (as compared with those receiving the nontargeted control) that was predominated by IgG1 and recognized conformationally dependent viral epitopes. Moreover, mice receiving the APC-targeted DNA vaccine had significantly reduced viral titers (100-fold) after a nonlethal virus challenge. The increased protective efficacy was most likely because of increased Ab responses, as cytotoxic T lymphocyte responses were not enhanced. Targeting was demonstrated by direct binding studies of CTLA4 fusion proteins to the cognate ligand (B7; expressed on APCs in vivo). In addition, a targeted protein was detected at 4-fold higher levels in draining lymph nodes within 2–24 h of administration. Therefore, this study demonstrates that targeting DNA-encoded antigen to APCs results in enhanced immunity and strongly suggests that this approach may be useful in improving the protective efficacy of DNA vaccines. PMID:10823919

  13. RNA polymerase II is aberrantly phosphorylated and localized to viral replication compartments following herpes simplex virus infection.

    PubMed Central

    Rice, S A; Long, M C; Lam, V; Spencer, C A

    1994-01-01

    During lytic infection, herpes simplex virus subverts the host cell RNA polymerase II transcription machinery to efficiently express its own genome while repressing the expression of most cellular genes. The mechanism by which RNA polymerase II is directed to the viral delayed-early and late genes is still unresolved. We report here that RNA polymerase II is preferentially localized to viral replication compartments early after infection with herpes simplex virus type 1. Concurrent with recruitment of RNA polymerase II into viral compartments is a rapid and aberrant phosphorylation of the large subunit carboxy-terminal domain (CTD). Aberrant phosphorylation of the CTD requires early viral gene expression but is not dependent on viral DNA replication or on the formation of viral replication compartments. Localization of RNA polymerase II and modifications to the CTD may be instrumental in favoring transcription of viral genes and repressing specific transcription of cellular genes. Images PMID:8289400

  14. Clustering and Mobility of HIV-1 Env at Viral Assembly Sites Predict Its Propensity To Induce Cell-Cell Fusion

    PubMed Central

    Roy, Nathan H.; Chan, Jany; Lambelé, Marie

    2013-01-01

    HIV-1 Env mediates virus attachment to and fusion with target cell membranes, and yet, while Env is still situated at the plasma membrane of the producer cell and before its incorporation into newly formed particles, Env already interacts with the viral receptor CD4 on target cells, thus enabling the formation of transient cell contacts that facilitate the transmission of viral particles. During this first encounter with the receptor, Env must not induce membrane fusion, as this would prevent the producer cell and the target cell from separating upon virus transmission, but how Env's fusion activity is controlled remains unclear. To gain a better understanding of the Env regulation that precedes viral transmission, we examined the nanoscale organization of Env at the surface of producer cells. Utilizing superresolution microscopy (stochastic optical reconstruction microscopy [STORM]) and fluorescence recovery after photobleaching (FRAP), we quantitatively assessed the clustering and dynamics of Env upon its arrival at the plasma membrane. We found that Gag assembly induced the aggregation of small Env clusters into larger domains and that these domains were completely immobile. Truncation of the cytoplasmic tail (CT) of Env abrogated Gag's ability to induce Env clustering and restored Env mobility at assembly sites, both of which correlated with increased Env-induced fusion of infected and uninfected cells. Hence, while Env trapping by Gag secures Env incorporation into viral particles, Env clustering and its sequestration at assembly sites likely also leads to the repression of its fusion function, and thus, by preventing the formation of syncytia, Gag helps to secure efficient transfer of viral particles to target cells. PMID:23637402

  15. Interaction between the Hemagglutinin-Neuraminidase and Fusion Glycoproteins of Human Parainfluenza Virus Type III Regulates Viral Growth In Vivo

    PubMed Central

    Xu, Rui; Palmer, Samantha G.; Porotto, Matteo; Palermo, Laura M.; Niewiesk, Stefan; Wilson, Ian A.; Moscona, Anne

    2013-01-01

    ABSTRACT Paramyxoviruses, enveloped RNA viruses that include human parainfluenza virus type 3 (HPIV3), cause the majority of childhood viral pneumonia. HPIV3 infection starts when the viral receptor-binding protein engages sialic acid receptors in the lung and the viral envelope fuses with the target cell membrane. Fusion/entry requires interaction between two viral surface glycoproteins: tetrameric hemagglutinin-neuraminidase (HN) and fusion protein (F). In this report, we define structural correlates of the HN features that permit infection in vivo. We have shown that viruses with an HN-F that promotes growth in cultured immortalized cells are impaired in differentiated human airway epithelial cell cultures (HAE) and in vivo and evolve in HAE into viable viruses with less fusogenic HN-F. In this report, we identify specific structural features of the HN dimer interface that modulate HN-F interaction and fusion triggering and directly impact infection. Crystal structures of HN, which promotes viral growth in vivo, show a diminished interface in the HN dimer compared to the reference strain’s HN, consistent with biochemical and biological data indicating decreased dimerization and decreased interaction with F protein. The crystallographic data suggest a structural explanation for the HN’s altered ability to activate F and reveal properties that are critical for infection in vivo. IMPORTANCE Human parainfluenza viruses cause the majority of childhood cases of croup, bronchiolitis, and pneumonia worldwide. Enveloped viruses must fuse their membranes with the target cell membranes in order to initiate infection. Parainfluenza fusion proceeds via a multistep reaction orchestrated by the two glycoproteins that make up its fusion machine. In vivo, viruses adapt for survival by evolving to acquire a set of fusion machinery features that provide key clues about requirements for infection in human beings. Infection of the lung by parainfluenzavirus is determined by

  16. Herpes Simplex Virus 1 gN Partners with gM To Modulate the Viral Fusion Machinery

    PubMed Central

    El Kasmi, Imane

    2014-01-01

    ABSTRACT Herpes simplex virus 1 (HSV-1) capsids are assembled in the nucleus, where they incorporate the viral genome. They then transit through the two nuclear membranes and are wrapped by a host-derived envelope. In the process, several HSV-1 proteins are targeted to the nuclear membranes, but their roles in viral nuclear egress are unclear. Among them, glycoprotein M (gM), a known modulator of virus-induced membrane fusion, is distributed on both the inner and outer nuclear membranes at the early stages of the infection, when no other viral glycoproteins are yet present there. Later on, it is found on perinuclear virions and ultimately redirected to the trans-Golgi network (TGN), where it cycles with the cell surface. In contrast, transfected gM is found only at the TGN and cell surface, hinting at an interaction with other viral proteins. Interestingly, many herpesvirus gM analogs interact with their gN counterparts, which typically alters their intracellular localization. To better understand how HSV-1 gM localization is regulated, we evaluated its ability to bind gN and discovered it does so in both transfected and infected cells, an interaction strongly weakened by the deletion of the gM amino terminus. Functionally, while gN had no impact on gM localization, gM redirected gN from the endoplasmic reticulum (ER) to the TGN. Most interestingly, gN overexpression stimulated the formation of syncytia in the context of an infection by a nonsyncytial strain, indicating that gM and gN not only physically but also functionally interact and that gN modulates gM's activity on membrane fusion. IMPORTANCE HSV-1 gM is an important modulator of virally induced cell-cell fusion and viral entry, a process that is likely finely modulated in time and space. Until now, little was known of the proteins that regulate gM's activity. In parallel, gM is found in various intracellular locations at different moments, ranging from nuclear membranes, perinuclear virions, the TGN, cell

  17. Novel Inhibitors of Influenza Virus Fusion: Structure-Activity Relationship and Interaction with the Viral Hemagglutinin▿

    PubMed Central

    Vanderlinden, Evelien; Göktaş, Fusun; Cesur, Zafer; Froeyen, Matheus; Reed, Mark L.; Russell, Charles J.; Cesur, Nesrin; Naesens, Lieve

    2010-01-01

    A new class of N-(1-thia-4-azaspiro[4.5]decan-4-yl)carboxamide inhibitors of influenza virus hemagglutinin (HA)-mediated membrane fusion that has a narrow and defined structure-activity relationship was identified. In Madin-Darby canine kidney (MDCK) cells infected with different strains of human influenza virus A/H3N2, the lead compound, 4c, displayed a 50% effective concentration of 3 to 23 μM and an antiviral selectivity index of 10. No activity was observed for A/H1N1, A/H5N1, A/H7N2, and B viruses. The activity of 4c was reduced considerably when added 30 min or later postinfection, indicating that 4c inhibits an early step in virus replication. 4c and its congeners inhibited influenza A/H3N2 virus-induced erythrocyte hemolysis at low pH. 4c-resistant virus mutants, selected in MDCK cells, contained either a single D112N change in the HA2 subunit of the viral HA or a combination of three substitutions, i.e., R220S (in HA1) and E57K (in HA2) and an A-T substitution at position 43 or 96 of HA2. The mutants showed efficiency for receptor binding and replication similar to that of wild-type virus yet displayed an increased pH of erythrocyte hemolysis. In polykaryon assays with cells expressing single-mutant HA proteins, the E57K, A96T, and D112N mutations resulted in 4c resistance, and the HA proteins containing R220S, A96T, and D112N mutations displayed an increased fusion pH. Molecular modeling identified a binding cavity for 4c involving arginine-54 and glutamic acid-57 in the HA2 subunit. Our studies with the new fusion inhibitor 4c confirm the importance of this HA region in the development of influenza virus fusion inhibitors. PMID:20181685

  18. Contribution of N-linked glycans on HSV-2 gB to cell–cell fusion and viral entry

    SciTech Connect

    Luo, Sukun; Hu, Kai; He, Siyi; Wang, Ping; Zhang, Mudan; Huang, Xin; Du, Tao; Zheng, Chunfu; Liu, Yalan; Hu, Qinxue

    2015-09-15

    HSV-2 is the major cause of genital herpes and its infection increases the risk of HIV-1 acquisition and transmission. HSV-2 glycoprotein B together with glycoproteins D, H and L are indispensable for viral entry, of which gB, as a class III fusogen, plays an essential role. HSV-2 gB has seven potential N-linked glycosylation (N-CHO) sites, but their significance has yet to be determined. For the first time, we systematically analyzed the contributions of N-linked glycans on gB to cell–cell fusion and viral entry. Our results demonstrated that, of the seven potential N-CHO sites on gB, mutation at N390, N483 or N668 decreased cell–cell fusion and viral entry, while mutation at N133 mainly affected protein expression and the production of infectious virus particles by blocking the transport of gB from the endoplasmic reticulum to Golgi. Our findings highlight the significance of N-linked glycans on HSV-2 gB expression and function. - Highlights: • N-linked glycan at N133 is important for gB intracellular trafficking and maturation. • N-linked glycans at N390, N483 and N668 on gB are necessary for optimal cell–cell fusion. • N-linked glycans at N390, N483 and N668 on gB are necessary for optimal viral entry.

  19. Cell-to-Cell Transfer of HIV-1 via Virological Synapses Leads to Endosomal Virion Maturation that Activates Viral Membrane Fusion

    PubMed Central

    Dale, Benjamin M.; McNerney, Gregory P.; Thompson, Deanna L.; Hubner, Wolfgang; de los Reyes, Kevin; Chuang, Frank Y.S.; Huser, Thomas; Chen, Benjamin K.

    2012-01-01

    SUMMARY HIV-1 can infect T cells by cell-free virus or by direct virion transfer between cells through cell contact-induced structures called virological synapses (VS). During VS-mediated infection, virions accumulate within target cell endosomes. We show that after crossing the VS, the transferred virus undergoes both maturation and viral membrane fusion. Following VS transfer, viral membrane fusion occurs with delayed kinetics and transferred virions display reduced sensitivity to patient antisera compared to mature, cell-free virus. Furthermore, particle fusion requires that the transferred virions undergo proteolytic maturation within acceptor cell endosomes, which occurs over several hours. Rapid, live cell confocal microscopy demonstrated that viral fusion can occur in compartments that have moved away from the VS. Thus, HIV particle maturation activates viral fusion in target CD4+ T cell endosomes following transfer across the VS and may represent a pathway by which HIV evades antibody neutralization. PMID:22177560

  20. Maturation of the viral core enhances the fusion of HIV-1 particles with primary human T cells and monocyte-derived macrophages

    SciTech Connect

    Jiang Jiyang; Aiken, Christopher . E-mail: chris.aiken@vanderbilt.edu

    2006-03-15

    HIV-1 infection requires fusion of viral and cellular membranes in a reaction catalyzed by the viral envelope proteins gp120 and gp41. We recently reported that efficient HIV-1 particle fusion with target cells is linked to maturation of the viral core by an activity of the gp41 cytoplasmic domain. Here, we show that maturation enhances the fusion of a variety of recombinant viruses bearing primary and laboratory-adapted Env proteins with primary human CD4{sup +} T cells. Overall, HIV-1 fusion was more dependent on maturation for viruses bearing X4-tropic envelope proteins than for R5-tropic viruses. Fusion of HIV-1 with monocyte-derived macrophages was also dependent on particle maturation. We conclude that the ability to couple fusion to particle maturation is a common feature of HIV-1 Env proteins and may play an important role during HIV-1 replication in vivo.

  1. Inhibition of Nipah Virus Infectin In Vivo: Targeting an Early Stage of Paramyxovirus Fusion Activation during Viral Entry

    SciTech Connect

    M Porotto; B Rockx; C Yokoyama; A Talekar; I DeVito; l Palermo; J Liu; R Cortese; M Lu; et al.

    2011-12-31

    In the paramyxovirus cell entry process, receptor binding triggers conformational changes in the fusion protein (F) leading to viral and cellular membrane fusion. Peptides derived from C-terminal heptad repeat (HRC) regions in F have been shown to inhibit fusion by preventing formation of the fusogenic six-helix bundle. We recently showed that the addition of a cholesterol group to HRC peptides active against Nipah virus targets these peptides to the membrane where fusion occurs, dramatically increasing their antiviral effect. In this work, we report that unlike the untagged HRC peptides, which bind to the postulated extended intermediate state bridging the viral and cell membranes, the cholesterol tagged HRC-derived peptides interact with F before the fusion peptide inserts into the target cell membrane, thus capturing an earlier stage in the F-activation process. Furthermore, we show that cholesterol tagging renders these peptides active in vivo: the cholesterol-tagged peptides cross the blood brain barrier, and effectively prevent and treat in an established animal model what would otherwise be fatal Nipah virus encephalitis. The in vivo efficacy of cholesterol-tagged peptides, and in particular their ability to penetrate the CNS, suggests that they are promising candidates for the prevention or therapy of infection by Nipah and other lethal paramyxoviruses.

  2. The Membrane Fusion Step of Vaccinia Virus Entry Is Cooperatively Mediated by Multiple Viral Proteins and Host Cell Components

    PubMed Central

    Laliberte, Jason P.; Weisberg, Andrea S.; Moss, Bernard

    2011-01-01

    For many viruses, one or two proteins allow cell attachment and entry, which occurs through the plasma membrane or following endocytosis at low pH. In contrast, vaccinia virus (VACV) enters cells by both neutral and low pH routes; four proteins mediate cell attachment and twelve that are associated in a membrane complex and conserved in all poxviruses are dedicated to entry. The aim of the present study was to determine the roles of cellular and viral proteins in initial stages of entry, specifically fusion of the membranes of the mature virion and cell. For analysis of the role of cellular components, we used well characterized inhibitors and measured binding of a recombinant VACV virion containing Gaussia luciferase fused to a core protein; viral and cellular membrane lipid mixing with a self-quenching fluorescent probe in the virion membrane; and core entry with a recombinant VACV expressing firefly luciferase and electron microscopy. We determined that inhibitors of tyrosine protein kinases, dynamin GTPase and actin dynamics had little effect on binding of virions to cells but impaired membrane fusion, whereas partial cholesterol depletion and inhibitors of endosomal acidification and membrane blebbing had a severe effect at the later stage of core entry. To determine the role of viral proteins, virions lacking individual membrane components were purified from cells infected with members of a panel of ten conditional-lethal inducible mutants. Each of the entry protein-deficient virions had severely reduced infectivity and except for A28, L1 and L5 greatly impaired membrane fusion. In addition, a potent neutralizing L1 monoclonal antibody blocked entry at a post-membrane lipid-mixing step. Taken together, these results suggested a 2-step entry model and implicated an unprecedented number of viral proteins and cellular components involved in signaling and actin rearrangement for initiation of virus-cell membrane fusion during poxvirus entry. PMID:22194690

  3. N-Glycans on the Nipah Virus Attachment Glycoprotein Modulate Fusion and Viral Entry as They Protect against Antibody Neutralization

    PubMed Central

    Biering, Scott B.; Huang, Andrew; Vu, Andy T.; Robinson, Lindsey R.; Bradel-Tretheway, Birgit; Choi, Eric

    2012-01-01

    Nipah virus (NiV) is the deadliest known paramyxovirus. Membrane fusion is essential for NiV entry into host cells and for the virus' pathological induction of cell-cell fusion (syncytia). The mechanism by which the attachment glycoprotein (G), upon binding to the cell receptors ephrinB2 or ephrinB3, triggers the fusion glycoprotein (F) to execute membrane fusion is largely unknown. N-glycans on paramyxovirus glycoproteins are generally required for proper protein conformational integrity, transport, and sometimes biological functions. We made conservative mutations (Asn to Gln) at the seven potential N-glycosylation sites in the NiV G ectodomain (G1 to G7) individually or in combination. Six of the seven N-glycosylation sites were found to be glycosylated. Moreover, pseudotyped virions carrying these N-glycan mutants had increased antibody neutralization sensitivities. Interestingly, our results revealed hyperfusogenic and hypofusogenic phenotypes for mutants that bound ephrinB2 at wild-type levels, and the mutant's cell-cell fusion phenotypes generally correlated to viral entry levels. In addition, when removing multiple N-glycans simultaneously, we observed synergistic or dominant-negative membrane fusion phenotypes. Interestingly, our data indicated that 4- to 6-fold increases in fusogenicity resulted from multiple mechanisms, including but not restricted to the increase of F triggering. Altogether, our results suggest that NiV-G N-glycans play a role in shielding virions against antibody neutralization, while modulating cell-cell fusion and viral entry via multiple mechanisms. PMID:22915812

  4. vCCL2/vMIP-II, the viral master KEYmokine.

    PubMed

    Szpakowska, Martyna; Chevigné, Andy

    2016-06-01

    Viral CC motif chemokine or viral macrophage inflammatory protein-II is 1 of the 3 chemokines encoded by the human herpesvirus-8 to interfere with the host chemokine receptor network, facilitate the immune escape, and promote its survival. Viral CC motif chemokine 2 binds to a broad spectrum of viral and human chemokine receptors of all 4 classes and, depending on the receptor, acts either as an agonist or an antagonist, inducing or blocking the recruitment of specific immune cell subsets. These atypical binding and signaling properties make this viral chemokine not only a useful tool to investigate the complexity of the chemokine-receptor interaction network or the virus-host interplay but also for the development of receptor inhibitors. This mini-review summarizes the knowledge currently available on viral CC motif chemokine 2 binding, signaling, and structural mimicry and discusses its role and importance for the virus, the therapeutic potential, and the open questions regarding the biology of this fascinating chemokine. PMID:26701133

  5. Mutations in the Cytoplasmic Domain of the Newcastle Disease Virus Fusion Protein Confer Hyperfusogenic Phenotypes Modulating Viral Replication and Pathogenicity

    PubMed Central

    Samal, Sweety; Khattar, Sunil K.; Paldurai, Anandan; Palaniyandi, Senthilkumar; Zhu, Xiaoping; Collins, Peter L.

    2013-01-01

    The Newcastle disease virus (NDV) fusion protein (F) mediates fusion of viral and host cell membranes and is a major determinant of NDV pathogenicity. In the present study, we demonstrate the effects of functional properties of F cytoplasmic tail (CT) amino acids on virus replication and pathogenesis. Out of a series of C-terminal deletions in the CT, we were able to rescue mutant viruses lacking two or four residues (rΔ2 and rΔ4). We further rescued viral mutants with individual amino acid substitutions at each of these four terminal residues (rM553A, rK552A, rT551A, and rT550A). In addition, the NDV F CT has two conserved tyrosine residues (Y524 and Y527) and a dileucine motif (LL536-537). In other paramyxoviruses, these residues were shown to affect fusion activity and are central elements in basolateral targeting. The deletion of 2 and 4 CT amino acids and single tyrosine substitution resulted in hyperfusogenic phenotypes and increased viral replication and pathogenesis. We further found that in rY524A and rY527A viruses, disruption of the targeting signals did not reduce the expression on the apical or basolateral surface in polarized Madin-Darby canine kidney cells, whereas in double tyrosine mutant, it was reduced on both the apical and basolateral surfaces. Interestingly, in rL536A and rL537A mutants, the F protein expression was more on the apical than on the basolateral surface, and this effect was more pronounced in the rL537A mutant. We conclude that these wild-type residues in the NDV F CT have an effect on regulating F protein biological functions and thus modulating viral replication and pathogenesis. PMID:23843643

  6. RTNS-II - a fusion materials research tool

    NASA Astrophysics Data System (ADS)

    Logan, C. M.; Heikkinen, D. W.

    1982-09-01

    Rotating Target Neutron Source-II (RTNS-II) is a national facility for fusion materials research. It contains two 14 MeV neutron sources. Deuterons are accelerated to ˜ 400 keV and transported to a rotating titanium tritide target. Present source strength is greater than 1 × 10 13 n/s and source diameter is 1 cm fwhm. An air-levitated vacuum seal permits rotation of the target at 5000 rpm with negligible impact on accelerator vacuum system gas load. Targets are cooled by chilled water flowing through internal channels in a copper alloy substrate. Substrates are produced by solid-state diffusion bonding of two sheets, one containing etched cooling channels. An electroforming process is being developed which will reduce substrate cost and improve reliability. Titanium tritide coating thickness is ˜ 10 μm giving an initial tritium inventory for the present 23 cm diameter targets of 3.7 × 10 7 MBq. Operating interval between target changes is typically about 80 h. Thirteen laboratories and universities have participated in the experimental program at RTNS-II. Most measurements have been directed at understanding defect production and low-dose damage microstructure. The principal diagnostic tools have been cryogenic resistivity measurements, mechanical properties assessment and transmission electron microscopy. Some engineering tests have been conducted in support of near-term magnetic confinement experiments and of reactor materials which will see small lifetime doses.

  7. Kinetically coupled folding of a single HIV-1 glycoprotein 41 complex in viral membrane fusion and inhibition

    PubMed Central

    Jiao, Junyi; Rebane, Aleksander A.; Ma, Lu; Gao, Ying; Zhang, Yongli

    2015-01-01

    HIV-1 glycoprotein 41 (gp41) mediates viral entry into host cells by coupling its folding energy to membrane fusion. Gp41 folding is blocked by fusion inhibitors, including the commercial drug T20, to treat HIV/AIDS. However, gp41 folding intermediates, energy, and kinetics are poorly understood. Here, we identified the folding intermediates of a single gp41 trimer-of-hairpins and measured their associated energy and kinetics using high-resolution optical tweezers. We found that folding of gp41 hairpins was energetically independent but kinetically coupled: Each hairpin contributed a folding energy of ∼−23 kBT, but folding of one hairpin successively accelerated the folding rate of the next one by ∼20-fold. Membrane-mimicking micelles slowed down gp41 folding and reduced the stability of the six-helix bundle. However, the stability was restored by cooperative folding of the membrane-proximal external region. Surprisingly, T20 strongly inhibited gp41 folding by actively displacing the C-terminal hairpin strand in a force-dependent manner. The inhibition was abolished by a T20-resistant gp41 mutation. The energetics and kinetics of gp41 folding established by us provides a basis to understand viral membrane fusion, infection, and therapeutic intervention. PMID:26038562

  8. Aqueous extract from a Chaga medicinal mushroom, Inonotus obliquus (higher Basidiomycetes), prevents herpes simplex virus entry through inhibition of viral-induced membrane fusion.

    PubMed

    Pan, Hong-Hui; Yu, Xiong-Tao; Li, Ting; Wu, Hong-Ling; Jiao, Chun-Wei; Cai, Mian-Hua; Li, Xiang-Min; Xie, Yi-Zhen; Wang, Yi; Peng, Tao

    2013-01-01

    Chaga medicinal mushroom, Inonotus obliquus, a popular prescription in traditional medicine in Europe and Asia, was used to reduce inflammation in the nasopharynx and to facilitate breathing. The aqueous extract from I. obliquus (AEIO) exhibited marked decrease in herpes simplex virus (HSV) infection (the 50% inhibitory concentration was 3.82 μg/mL in the plaque reduction assay and 12.29 μg/mL in the HSV-1/blue assay) as well as safety in Vero cells (the 50% cellular cytotoxicity was > 1 mg/mL, and selection index was > 80). Using a time course assay, effective stage analysis, and fusion inhibition assay, the mechanism of anti-HSV activity was found against the early stage of viral infection through inhibition of viral-induced membrane fusion. Therefore, AEIO could effectively prevent HSV-1 entry by acting on viral glycoproteins, leading to the prevention of membrane fusion, which is different from nucleoside analog antiherpetics. PMID:23510282

  9. A Multiepitope Fusion Antigen Elicits Neutralizing Antibodies against Enterotoxigenic Escherichia coli and Homologous Bovine Viral Diarrhea Virus In Vitro

    PubMed Central

    Hashish, Emad A.; Zhang, Chengxian; Ruan, Xiaosai; Knudsen, David E.; Chase, Christopher C.; Isaacson, Richard E.; Zhou, Guoqiang

    2013-01-01

    Diarrhea is one of the most important bovine diseases. Enterotoxigenic Escherichia coli (ETEC) and bovine viral diarrhea virus (BVDV) are the major causes of diarrhea in calves and cattle. ETEC expressing K99 (F5) fimbriae and heat-stable type Ia (STa) toxin are the leading bacteria causing calf diarrhea, and BVDV causes diarrhea and other clinical illnesses in cattle of all ages. It is reported that maternal immunization with K99 fimbrial antigens provides passive protection to calves against K99 fimbrial ETEC and that BVDV major structural protein E2 elicits antibodies neutralizing against BVDV viral infection. Vaccines inducing anti-K99 and anti-STa immunity would protect calves more effectively against ETEC diarrhea, and those also inducing anti-E2 neutralizing antibodies would protect calves and cattle against diarrhea caused by both ETEC and BVDV. In this study, we used the ETEC K99 major subunit FanC as a backbone, genetically embedded the STa toxoid STaP12F and the most-antigenic B-cell epitope and T-cell epitope predicted from the BVDV E2 glycoprotein into FanC for the multivalent antigen FanC-STa-E2, and examined immunogenicity of this multivalent antigen to assess vaccine potential against bovine diarrhea. Mice intraperitoneally (i.p.) immunized with this multivalent antigen developed anti-K99, anti-STa, and anti-BVDV antibodies. Moreover, elicited antibodies showed neutralization activities, as they inhibited adherence of K99 fimbrial E. coli, neutralized STa toxin, and prevented homologous BVDV viral infection in vitro. Results from this study suggest that this multiepitope fusion antigen can potentially be developed as a vaccine for broad protection against bovine diarrhea and that the multiepitope fusion strategy may be generally applied for multivalent vaccine development against heterogeneous pathogens. PMID:23697572

  10. A multiepitope fusion antigen elicits neutralizing antibodies against enterotoxigenic Escherichia coli and homologous bovine viral diarrhea virus in vitro.

    PubMed

    Hashish, Emad A; Zhang, Chengxian; Ruan, Xiaosai; Knudsen, David E; Chase, Christopher C; Isaacson, Richard E; Zhou, Guoqiang; Zhang, Weiping

    2013-07-01

    Diarrhea is one of the most important bovine diseases. Enterotoxigenic Escherichia coli (ETEC) and bovine viral diarrhea virus (BVDV) are the major causes of diarrhea in calves and cattle. ETEC expressing K99 (F5) fimbriae and heat-stable type Ia (STa) toxin are the leading bacteria causing calf diarrhea, and BVDV causes diarrhea and other clinical illnesses in cattle of all ages. It is reported that maternal immunization with K99 fimbrial antigens provides passive protection to calves against K99 fimbrial ETEC and that BVDV major structural protein E2 elicits antibodies neutralizing against BVDV viral infection. Vaccines inducing anti-K99 and anti-STa immunity would protect calves more effectively against ETEC diarrhea, and those also inducing anti-E2 neutralizing antibodies would protect calves and cattle against diarrhea caused by both ETEC and BVDV. In this study, we used the ETEC K99 major subunit FanC as a backbone, genetically embedded the STa toxoid STaP12F and the most-antigenic B-cell epitope and T-cell epitope predicted from the BVDV E2 glycoprotein into FanC for the multivalent antigen FanC-STa-E2, and examined immunogenicity of this multivalent antigen to assess vaccine potential against bovine diarrhea. Mice intraperitoneally (i.p.) immunized with this multivalent antigen developed anti-K99, anti-STa, and anti-BVDV antibodies. Moreover, elicited antibodies showed neutralization activities, as they inhibited adherence of K99 fimbrial E. coli, neutralized STa toxin, and prevented homologous BVDV viral infection in vitro. Results from this study suggest that this multiepitope fusion antigen can potentially be developed as a vaccine for broad protection against bovine diarrhea and that the multiepitope fusion strategy may be generally applied for multivalent vaccine development against heterogeneous pathogens. PMID:23697572

  11. Force-induced globule-coil transition in laminin binding protein and its role for viral-cell membrane fusion.

    PubMed

    Zaitsev, Boris N; Benedetti, Fabrizio; Mikhaylov, Andrey G; Korneev, Denis V; Sekatskii, Sergey K; Karakouz, Tanya; Belavin, Pavel A; Netesova, Nina A; Protopopova, Elena V; Konovalova, Svetlana N; Dietler, Giovanni; Loktev, Valery B

    2014-12-01

    The specific interactions of the pairs laminin binding protein (LBP)-purified tick-borne encephalitis viral surface protein E and certain recombinant fragments of this protein, as well as West Nile viral surface protein E and certain recombinant fragments of that protein, are studied by combined methods of single-molecule dynamic force spectroscopy (SMDFS), enzyme immunoassay and optical surface waves-based biosensor measurements. The experiments were performed at neutral pH (7.4) and acid pH (5.3) conditions. The data obtained confirm the role of LBP as a cell receptor for two typical viral species of the Flavivirus genus. A comparison of these data with similar data obtained for another cell receptor of this family, namely human αVβ3 integrin, reveals that both these receptors are very important. Studying the specific interaction between the cell receptors in question and specially prepared monoclonal antibodies against them, we could show that both interaction sites involved in the process of virus-cell interaction remain intact at pH 5.3. At the same time, for these acid conditions characteristic for an endosome during flavivirus-cell membrane fusion, SMDFS data reveal the existence of a force-induced (effective already for forces as small as 30-70 pN) sharp globule-coil transition for LBP and LBP-fragments of protein E complexes. We argue that this conformational transformation, being an analog of abrupt first-order phase transition and having similarity with the famous Rayleigh hydrodynamic instability, might be indispensable for the flavivirus-cell membrane fusion process. PMID:25319621

  12. Measuring T Cell-to-T Cell HIV-1 Transfer, Viral Fusion, and Infection Using Flow Cytometry.

    PubMed

    Durham, Natasha D; Chen, Benjamin K

    2016-01-01

    Direct T cell-to-T cell HIV-1 infection is a distinct mode of HIV-1 infection that requires physical contact between an HIV-1-infected "donor" cell and an uninfected, CD4-expressing "target" cell. In vitro studies indicate that HIV-1 cell-to-cell infection is much more efficient than infection by cell-free viral particles; however, the exact mechanisms of the enhanced efficiency of this infection pathway are still unclear. Several assays have been developed to study the mechanism of direct cell-to-cell HIV-1 transmission and to assess sensitivity to neutralizing antibodies and pharmacologic inhibitors. These assays are based on the coculture of donor and target cells. Here, we describe methods that utilize flow cytometry, which can discriminate donor and target cells and can assess different stages of entry and infection following cell-to-cell contact. HIV Gag-iGFP, a clone that makes fluorescent virus particles, can be used to measure cell-to-cell transfer of virus particles. HIV NL-GI, a clone that expresses GFP as an early gene, facilitates the measure of productive infection after cell-to-cell contact. Lastly, a variation of the β-lactamase (BlaM)-Vpr fusion assay can be used to measure the viral membrane fusion process after coculture of donor and target cells in a manner that is independent of cell-cell fusion. These assays can be performed in the presence of neutralizing antibodies/inhibitors to determine the 50 % inhibitory concentration (IC50) required to block infection specifically in the target cells. PMID:26714702

  13. Viral Gastroenteritis Associated with Genogroup II Norovirus among U.S. Military Personnel in Turkey, 2009

    PubMed Central

    Ahmed, Salwa F.; Klena, John D.; Mostafa, Manal; Dogantemur, Jessica; Middleton, Tracy; Hanson, James; Sebeny, Peter J.

    2012-01-01

    The present study demonstrates that multiple NoV genotypes belonging to genogroup II contributed to an acute gastroenteritis outbreak at a US military facility in Turkey that was associated with significant negative operational impact. Norovirus (NoV) is an important pathogen associated with acute gastroenteritis among military populations. We describe the genotypes of NoV outbreak occurred at a United States military facility in Turkey. Stool samples were collected from 37 out of 97 patients presenting to the clinic on base with acute gastroenteritis and evaluated for bacterial and viral pathogens. NoV genogroup II (GII) was identified by RT-PCR in 43% (16/37) stool samples. Phylogenetic analysis of a 260 base pair fragment of the NoV capsid gene from ten stool samples indicated the circulation of multiple and rare genotypes of GII NoV during the outbreak. We detected four GII.8 isolates, three GII.15, two GII.9 and a sole GII.10 NoV. Viral sequences could be grouped into four clusters, three of which have not been previously reported in Turkey. The fact that current NoV outbreak was caused by rare genotypes highlights the importance of norovirus strain typing. While NoV genogroup II is recognized as causative agent of outbreak, circulation of current genotypes has been rarely observed in large number of outbreaks. PMID:22606235

  14. Alanine substitution of conserved residues in the cytoplasmic tail of herpes simplex virus gB can enhance or abolish cell fusion activity and viral entry

    SciTech Connect

    Ruel, Nancy . E-mail: n-ruel@northwestern.edu; Zago, Anna . E-mail: anna_zago@acgtinc.com; Spear, Patricia G. . E-mail: p-spear@northwestern.edu

    2006-03-01

    Herpes simplex virus (HSV) glycoprotein B (gB) is one of the four viral glycoproteins required for viral entry and cell fusion and is highly conserved among herpesviruses. Mutants of HSV type 2 gB were generated by substituting conserved residues in the cytoplasmic tail with alanine or by deleting 41 amino acids from the C-terminus. Some of the mutations abolished cell fusion activity and also prevented transport of gB to the cell surface, identifying residues in the gB cytoplasmic tail that are critical for intracellular transport of this glycoprotein. These mutations also prevented production of infectious virus, possibly because the mutant forms of gB were not transported to the site of envelopment. Other mutations, particularly the deletion, significantly enhanced cell fusion activity. These mutations, as well as others described previously, identify regions of the gB cytoplasmic domain that modulate cell fusion activity.

  15. Enhanced Vaccine-Induced CD8+ T Cell Responses to Malaria Antigen ME-TRAP by Fusion to MHC Class II Invariant Chain

    PubMed Central

    Spencer, Alexandra J.; Cottingham, Matthew G.; Jenks, Jennifer A.; Longley, Rhea J.; Capone, Stefania; Colloca, Stefano; Folgori, Antonella; Cortese, Riccardo; Nicosia, Alfredo; Bregu, Migena; Hill, Adrian V. S.

    2014-01-01

    The orthodox role of the invariant chain (CD74; Ii) is in antigen presentation to CD4+ T cells, but enhanced CD8+ T cells responses have been reported after vaccination with vectored viral vaccines encoding a fusion of Ii to the antigen of interest. In this study we assessed whether fusion of the malarial antigen, ME-TRAP, to Ii could increase the vaccine-induced CD8+ T cell response. Following single or heterologous prime-boost vaccination of mice with a recombinant chimpanzee adenovirus vector, ChAd63, or recombinant modified vaccinia virus Ankara (MVA), higher frequencies of antigen-specific CD4+ and CD8+ T cells were observed, with the largest increases observed following a ChAd63-MVA heterologous prime-boost regimen. Studies in non-human primates confirmed the ability of Ii-fusion to augment the T cell response, where a 4-fold increase was maintained up to 11 weeks after the MVA boost. Of the numerous different approaches explored to increase vectored vaccine induced immunogenicity over the years, fusion to the invariant chain showed a consistent enhancement in CD8+ T cell responses across different animal species and may therefore find application in the development of vaccines against human malaria and other diseases where high levels of cell-mediated immunity are required. PMID:24945248

  16. ZstatFlu-II test: a chemiluminescent neuraminidase assay for influenza viral diagnostics.

    PubMed

    Achyuthan, Komandoor E; Pence, Lisa M; Appleman, James R; Shimasaki, Craig D

    2003-01-01

    The ZstatFlu-II test is a highly sensitive, specific, rapid, point-of-care chemiluminescent diagnostic test for influenza infection. Influenza viral neuraminidase-specific substrate, spiroadamantyl-1,2-dioxetane-4,7-dimethoxy-N-acetyl-neuraminic acid, is at the core of the ZstatFlu-II Test. The enzymatic reaction was carried out at 25 degrees C and neutral pH, representing the optimum assay conditions for influenza types A and B viral neuraminidases. The results were outputted on a Polaroid trade mark High Speed Detector Film. Positive results appeared as a '+'-shaped white film image; negative results produced no image. The 'glow' kinetics, facilitated by a unique combination of light enhancers, also 'tuned' the wavelength of emission to match the spectral properties of the film. The substrate hydrolysed non-enzymatically at acid pH or at temperatures above 25 degrees C. In order to minimize false positives, the ZstatFlu-II Test was formatted with 0.3-0.4 K(m) substrate and freezing the test kit until use. The pH optimization of the ZstatFlu-II test is discussed with reference to model compounds of sialyl-glycosides. A nucleophilic attack or an electrostatic stabilization of a developing carbonium ion under the influence of the adjacent carboxyl group was probably responsible for non-enzymatic hydrolysis of the substrate. Intramolecular general acid catalysis is proposed as a mechanism for the lability of the O-glycosidic linkage of the substrate. PMID:12701088

  17. Dendritic cell preactivation impairs MHC class II presentation of vaccines and endogenous viral antigens

    PubMed Central

    Young, Louise J.; Wilson, Nicholas S.; Schnorrer, Petra; Mount, Adele; Lundie, Rachel J.; La Gruta, Nicole L.; Crabb, Brendan S.; Belz, Gabrielle T.; Heath, William R.; Villadangos, Jose A.

    2007-01-01

    When dendritic cells (DCs) encounter signals associated with infection or inflammation, they become activated and undergo maturation. Mature DCs are very efficient at presenting antigens captured in association with their activating signal but fail to present subsequently encountered antigens, at least in vitro. Such impairment of MHC class II (MHC II) antigen presentation has generally been thought to be a consequence of down-regulation of endocytosis, so it might be expected that antigens synthesized by the DCs themselves (for instance, viral antigens) would still be presented by mature DCs. Here, we show that DCs matured in vivo could still capture and process soluble antigens, but were unable to present peptides derived from these antigens. Furthermore, presentation of viral antigens synthesized by the DCs themselves was also severely impaired. Indeed, i.v. injection of pathogen mimics, which caused systemic DC activation in vivo, impaired the induction of CD4 T cell responses against subsequently encountered protein antigens. This immunosuppressed state could be reversed by adoptive transfer of DCs loaded exogenously with antigens, demonstrating that impairment of CD4 T cell responses was due to lack of antigen presentation rather than to overt suppression of T cell activation. The biochemical mechanism underlying this phenomenon was the down-regulation of MHC II–peptide complex formation that accompanied DC maturation. These observations have important implications for the design of prophylactic and therapeutic DC vaccines and contribute to the understanding of the mechanisms causing immunosuppression during systemic blood infections. PMID:17978177

  18. Nuclear envelope breakdown induced by herpes simplex virus type 1 involves the activity of viral fusion proteins

    SciTech Connect

    Maric, Martina; Haugo, Alison C.; Dauer, William; Johnson, David; Roller, Richard J.

    2014-07-15

    Herpesvirus infection reorganizes components of the nuclear lamina usually without loss of integrity of the nuclear membranes. We report that wild-type HSV infection can cause dissolution of the nuclear envelope in transformed mouse embryonic fibroblasts that do not express torsinA. Nuclear envelope breakdown is accompanied by an eight-fold inhibition of virus replication. Breakdown of the membrane is much more limited during infection with viruses that lack the gB and gH genes, suggesting that breakdown involves factors that promote fusion at the nuclear membrane. Nuclear envelope breakdown is also inhibited during infection with virus that does not express UL34, but is enhanced when the US3 gene is deleted, suggesting that envelope breakdown may be enhanced by nuclear lamina disruption. Nuclear envelope breakdown cannot compensate for deletion of the UL34 gene suggesting that mixing of nuclear and cytoplasmic contents is insufficient to bypass loss of the normal nuclear egress pathway. - Highlights: • We show that wild-type HSV can induce breakdown of the nuclear envelope in a specific cell system. • The viral fusion proteins gB and gH are required for induction of nuclear envelope breakdown. • Nuclear envelope breakdown cannot compensate for deletion of the HSV UL34 gene.

  19. Some design aspects of laser fusion rocket(II)

    SciTech Connect

    Nakashima, H.; Shoyama, H.; Nagamine, Y.; Fusuki, T.; Kanda, Y.; Yoshimi, N.; Nakao, Y.

    1996-05-01

    A rocket powered by a laser-induced fusion microexplosion is an attractive spacecraft for manned exploration of the solar system because of its potential advantages of high specific impulse and of large specific power. We here discuss some design aspects of a laser fusion rocket. Included are discussion on thrust conversion efficiency, plasma instability in a magnetic nozzle and DT igniter/D{sup 3}He fuel target design. {copyright} {ital 1996 American Institute of Physics.}

  20. The UL24 protein of herpes simplex virus 1 affects the sub-cellular distribution of viral glycoproteins involved in fusion

    SciTech Connect

    Ben Abdeljelil, Nawel; Rochette, Pierre-Alexandre; Pearson, Angela

    2013-09-15

    Mutations in UL24 of herpes simplex virus type 1 can lead to a syncytial phenotype. We hypothesized that UL24 affects the sub-cellular distribution of viral glycoproteins involved in fusion. In non-immortalized human foreskin fibroblasts (HFFs) we detected viral glycoproteins B (gB), gD, gH and gL present in extended blotches throughout the cytoplasm with limited nuclear membrane staining; however, in HFFs infected with a UL24-deficient virus (UL24X), staining for the viral glycoproteins appeared as long, thin streaks running across the cell. Interestingly, there was a decrease in co-localized staining of gB and gD with F-actin at late times in UL24X-infected HFFs. Treatment with chemical agents that perturbed the actin cytoskeleton hindered the formation of UL24X-induced syncytia in these cells. These data support a model whereby the UL24 syncytial phenotype results from a mislocalization of viral glycoproteins late in infection. - Highlights: • UL24 affects the sub-cellular distribution of viral glycoproteins required for fusion. • Sub-cellular distribution of viral glycoproteins varies in cell-type dependent manner. • Drugs targeting actin microfilaments affect formation of UL24-related syncytia in HFFs.

  1. Viral-mediated fusion of mesenchymal stem cells with cells of the infarcted heart hinders healing via decreased vascularization and immune modulation

    PubMed Central

    Freeman, Brian T.; Ogle, Brenda M.

    2016-01-01

    Cell fusion can occur between mesenchymal stem cells (MSCs) transplanted to improve cardiac function and cells of the recipient. The therapeutic benefit or detriment of resultant cell hybrids is unknown. Here we augment fusion of transplanted MSCs with recipient cardiac cell types via viral fusogens to determine how cardiac function is impacted. Using a Cre/LoxP-based luciferase reporter system coupled to biophotonic imaging and echocardiography, we found that augmenting fusion with the vesicular stomatitis virus glycoprotein (VSVG) increased the amount of fusion in the recipient mouse heart, but led to diminished cardiac function. Specifically, MSCs transfected with VSVG (MSC-VSVG) had the lowest mean fold increase in fractional area change (FAC) and cardiac output (CO). Although the amount of fusion detected had a strong positive correlation (Pearson) with fractional area change and cardiac output at day 7, this effect was lost by day 28. The decrease in cardiac function seen with MSC-VSVG treatment versus MSC alone or sham treatment was associated with decreased MSC retention, altered immune cell responsiveness and reduced vascularization in the heart. This outcome garners consideration in the context of cellular transplantation to damaged tissues, those with viral infection or other microenvironmental conditions that might promote fusion. PMID:26846200

  2. HIV-1 viral envelope protein gp41: An NMR investigation of dodecyl phosphocholine embedded gp41 reveals a dynamic pre-fusion intermediate conformation

    PubMed Central

    Lakomek, Nils-Alexander; Kaufman, Joshua D.; Stahl, Stephen J.; Wingfield, Paul T.

    2014-01-01

    Summary Human immunodeficiency viral (HIV-1) fusion is mediated by the viral envelope gp120/gp41 complex (ENVelope glycoprotein). After gp120 shedding, gp41 is exposed and elicits membrane fusion via a cascade of conformational changes. In contrast to pre-fusion and post-fusion conformation, little is known about any intermediate conformation. We report on a solution NMR investigation of homotrimeric HIV-1 gp4127–194, comprising the transmembrane region and reconstituted in dodecyl phosphocholine (DPC) micelles. The protein is mainly α-helical but experiences internal dynamics on the nanosecond and micro-to millisecond time scale and transient α-helical behavior for certain residues in the N-terminal heptad repeat (NHR). Strong lipid interactions are observed, in particular for C-terminal residues of the NHR and imunodominant loop region connecting NHR and C-terminal heptad repeat (CHR). Our data indicate an extended conformation with features anticipated for a pre-fusion intermediate, presumably in exchange with a lowly populated post-fusion six-helical bundle conformation. PMID:25132083

  3. Viral-mediated fusion of mesenchymal stem cells with cells of the infarcted heart hinders healing via decreased vascularization and immune modulation.

    PubMed

    Freeman, Brian T; Ogle, Brenda M

    2016-01-01

    Cell fusion can occur between mesenchymal stem cells (MSCs) transplanted to improve cardiac function and cells of the recipient. The therapeutic benefit or detriment of resultant cell hybrids is unknown. Here we augment fusion of transplanted MSCs with recipient cardiac cell types via viral fusogens to determine how cardiac function is impacted. Using a Cre/LoxP-based luciferase reporter system coupled to biophotonic imaging and echocardiography, we found that augmenting fusion with the vesicular stomatitis virus glycoprotein (VSVG) increased the amount of fusion in the recipient mouse heart, but led to diminished cardiac function. Specifically, MSCs transfected with VSVG (MSC-VSVG) had the lowest mean fold increase in fractional area change (FAC) and cardiac output (CO). Although the amount of fusion detected had a strong positive correlation (Pearson) with fractional area change and cardiac output at day 7, this effect was lost by day 28. The decrease in cardiac function seen with MSC-VSVG treatment versus MSC alone or sham treatment was associated with decreased MSC retention, altered immune cell responsiveness and reduced vascularization in the heart. This outcome garners consideration in the context of cellular transplantation to damaged tissues, those with viral infection or other microenvironmental conditions that might promote fusion. PMID:26846200

  4. Different receptors binding to distinct interfaces on herpes simplex virus gD can trigger events leading to cell fusion and viral entry

    SciTech Connect

    Spear, Patricia G. . E-mail: p-spear@northwestern.edu; Manoj, Sharmila; Yoon, Miri; Jogger, Cheryl R.; Zago, Anna; Myscofski, Dawn

    2006-01-05

    One of the herpes simplex virus envelope glycoproteins, designated gD, is the principal determinant of cell recognition for viral entry. Other viral glycoproteins, gB, gH and gL, cooperate with gD to mediate the membrane fusion that is required for viral entry and cell fusion. Membrane fusion is triggered by the binding of gD to one of its receptors. These receptors belong to three different classes of cell surface molecules. This review summarizes recent findings on the structure and function of gD. The results presented indicate that gD may assume more than one conformation, one in the absence of receptor, another when gD is bound to the herpesvirus entry mediator, a member of the TNF receptor family, and a third when gD is bound to nectin-1, a cell adhesion molecule in the immunoglobulin superfamily. Finally, information and ideas are presented about a membrane-proximal region of gD that is required for membrane fusion, but not for receptor binding, and that may have a role in activating the fusogenic activity of gB, gH and gL.

  5. Homopolar Gun for Pulsed Spheromak Fusion Reactors II

    SciTech Connect

    Fowler, T

    2004-06-14

    A homopolar gun is discussed that could produce the high currents required for pulsed spheromak fusion reactors even with unit current amplification and open field lines during injection, possible because close coupling between the gun and flux conserver reduces gun losses to acceptable levels. Example parameters are given for a gun compatible with low cost pulsed reactors and for experiments to develop the concept.

  6. Analysis of cathepsin and furin proteolytic enzymes involved in viral fusion protein activation in cells of the bat reservoir host.

    PubMed

    El Najjar, Farah; Lampe, Levi; Baker, Michelle L; Wang, Lin-Fa; Dutch, Rebecca Ellis

    2015-01-01

    Bats of different species play a major role in the emergence and transmission of highly pathogenic viruses including Ebola virus, SARS-like coronavirus and the henipaviruses. These viruses require proteolytic activation of surface envelope glycoproteins needed for entry, and cellular cathepsins have been shown to be involved in proteolysis of glycoproteins from these distinct virus families. Very little is currently known about the available proteases in bats. To determine whether the utilization of cathepsins by bat-borne viruses is related to the nature of proteases in their natural hosts, we examined proteolytic processing of several viral fusion proteins in cells derived from two fruit bat species, Pteropus alecto and Rousettus aegyptiacus. Our work shows that fruit bat cells have homologs of cathepsin and furin proteases capable of cleaving and activating both the cathepsin-dependent Hendra virus F and the furin-dependent parainfluenza virus 5 F proteins. Sequence analysis comparing Pteropus alecto furin and cathepsin L to proteases from other mammalian species showed a high degree of conservation; however significant amino acid variation occurs at the C-terminus of Pteropus alecto furin. Further analysis of furin-like proteases from fruit bats revealed that these proteases are catalytically active and resemble other mammalian furins in their response to a potent furin inhibitor. However, kinetic analysis suggests that differences may exist in the cellular localization of furin between different species. Collectively, these results indicate that the unusual role of cathepsin proteases in the life cycle of bat-borne viruses is not due to the lack of active furin-like proteases in these natural reservoir species; however, differences may exist between furin proteases present in fruit bats compared to furins in other mammalian species, and these differences may impact protease usage for viral glycoprotein processing. PMID:25706132

  7. Analysis of Cathepsin and Furin Proteolytic Enzymes Involved in Viral Fusion Protein Activation in Cells of the Bat Reservoir Host

    PubMed Central

    El Najjar, Farah; Lampe, Levi; Baker, Michelle L.; Wang, Lin-Fa; Dutch, Rebecca Ellis

    2015-01-01

    Bats of different species play a major role in the emergence and transmission of highly pathogenic viruses including Ebola virus, SARS-like coronavirus and the henipaviruses. These viruses require proteolytic activation of surface envelope glycoproteins needed for entry, and cellular cathepsins have been shown to be involved in proteolysis of glycoproteins from these distinct virus families. Very little is currently known about the available proteases in bats. To determine whether the utilization of cathepsins by bat-borne viruses is related to the nature of proteases in their natural hosts, we examined proteolytic processing of several viral fusion proteins in cells derived from two fruit bat species, Pteropus alecto and Rousettus aegyptiacus. Our work shows that fruit bat cells have homologs of cathepsin and furin proteases capable of cleaving and activating both the cathepsin-dependent Hendra virus F and the furin-dependent parainfluenza virus 5 F proteins. Sequence analysis comparing Pteropus alecto furin and cathepsin L to proteases from other mammalian species showed a high degree of conservation; however significant amino acid variation occurs at the C-terminus of Pteropus alecto furin. Further analysis of furin-like proteases from fruit bats revealed that these proteases are catalytically active and resemble other mammalian furins in their response to a potent furin inhibitor. However, kinetic analysis suggests that differences may exist in the cellular localization of furin between different species. Collectively, these results indicate that the unusual role of cathepsin proteases in the life cycle of bat-borne viruses is not due to the lack of active furin-like proteases in these natural reservoir species; however, differences may exist between furin proteases present in fruit bats compared to furins in other mammalian species, and these differences may impact protease usage for viral glycoprotein processing. PMID:25706132

  8. Influence of hydrophobic and electrostatic residues on SARS-coronavirus S2 protein stability: Insights into mechanisms of general viral fusion and inhibitor design

    PubMed Central

    Aydin, Halil; Al-Khooly, Dina; Lee, Jeffrey E

    2014-01-01

    Severe acute respiratory syndrome (SARS) is an acute respiratory disease caused by the SARS-coronavirus (SARS-CoV). SARS-CoV entry is facilitated by the spike protein (S), which consists of an N-terminal domain (S1) responsible for cellular attachment and a C-terminal domain (S2) that mediates viral and host cell membrane fusion. The SARS-CoV S2 is a potential drug target, as peptidomimetics against S2 act as potent fusion inhibitors. In this study, site-directed mutagenesis and thermal stability experiments on electrostatic, hydrophobic, and polar residues to dissect their roles in stabilizing the S2 postfusion conformation was performed. It was shown that unlike the pH-independent retroviral fusion proteins, SARS-CoV S2 is stable over a wide pH range, supporting its ability to fuse at both the plasma membrane and endosome. A comprehensive SARS-CoV S2 analysis showed that specific hydrophobic positions at the C-terminal end of the HR2, rather than electrostatics are critical for fusion protein stabilization. Disruption of the conserved C-terminal hydrophobic residues destabilized the fusion core and reduced the melting temperature by 30°C. The importance of the C-terminal hydrophobic residues led us to identify a 42-residue substructure on the central core that is structurally conserved in all existing CoV S2 fusion proteins (root mean squared deviation = 0.4 Å). This is the first study to identify such a conserved substructure and likely represents a common foundation to facilitate viral fusion. We have discussed the role of key residues in the design of fusion inhibitors and the potential of the substructure as a general target for the development of novel therapeutics against CoV infections. PMID:24519901

  9. Annexin II Binds to Capsid Protein VP1 of Enterovirus 71 and Enhances Viral Infectivity ▿

    PubMed Central

    Yang, Su-Lin; Chou, Ying-Ting; Wu, Cheng-Nan; Ho, Mei-Shang

    2011-01-01

    Enterovirus type 71 (EV71) causes hand, foot, and mouth disease (HFMD), which is mostly self-limited but may be complicated with a severe to fatal neurological syndrome in some children. Understanding the molecular basis of virus-host interactions might help clarify the largely unknown neuropathogenic mechanisms of EV71. In this study, we showed that human annexin II (Anx2) protein could bind to the EV71 virion via the capsid protein VP1. Either pretreatment of EV71 with soluble recombinant Anx2 or pretreatment of host cells with an anti-Anx2 antibody could result in reduced viral attachment to the cell surface and a reduction of the subsequent virus yield in vitro. HepG2 cells, which do not express Anx2, remained permissive to EV71 infection, though the virus yield was lower than that for a cognate lineage expressing Anx2. Stable transfection of plasmids expressing Anx2 protein into HepG2 cells (HepG2-Anx2 cells) could enhance EV71 infectivity, with an increased virus yield, especially at a low infective dose, and the enhanced infectivity could be reversed by pretreating HepG2-Anx2 cells with an anti-Anx2 antibody. The Anx2-interacting domain was mapped by yeast two-hybrid analysis to VP1 amino acids 40 to 100, a region different from the known receptor binding domain on the surface of the picornavirus virion. Our data suggest that binding of EV71 to Anx2 on the cell surface can enhance viral entry and infectivity, especially at a low infective dose. PMID:21900167

  10. Dual Mutation Events in the Haemagglutinin-Esterase and Fusion Protein from an Infectious Salmon Anaemia Virus HPR0 Genotype Promote Viral Fusion and Activation by an Ubiquitous Host Protease

    PubMed Central

    Fourrier, Mickael; Lester, Katherine; Markussen, Turhan; Falk, Knut; Secombes, Christopher J.; McBeath, Alastair; Collet, Bertrand

    2015-01-01

    In Infectious salmon anaemia virus (ISAV), deletions in the highly polymorphic region (HPR) in the near membrane domain of the haemagglutinin-esterase (HE) stalk, influence viral fusion. It is suspected that selected mutations in the associated Fusion (F) protein may also be important in regulating fusion activity. To better understand the underlying mechanisms involved in ISAV fusion, several mutated F proteins were generated from the Scottish Nevis and Norwegian SK779/06 HPR0. Co-transfection with constructs encoding HE and F were performed, fusion activity assessed by content mixing assay and the degree of proteolytic cleavage by western blot. Substitutions in Nevis F demonstrated that K276 was the most likely cleavage site in the protein. Furthermore, amino acid substitutions at three sites and two insertions, all slightly upstream of K276, increased fusion activity. Co-expression with HE harbouring a full-length HPR produced high fusion activities when trypsin and low pH were applied. In comparison, under normal culture conditions, groups containing a mutated HE with an HPR deletion were able to generate moderate fusion levels, while those with a full length HPR HE could not induce fusion. This suggested that HPR length may influence how the HE primes the F protein and promotes fusion activation by an ubiquitous host protease and/or facilitate subsequent post-cleavage refolding steps. Variations in fusion activity through accumulated mutations on surface glycoproteins have also been reported in other orthomyxoviruses and paramyxoviruses. This may in part contribute to the different virulence and tissue tropism reported for HPR0 and HPR deleted ISAV genotypes. PMID:26517828

  11. Physics of laser fusion. Volume II. Diagnostics of experiments on laser fusion targets at LLNL

    SciTech Connect

    Ahlstrom, H.G.

    1982-01-01

    These notes present the experimental basis and status for laser fusion as developed at LLNL. There are two other volumes in this series: Vol. I, by C.E. Max, presents the theoretical laser-plasma interaction physics; Vol. III, by J.F. Holzrichter et al., presents the theory and design of high-power pulsed lasers. A fourth volume will present the theoretical implosion physics. The notes consist of six sections. The first, an introductory section, provides some of the history of inertial fusion and a simple explanation of the concepts involved. The second section presents an extensive discussion of diagnostic instrumentation used in the LLNL Laser Fusion Program. The third section is a presentation of laser facilities and capabilities at LLNL. The purpose here is to define capability, not to derive how it was obtained. The fourth and fifth sections present the experimental data on laser-plasma interaction and implosion physics. The last chapter is a short projection of the future.

  12. A Fusion-Inhibiting Peptide against Rift Valley Fever Virus Inhibits Multiple, Diverse Viruses

    PubMed Central

    Koehler, Jeffrey W.; Smith, Jeffrey M.; Ripoll, Daniel R.; Spik, Kristin W.; Taylor, Shannon L.; Badger, Catherine V.; Grant, Rebecca J.; Ogg, Monica M.; Wallqvist, Anders; Guttieri, Mary C.; Garry, Robert F.; Schmaljohn, Connie S.

    2013-01-01

    For enveloped viruses, fusion of the viral envelope with a cellular membrane is critical for a productive infection to occur. This fusion process is mediated by at least three classes of fusion proteins (Class I, II, and III) based on the protein sequence and structure. For Rift Valley fever virus (RVFV), the glycoprotein Gc (Class II fusion protein) mediates this fusion event following entry into the endocytic pathway, allowing the viral genome access to the cell cytoplasm. Here, we show that peptides analogous to the RVFV Gc stem region inhibited RVFV infectivity in cell culture by inhibiting the fusion process. Further, we show that infectivity can be inhibited for diverse, unrelated RNA viruses that have Class I (Ebola virus), Class II (Andes virus), or Class III (vesicular stomatitis virus) fusion proteins using this single peptide. Our findings are consistent with an inhibition mechanism similar to that proposed for stem peptide fusion inhibitors of dengue virus in which the RVFV inhibitory peptide first binds to both the virion and cell membranes, allowing it to traffic with the virus into the endocytic pathway. Upon acidification and rearrangement of Gc, the peptide is then able to specifically bind to Gc and prevent fusion of the viral and endocytic membranes, thus inhibiting viral infection. These results could provide novel insights into conserved features among the three classes of viral fusion proteins and offer direction for the future development of broadly active fusion inhibitors. PMID:24069485

  13. Fusion-reactor plasmas with polarized nuclei. II

    SciTech Connect

    Kulsrud, R.M.; Furth, H.P.; Valeo, E.J.; Budny, R.V.; Jassby, D.L.; Micklich, B.J.; Post, D.E.; Goldhaber, M.; Happer, W.

    1982-11-01

    New techniques of bulk polarization could be used to fuel a reactor with polarized hydrogenic atoms, so as to form a plasma of polarized nuclei. Theoretical calculations indicate that, once the nuclei of the plasma are polarized in some preferred state, they can maintain this state with a probability near 100% during their lifetime in the reactor, including possible recycling. There are a number of practical advantages to be gained from the use of polarized plasma in a fusion reactor. The nuclear reaction rates can be increased or decreased, and/or the direction of emission of the reaction products can be controlled. The D-T reaction rate can be enhanced by as much as 50%, with the reaction products emitted perpendicular to the magnetic field. Alternatively, it is possible to direct the reaction products primarily along the field, with no enhancement. In this case of the D-D reaction, the theoretical predictions are somewhat less certain. Enhancement of the reaction rate by a factor of 1.5-2.5 is to be expected. In a different polarization state, suppression of D-D reactions may be feasible - a possibility that would be of interest for a neutron-free D-He/sup 3/ reactor. A quantitative discussion of the relevant nuclear physics as well as of the various mechanisms producing depolarization is given.

  14. HYLIFE-II inertial confinement fusion reactor design

    SciTech Connect

    Moir, R.W.

    1990-12-14

    The HYLIFE-2 inertial fusion power plant design study uses a liquid fall, in the form of jets to protect the first structural wall from neutron damage, x rays, and blast to provide a 30-y lifetime. HYLIFE-1 used liquid lithium. HYLIFE 2 avoids the fire hazard of lithium by using a molten salt composed of fluorine, lithium, and beryllium (Li{sub 2}BeF{sub 4}) called Flibe. Access for heavy-ion beams is provided. Calculations for assumed heavy-ion beam performance show a nominal gain of 70 at 5 MJ producing 350 MJ, about 5.2 times less yield than the 1.8 GJ from a driver energy of 4.5 MJ with gain of 400 for HYLIFE-1. The nominal 1 GWe of power can be maintained by increasing the repetition rate by a factor of about 5.2, from 1.5 to 8 Hz. A higher repetition rate requires faster re-establishment of the jets after a shot, which can be accomplished in part by decreasing the jet fall height and increasing the jet flow velocity. Multiple chambers may be required. In addition, although not considered for HYLIFE-1, there is undoubtedly liquid splash that must be forcibly cleared because gravity is too slow, especially at high repetition rates. Splash removal can be accomplished by either pulsed or oscillating jet flows. The cost of electricity is estimated to be 0.09 $/kW{center dot}h in constant 1988 dollars, about twice that of future coal and light water reactor nuclear power. The driver beam cost is about one-half the total cost. 15 refs., 9 figs., 3 tabs.

  15. HYLIFE-II inertial confinement: Fusion power plant design

    SciTech Connect

    Moir, R.W.

    1990-12-14

    The HYLIFE-2 inertial fusion power plant design study uses a liquid fall, in the form of jets to protect the first structural wall from neutron damage, x rays, and blast to provide a 30-y lifetime. HYLIFE-1 used liquid lithium. HYLIFE 2 avoids the fire hazard of lithium by using a molten salt composed of fluorine, lithium, and beryllium (Li{sub 2}BeF{sub 4}) called Flibe. Access for heavy-ion beams is provided. Calculations for assumed heavy-ion beam performance show a nominal gain of 70 at 5 MJ producing 350 MJ, about 5.2 times less yield than the 1.8 GJ from a driver energy of 4.5 MJ with gain of 400 for HYLIFE-1. The nominal 1 GWe of power can be maintained by increasing the repetition rate by a factor of about 5.2, from 1.5 to 8 Hz. A higher repetition rate requires faster re-establishment of the jets after a shot, which can be accomplished in part by decreasing the jet fall height and increasing the jet flow velocity. Multiple chambers may be required. In addition, although not considered for HYLIFE-1, there is undoubtedly liquid splash that must be forcibly cleared because gravity is too slow, especially at high repetition rates. Splash removal can be accomplished by either pulsed or oscillating jet flows. The cost of electricity is estimated to be 0.09 $/kW{center dot}h in constant 1988 dollars, about twice that of future coal and light water reactor nuclear power. The driver beam cost is about one-half the total cost. 16 refs., 6 figs., 2 tabs.

  16. Activation of a novel gene in 3q21 and identification of intergenic fusion transcripts with ecotropic viral insertion site I in leukemia.

    PubMed

    Pekarsky, Y; Rynditch, A; Wieser, R; Fonatsch, C; Gardiner, K

    1997-09-15

    We have identified a novel gene, GR6, located within the leukemia breakpoint region of 3q21, that is normally expressed in early fetal development but not in adult peripheral blood. GR6 is activated in the UCSD-AML1 cell line and in a leukemic sample, both of which carry a t(3;3)(q21;q26). In UCSD-AML1, we have also identified fusion transcripts between the ecotropic viral insertion site I (EVI1) gene in 3q26 and GR6 and between EVI1 and Ribophorin I that maps 30 kb telomeric to GR6 in 3q21. All fusions splice the 5' ends of the 3q21 genes into exon 2 of the EVI1 gene, an event that is similar to the normal intergenic splicing of MDS1-EVI1 and to those previously documented in leukemias with t(3;21) and t(3;12), in which acute myelogenous leukemia 1-EVI1 fusions and ETV6-EVI1 fusions, respectively, occur. The Ribophorin I-EVI1 fusion in particular may be a common occurrence in t(3;3). PMID:9307271

  17. Progress in accident analysis of the HYLIFE-II inertial fusion energy power plant design

    SciTech Connect

    Reyes, S; Latkowski, J F; Gomez del Rio, J; Sanz, J

    2000-10-11

    The present work continues our effort to perform an integrated safety analysis for the HYLIFE-II inertial fusion energy (IFE) power plant design. Recently we developed a base case for a severe accident scenario in order to calculate accident doses for HYLIFE-II. It consisted of a total loss of coolant accident (LOCA) in which all the liquid flibe (Li{sub 2}BeF{sub 4}) was lost at the beginning of the accident. Results showed that the off-site dose was below the limit given by the DOE Fusion Safety Standards for public protection in case of accident, and that his dose was dominated by the tritium released during the accident.

  18. Type II integral membrane protein, TM of J paramyxovirus promotes cell-to-cell fusion

    PubMed Central

    Li, Zhuo; Hung, Cher; Paterson, Reay G.; Michel, Frank; Fuentes, Sandra; Place, Ryan; Lin, Yuan; Hogan, Robert J.; Lamb, Robert A.; He, Biao

    2015-01-01

    Paramyxoviruses include many important animal and human pathogens. Most paramyxoviruses have two integral membrane proteins: fusion protein (F) and attachment proteins hemagglutinin, hemagglutinin–neuraminidase, or glycoprotein (G), which are critical for viral entry into cells. J paramyxovirus (JPV) encodes four integral membrane proteins: F, G, SH, and transmembrane (TM). The function of TM is not known. In this work, we have generated a viable JPV lacking TM (JPV∆TM). JPV∆TM formed opaque plaques compared with JPV. Quantitative syncytia assays showed that JPV∆TM was defective in promoting cell-to-cell fusion (i.e., syncytia formation) compared with JPV. Furthermore, cells separately expressing F, G, TM, or F plus G did not form syncytia whereas cells expressing F plus TM formed some syncytia. However, syncytia formation was much greater with coexpression of F, G, and TM. Biochemical analysis indicates that F, G, and TM interact with each other. A small hydrophobic region in the TM ectodomain from amino acid residues 118 to 132, the hydrophobic loop (HL), was important for syncytial promotion, suggesting that the TM HL region plays a critical role in cell-to-cell fusion. PMID:26392524

  19. Activation analysis of the PULSAR-II fusion power reactor

    SciTech Connect

    Khater, H.Y.

    1995-12-31

    The PULSAR-II pulsed tokamak power plant design utilizes a blanket made of the vanadium alloy, V-5Cr-5Ti, and cooled with liquid lithium. The shield is made of a mixture of the low activation austenitic steel (Tenelon) and vanadium. The blanket is assumed to be replaced every 5.6 full power years (FPY) and the shield is assumed to stay in place for 30 FPY. The activity induced in the blanket at the end of its lifetime is higher than the activity induced in the shield after 30 FPY. At shutdown, the blanket and shield activities are 2678 MCi and 1747 MCi, respectively. One year after shutdown the shield activity drops to 18 MCi compared to 84 MCi for the blanket. The total decay heat generated in the blanket at the end of its lifetime is 34.7 MW and drops to 17.6 MW within an hour. At shutdown, 25.3 MW of decay heat are generated in the shield, dropping to only 0.1 MW within the first year. One week after shutdown, the values of the integrated decay heat are 1770 GJ for the blanket and 469 GJ for the shield. The radwaste classification of the reactor structure is evaluated according to both the NRC 10CFR61 and Fetter waste disposal concentration limits. After 5.6 years of irradiation, the blanket will only qualify for Class C low level waste. After 30 years of operation, the shield will also qualify for disposal as Class C waste. Only remote maintenance will be allowed inside the containment building.

  20. Accident consequences analysis of the HYLIFE-II inertial fusion energy power plant design

    NASA Astrophysics Data System (ADS)

    Reyes, S.; Latkowski, J. F.; Gomez del Rio, J.; Sanz, J.

    2001-05-01

    Previous studies of the safety and environmental aspects of the HYLIFE-II inertial fusion energy power plant design have used simplistic assumptions in order to estimate radioactivity releases under accident conditions. Conservatisms associated with these traditional analyses can mask the actual behavior of the plant and have revealed the need for more accurate modeling and analysis of accident conditions and radioactivity mobilization mechanisms. In the present work, computer codes traditionally used for magnetic fusion safety analyses (CHEMCON, MELCOR) have been applied for simulating accident conditions in a simple model of the HYLIFE-II IFE design. Here we consider a severe loss of coolant accident (LOCA) in conjunction with simultaneous failures of the beam tubes (providing a pathway for radioactivity release from the vacuum vessel towards the confinement) and of the two barriers surrounding the chamber (inner shielding and confinement building itself). Even though confinement failure would be a very unlikely event it would be needed in order to produce significant off-site doses. CHEMCON code allows calculation of long-term temperature transients in fusion reactor first wall, blanket, and shield structures resulting from decay heating. MELCOR is used to simulate a wide range of physical phenomena including thermal-hydraulics, heat transfer, aerosol physics and fusion product transport and release. The results of these calculations show that the estimated off-site dose is less than 5 mSv (0.5 rem), which is well below the value of 10 mSv (1 rem) given by the DOE Fusion Safety Standards for protection of the public from exposure to radiation during off-normal conditions.

  1. Accident consequences analysis of the HYLIFE-II inertial fusion energy power plant design

    SciTech Connect

    Reyes, S; Gomez del Rio, J; Sanz, J

    2000-02-23

    Previous studies of the safety and environmental (S and E) aspects of the HYLIFE-II inertial fusion energy (IFE) power plant design have used simplistic assumptions in order to estimate radioactivity releases under accident conditions. Conservatisms associated with these traditional analyses can mask the actual behavior of the plant and have revealed the need for more accurate modeling and analysis of accident conditions and radioactivity mobilization mechanisms. In the present work a set of computer codes traditionally used for magnetic fusion safety analyses (CHEMCON, MELCOR) has been applied for simulating accident conditions in a simple model of the HYLIFE-II IFE design. Here the authors consider a severe lost of coolant accident (LOCA) producing simultaneous failures of the beam tubes (providing a pathway for radioactivity release from the vacuum vessel towards the containment) and of the two barriers surrounding the chamber (inner shielding and containment building it self). Even though containment failure would be a very unlikely event it would be needed in order to produce significant off-site doses. CHEMCON code allows calculation of long-term temperature transients in fusion reactor first wall, blanket, and shield structures resulting from decay heating. MELCOR is used to simulate a wide range of physical phenomena including thermal-hydraulics, heat transfer, aerosol physics and fusion product release and transport. The results of these calculations show that the estimated off-site dose is less than 6 mSv (0.6 rem), which is well below the value of 10 mSv (1 rem) given by the DOE Fusion Safety Standards for protection of the public from exposure to radiation during off-normal conditions.

  2. Fusion

    NASA Astrophysics Data System (ADS)

    Herman, Robin

    1990-10-01

    The book abounds with fascinating anecdotes about fusion's rocky path: the spurious claim by Argentine dictator Juan Peron in 1951 that his country had built a working fusion reactor, the rush by the United States to drop secrecy and publicize its fusion work as a propaganda offensive after the Russian success with Sputnik; the fortune Penthouse magazine publisher Bob Guccione sank into an unconventional fusion device, the skepticism that met an assertion by two University of Utah chemists in 1989 that they had created "cold fusion" in a bottle. Aimed at a general audience, the book describes the scientific basis of controlled fusion--the fusing of atomic nuclei, under conditions hotter than the sun, to release energy. Using personal recollections of scientists involved, it traces the history of this little-known international race that began during the Cold War in secret laboratories in the United States, Great Britain and the Soviet Union, and evolved into an astonishingly open collaboration between East and West.

  3. Association between the p170 form of human topoisomerase II and progeny viral DNA in cells infected with herpes simplex virus type 1.

    PubMed Central

    Ebert, S N; Subramanian, D; Shtrom, S S; Chung, I K; Parris, D S; Muller, M T

    1994-01-01

    Endogenous host topoisomerase II acts upon herpes simplex virus type 1 (HSV-1) DNA in infected cells (S.N. Ebert, S.S. Shtrom, and M.T. Muller, J. Virol. 56:4059-4066, 1990), and cleavage is directed exclusively at progeny viral DNA while parental DNA is resistant. To evaluate the possibility that HSV-1 induces topoisomerase II activity which could account for the preferential cleavage of progeny viral DNA, we assessed topoisomerase II cleavage activity on cellular and viral DNA substrates before and after the initiation of viral DNA replication. We show that cleavage of a host gene in mock-infected cells was similar to that observed in HSV-1-infected cells, regardless of whether viral DNA replication had occurred. In addition, quantitative measurements revealed comparable amounts of topoisomerase II activity in infected and mock-infected cells; thus, HSV-1 neither induces nor encodes its own type II topoisomerase and cleavages in vivo are due to a preexisting host topoisomerase. Human cells contain two isozymes of topoisomerase II (p170 and p180), encoded by separate genes. Through the use of isozyme-specific antibodies, we demonstrate that only p170 was found to be cross-linked to HSV-1 DNA even though both forms were present at nearly constant levels in HSV-1-infected cells. Immunofluorescence revealed that by 6 h postinfection, p170 becomes redistributed and localized to sites of active viral DNA synthesis. The data suggest that p170 gains preferential access to replicated viral DNA molecules, which explains why topoisomerase II activity is concentrated on progeny DNA. Images PMID:8289331

  4. Diverse repertoire of the MHC class II-peptide complexes is required for presentation of viral superantigens.

    PubMed

    Golovkina, T; Agafonova, Y; Kazansky, D; Chervonsky, A

    2001-02-15

    Among other features, peptides affect MHC class II molecules, causing changes in the binding of bacterial superantigens (b-Sag). Whether peptides can alter binding of viral superantigens (v-Sag) to MHC class II was not known. Here we addressed the question of whether mutations limiting the diversity of peptides bound by the MHC class II molecules influenced the presentation of v-Sag and, subsequently, the life cycle of the mouse mammary tumor virus (MMTV). T cells reactive to v-Sag were found in mice lacking DM molecules as well as in A(b)Ep-transgenic mice in which MHC class II binding grooves were predominantly occupied by an invariant chain fragment or Ealpha(52-68) peptide, respectively. APCs from the mutant mice failed to present v-Sag, as determined by the lack of Sag-specific T cell activation, Sag-induced T cell deletion, and by the aborted MMTV infection. In contrast, mice that express I-A(b) with a variety of bound peptides presented v-Sag and were susceptible to MMTV infection. Comparison of v-Sag and b-Sag presentation by the same mutant cells suggested that presentation of v-Sag had requirements similar to that for presentation of toxic shock syndrome toxin-1. Thus, MHC class II peptide repertoire is critical for recognition of v-Sag by the T cells and affects the outcome of infection with a retrovirus. PMID:11160278

  5. Ion beam generation and focusing on PBFA (Particle Beam Fusion Accelerator) II

    SciTech Connect

    Stinnett, R.W.; Bailey, J.E.; Bieg, K.W.; Coats, R.S.; Chandler, G.; Derzon, M.S.; Desjarlais, M.P.; Dreike, P.L.; Gerber, R.A.; Johnson, D.J.; Leeper, R.J.; Lockner, T.R.; Maenchen, J.; Mehlhorn, T.A.; Pregenzer, A.L.; Quintenz, J.P.; Renk, T.J.; Rosenthal, S.E.; Ruiz, C.L.; Slutz, S.A.; Stygar, W.A.; Tisone, G.C.; Woodworth, J.R. ); Maron, Y. (Weizmann Inst. of Science, R

    1990-01-01

    During the past year we have succeeded in obtaining a 5 TW/cm{sup 2} proton focus on Sandia National Laboratories' Particle Beam Fusion Accelerator (PBFA) II. This has allowed us to shift our experimental emphasis to the implementation of an improved ion diode geometry for higher voltage operation, full azimuthal beam characterization, and especially lithium ion source experiments. We have made significant progress in each of these areas during the past year, demonstrating 10 MV diode operation, {plus minus}10% azimuthal beam symmetry, and promising initial results from lithium ion source experiments. 8 refs., 6 figs.

  6. Genetic fusions of a CFA/I/II/IV MEFA (multiepitope fusion antigen) and a toxoid fusion of heat-stable toxin (STa) and heat-labile toxin (LT) of enterotoxigenic Escherichia coli (ETEC) retain broad anti-CFA and antitoxin antigenicity.

    PubMed

    Ruan, Xiaosai; Sack, David A; Zhang, Weiping

    2015-01-01

    Immunological heterogeneity has long been the major challenge in developing broadly effective vaccines to protect humans and animals against bacterial and viral infections. Enterotoxigenic Escherichia coli (ETEC) strains, the leading bacterial cause of diarrhea in humans, express at least 23 immunologically different colonization factor antigens (CFAs) and two distinct enterotoxins [heat-labile toxin (LT) and heat-stable toxin type Ib (STa or hSTa)]. ETEC strains expressing any one or two CFAs and either toxin cause diarrhea, therefore vaccines inducing broad immunity against a majority of CFAs, if not all, and both toxins are expected to be effective against ETEC. In this study, we applied the multiepitope fusion antigen (MEFA) strategy to construct ETEC antigens and examined antigens for broad anti-CFA and antitoxin immunogenicity. CFA MEFA CFA/I/II/IV [CVI 2014, 21(2):243-9], which carried epitopes of seven CFAs [CFA/I, CFA/II (CS1, CS2, CS3), CFA/IV (CS4, CS5, CS6)] expressed by the most prevalent and virulent ETEC strains, was genetically fused to LT-STa toxoid fusion monomer 3xSTaA14Q-dmLT or 3xSTaN12S-dmLT [IAI 2014, 82(5):1823-32] for CFA/I/II/IV-STaA14Q-dmLT and CFA/I/II/IV-STaN12S-dmLT MEFAs. Mice intraperitoneally immunized with either CFA/I/II/IV-STa-toxoid-dmLT MEFA developed antibodies specific to seven CFAs and both toxins, at levels equivalent or comparable to those induced from co-administration of the CFA/I/II/IV MEFA and toxoid fusion 3xSTaN12S-dmLT. Moreover, induced antibodies showed in vitro adherence inhibition activities against ETEC or E. coli strains expressing these seven CFAs and neutralization activities against both toxins. These results indicated CFA/I/II/IV-STa-toxoid-dmLT MEFA or CFA/I/II/IV MEFA combined with 3xSTaN12S-dmLT induced broadly protective anti-CFA and antitoxin immunity, and suggested their potential application in broadly effective ETEC vaccine development. This MEFA strategy may be generally used in multivalent

  7. Lipophilic tetranuclear ruthenium(II) complexes as two-photon luminescent tracking non-viral gene vectors.

    PubMed

    Yu, Bole; Ouyang, Cheng; Qiu, Kangqiang; Zhao, Jing; Ji, Liangnian; Chao, Hui

    2015-02-23

    Fluorescence detection is the most effective tool for tracking gene delivery in living cells. To reduce photodamage and autofluorescence and to increase deep penetration into cells, choosing appropriate fluorophores that are capable of two-photon activation under irradiation in the NIR or IR regions is an effective approach. In this work, we have developed six tetranuclear ruthenium(II) complexes, GV1-6, and have studied their one- and two-photon luminescence properties. DNA interaction studies have demonstrated that GV2-6, bearing hydrophobic alkyl ether chains, show more efficient DNA condensing ability but lower DNA binding constants than GV1. However, the hydrophobic alkyl ether chains also enhance the DNA delivery ability of GV2-6 compared with that of GV1. More importantly, we have applied GV1-6 as non-viral gene vectors for tracking DNA delivery in living cells by one- and two-photon fluorescence microscopies. In two-photon microscopy, a high signal-to-noise contrast was achieved by irradiation with an 830 nm laser. This is the first example of the use of transition-metal complexes for two-photon luminescent tracking of the cellular pathways of gene delivery and as DNA carriers. Our work provides new insights into improving real-time tracking during gene delivery and transfection as well as important information for the design of multifunctional non-viral vectors. PMID:25597394

  8. Light ion sources and target results on PBFA II (Particle Beam Fusion Accelerator II)

    SciTech Connect

    Cook, D.L.; Bailey, J.E.; Bieg, K.W.; Bloomquist, D.D.; Coats, R.S.; Chandler, G.C.; Cuneo, M.E.; Derzon, M.S.; Desjarlais, M.P.; Dreike, P.L.; Dukart, R.J.; Gerber, R.A.; Johnson, D.J.; Leeper, R.J.; Lockner, T.R.; McDaniel, D.H.; Maenchen, J.E.; Matzen, M.K.; Mehlhorn, T.A.; Mix, L.P.; Moats, A.R.; Nelson, W.E.; Pointon, T.D.; Pregenzer, A.L.; Quintenz, J.P.; Renk, T.J.; Rosenthal, S.E.; Ruiz, C.L.; Slutz, S.A.; Stinnett, R

    1990-01-01

    Advances in ion beam theory, diagnostics, and experiments in the past two years have enabled efficient generation of intense proton beams on PBFA II, and focusing of the beam power to 5.4 TW/cm{sup 2} on a 6-mm-diameter target. Target experiments have been started with the intense proton beams, since the range of protons at 4--5 MeV is equivalent to that of lithium at 30 MeV. Three series of experiments have been conducted using planar, conical, and cylindrical targets. These tests have provided information on ion beam power density, uniformity, and energy deposition. In order to increase the power density substantially for target implosion experiments, we are now concentrating on development of high voltage lithium ion beams. 10 refs., 13 figs.

  9. Entry of bovine viral diarrhea virus into ovine cells occurs through clathrin-dependent endocytosis and low pH-dependent fusion.

    PubMed

    Mathapati, Basavaraj Shrishail; Mishra, Niranjan; Rajukumar, Katherukamem; Nema, Ram Kumar; Behera, Sthita Pragnya; Dubey, Shiv Chandra

    2010-05-01

    Although mechanisms of bovine viral diarrhea virus (BVDV) entry into bovine cells have been elucidated, little is known concerning pestivirus entry and receptor usage in ovine cells. In this study, we determined the entry mechanisms of BVDV-1 and BVDV-2 in sheep fetal thymus cells. Both BVDV-1 and BVDV-2 infections were inhibited completely by chlorpromazine, beta-methyl cyclodextrin, sucrose, bafilomycin A1, chloroquine, and ammonium chloride. Simultaneous presence of reducing agent and low pH resulted in marked loss of BVDV infectivity. Moreover, BVDV was unable to fuse with ovine cell membrane by the presence of reducing agent or low pH alone, while combination of both led to fusion at low efficiency. Furthermore, sheep fetal thymus cells acutely infected with BVDV-1 or BVDV-2 were found protected from heterologous BVDV infection. Taken together, our results showed for the first time that entry of both BVDV-1 and BVDV-2 into ovine cells occurred through clathrin-dependent endocytosis, endosomal acidification, and low pH-dependent fusion following an activation step, besides suggesting the involvement of a common ovine cellular receptor during attachment and entry. PMID:19997866

  10. Inhibition of the Hantavirus Fusion Process by Predicted Domain III and Stem Peptides from Glycoprotein Gc

    PubMed Central

    Barriga, Gonzalo P.; Villalón-Letelier, Fernando; Márquez, Chantal L.; Bignon, Eduardo A.; Acuña, Rodrigo; Ross, Breyan H.; Monasterio, Octavio; Mardones, Gonzalo A.; Vidal, Simon E.; Tischler, Nicole D.

    2016-01-01

    Hantaviruses can cause hantavirus pulmonary syndrome or hemorrhagic fever with renal syndrome in humans. To enter cells, hantaviruses fuse their envelope membrane with host cell membranes. Previously, we have shown that the Gc envelope glycoprotein is the viral fusion protein sharing characteristics with class II fusion proteins. The ectodomain of class II fusion proteins is composed of three domains connected by a stem region to a transmembrane anchor in the viral envelope. These fusion proteins can be inhibited through exogenous fusion protein fragments spanning domain III (DIII) and the stem region. Such fragments are thought to interact with the core of the fusion protein trimer during the transition from its pre-fusion to its post-fusion conformation. Based on our previous homology model structure for Gc from Andes hantavirus (ANDV), here we predicted and generated recombinant DIII and stem peptides to test whether these fragments inhibit hantavirus membrane fusion and cell entry. Recombinant ANDV DIII was soluble, presented disulfide bridges and beta-sheet secondary structure, supporting the in silico model. Using DIII and the C-terminal part of the stem region, the infection of cells by ANDV was blocked up to 60% when fusion of ANDV occurred within the endosomal route, and up to 95% when fusion occurred with the plasma membrane. Furthermore, the fragments impaired ANDV glycoprotein-mediated cell-cell fusion, and cross-inhibited the fusion mediated by the glycoproteins from Puumala virus (PUUV). The Gc fragments interfered in ANDV cell entry by preventing membrane hemifusion and pore formation, retaining Gc in a non-resistant homotrimer stage, as described for DIII and stem peptide inhibitors of class II fusion proteins. Collectively, our results demonstrate that hantavirus Gc shares not only structural, but also mechanistic similarity with class II viral fusion proteins, and will hopefully help in developing novel therapeutic strategies against hantaviruses

  11. Inhibition of the Hantavirus Fusion Process by Predicted Domain III and Stem Peptides from Glycoprotein Gc.

    PubMed

    Barriga, Gonzalo P; Villalón-Letelier, Fernando; Márquez, Chantal L; Bignon, Eduardo A; Acuña, Rodrigo; Ross, Breyan H; Monasterio, Octavio; Mardones, Gonzalo A; Vidal, Simon E; Tischler, Nicole D

    2016-07-01

    Hantaviruses can cause hantavirus pulmonary syndrome or hemorrhagic fever with renal syndrome in humans. To enter cells, hantaviruses fuse their envelope membrane with host cell membranes. Previously, we have shown that the Gc envelope glycoprotein is the viral fusion protein sharing characteristics with class II fusion proteins. The ectodomain of class II fusion proteins is composed of three domains connected by a stem region to a transmembrane anchor in the viral envelope. These fusion proteins can be inhibited through exogenous fusion protein fragments spanning domain III (DIII) and the stem region. Such fragments are thought to interact with the core of the fusion protein trimer during the transition from its pre-fusion to its post-fusion conformation. Based on our previous homology model structure for Gc from Andes hantavirus (ANDV), here we predicted and generated recombinant DIII and stem peptides to test whether these fragments inhibit hantavirus membrane fusion and cell entry. Recombinant ANDV DIII was soluble, presented disulfide bridges and beta-sheet secondary structure, supporting the in silico model. Using DIII and the C-terminal part of the stem region, the infection of cells by ANDV was blocked up to 60% when fusion of ANDV occurred within the endosomal route, and up to 95% when fusion occurred with the plasma membrane. Furthermore, the fragments impaired ANDV glycoprotein-mediated cell-cell fusion, and cross-inhibited the fusion mediated by the glycoproteins from Puumala virus (PUUV). The Gc fragments interfered in ANDV cell entry by preventing membrane hemifusion and pore formation, retaining Gc in a non-resistant homotrimer stage, as described for DIII and stem peptide inhibitors of class II fusion proteins. Collectively, our results demonstrate that hantavirus Gc shares not only structural, but also mechanistic similarity with class II viral fusion proteins, and will hopefully help in developing novel therapeutic strategies against hantaviruses

  12. Fusion pore expansion is a slow, discontinuous, and Ca2+-dependent process regulating secretion from alveolar type II cells.

    PubMed

    Haller, T; Dietl, P; Pfaller, K; Frick, M; Mair, N; Paulmichl, M; Hess, M W; Furst, J; Maly, K

    2001-10-15

    In alveolar type II cells, the release of surfactant is considerably delayed after the formation of exocytotic fusion pores, suggesting that content dispersal may be limited by fusion pore diameter and subject to regulation at a postfusion level. To address this issue, we used confocal FRAP and N-(3-triethylammoniumpropyl)-4-(4-[dibutylamino]styryl) pyridinium dibromide (FM 1-43), a dye yielding intense localized fluorescence of surfactant when entering the vesicle lumen through the fusion pore (Haller, T., J. Ortmayr, F. Friedrich, H. Volkl, and P. Dietl. 1998. Proc. Natl. Acad. Sci. USA. 95:1579-1584). Thus, we have been able to monitor the dynamics of individual fusion pores up to hours in intact cells, and to calculate pore diameters using a diffusion model derived from Fick's law. After formation, fusion pores were arrested in a state impeding the release of vesicle contents, and expanded at irregular times thereafter. The expansion rate of initial pores and the probability of late expansions were increased by elevation of the cytoplasmic Ca2+ concentration. Consistently, content release correlated with the occurrence of Ca2+ oscillations in ATP-treated cells, and expanded fusion pores were detectable by EM. This study supports a new concept in exocytosis, implicating fusion pores in the regulation of content release for extended periods after initial formation. PMID:11604423

  13. Fusion of adenovirus E1A to the glucocorticoid receptor by high-resolution deletion cloning creates a hormonally inducible viral transactivator.

    PubMed Central

    Becker, D M; Hollenberg, S M; Ricciardi, R P

    1989-01-01

    The 289-amino-acid E1A protein of adenovirus type 2 stimulates transcription from early viral and certain cellular promoters. Its mechanism is not known, and there exist no temperature-sensitive mutants of E1A that could help to elucidate the details of E1A transcriptional activation. To create for E1A such a conditional phenotype, we fused portions of E1A to the human glucocorticoid receptor (GR) to make transactivation by E1A dependent on the presence of dexamethasone. Nested subsets of the E1A coding region, centered around the 46-amino-acid transactivating domain, were substituted for the DNA-binding domain of the GR. One of the resulting chimeric proteins (GR/E1A-99), which included the entire E1A transactivating domain, stimulated expression from a viral early promoter (E3) exclusively in the presence of hormone. GR/E1A-99 did not transactivate a GR-responsive promoter. It therefore exhibited the promoter specificity of E1A while possessing the hormone inducibility of the GR. Two smaller chimeras that contained only portions of the E1A transactivating domain failed to transactivate E3. These three chimeras were constructed by a novel strategy, high-resolution deletion cloning. In this procedure, series of unidirectional deletions were made with exonuclease III on each side of the E1A coding region at a resolution of 1 to 2 nucleotides. The large number of in-frame fragments present in the collection of deleted clones facilitated the construction of the GR/E1A chimeras and can be used to create many additional fusions. Images PMID:2550806

  14. Nonreplicating viral vectors as potential vaccines: recombinant canarypox virus expressing measles virus fusion (F) and hemagglutinin (HA) glycoproteins.

    PubMed

    Taylor, J; Weinberg, R; Tartaglia, J; Richardson, C; Alkhatib, G; Briedis, D; Appel, M; Norton, E; Paoletti, E

    1992-03-01

    The development of canarypox virus (CPV) recombinants expressing the hemagglutinin (HA) and fusion (F) glycoproteins of measles virus (MV) is described. Inoculation of the CPV-MV recombinants into avian or nonavian tissue culture substrates led to the expression of authentic MVF and MVHA as determined by radioimmunoprecipitation and surface immunofluorescence. In contrast to avian-derived tissue culture, no productive replication of the CPV recombinant was evident in tissue culture cells derived from nonavian origin. On inoculation of dogs, a species restricted for avipoxvirus replication, the recombinants elicited a protective immune response against a lethal canine distemper virus (CDV) challenge. The level of MV neutralizing antibodies and the level of protection induced against CDV challenge achieved by the host-restricted CPV vector were equivalent to that obtained by vaccinia virus vectors expressing the same MV antigens. PMID:1736535

  15. Recombinant Newcastle disease viral vector expressing hemagglutinin or fusion of canine distemper virus is safe and immunogenic in minks.

    PubMed

    Ge, Jinying; Wang, Xijun; Tian, Meijie; Gao, Yuwei; Wen, Zhiyuan; Yu, Guimei; Zhou, Weiwei; Zu, Shulong; Bu, Zhigao

    2015-05-15

    Canine Distemper Virus (CDV) infects many carnivores and cause several high-mortality disease outbreaks. The current CDV live vaccine cannot be safely used in some exotic species, such as mink and ferret. Here, we generated recombinant lentogenic Newcastle disease virus (NDV) LaSota expressing either envelope glycoproyein, heamagglutinine (H) or fusion protein (F), named as rLa-CDVH and rLa-CDVF, respectively. The feasibility of these recombinant NDVs to serve as live virus-vectored CD vaccine was evaluated in minks. rLa-CDVH induced significant neutralization antibodies (NA) to CDV and provided solid protection against virulent CDV challenge. On the contrast, rLa-CDVF induced much lower NA to CDV and fail to protected mink from virulent CDV challenge. Results suggest that recombinant NDV expressing CDV H is safe and efficient candidate vaccine against CDV in mink, and maybe other host species. PMID:25865465

  16. Advanced control strategies for HVAC&R systems—An overview: Part II: Soft and fusion control

    SciTech Connect

    D. Subbaram Naidu; Craig G. Rieger

    2011-04-01

    A chronological overview of the advanced control strategies for HVAC&R is presented. The overview focuses on hard-computing or control techniques, such as proportional-integral-derivative, optimal, nonlinear, adaptive, and robust; soft-computing or control techniques, such as neural networks, fuzzy logic, genetic algorithms; and the fusion or hybrid of hard and soft control techniques. Part I focused on hardcontrol strategies; Part II focuses on soft and fusion control and some future directions in HVA&R research. This overview is not intended to be an exhaustive survey on this topic, and any omissions of other works is purely unintentional.

  17. Sulphated polysaccharides from Ulva clathrata and Cladosiphon okamuranus seaweeds both inhibit viral attachment/entry and cell-cell fusion, in NDV infection.

    PubMed

    Aguilar-Briseño, José Alberto; Cruz-Suarez, Lucia Elizabeth; Sassi, Jean-François; Ricque-Marie, Denis; Zapata-Benavides, Pablo; Mendoza-Gamboa, Edgar; Rodríguez-Padilla, Cristina; Trejo-Avila, Laura María

    2015-02-01

    Sulphated polysaccharides (SP) extracted from seaweeds have antiviral properties and are much less cytotoxic than conventional drugs, but little is known about their mode of action. Combination antiviral chemotherapy may offer advantages over single agent therapy, increasing efficiency, potency and delaying the emergence of resistant virus. The paramyxoviridae family includes pathogens causing morbidity and mortality worldwide in humans and animals, such as the Newcastle Disease Virus (NDV) in poultry. This study aims at determining the antiviral activity and mechanism of action in vitro of an ulvan (SP from the green seaweed Ulva clathrata), and of its mixture with a fucoidan (SP from Cladosiphon okamuranus), against La Sota NDV strain. The ulvan antiviral activity was tested using syncytia formation, exhibiting an IC50 of 0.1 μg/mL; ulvan had a better anti cell-cell spread effect than that previously shown for fucoidan, and inhibited cell-cell fusion via a direct effect on the F0 protein, but did not show any virucidal effect. The mixture of ulvan and fucoidan showed a greater anti-spread effect than SPs alone, but ulvan antagonizes the effect of fucoidan on the viral attachment/entry. Both SPs may be promising antivirals against paramyxovirus infection but their mixture has no clear synergistic advantage. PMID:25629385

  18. Sulphated Polysaccharides from Ulva clathrata and Cladosiphon okamuranus Seaweeds both Inhibit Viral Attachment/Entry and Cell-Cell Fusion, in NDV Infection

    PubMed Central

    Aguilar-Briseño, José Alberto; Cruz-Suarez, Lucia Elizabeth; Sassi, Jean-François; Ricque-Marie, Denis; Zapata-Benavides, Pablo; Mendoza-Gamboa, Edgar; Rodríguez-Padilla, Cristina; Trejo-Avila, Laura María

    2015-01-01

    Sulphated polysaccharides (SP) extracted from seaweeds have antiviral properties and are much less cytotoxic than conventional drugs, but little is known about their mode of action. Combination antiviral chemotherapy may offer advantages over single agent therapy, increasing efficiency, potency and delaying the emergence of resistant virus. The paramyxoviridae family includes pathogens causing morbidity and mortality worldwide in humans and animals, such as the Newcastle Disease Virus (NDV) in poultry. This study aims at determining the antiviral activity and mechanism of action in vitro of an ulvan (SP from the green seaweed Ulva clathrata), and of its mixture with a fucoidan (SP from Cladosiphon okamuranus), against La Sota NDV strain. The ulvan antiviral activity was tested using syncytia formation, exhibiting an IC50 of 0.1 μg/mL; ulvan had a better anti cell-cell spread effect than that previously shown for fucoidan, and inhibited cell-cell fusion via a direct effect on the F0 protein, but did not show any virucidal effect. The mixture of ulvan and fucoidan showed a greater anti-spread effect than SPs alone, but ulvan antagonizes the effect of fucoidan on the viral attachment/entry. Both SPs may be promising antivirals against paramyxovirus infection but their mixture has no clear synergistic advantage. PMID:25629385

  19. A single amino acid change, Q114R, in the cleavage-site sequence of Newcastle disease virus fusion protein attenuates viral replication and pathogenicity.

    PubMed

    Samal, Sweety; Kumar, Sachin; Khattar, Sunil K; Samal, Siba K

    2011-10-01

    A key determinant of Newcastle disease virus (NDV) virulence is the amino acid sequence at the fusion (F) protein cleavage site. The NDV F protein is synthesized as an inactive precursor, F(0), and is activated by proteolytic cleavage between amino acids 116 and 117 to produce two disulfide-linked subunits, F(1) and F(2). The consensus sequence of the F protein cleavage site of virulent [(112)(R/K)-R-Q-(R/K)-R↓F-I(118)] and avirulent [(112)(G/E)-(K/R)-Q-(G/E)-R↓L-I(118)] strains contains a conserved glutamine residue at position 114. Recently, some NDV strains from Africa and Madagascar were isolated from healthy birds and have been reported to contain five basic residues (R-R-R-K-R↓F-I/V or R-R-R-R-R↓F-I/V) at the F protein cleavage site. In this study, we have evaluated the role of this conserved glutamine residue in the replication and pathogenicity of NDV by using the moderately pathogenic Beaudette C strain and by making Q114R, K115R and I118V mutants of the F protein in this strain. Our results showed that changing the glutamine to a basic arginine residue reduced viral replication and attenuated the pathogenicity of the virus in chickens. The pathogenicity was further reduced when the isoleucine at position 118 was substituted for valine. PMID:21677091

  20. Lesions and distribution of viral antigen following an experimental infection of young seronegative calves with virulent bovine virus diarrhea virus-type II.

    PubMed Central

    Ellis, J A; West, K H; Cortese, V S; Myers, S L; Carman, S; Martin, K M; Haines, D M

    1998-01-01

    During the past several years, acute infections with bovine viral diarrhea virus (BVDV) have been causally linked to hemorrhagic and acute mucosal disease-like syndromes with high mortality. The majority of BVDVs isolated in such cases have been classified as type II on the basis of genetic and antigenic characteristics. It was our objective to examine clinical disease, lesions and potential sites of viral replication, following experimental BVDV type II infection in young calves. On approximately day 35 after birth, calves that had received BVDV-antibody-negative colostrum were infected by intranasal inoculation of 5 x 10(5) TCID50 of BVDV type II isolate 24,515 in 5 mL of tissue culture fluid (2.5 mL/nostril). Calves were monitored twice daily for signs of clinical disease. Approximately 48-72 h after infection, all calves developed transient pyrexia (39.4-40.5 degrees C) and leukopenia. Beginning on approximately day 7 after infection, all calves developed watery diarrhea, pyrexia (40.5-41.6 degrees C), marked leukopenia (> or = 75% drop from preinoculation values), variable thrombocytopenia, and moderate to severe depression. Calves were euthanized on days 10, 11, or 12 after infection due to severe disease. Gross and histological lesions consisted of multifocal bronchointerstitial pneumonia (involving 10%-25% of affected lungs), bone marrow hypoplasia and necrosis, and minimal erosive lesions in the alimentary tract. Immunohistochemical staining for BVDV revealed widespread viral antigen usually within epithelial cells, smooth muscle cells and mononuclear phagocytes in multiple organs, including lung, Peyer's patches, gastric mucosa, thymus, adrenal gland, spleen, lymph nodes, bone marrow, and skin. This BVDV type II isolate caused rapidly progressive, severe multisystemic disease in seronegative calves that was associated with widespread distribution of viral antigen and few gross or histological inflammatory lesions. Images Figure 1. Figure 2. Figure 3

  1. A Shot Parameter Specification Subsystem for automated control of PBFA (Particle Beam Fusion Accelerator) II accelerator shots

    SciTech Connect

    Spiller, J.L.

    1987-01-01

    The Shot Parameter Specification Subsystem (SPSS) is an integral part of the automatic control system developed for the Particle Beam Fusion Accelerator II (PBFA II) by the Control Monitor (C/M) Software Development Team. This system has been designed to fully utilize the accelerator by tailoring shot parameters to the needs of the experimenters. The SPSS is the key to this flexibility. Automatic systems will be required on many pulsed power machines for the fastest turnaround, the highest reliability, and most cost effective operation. These systems will require the flexibility and the ease of use that is part of the SPSS. The PBFA II control system has proved to be an effective modular system, flexible enough to meet the demands of both the fast track construction of PBFA II and the control needs of Hermes III at the Simulation Technology Laboratory. This system is expected to meet the demands of most future machine changes.

  2. Use of Clearance Indexes to Assess Waste Disposal Issues for the HYLIFE-II Inertial Fusion Energy Power Plant Design

    SciTech Connect

    Reyes, S; Latkowski, J F; Sanz, J

    2002-01-17

    Traditionally, waste management studies for fusion energy have used the Waste Disposal Rating (WDR) to evaluate if radioactive material from irradiated structures could qualify for shallow land burial. However, given the space limitations and the negative public perception of large volumes of waste, there is a growing international motivation to develop a fusion waste management system that maximizes the amount of material that can be cleared or recycled. In this work, we present an updated assessment of the waste management options for the HYLIFE-II inertial fusion energy (IFE) power plant, using the concept of Clearance Index (CI) for radioactive waste disposal. With that purpose, we have performed a detailed neutronics analysis of the HYLIFE-II design, using the TART and ACAB computer codes for neutron transport and activation, respectively. Whereas the traditional version of ACAB only provided the user with the WDR as an index for waste considerations, here we have modified the code to calculate Clearance Indexes using the current International Atomic Energy Agency (IAEA) clearance limits for radiological waste disposal. The results from the analysis are used to perform an assessment of the waste management options for the HYLIFE-II IFE design.

  3. Preclinical Assessment of Viral Vectored and Protein Vaccines Targeting the Duffy-Binding Protein Region II of Plasmodium Vivax

    PubMed Central

    de Cassan, Simone C.; Shakri, A. Rushdi; Llewellyn, David; Elias, Sean C.; Cho, Jee Sun; Goodman, Anna L.; Jin, Jing; Douglas, Alexander D.; Suwanarusk, Rossarin; Nosten, François H.; Rénia, Laurent; Russell, Bruce; Chitnis, Chetan E.; Draper, Simon J.

    2015-01-01

    Malaria vaccine development has largely focused on Plasmodium falciparum; however, a reawakening to the importance of Plasmodium vivax has spurred efforts to develop vaccines against this difficult to treat and at times severe form of relapsing malaria, which constitutes a significant proportion of human malaria cases worldwide. The almost complete dependence of P. vivax red blood cell invasion on the interaction of the P. vivax Duffy-binding protein region II (PvDBP_RII) with the human Duffy antigen receptor for chemokines (DARC) makes this antigen an attractive vaccine candidate against blood-stage P. vivax. Here, we generated both preclinical and clinically compatible adenoviral and poxviral vectored vaccine candidates expressing the Salvador I allele of PvDBP_RII – including human adenovirus serotype 5 (HAdV5), chimpanzee adenovirus serotype 63 (ChAd63), and modified vaccinia virus Ankara (MVA) vectors. We report on the antibody and T cell immunogenicity of these vaccines in mice or rabbits, either used alone in a viral vectored prime-boost regime or in “mixed-modality” adenovirus prime – protein-in-­adjuvant boost regimes (using a recombinant PvDBP_RII protein antigen formulated in Montanide®ISA720 or Abisco®100 adjuvants). Antibodies induced by these regimes were found to bind to native parasite antigen from P. vivax infected Thai patients and were capable of inhibiting the binding of PvDBP_RII to its receptor DARC using an in vitro binding inhibition assay. In recent years, recombinant ChAd63 and MVA vectors have been quickly translated into human clinical trials for numerous antigens from P. falciparum as well as a growing number of other pathogens. The vectors reported here are immunogenic in small animals, elicit antibodies against PvDBP_RII, and have recently entered clinical trials, which will provide the first assessment of the safety and immunogenicity of the PvDBP_RII antigen in humans. PMID:26217340

  4. Flibe Coolant Cleanup and Processing in the HYLIFE-II Inertial Fusion Energy Power Plant

    SciTech Connect

    Moir, R W

    2001-03-23

    In the HYLIFE-II chamber design, a thick flowing blanket of molten-salt (Li{sub 2}BeF{sub 4}) called flibe is used to protect structures from radiation damage. Since it is directly exposed to the fusion target, the flibe will absorb the target debris. Removing the materials left over from target explosions at the rate of {approx}6/s and then recycling some of these materials poses a challenge for the inertial fusion energy power plant. The choice of target materials derives from multi-disciplinary criteria such as target performance, fabricability, safety and environment, corrosion, and cost of recycle. Indirect-drive targets require high-2 materials for the hohlraum. Gold and gadolinium are favorite target materials for laboratory experiments but cost considerations may preclude their use in power plants or at least requires cost effective recycle because a year's supply of gold and gadolinium is estimated at 520 M$ and 40 M$. Environmental and waste considerations alone require recycle of this material. Separation by volatility appears to be the most attractive (e.g., Hg and Xe); centrifugation (e.g., Pb) is acceptable with some problems (e.g., materials compatibility) and chemical separation is the least attractive (e.g. Gd and Hf). Mercury, hafnium and xenon might be substituted with equal target performance and have advantages in removal and recycle due to their high volatility, except for hafnium. Alternatively, lead, tungsten and xenon might be used due to the ability to use centrifugation and gaseous separation. Hafnium or tantalum form fluorides, which will complicate materials compatibility, corrosion and require sufficient volatility of the fluoride for separation. Further complicating the coolant cleanup and processing is the formation of free fluorine due to nuclear transformation of lithium and beryllium in the flibe, which requires chemical control of the fluoride level to minimize corrosion. The study of the choice of target materials and the

  5. Kaposi's Sarcoma-Associated Herpesvirus Viral Interferon Regulatory Factor 3 Inhibits Gamma Interferon and Major Histocompatibility Complex Class II Expression▿†

    PubMed Central

    Schmidt, Katharina; Wies, Effi; Neipel, Frank

    2011-01-01

    Kaposi's sarcoma-associated herpesvirus (KSHV) carries four genes with homology to human interferon regulatory factors (IRFs). One of these IRFs, the viral interferon regulatory factor 3 (vIRF-3), is expressed in latently infected primary effusion lymphoma (PEL) cells and required for their continuous proliferation. Moreover, vIRF-3 is known to be involved in modulation of the type I interferon (IFN) response. We now show that vIRF-3 also interferes with the type II interferon system and antigen presentation to the adaptive immune system. Starting with an analysis of the transcriptome, we show that vIRF-3 inhibits expression of major histocompatibility complex class II (MHC II) molecules: small interfering RNA (siRNA)-mediated knockdown of vIRF-3 in KSHV-infected PEL cell lines resulted in increased MHC II levels; overexpression of vIRF-3 in KSHV-negative B cells leads to downmodulation of MHC II. This regulation could be traced back to inhibition of class II transactivator (CIITA) transcription by vIRF-3. Reporter assays revealed that the gamma interferon (IFN-γ)-sensitive CIITA promoters PIV and PIII were inhibited by vIRF-3. Consistently, IFN-γ levels increased upon vIRF-3 knockdown in PEL cells. IFN-γ regulation by vIRF-3 was confirmed in reporter assays as well as by upregulation of typical IFN-γ target genes upon knockdown of vIRF-3 in PEL cells. In summary, we conclude that vIRF-3 contributes to the viral immunoevasion by downregulation of IFN-γ and CIITA and thus MHC II expression. PMID:21345951

  6. Transgenic mice expressing an intracellular fluorescent fusion of angiotensin II demonstrate renal thrombotic microangiopathy and elevated blood pressure

    PubMed Central

    Redding, K. M.; Chen, B. L.; Singh, A.; Re, R. N.; Navar, L. G.; Seth, D. M.; Sigmund, C. D.; Tang, W. W.

    2010-01-01

    We have generated transgenic mice that express angiotensin II (ANG II) fused downstream of enhanced cyan fluorescent protein, expression of which is regulated by the mouse metallothionein promoter. The fusion protein, which lacks a secretory signal, is retained intracellularly. In the present study, RT-PCR, immunoblot analyses, whole-animal fluorescent imaging, and fluorescent microscopy of murine embryonic fibroblasts confirm expression of the fusion protein in vivo and in vitro. The transgene is expressed in all tissues tested (including brain, heart, kidney, liver, lung, and testes), and radioimmunoassay of plasma samples obtained from transgenic mice indicate no increase in circulating ANG II over wild-type levels, consistent with intracellular retention of the transgene product. Kidneys from transgenic and corresponding wild-type littermates were histologically evaluated, and abnormalities in transgenic mice consistent with thrombotic microangiopathy were observed; microthrombosis was frequently observed within the glomerular capillaries and small vessels. In addition, systolic and diastolic blood pressures, measured by telemetry (n = 8 for each group), were significantly higher in transgenic mice compared with wild-type littermates. Blood pressure of line A male transgenic mice was 125 ± 1.7 over 97 ± 1.6 compared with 109 ± 1.7 over 83 ± 1.4 mmHg in wild-type littermates (systolic over diastolic). In summary, overexpression of an intracellular fluorescent fusion protein of ANG II correlates with elevated blood pressure and kidney pathology. This transgenic model may be useful to further explore the intracellular renin-angiotensin system and its implication in abnormal kidney function and hypertension. PMID:20363893

  7. Viral Hepatitis

    MedlinePlus

    ... Public Home » For Veterans and the Public Viral Hepatitis Menu Menu Viral Hepatitis Viral Hepatitis Home For ... the Public Veterans and Public Home How is Hepatitis C Treated? Find the facts about the newest ...

  8. Inhibition of iridovirus protein synthesis and virus replication by antisense morpholino oligonucleotides targeted to the major capsid protein, the 18 kDa immediate-early protein, and a viral homolog of RNA polymerase II

    SciTech Connect

    Sample, Robert; Bryan, Locke; Long, Scott; Majji, Sai; Hoskins, Glenn; Sinning, Allan; Olivier, Jake; Chinchar, V. Gregory . E-mail: vchinchar@microbio.umsmed.edu

    2007-02-20

    Frog virus 3 (FV3) is a large DNA virus that encodes {approx} 100 proteins. Although the general features of FV3 replication are known, the specific roles that most viral proteins play in the virus life cycle have not yet been elucidated. To address the question of viral gene function, antisense morpholino oligonucleotides (asMOs) were used to transiently knock-down expression of specific viral genes and thus infer their role in virus replication. We designed asMOs directed against the major capsid protein (MCP), an 18 kDa immediate-early protein (18K) that was thought to be a viral regulatory protein, and the viral homologue of the largest subunit of RNA polymerase II (vPol-II{alpha}). All three asMOs successfully inhibited translation of the targeted protein, and two of the three asMOs resulted in marked phenotypic changes. Knock-down of the MCP resulted in a marked reduction in viral titer without a corresponding drop in the synthesis of other late viral proteins. Transmission electron microscopy (TEM) showed that in cells treated with the anti-MCP MO assembly sites were devoid of viral particles and contained numerous aberrant structures. In contrast, inhibition of 18K synthesis did not block virion formation, suggesting that the 18K protein was not essential for replication of FV3 in fathead minnow (FHM) cells. Finally, consistent with the view that late viral gene expression is catalyzed by a virus-encoded or virus-modified Pol-II-like protein, knock-down of vPol-II{alpha} triggered a global decline in late gene expression and virus yields without affecting the synthesis of early viral genes. Collectively, these results demonstrate the utility of using asMOs to elucidate the function of FV3 proteins.

  9. Fatal viral infection-associated encephalopathy in two Chinese boys: a genetically determined risk factor of thermolabile carnitine palmitoyltransferase II variants.

    PubMed

    Mak, Chloe Miu; Lam, Ching-wan; Fong, Nai-chung; Siu, Wai-kwan; Lee, Han-chih Hencher; Siu, Tak-shing; Lai, Chi-kong; Law, Chun-yiu; Tong, Sui-fun; Poon, Wing-tat; Lam, David Shu-yan; Ng, Ho-leung; Yuen, Yuet-ping; Tam, Sidney; Que, Tak-lun; Kwong, Ngai-shan; Chan, Albert Yan-wo

    2011-08-01

    Influenza-associated encephalopathy (IAE) is a potentially fatal neurological complication of influenza infection usually in the presence of high and persistent fever. Thermolabile carnitine palmitoyltransferase II enzyme (CPT-II) predisposes IAE, so far only described in Japanese. As the genetic origins of Japanese and Chinese are alike, similar genetic risk factors in CPT-II are expected. We report the first two unrelated Chinese patients of thermolabile CPT-II variants that underlain the persistent high fever-triggered viral infection-associated encephalopathy, multi-organ failure and death. Elevated (C16:0+C18:1)/C2 acylcarnitines ratio and the CPT2 susceptibility variant allele [p.Phe352Cys; p.Val368Ile] were detected. The asymptomatic family members of one patient also had abnormal long-chain acylcarnitines. In our experience of biochemical genetics, the elevated (C16:0+C18:1)/C2 acylcarnitines ratio is unusual and specific for thermolabile CPT-II variants. Allele frequency of [p.Phe352Cys; p.Val368Ile] among Hong Kong Chinese was 0.104, similar to Japanese data, and [p.Phe352Cys] has not been reported in Caucasians. This may explain the Asian-specific phenomenon of thermolabile CPT-II-associated IAE. We successfully demonstrated the thermolabile CPT-II variants in patients with viral infection-associated encephalopathy in another Asian population outside Japanese. The condition is likely under-recognized. With our first cases, it is envisaged that more cases will be diagnosed in subsequent years. The exact pathogenic mechanism of how other factors interplay with thermolabile CPT-II variants and high fever leading to IAE, is yet to be elucidated. Fasting and decreased intake during illness may aggravate the disease. Further studies including high risk and neonatal screening are warranted to investigate its expressivity, penetrance and temperature-dependent behaviors in thermolabile CPT-II carriers. This may lead to discovery of the therapeutic golden window

  10. Statistical Mechanics of Viral Entry

    NASA Astrophysics Data System (ADS)

    Zhang, Yaojun; Dudko, Olga K.

    2015-01-01

    Viruses that have lipid-membrane envelopes infect cells by fusing with the cell membrane to release viral genes. Membrane fusion is known to be hindered by high kinetic barriers associated with drastic structural rearrangements—yet viral infection, which occurs by fusion, proceeds on remarkably short time scales. Here, we present a quantitative framework that captures the principles behind the invasion strategy shared by all enveloped viruses. The key to this strategy—ligand-triggered conformational changes in the viral proteins that pull the membranes together—is treated as a set of concurrent, bias field-induced activated rate processes. The framework results in analytical solutions for experimentally measurable characteristics of virus-cell fusion and enables us to express the efficiency of the viral strategy in quantitative terms. The predictive value of the theory is validated through simulations and illustrated through recent experimental data on influenza virus infection.

  11. A review of potential image fusion methods for remote sensing-based irrigation management: Part II

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Satellite-based sensors provide data at either greater spectral and coarser spatial resolutions, or lower spectral and finer spatial resolutions due to complementary spectral and spatial characteristics of optical sensor systems. In order to overcome this limitation, image fusion has been suggested ...

  12. NMR structures of anti-HIV D-peptides derived from the N-terminus of viral chemokine vMIP-II

    SciTech Connect

    Mori, Mayuko; Liu Dongxiang; Kumar, Santosh; Huang Ziwei; E-mail: ziweihuang@burnham.org

    2005-09-30

    The viral macrophage inflammatory protein-II (vMIP-II) encoded by Kaposi's sarcoma-associated herpesvirus has unique biological activities in that it blocks the cell entry by several different human immunodeficiency virus type 1 (HIV-1) strains via chemokine receptors including CXCR4 and CCR5. In this paper, we report the solution structure of all-D-amino acid peptides derived from the N-terminus of vMIP-II, which have been shown to have strong CXCR4 binding activity and potently inhibit HIV-1 entry via CXCR4, by using long mixing time two-dimensional nuclear Overhauser enhancement spectroscopy experiments. Both of all-D-peptides vMIP-II (1-10) and vMIP-II (1-21), which are designated as DV3 and DV1, respectively, have higher CXCR4 binding ability than their L-peptide counterparts. They are partially structured in aqueous solution, displaying a turn-like structure over residues 5-8. The small temperature coefficients of His-6 amide proton for both peptides also suggest the formation of a small hydrophobic pocket centered on His-6. The structural features of DV3 are very similar to the reported solution structure of all-L-peptide vMIP-II (1-10) [M.P. Crump, E. Elisseeva, J. Gong, I. Clark-Lewis, B.D. Sykes, Structure/function of human herpesvirus-8 MIP-II (1-71) and the antagonist N-terminal segment (1-10), FEBS Lett. 489 (2001) 171], which is consistent with the notion that D- and L-enantiomeric peptides can adopt mirror image conformations. The NMR structures of the D-peptides provide a structural basis to understand their mechanism of action and design new peptidomimetic analogs to further explore the structure-activity relationship of D-peptide ligand binding to CXCR4.

  13. Insulin-like growth factor II peptide fusion enables uptake and lysosomal delivery of α-N-acetylglucosaminidase to mucopolysaccharidosis type IIIB fibroblasts

    PubMed Central

    Kan, Shih-hsin; Troitskaya, Larisa A.; Sinow, Carolyn S.; Haitz, Karyn; Todd, Amanda K.; Di Stefano, Ariana; Le, Steven Q.; Dickson, Patricia I.; Tippin, Brigette L.

    2014-01-01

    Enzyme replacement therapy for mucopolysaccharidosis type IIIB (MPS IIIB; Sanfilippo B syndrome) has been hindered by inadequate mannose 6-phosphorylation and cellular uptake of recombinantly produced human α-N-acetyl-glucosamindase (rhNAGLU). We expressed and characterized a modified, recombinant human NAGLU fused to the receptor binding motif of insulin-like growth factor-II (rhNAGLU-IGF-II) to enhance its ability to enter cells using the cation-independent mannose 6-phosphate receptor, which is also the receptor for IGF-II (at a different binding site). RhNAGLU-IGF-II was stably expressed in Chinese hamster ovary cells, secreted and purified to apparent homogeneity. The Km and pH optimum of the fusion enzyme was similar to those reported for rhNAGLU. Both intracellular uptake and confocal microscopy suggested MPS IIIB fibroblasts readily take up the fusion enzyme via receptor-mediated endocytosis that was significantly inhibited (p<0.001) by monomeric IGF-II peptide. Glycosaminoglycan storage was reduced by 60% (p<0.001) to near background levels in MPS IIIB cells after treatment with rhNAGLU-IGF-II, with half-maximal correction at concentrations of 3–12 pM. Similar cellular uptake mechanism via the IGF-II receptor was also demonstrated in two different brain tumor-derived cell lines. Fusion of NAGLU to IGF-II enhanced its cellular uptake while maintaining enzymatic activity, supporting its potential as a therapeutic candidate for MPS IIIB. PMID:24266751

  14. Viral Phylodynamics

    PubMed Central

    Volz, Erik M.; Koelle, Katia; Bedford, Trevor

    2013-01-01

    Viral phylodynamics is defined as the study of how epidemiological, immunological, and evolutionary processes act and potentially interact to shape viral phylogenies. Since the coining of the term in 2004, research on viral phylodynamics has focused on transmission dynamics in an effort to shed light on how these dynamics impact viral genetic variation. Transmission dynamics can be considered at the level of cells within an infected host, individual hosts within a population, or entire populations of hosts. Many viruses, especially RNA viruses, rapidly accumulate genetic variation because of short generation times and high mutation rates. Patterns of viral genetic variation are therefore heavily influenced by how quickly transmission occurs and by which entities transmit to one another. Patterns of viral genetic variation will also be affected by selection acting on viral phenotypes. Although viruses can differ with respect to many phenotypes, phylodynamic studies have to date tended to focus on a limited number of viral phenotypes. These include virulence phenotypes, phenotypes associated with viral transmissibility, cell or tissue tropism phenotypes, and antigenic phenotypes that can facilitate escape from host immunity. Due to the impact that transmission dynamics and selection can have on viral genetic variation, viral phylogenies can therefore be used to investigate important epidemiological, immunological, and evolutionary processes, such as epidemic spread [2], spatio-temporal dynamics including metapopulation dynamics [3], zoonotic transmission, tissue tropism [4], and antigenic drift [5]. The quantitative investigation of these processes through the consideration of viral phylogenies is the central aim of viral phylodynamics. PMID:23555203

  15. Sensor fusion II: Human and machine strategies; Proceedings of the Meeting, Philadelphia, PA, Nov. 6-9, 1989

    NASA Technical Reports Server (NTRS)

    Schenker, Paul S. (Editor)

    1990-01-01

    Various papers on human and machine strategies in sensor fusion are presented. The general topics addressed include: active vision, measurement and analysis of visual motion, decision models for sensor fusion, implementation of sensor fusion algorithms, applying sensor fusion to image analysis, perceptual modules and their fusion, perceptual organization and object recognition, planning and the integration of high-level knowledge with perception, using prior knowledge and context in sensor fusion.

  16. Viral pneumonia

    MedlinePlus

    ... Names Pneumonia - viral; "Walking pneumonia" - viral Images Lungs Respiratory system References Lee FE, Treanor J. Viral infections. In: Mason RJ, VC Broaddus, Martin TR, et al, eds. Murray and Nadel’s Textbook of Respiratory Medicine . 5th ed. Philadelphia, PA: Saunders Elsevier; 2010: ...

  17. Transcription elongation regulator 1 (TCERG1) regulates competent RNA polymerase II-mediated elongation of HIV-1 transcription and facilitates efficient viral replication

    PubMed Central

    2013-01-01

    Background Control of RNA polymerase II (RNAPII) release from pausing has been proposed as a checkpoint mechanism to ensure optimal RNAPII activity, especially in large, highly regulated genes. HIV-1 gene expression is highly regulated at the level of elongation, which includes transcriptional pausing that is mediated by both viral and cellular factors. Here, we present evidence for a specific role of the elongation-related factor TCERG1 in regulating the extent of HIV-1 elongation and viral replication in vivo. Results We show that TCERG1 depletion diminishes the basal and viral Tat-activated transcription from the HIV-1 LTR. In support of a role for an elongation mechanism in the transcriptional control of HIV-1, we found that TCERG1 modifies the levels of pre-mRNAs generated at distal regions of HIV-1. Most importantly, TCERG1 directly affects the elongation rate of RNAPII transcription in vivo. Furthermore, our data demonstrate that TCERG1 regulates HIV-1 transcription by increasing the rate of RNAPII elongation through the phosphorylation of serine 2 within the carboxyl-terminal domain (CTD) of RNAPII and suggest a mechanism for the involvement of TCERG1 in relieving pausing. Finally, we show that TCERG1 is required for HIV-1 replication. Conclusions Our study reveals that TCERG1 regulates HIV-1 transcriptional elongation by increasing the elongation rate of RNAPII and phosphorylation of Ser 2 within the CTD. Based on our data, we propose a general mechanism for TCERG1 acting on genes that are regulated at the level of elongation by increasing the rate of RNAPII transcription through the phosphorylation of Ser2. In the case of HIV-1, our evidence provides the basis for further investigation of TCERG1 as a potential therapeutic target for the inhibition of HIV-1 replication PMID:24165037

  18. Type I and Type II Interferon Coordinately Regulate Suppressive Dendritic Cell Fate and Function during Viral Persistence

    PubMed Central

    Cunningham, Cameron R.; Champhekar, Ameya; Tullius, Michael V.; Dillon, Barbara Jane; Zhen, Anjie; de la Fuente, Justin Rafael; Herskovitz, Jonathan; Elsaesser, Heidi; Snell, Laura M.; Wilson, Elizabeth B.; de la Torre, Juan Carlos; Kitchen, Scott G.; Horwitz, Marcus A.; Bensinger, Steven J.; Smale, Stephen T.; Brooks, David G.

    2016-01-01

    Persistent viral infections are simultaneously associated with chronic inflammation and highly potent immunosuppressive programs mediated by IL-10 and PDL1 that attenuate antiviral T cell responses. Inhibiting these suppressive signals enhances T cell function to control persistent infection; yet, the underlying signals and mechanisms that program immunosuppressive cell fates and functions are not well understood. Herein, we use lymphocytic choriomeningitis virus infection (LCMV) to demonstrate that the induction and functional programming of immunosuppressive dendritic cells (DCs) during viral persistence are separable mechanisms programmed by factors primarily considered pro-inflammatory. IFNγ first induces the de novo development of naive monocytes into DCs with immunosuppressive potential. Type I interferon (IFN-I) then directly targets these newly generated DCs to program their potent T cell immunosuppressive functions while simultaneously inhibiting conventional DCs with T cell stimulating capacity. These mechanisms of monocyte conversion are constant throughout persistent infection, establishing a system to continuously interpret and shape the immunologic environment. MyD88 signaling was required for the differentiation of suppressive DCs, whereas inhibition of stimulatory DCs was dependent on MAVS signaling, demonstrating a bifurcation in the pathogen recognition pathways that promote distinct elements of IFN-I mediated immunosuppression. Further, a similar suppressive DC origin and differentiation was also observed in Mycobacterium tuberculosis infection, HIV infection and cancer. Ultimately, targeting the underlying mechanisms that induce immunosuppression could simultaneously prevent multiple suppressive signals to further restore T cell function and control persistent infections. PMID:26808628

  19. Type I and Type II Interferon Coordinately Regulate Suppressive Dendritic Cell Fate and Function during Viral Persistence.

    PubMed

    Cunningham, Cameron R; Champhekar, Ameya; Tullius, Michael V; Dillon, Barbara Jane; Zhen, Anjie; de la Fuente, Justin Rafael; Herskovitz, Jonathan; Elsaesser, Heidi; Snell, Laura M; Wilson, Elizabeth B; de la Torre, Juan Carlos; Kitchen, Scott G; Horwitz, Marcus A; Bensinger, Steven J; Smale, Stephen T; Brooks, David G

    2016-01-01

    Persistent viral infections are simultaneously associated with chronic inflammation and highly potent immunosuppressive programs mediated by IL-10 and PDL1 that attenuate antiviral T cell responses. Inhibiting these suppressive signals enhances T cell function to control persistent infection; yet, the underlying signals and mechanisms that program immunosuppressive cell fates and functions are not well understood. Herein, we use lymphocytic choriomeningitis virus infection (LCMV) to demonstrate that the induction and functional programming of immunosuppressive dendritic cells (DCs) during viral persistence are separable mechanisms programmed by factors primarily considered pro-inflammatory. IFNγ first induces the de novo development of naive monocytes into DCs with immunosuppressive potential. Type I interferon (IFN-I) then directly targets these newly generated DCs to program their potent T cell immunosuppressive functions while simultaneously inhibiting conventional DCs with T cell stimulating capacity. These mechanisms of monocyte conversion are constant throughout persistent infection, establishing a system to continuously interpret and shape the immunologic environment. MyD88 signaling was required for the differentiation of suppressive DCs, whereas inhibition of stimulatory DCs was dependent on MAVS signaling, demonstrating a bifurcation in the pathogen recognition pathways that promote distinct elements of IFN-I mediated immunosuppression. Further, a similar suppressive DC origin and differentiation was also observed in Mycobacterium tuberculosis infection, HIV infection and cancer. Ultimately, targeting the underlying mechanisms that induce immunosuppression could simultaneously prevent multiple suppressive signals to further restore T cell function and control persistent infections. PMID:26808628

  20. Solar fusion cross sections II: the pp chain and CNO cycles

    SciTech Connect

    Adelberger, E G; Bemmerer, D; Bertulani, C A; Chen, J -W; Costantini, H; Couder, M; Cyburt, R; Davids, B; Freedman, S J; Gai, M; Garcia, A; Gazit, D; Gialanella, L; Greife, U; Hass, M; Heeger, K; Haxton, W C; Imbriani, G; Itahashi, T; Junghans, A; Kubodera, K; Langanke, K; Leitner, D; Leitner, M; Marcucci, L E; Motobayashi, T; Mukhamedzhanov, A; Nollett, Kenneth M; Nunes, F M; Park, T -S; Parker, P D; Prati, P; Ramsey-Musolf, M J; Hamish Robertson, R G; Schiavilla, R; Simpson, E C; Snover, K A; Spitaleri, C; Strieder, F; Suemmerer, K; Trautvetter, R E; Tribble, R E; Typel, S; Uberseder, E; Vetter, P; Wiescher, M; Winslow, L

    2011-04-01

    The available data on nuclear fusion cross sections important to energy generation in the Sun and other hydrogen-burning stars and to solar neutrino production are summarized and critically evaluated. Recommended values and uncertainties are provided for key cross sections, and a recommended spectrum is given for 8B solar neutrinos. Opportunities for further increasing the precision of key rates are also discussed, including new facilities, new experimental techniques, and improvements in theory. This review, which summarizes the conclusions of a workshop held at the Institute for Nuclear Theory, Seattle, in January 2009, is intended as a 10-year update and supplement to 1998, Rev. Mod. Phys. 70, 1265.

  1. FINESSE: study of the issues, experiments and facilities for fusion nuclear technology research and development. Interim report. Volume II

    SciTech Connect

    Abdou, M.

    1984-10-01

    The Nuclear Fusion Issues chapter contains a comprehensive list of engineering issues for fusion reactor nuclear components. The list explicitly defines the uncertainties associated with the engineering option of a fusion reactor and addresses the potential consequences resulting from each issue. The next chapter identifies the fusion nuclear technology testing needs up to the engineering demonstration stage. (MOW)

  2. Giving CD4+ T cells the slip: viral interference with MHC class II-restricted antigen processing and presentation.

    PubMed

    Forsyth, Katherine S; Eisenlohr, Laurence C

    2016-06-01

    Activation of CD4+ T cells through interactions with peptides bound to Major Histocompatibility Complex Class II (MHC-II) molecules is a crucial step in clearance of most pathogens. Consequently, many viruses have evolved ways of blocking this aspect of adaptive immunity, from specific targeting of processing and presentation components to modulation of signaling pathways that regulate peptide presentation in addition to many other host defense mechanisms. Such cases of interference are far less common compared to what has been elucidated in MHC-I processing and presentation. This may be attributable in part to the complexity of MHC-II antigen processing, the scope of which is only now coming to light. PMID:27115617

  3. Iron(II) supramolecular helicates interfere with the HIV-1 Tat–TAR RNA interaction critical for viral replication

    NASA Astrophysics Data System (ADS)

    Malina, Jaroslav; Hannon, Michael J.; Brabec, Viktor

    2016-07-01

    The interaction between the HIV-1 transactivator protein Tat and TAR (transactivation responsive region) RNA, plays a critical role in HIV-1 transcription. Iron(II) supramolecular helicates were evaluated for their in vitro activity to inhibit Tat–TAR RNA interaction using UV melting studies, electrophoretic mobility shift assay, and RNase A footprinting. The results demonstrate that iron(II) supramolecular helicates inhibit Tat-TAR interaction at nanomolar concentrations by binding to TAR RNA. These studies provide a new insight into the biological potential of metallosupramolecular helicates.

  4. Iron(II) supramolecular helicates interfere with the HIV-1 Tat–TAR RNA interaction critical for viral replication

    PubMed Central

    Malina, Jaroslav; Hannon, Michael J.; Brabec, Viktor

    2016-01-01

    The interaction between the HIV-1 transactivator protein Tat and TAR (transactivation responsive region) RNA, plays a critical role in HIV-1 transcription. Iron(II) supramolecular helicates were evaluated for their in vitro activity to inhibit Tat–TAR RNA interaction using UV melting studies, electrophoretic mobility shift assay, and RNase A footprinting. The results demonstrate that iron(II) supramolecular helicates inhibit Tat-TAR interaction at nanomolar concentrations by binding to TAR RNA. These studies provide a new insight into the biological potential of metallosupramolecular helicates. PMID:27405089

  5. Iron(II) supramolecular helicates interfere with the HIV-1 Tat-TAR RNA interaction critical for viral replication.

    PubMed

    Malina, Jaroslav; Hannon, Michael J; Brabec, Viktor

    2016-01-01

    The interaction between the HIV-1 transactivator protein Tat and TAR (transactivation responsive region) RNA, plays a critical role in HIV-1 transcription. Iron(II) supramolecular helicates were evaluated for their in vitro activity to inhibit Tat-TAR RNA interaction using UV melting studies, electrophoretic mobility shift assay, and RNase A footprinting. The results demonstrate that iron(II) supramolecular helicates inhibit Tat-TAR interaction at nanomolar concentrations by binding to TAR RNA. These studies provide a new insight into the biological potential of metallosupramolecular helicates. PMID:27405089

  6. Power Oscillator Circuit Modeling And Redesign For The Particle Beam Fusion Accelerator II (PBFA-II) Switch Trigger Laser

    NASA Astrophysics Data System (ADS)

    Smith, David L.; Hamil, Roy A.; Prestwich, Kenneth R.; Rohwein, Gerald J.; Donovan, Guy L.; Schaub, Charles M.

    1987-05-01

    The energy output and reliability of the multi-joule, injection-locked KrF laser used to trigger the PBFA II accelerator gas switches were improved through modifications identified in modeling the Blumlein driver circuit for the power oscillator. A combination of the SCEPTRE1 network solver code and JASON2 electrostatic field code were used to model the laser pulse-forming circuit in its single-channel rail gap configuration and modified versions with three or five discrete switches across the 1.45-m-wide, water-insulated transmission line. Three regularly spaced trigatron spark gaps resulted in a more uniformly driven laser volume with lower variations in voltages (10%) and rise times (9%) along its length. With the new configuration, over 3000 shots have been recorded without a single misfire compared to an average of ---25 shots before a prefire with the original design. The gas mix and pressure had to be optimized to match a given driver pulse voltage and rise time to achieve maximum performance from the laser. We summarize the model results which led to our decision to change the Blumlein switch configuration.

  7. HYFIRE II: fusion/high-temperature electrolysis conceptual-design study. Annual report

    SciTech Connect

    Fillo, J.A.

    1983-08-01

    As in the previous HYFIRE design study, the current study focuses on coupling a Tokamak fusion reactor with a high-temperature blanket to a High-Temperature Electrolyzer (HTE) process to produce hydrogen and oxygen. Scaling of the STARFIRE reactor to allow a blanket power to 6000 MW(th) is also assumed. The primary difference between the two studies is the maximum inlet steam temperature to the electrolyzer. This temperature is decreased from approx. 1300/sup 0/ to approx. 1150/sup 0/C, which is closer to the maximum projected temperature of the Westinghouse fuel cell design. The process flow conditions change but the basic design philosophy and approaches to process design remain the same as before. Westinghouse assisted in the study in the areas of systems design integration, plasma engineering, balance-of-plant design, and electrolyzer technology.

  8. IFITM Proteins Restrict Viral Membrane Hemifusion

    PubMed Central

    Golfetto, Ottavia; Bungart, Brittani; Li, Minghua; Ding, Shilei; He, Yuxian; Liang, Chen; Lee, James C.; Gratton, Enrico; Cohen, Fredric S.; Liu, Shan-Lu

    2013-01-01

    The interferon-inducible transmembrane (IFITM) protein family represents a new class of cellular restriction factors that block early stages of viral replication; the underlying mechanism is currently not known. Here we provide evidence that IFITM proteins restrict membrane fusion induced by representatives of all three classes of viral membrane fusion proteins. IFITM1 profoundly suppressed syncytia formation and cell-cell fusion induced by almost all viral fusion proteins examined; IFITM2 and IFITM3 also strongly inhibited their fusion, with efficiency somewhat dependent on cell types. Furthermore, treatment of cells with IFN also markedly inhibited viral membrane fusion and entry. By using the Jaagsiekte sheep retrovirus envelope and influenza A virus hemagglutinin as models for study, we showed that IFITM-mediated restriction on membrane fusion is not at the steps of receptor- and/or low pH-mediated triggering; instead, the creation of hemifusion was essentially blocked by IFITMs. Chlorpromazine (CPZ), a chemical known to promote the transition from hemifusion to full fusion, was unable to rescue the IFITM-mediated restriction on fusion. In contrast, oleic acid (OA), a lipid analog that generates negative spontaneous curvature and thereby promotes hemifusion, virtually overcame the restriction. To explore the possible effect of IFITM proteins on membrane molecular order and fluidity, we performed fluorescence labeling with Laurdan, in conjunction with two-photon laser scanning and fluorescence-lifetime imaging microscopy (FLIM). We observed that the generalized polarizations (GPs) and fluorescence lifetimes of cell membranes expressing IFITM proteins were greatly enhanced, indicating higher molecularly ordered and less fluidized membranes. Collectively, our data demonstrated that IFITM proteins suppress viral membrane fusion before the creation of hemifusion, and suggested that they may do so by reducing membrane fluidity and conferring a positive spontaneous

  9. Recruitment of Oligoclonal Viral-Specific T cells to Kill Human Tumor Cells Using Single-Chain Antibody-Peptide-HLA Fusion Molecules.

    PubMed

    Noy, Roy; Haus-Cohen, Maya; Oved, Kfir; Voloshin, Tali; Reiter, Yoram

    2015-06-01

    Tumor progression is often associated with the development of diverse immune escape mechanisms. One of the main tumor escape mechanism is HLA loss, in which human solid tumors exhibit alterations in HLA expression. Moreover, tumors that present immunogenic peptides via class I MHC molecules are not susceptible to CTL-mediated lysis, because of the relatively low potency of the tumor-specific CLTs. Here, we present a novel cancer immunotherapy approach that overcomes these problems by using the high affinity and specificity of antitumor antibodies to recruit potent antiviral memory CTLs to attack tumor cells. We constructed a recombinant molecule by genetic fusion of a cytomegalovirus (CMV)-derived peptide pp65 (NLVPMVATV) to scHLA-A2 molecules that were genetically fused to a single-chain Fv Ab fragment specific for the tumor cell surface antigen mesothelin. This fully covalent fusion molecule was expressed in E. coli as inclusion bodies and refolded in vitro. The fusion molecules could specifically bind mesothelin-expressing cells and mediate their lysis by NLVPMVATV-specific HLA-A2-restricted human CTLs. More importantly, these molecules exhibited very potent antitumor activity in vivo in a nude mouse model bearing preestablished human tumor xenografts that were adoptively transferred along with human memory CTLs. These results represent a novel and powerful approach to immunotherapy for solid tumors, as demonstrated by the ability of the CMV-scHLA-A2-SS1(scFv) fusion molecule to mediate specific and efficient recruitment of CMV-specific CTLs to kill tumor cells. PMID:25852061

  10. Induction of Heterosubtypic Cross-Protection against Influenza by a Whole Inactivated Virus Vaccine: The Role of Viral Membrane Fusion Activity

    PubMed Central

    Budimir, Natalija; Huckriede, Anke; Meijerhof, Tjarko; Boon, Louis; Gostick, Emma; Price, David A.; Wilschut, Jan; de Haan, Aalzen

    2012-01-01

    Background The inability of seasonal influenza vaccines to effectively protect against infection with antigenically drifted viruses or newly emerging pandemic viruses underlines the need for development of cross-reactive influenza vaccines that induce immunity against a variety of virus subtypes. Therefore, potential cross-protective vaccines, e.g., whole inactivated virus (WIV) vaccine, that can target conserved internal antigens such as the nucleoprotein (NP) and/or matrix protein (M1) need to be explored. Methodology/Principal Findings In the current study we show that a WIV vaccine, through induction of cross-protective cytotoxic T lymphocytes (CTLs), protects mice from heterosubtypic infection. This protection was abrogated after depletion of CD8+ cells in vaccinated mice, indicating that CTLs were the primary mediators of protection. Previously, we have shown that different procedures used for virus inactivation influence optimal activation of CTLs by WIV, most likely by affecting the membrane fusion properties of the virus. Specifically, inactivation with formalin (FA) severely compromises fusion activity of the virus, while inactivation with β-propiolactone (BPL) preserves fusion activity. Here, we demonstrate that vaccination of mice with BPL-inactivated H5N1 WIV vaccine induces solid protection from lethal heterosubtypic H1N1 challenge. By contrast, vaccination with FA-inactivated WIV, while preventing death after lethal challenge, failed to protect against development of disease and severe body weight loss. Vaccination with BPL-inactivated WIV, compared to FA-inactivated WIV, induced higher levels of specific CD8+ T cells in blood, spleen and lungs, and a higher production of granzyme B in the lungs upon H1N1 virus challenge. Conclusion/Significance The results underline the potential use of WIV as a cross-protective influenza vaccine candidate. However, careful choice of the virus inactivation procedure is important to retain membrane fusion activity

  11. Viral meningitis.

    PubMed

    Chadwick, David R

    2005-01-01

    Viruses probably account for most cases of acute meningitis. Viral meningitis is often assumed to be a largely benign disease. For the commonest pathogens causing meningitis, enteroviruses, this is usually the case; however, for many of the other pathogens causing viral meningitis, and for common pathogens in the immunocompromised or infants, viral meningitis is frequently associated with substantial neurological complications and a significant mortality. Diagnostic methods for rapid and accurate identification of pathogens have improved over recent years, permitting more precise and earlier diagnoses. There have been fewer developments in therapies for viral meningitis, and there remain no effective therapies for most pathogens, emphasising the importance of prevention and early diagnosis. This review focuses on the presentation, diagnosis and management of viral meningitis and also covers the prevention of meningitis for pathogens where effective vaccines are available. PMID:16474042

  12. Lipids in innate anti-viral defense

    PubMed Central

    Schoggins, John W.; Randall, Glenn

    2013-01-01

    Summary It is becoming apparent that infections by a major class of viruses, those with envelopes, can be inhibited during their entry at the step of fusion with cellular membranes. In this review, we discuss multiple innate immune mechanisms that have evolved to modify the lipid composition of cellular and viral membranes to inhibit virion fusion of enveloped viruses. PMID:24139397

  13. Pediatric cancer gone viral. Part II: potential clinical application of oncolytic herpes simplex virus-1 in children

    PubMed Central

    Friedman, Gregory K; Beierle, Elizabeth A; Gillespie, George Yancey; Markert, James M; Waters, Alicia M; Chen, Chun-Yu; Denton, Nicholas L; Haworth, Kellie B; Hutzen, Brian; Leddon, Jennifer L; Streby, Keri A; Wang, Pin-Yi; Cripe, Timothy P

    2015-01-01

    Oncolytic engineered herpes simplex viruses (HSVs) possess many biologic and functional attributes that support their use in clinical trials in children with solid tumors. Tumor cells, in an effort to escape regulatory mechanisms that would impair their growth and progression, have removed many mechanisms that would have protected them from virus infection and eventual virus-mediated destruction. Viruses engineered to exploit this weakness, like mutant HSV, can be safely employed as tumor cell killers, since normal cells retain these antiviral strategies. Many preclinical studies and early phase trials in adults demonstrated that oncolytic HSV can be safely used and are highly effective in killing tumor cells that comprise pediatric malignancies, without generating the toxic side effects of nondiscriminatory chemotherapy or radiation therapy. A variety of engineered viruses have been developed and tested in numerous preclinical models of pediatric cancers and initial trials in patients are underway. In Part II of this review series, we examine the preclinical evidence to support the further advancement of oncolytic HSV in the pediatric population. We discuss clinical advances made to date in this emerging era of oncolytic virotherapy. PMID:26436134

  14. Viral pneumonia

    MedlinePlus

    More serious infections can result in respiratory failure, liver failure, and heart failure. Sometimes, bacterial infections occur during or just after viral pneumonia, which may lead to more serious forms ...

  15. Viral arthritis

    MedlinePlus

    Infectious arthritis - viral ... Arthritis may be a symptom of many virus-related illnesses. It usually disappears on its own without ... the rubella vaccine, only a few people develop arthritis. No risk factors are known.

  16. Viral Infections

    MedlinePlus

    ... much smaller than bacteria. Viruses cause familiar infectious diseases such as the common cold, flu and warts. ... can help prevent you from getting many viral diseases. NIH: National Institute of Allergy and Infectious Diseases

  17. Viral Gastroenteritis

    MedlinePlus

    ... stomach, small intestine, and large intestine. Several different viruses can cause viral gastroenteritis, which is highly contagious ... and last for 1 to 3 days. Some viruses cause symptoms that last longer. [ Top ] What are ...

  18. Pharyngitis - viral

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/001392.htm Pharyngitis - viral To use the sharing features on this page, please enable JavaScript. Pharyngitis , or sore throat, is swelling, discomfort, pain, or ...

  19. Safety training and safe operating procedures written for PBFA (Particle Beam Fusion Accelerator) II and applicable to other pulsed power facilities

    SciTech Connect

    Donovan, G.L.; Goldstein, S.A.

    1986-12-01

    To ensure that work in advancing pulsed power technology is performed with an acceptably low risk, pulsed power research facilities at Sandia National Laboratories must satisfy general safety guidelines established by the Department of Energy, policies and formats of the Environment, Safety, and Health (ES and H) Department, and detailed procedures formulated by the Pulsed Power Sciences Directorate. The approach to safety training and to writing safe operating procedures, and the procedures presented here are specific to the Particle Beam Fusion Accelerator II (PBFA II) Facility but are applicable as guidelines to other research and development facilities which have similar hazards.

  20. A bio-synthetic interface for discovery of viral entry mechanisms.

    SciTech Connect

    Gutzler, Mike; Maar, Dianna; Negrete, Oscar; Hayden, Carl C.; Sasaki, Darryl Yoshio; Stachowiak, Jeanne C.; Wang, Julia

    2010-09-01

    Understanding and defending against pathogenic viruses is an important public health and biodefense challenge. The focus of our LDRD project has been to uncover the mechanisms enveloped viruses use to identify and invade host cells. We have constructed interfaces between viral particles and synthetic lipid bilayers. This approach provides a minimal setting for investigating the initial events of host-virus interaction - (i) recognition of, and (ii) entry into the host via membrane fusion. This understanding could enable rational design of therapeutics that block viral entry as well as future construction of synthetic, non-proliferating sensors that detect live virus in the environment. We have observed fusion between synthetic lipid vesicles and Vesicular Stomatitis virus particles, and we have observed interactions between Nipah virus-like particles and supported lipid bilayers and giant unilamellar vesicles.

  1. Surface glycoproteins of the recently identified African Henipavirus promote viral entry and cell fusion in a range of human, simian and bat cell lines.

    PubMed

    Lawrence, Philip; Escudero Pérez, Beatriz; Drexler, Jan Felix; Corman, Victor Max; Müller, Marcel A; Drosten, Christian; Volchkov, Viktor

    2014-03-01

    The recent discovery of a wide range of henipavirus-like viruses circulating in Megabats in Africa raises the question as to the zoonotic potential of these pathogens given the high human mortality rates seen with their pathogenic relatives Nipah virus and Hendra virus. In the absence of cultured infectious African Henipavirus we have performed experiments with recombinant F and G glycoproteins from the representative African Henipavirus strain M74a aimed at estimating its cellular tropism and capacity to use similar receptors to its highly pathogenic counterparts. The ability of the M74a virus G surface protein to use the ubiquitous Ephrin B2 host cell receptor and its heterologous cross-compatibility with Nipah virus could be expected to impart upon this virus a reasonable potential for species spillover, although differences in fusion efficiency seen with the M74a virus F protein in certain cell lines could present a barrier for zoonotic transmission. PMID:24452140

  2. Thermostable group II intron reverse transcriptase fusion proteins and their use in cDNA synthesis and next-generation RNA sequencing

    PubMed Central

    Mohr, Sabine; Ghanem, Eman; Smith, Whitney; Sheeter, Dennis; Qin, Yidan; King, Olga; Polioudakis, Damon; Iyer, Vishwanath R.; Hunicke-Smith, Scott; Swamy, Sajani; Kuersten, Scott; Lambowitz, Alan M.

    2013-01-01

    Mobile group II introns encode reverse transcriptases (RTs) that function in intron mobility (“retrohoming”) by a process that requires reverse transcription of a highly structured, 2–2.5-kb intron RNA with high processivity and fidelity. Although the latter properties are potentially useful for applications in cDNA synthesis and next-generation RNA sequencing (RNA-seq), group II intron RTs have been difficult to purify free of the intron RNA, and their utility as research tools has not been investigated systematically. Here, we developed general methods for the high-level expression and purification of group II intron-encoded RTs as fusion proteins with a rigidly linked, noncleavable solubility tag, and we applied them to group II intron RTs from bacterial thermophiles. We thus obtained thermostable group II intron RT fusion proteins that have higher processivity, fidelity, and thermostability than retroviral RTs, synthesize cDNAs at temperatures up to 81°C, and have significant advantages for qRT-PCR, capillary electrophoresis for RNA-structure mapping, and next-generation RNA sequencing. Further, we find that group II intron RTs differ from the retroviral enzymes in template switching with minimal base-pairing to the 3′ ends of new RNA templates, making it possible to efficiently and seamlessly link adaptors containing PCR-primer binding sites to cDNA ends without an RNA ligase step. This novel template-switching activity enables facile and less biased cloning of nonpolyadenylated RNAs, such as miRNAs or protein-bound RNA fragments. Our findings demonstrate novel biochemical activities and inherent advantages of group II intron RTs for research, biotechnological, and diagnostic methods, with potentially wide applications. PMID:23697550

  3. Thermostable group II intron reverse transcriptase fusion proteins and their use in cDNA synthesis and next-generation RNA sequencing.

    PubMed

    Mohr, Sabine; Ghanem, Eman; Smith, Whitney; Sheeter, Dennis; Qin, Yidan; King, Olga; Polioudakis, Damon; Iyer, Vishwanath R; Hunicke-Smith, Scott; Swamy, Sajani; Kuersten, Scott; Lambowitz, Alan M

    2013-07-01

    Mobile group II introns encode reverse transcriptases (RTs) that function in intron mobility ("retrohoming") by a process that requires reverse transcription of a highly structured, 2-2.5-kb intron RNA with high processivity and fidelity. Although the latter properties are potentially useful for applications in cDNA synthesis and next-generation RNA sequencing (RNA-seq), group II intron RTs have been difficult to purify free of the intron RNA, and their utility as research tools has not been investigated systematically. Here, we developed general methods for the high-level expression and purification of group II intron-encoded RTs as fusion proteins with a rigidly linked, noncleavable solubility tag, and we applied them to group II intron RTs from bacterial thermophiles. We thus obtained thermostable group II intron RT fusion proteins that have higher processivity, fidelity, and thermostability than retroviral RTs, synthesize cDNAs at temperatures up to 81°C, and have significant advantages for qRT-PCR, capillary electrophoresis for RNA-structure mapping, and next-generation RNA sequencing. Further, we find that group II intron RTs differ from the retroviral enzymes in template switching with minimal base-pairing to the 3' ends of new RNA templates, making it possible to efficiently and seamlessly link adaptors containing PCR-primer binding sites to cDNA ends without an RNA ligase step. This novel template-switching activity enables facile and less biased cloning of nonpolyadenylated RNAs, such as miRNAs or protein-bound RNA fragments. Our findings demonstrate novel biochemical activities and inherent advantages of group II intron RTs for research, biotechnological, and diagnostic methods, with potentially wide applications. PMID:23697550

  4. Viral arthritis.

    PubMed

    Marks, Michael; Marks, Jonathan L

    2016-04-01

    Acute-onset arthritis is a common clinical problem facing both the general clinician and the rheumatologist. A viral aetiology is though to be responsible for approximately 1% of all cases of acute arthritis with a wide range of causal agents recognised. The epidemiology of acute viral arthritis continues to evolve, with some aetiologies, such as rubella, becoming less common due to vaccination, while some vector-borne viruses have become more widespread. A travel history therefore forms an important part of the assessment of patients presenting with an acute arthritis. Worldwide, parvovirus B19, hepatitis B and C, HIV and the alphaviruses are among the most important causes of virally mediated arthritis. Targeted serological testing may be of value in establishing a diagnosis, and clinicians must also be aware that low-titre autoantibodies, such as rheumatoid factor and antinuclear antibody, can occur in the context of acute viral arthritis. A careful consideration of epidemiological, clinical and serological features is therefore required to guide clinicians in making diagnostic and treatment decisions. While most virally mediated arthritides are self-limiting some warrant the initiation of specific antiviral therapy. PMID:27037381

  5. Viral quasispecies

    PubMed Central

    Andino, Raul; Domingo, Esteban

    2016-01-01

    New generation sequencing is greatly expanding the capacity to examine the composition of mutant spectra of viral quasispecies in infected cells and host organisms. Here we review recent progress in the understanding of quasispecies dynamics, notably the occurrence of intra-mutant spectrum interactions, and implications of fitness landscapes for virus adaptation and de-adaptation. Complementation or interference can be established among components of the same mutant spectrum, dependent on the mutational status of the ensemble. Replicative fitness relates to an optimal mutant spectrum that provides the molecular basis for phenotypic flexibility, with implications for antiviral therapy. The biological impact of viral fitness renders particularly relevant the capacity of new generation sequencing to establish viral fitness landscapes. Progress with experimental model systems is becoming an important asset to understand virus behavior in the more complex environments faced during natural infections. PMID:25824477

  6. A single amino acid change resulting in loss of fluorescence of eGFP in a viral fusion protein confers fitness and growth advantage to the recombinant vesicular stomatitis virus

    SciTech Connect

    Dinh, Phat X.; Panda, Debasis; Das, Phani B.; Das, Subash C.; Das, Anshuman; Pattnaik, Asit K.

    2012-10-25

    Using a recombinant vesicular stomatitis virus encoding eGFP fused in-frame with an essential viral replication protein, the phosphoprotein P, we show that during passage in culture, the virus mutates the nucleotide C289 within eGFP of the fusion protein PeGFP to A or T, resulting in R97S/C amino acid substitution and loss of fluorescence. The resultant non-fluorescent virus exhibits increased fitness and growth advantage over its fluorescent counterpart. The growth advantage of the non-fluorescent virus appears to be due to increased transcription and replication activities of the PeGFP protein carrying the R97S/C substitution. Further, our results show that the R97S/C mutation occurs prior to accumulation of mutations that can result in loss of expression of the gene inserted at the G-L gene junction. These results suggest that fitness gain is more important for the recombinant virus than elimination of expression of the heterologous gene.

  7. The Conserved Disulfide Bond within Domain II of Epstein-Barr Virus gH Has Divergent Roles in Membrane Fusion with Epithelial Cells and B Cells

    PubMed Central

    Möhl, Britta S.; Sathiyamoorthy, Karthik; Jardetzky, Theodore S.

    2014-01-01

    ABSTRACT Epstein-Barr virus (EBV) infects target cells via fusion with cellular membranes. For entry into epithelial cells, EBV requires the herpesvirus conserved core fusion machinery, composed of glycoprotein B (gB) and gH/gL. In contrast, for B cell fusion it requires gB and gH/gL with gp42 serving as a cell tropism switch. The available crystal structures for gH/gL allow the targeted analysis of structural determinants of gH to identify functional regions critical for membrane fusion. Domain II of EBV gH contains two disulfide bonds (DBs). The first is unique for EBV and closely related gammaherpesviruses. The second is conserved across the beta- and gammaherpesviruses and is positioned to stabilize a putative syntaxin-like bundle motif. To analyze the role of these DBs in membrane fusion, gH was mutated by amino acid substitution of the DB cysteines. Mutation of the EBV-specific DB resulted in diminished gH/gL cell surface expression that correlated with diminished B cell and epithelial cell fusion. In contrast, mutation of the conserved DB resulted in wild-type-like B cell fusion, whereas epithelial cell fusion was greatly reduced. The gH mutants bound well to gp42 but had diminished binding to epithelial cells. Tyrosine 336, located adjacent to cysteine 335 of the conserved DB, also was found to be important for DB stabilization and gH/gL function. We conclude that the conserved DB has a cell type-specific function, since it is important for the binding of gH to epithelial cells initiating epithelial cell fusion but not for fusion with B cells and gp42 binding. IMPORTANCE EBV predominantly infects epithelial and B cells in humans, which can result in EBV-associated cancers, such as Burkitt and Hodgkin lymphoma, as well as nasopharyngeal carcinoma. EBV is also associated with a variety of lymphoproliferative disorders, typically of B cell origin, observed in immunosuppressed individuals, such as posttransplant or HIV/AIDS patients. The gH/gL complex plays an

  8. Viral haemorrhagic septicaemia virus (VHSV) genotype II isolated from European river lamprey Lampetra fluviatilis in Finland during surveillance from 1999 to 2008.

    PubMed

    Gadd, Tuija; Jakava-Viljanen, Miia; Einer-Jensen, Katja; Ariel, Ellen; Koski, Perttu; Sihvonen, Liisa

    2010-02-17

    We examined the occurrence of viral haemorrhagic septicaemia virus (VHSV) in the main spawning stocks of wild European river lamprey Lampetra fluviatilis in the rivers of Finland from 1999 to 2008. Pooled samples of internal organs (kidney, liver and heart or brain) from 2621 lampreys were examined for the presence of VHSV by standard virological techniques. VHSV was isolated from 5 samples from the rivers Lestijoki and Kalajoki, which flow from Finland into the Bothnian Bay of the Baltic Sea. The presence of VHSV was confirmed by immunofluorescent antibody technique (IFAT), ELISA and RT-PCR. Phylogenetic analysis based on the full-length VHSV glycoprotein (G) gene sequence revealed that the isolates were most closely related to the VHSV strain isolated in 1996 from herring Clupea harengus and sprat Sprattus sprattus in the Eastern Gotland Basin of the Baltic Sea, and were therefore assigned to VHSV genotype II. The partial G gene sequences obtained (nt 1 to 672-1129) of all 5 lamprey VHSV isolates were identical, and so were the entire G genes (nt 1 to 1524) of 2 isolates sequenced. The virulence of one of the lamprey isolates was evaluated by an experimental infection trial in rainbow trout Oncorhynchus mykiss fry. No mortality was induced postinfection by waterborne and intraperitoneal challenge, respectively, while 2 genotype Id isolates originating from Finnish rainbow trout caused marked mortality under the same conditions. The infection in the European river lamprey is thought to be independent from the epidemic in farmed rainbow trout in Finnish brackish waters, because the isolates from rainbow trout were of a different genotype. This is the first report of VHSV found in the European river lamprey. The role of wild river lampreys in maintaining the infection in the marine environment remains unclear. PMID:20377008

  9. Going Viral with Fluorescent Proteins

    PubMed Central

    Costantini, Lindsey M.

    2015-01-01

    Many longstanding questions about dynamics of virus-cell interactions can be answered by combining fluorescence imaging techniques with fluorescent protein (FP) tagging strategies. Successfully creating a FP fusion with a cellular or viral protein of interest first requires selecting the appropriate FP. However, while viral architecture and cellular localization often dictate the suitability of a FP, a FP's chemical and physical properties must also be considered. Here, we discuss the challenges of and offer suggestions for identifying the optimal FPs for studying the cell biology of viruses. PMID:26202231

  10. VIRAL GASTROENTERITIS

    EPA Science Inventory

    Two virus types have been clearly shown to have epidemiologic importance in viral gastroenteritis, i.e., rotavirus and Norwalk virus. Four other virus types have been associated with gastroenteritis but their epidemiologic importance is not yet known, i.e., enteric adenovirus, ca...

  11. Viral Hepatitis

    MedlinePlus

    ... with hepatitis? How does a pregnant woman pass hepatitis B virus to her baby? If I have hepatitis B, what does my baby need so that she ... Can I breastfeed my baby if I have hepatitis B? More information on viral hepatitis What is hepatitis? ...

  12. Constancy and diversity in the flavivirus fusion peptide

    PubMed Central

    Seligman, Stephen J

    2008-01-01

    Background Flaviviruses include the mosquito-borne dengue, Japanese encephalitis, yellow fever and West Nile and the tick-borne encephalitis viruses. They are responsible for considerable world-wide morbidity and mortality. Viral entry is mediated by a conserved fusion peptide containing 16 amino acids located in domain II of the envelope protein E. Highly orchestrated conformational changes initiated by exposure to acidic pH accompany the fusion process and are important factors limiting amino acid changes in the fusion peptide that still permit fusion with host cell membranes in both arthropod and vertebrate hosts. The cell-fusing related agents, growing only in mosquitoes or insect cell lines, possess a different homologous peptide. Results Analysis of 46 named flaviviruses deposited in the Entrez Nucleotides database extended the constancy in the canonical fusion peptide sequences of mosquito-borne, tick-borne and viruses with no known vector to include more recently-sequenced viruses. The mosquito-borne signature amino acid, G104, was also found in flaviviruses with no known vector and with the cell-fusion related viruses. Despite the constancy in the canonical sequences in pathogenic flaviviruses, mutations were surprisingly frequent with a 27% prevalence of nonsynonymous mutations in yellow fever virus fusion peptide sequences, and 0 to 7.4% prevalence in the others. Six of seven yellow fever patients whose virus had fusion peptide mutations died. In the cell-fusing related agents, not enough sequences have been deposited to estimate reliably the prevalence of fusion peptide mutations. However, the canonical sequences homologous to the fusion peptide and the pattern of disulfide linkages in protein E differed significantly from the other flaviviruses. Conclusion The constancy of the canonical fusion peptide sequences in the arthropod-borne flaviviruses contrasts with the high prevalence of mutations in most individual viruses. The discrepancy may be the

  13. Fusion of Enveloped Viruses in Endosomes.

    PubMed

    White, Judith M; Whittaker, Gary R

    2016-06-01

    Ari Helenius launched the field of enveloped virus fusion in endosomes with a seminal paper in the Journal of Cell Biology in 1980. In the intervening years, a great deal has been learned about the structures and mechanisms of viral membrane fusion proteins as well as about the endosomes in which different enveloped viruses fuse and the endosomal cues that trigger fusion. We now recognize three classes of viral membrane fusion proteins based on structural criteria and four mechanisms of fusion triggering. After reviewing general features of viral membrane fusion proteins and viral fusion in endosomes, we delve into three characterized mechanisms for viral fusion triggering in endosomes: by low pH, by receptor binding plus low pH and by receptor binding plus the action of a protease. We end with a discussion of viruses that may employ novel endosomal fusion-triggering mechanisms. A key take-home message is that enveloped viruses that enter cells by fusing in endosomes traverse the endocytic pathway until they reach an endosome that has all of the environmental conditions (pH, proteases, ions, intracellular receptors and lipid composition) to (if needed) prime and (in all cases) trigger the fusion protein and to support membrane fusion. PMID:26935856

  14. Cholesterol-binding viral proteins in virus entry and morphogenesis.

    PubMed

    Schroeder, Cornelia

    2010-01-01

    Up to now less than a handful of viral cholesterol-binding proteins have been characterized, in HIV, influenza virus and Semliki Forest virus. These are proteins with roles in virus entry or morphogenesis. In the case of the HIV fusion protein gp41 cholesterol binding is attributed to a cholesterol recognition consensus (CRAC) motif in a flexible domain of the ectodomain preceding the trans-membrane segment. This specific CRAC sequence mediates gp41 binding to a cholesterol affinity column. Mutations in this motif arrest virus fusion at the hemifusion stage and modify the ability of the isolated CRAC peptide to induce segregation of cholesterol in artificial membranes.Influenza A virus M2 protein co-purifies with cholesterol. Its proton translocation activity, responsible for virus uncoating, is not cholesterol-dependent, and the transmembrane channel appears too short for integral raft insertion. Cholesterol binding may be mediated by CRAC motifs in the flexible post-TM domain, which harbours three determinants of binding to membrane rafts. Mutation of the CRAC motif of the WSN strain attenuates virulence for mice. Its affinity to the raft-non-raft interface is predicted to target M2 protein to the periphery of lipid raft microdomains, the sites of virus assembly. Its influence on the morphology of budding virus implicates M2 as factor in virus fission at the raft boundary. Moreover, M2 is an essential factor in sorting the segmented genome into virus particles, indicating that M2 also has a role in priming the outgrowth of virus buds.SFV E1 protein is the first viral type-II fusion protein demonstrated to directly bind cholesterol when the fusion peptide loop locks into the target membrane. Cholesterol binding is modulated by another, proximal loop, which is also important during virus budding and as a host range determinant, as shown by mutational studies. PMID:20213541

  15. Spinal fusion

    MedlinePlus

    ... Anterior spinal fusion; Spine surgery - spinal fusion; Low back pain - fusion; Herniated disk - fusion ... If you had chronic back pain before surgery, you will likely still have some pain afterward. Spinal fusion is unlikely to take away all your pain ...

  16. P‐TEFb goes viral

    PubMed Central

    Zaborowska, Justyna; Isa, Nur F.

    2015-01-01

    Positive transcription elongation factor b (P‐TEFb), which comprises cyclin‐dependent kinase 9 (CDK9) kinase and cyclin T subunits, is an essential kinase complex in human cells. Phosphorylation of the negative elongation factors by P‐TEFb is required for productive elongation of transcription of protein‐coding genes by RNA polymerase II (pol II). In addition, P‐TEFb‐mediated phosphorylation of the carboxyl‐terminal domain (CTD) of the largest subunit of pol II mediates the recruitment of transcription and RNA processing factors during the transcription cycle. CDK9 also phosphorylates p53, a tumor suppressor that plays a central role in cellular responses to a range of stress factors. Many viral factors affect transcription by recruiting or modulating the activity of CDK9. In this review, we will focus on how the function of CDK9 is regulated by viral gene products. The central role of CDK9 in viral life cycles suggests that drugs targeting the interaction between viral products and P‐TEFb could be effective anti‐viral agents. PMID:27398404

  17. [Viral superantigens].

    PubMed

    Us, Dürdal

    2016-07-01

    Superantigens (SAgs) are microbial proteins produced by various microorganisms that elicit excessive and strong stimulation of T cells via an unconventional mechanism. They cause polyclonal activation of T cells in a non-specific manner, by binding to a particular variable-beta (Vβ) chain of T-cell receptor (TCR) and MHC class II molecule, in unprocessed form and outside of peptide-binding cleft, forming a bridge between the antigen presenting cell and the T cell. SAgs are classified into three groups, namely 1) exogenous (soluble proteins and exotoxins secreted by microorganisms), 2) endogenous (transmembrane proteins encoded by viruses which are integrated into the genome) and 3) B-cell SAgs (proteins which stimulate predominantly B cells). The best characterized and mostly studied SAgs are staphylococcal and streptococcal exotoxins, however it is well-known that many other microorganisms also possess SAg activities. Despite the presence of several viruses that cause severe infections in humans, the number of viruses that have proteins identified with SAg property in their pathogenesis, is relatively low. To date, the defined viruses that encoded SAgs are as follows; mouse mammary tumor virus (MMTV) (Marrack, et al. 1991), rabies virus (Lafon, et al. 1992), Epstein-Barr virus (EBV) (Sutkowski, et al. 1996), human endogenous retrovirus (HERV) (Conrad, et al. 1997), human immunodeficiency virus (HIV) (Posnett, et al. 1995; Torres, et al. 1996; Townsley-Fuchs, et al. 1997) and Ebola virus (Leroy, et al. 2011). SAgs were first described in the MMTV, a polymorphic B-type retrovirus that is either contained in the genome as an endogenous provirus (germline transmission) or exogenous infectious virus that transmits vertically via breast milk. Both MMTV forms encode SAgs. The SAg-mediated massive T cell activation is required for the spread of exogenous MMTV from intestines to mammary glands, facilitating the transmission of infectious virus. On the other hand

  18. A Recombinant Trivalent Fusion Protein F1–LcrV–HSP70(II) Augments Humoral and Cellular Immune Responses and Imparts Full Protection against Yersinia pestis

    PubMed Central

    Verma, Shailendra K.; Batra, Lalit; Tuteja, Urmil

    2016-01-01

    Plague is one of the most dangerous infections in humans caused by Yersinia pestis, a Gram-negative bacterium. Despite of an overwhelming research success, no ideal vaccine against plague is available yet. It is well established that F1/LcrV based vaccine requires a strong cellular immune response for complete protection against plague. In our earlier study, we demonstrated that HSP70(II) of Mycobacterium tuberculosis modulates the humoral and cellular immunity of F1/LcrV vaccine candidates individually as well as in combinations in a mouse model. Here, we made two recombinant constructs caf1–lcrV and caf1–lcrV–hsp70(II). The caf1 and lcrV genes of Y. pestis and hsp70 domain II of M. tuberculosis were amplified by polymerase chain reaction. Both the recombinant constructs caf1–lcrV and caf1–lcrV–hsp70(II) were cloned in pET28a vector and expressed in Escherichia coli. The recombinant fusion proteins F1–LcrV and F1–LcrV–HSP70(II) were purified using Ni-NTA columns and formulated with alum to evaluate the humoral and cell mediated immune responses in mice. The protective efficacies of F1–LcrV and F1–LcrV–HSP70(II) were determined following challenge of immunized mice with 100 LD50 of Y. pestis through intraperitoneal route. Significant differences were noticed in the titers of IgG and it’s isotypes, i.e., IgG1, IgG2b, and IgG3 in anti- F1–LcrV–HSP70(II) sera in comparison to anti-F1–LcrV sera. Similarly, significant differences were also noticed in the expression levels of IL-2, IFN-γ and TNF-α in splenocytes of F1–LcrV–HSP(II) immunized mice in comparison to F1–LcrV. Both F1–LcrV and F1–LcrV–HSP70(II) provided 100% protection. Our research findings suggest that F1–LcrV fused with HSP70 domain II of M. tuberculosis significantly enhanced the humoral and cellular immune responses in mouse model. PMID:27458447

  19. A Recombinant Trivalent Fusion Protein F1-LcrV-HSP70(II) Augments Humoral and Cellular Immune Responses and Imparts Full Protection against Yersinia pestis.

    PubMed

    Verma, Shailendra K; Batra, Lalit; Tuteja, Urmil

    2016-01-01

    Plague is one of the most dangerous infections in humans caused by Yersinia pestis, a Gram-negative bacterium. Despite of an overwhelming research success, no ideal vaccine against plague is available yet. It is well established that F1/LcrV based vaccine requires a strong cellular immune response for complete protection against plague. In our earlier study, we demonstrated that HSP70(II) of Mycobacterium tuberculosis modulates the humoral and cellular immunity of F1/LcrV vaccine candidates individually as well as in combinations in a mouse model. Here, we made two recombinant constructs caf1-lcrV and caf1-lcrV-hsp70(II). The caf1 and lcrV genes of Y. pestis and hsp70 domain II of M. tuberculosis were amplified by polymerase chain reaction. Both the recombinant constructs caf1-lcrV and caf1-lcrV-hsp70(II) were cloned in pET28a vector and expressed in Escherichia coli. The recombinant fusion proteins F1-LcrV and F1-LcrV-HSP70(II) were purified using Ni-NTA columns and formulated with alum to evaluate the humoral and cell mediated immune responses in mice. The protective efficacies of F1-LcrV and F1-LcrV-HSP70(II) were determined following challenge of immunized mice with 100 LD50 of Y. pestis through intraperitoneal route. Significant differences were noticed in the titers of IgG and it's isotypes, i.e., IgG1, IgG2b, and IgG3 in anti- F1-LcrV-HSP70(II) sera in comparison to anti-F1-LcrV sera. Similarly, significant differences were also noticed in the expression levels of IL-2, IFN-γ and TNF-α in splenocytes of F1-LcrV-HSP(II) immunized mice in comparison to F1-LcrV. Both F1-LcrV and F1-LcrV-HSP70(II) provided 100% protection. Our research findings suggest that F1-LcrV fused with HSP70 domain II of M. tuberculosis significantly enhanced the humoral and cellular immune responses in mouse model. PMID:27458447

  20. GS-5806 Inhibits Pre- to Postfusion Conformational Changes of the Respiratory Syncytial Virus Fusion Protein

    PubMed Central

    Xing, Weimei; Niedziela-Majka, Anita; Wong, Jinny S.; Hung, Magdeleine; Brendza, Katherine M.; Perron, Michel; Jordan, Robert; Sperandio, David; Liu, Xiaohong; Mackman, Richard; Sakowicz, Roman

    2015-01-01

    GS-5806 is a small-molecule inhibitor of human respiratory syncytial virus fusion protein-mediated viral entry. During viral entry, the fusion protein undergoes major conformational changes, resulting in fusion of the viral envelope with the host cell membrane. This process is reproduced in vitro using a purified, truncated respiratory syncytial virus (RSV) fusion protein. GS-5806 blocked these conformational changes, suggesting a possible mechanism for antiviral activity. PMID:26324264

  1. GS-5806 inhibits pre- to postfusion conformational changes of the respiratory syncytial virus fusion protein.

    PubMed

    Samuel, Dharmaraj; Xing, Weimei; Niedziela-Majka, Anita; Wong, Jinny S; Hung, Magdeleine; Brendza, Katherine M; Perron, Michel; Jordan, Robert; Sperandio, David; Liu, Xiaohong; Mackman, Richard; Sakowicz, Roman

    2015-11-01

    GS-5806 is a small-molecule inhibitor of human respiratory syncytial virus fusion protein-mediated viral entry. During viral entry, the fusion protein undergoes major conformational changes, resulting in fusion of the viral envelope with the host cell membrane. This process is reproduced in vitro using a purified, truncated respiratory syncytial virus (RSV) fusion protein. GS-5806 blocked these conformational changes, suggesting a possible mechanism for antiviral activity. PMID:26324264

  2. Human HLA class I- and HLA class II-restricted cloned cytotoxic T lymphocytes identify a cluster of epitopes on the measles virus fusion protein.

    PubMed Central

    van Binnendijk, R S; Versteeg-van Oosten, J P; Poelen, M C; Brugghe, H F; Hoogerhout, P; Osterhaus, A D; Uytdehaag, F G

    1993-01-01

    The transmembrane fusion (F) glycoprotein of measles virus is an important target antigen of human HLA class I- and class II-restricted cytotoxic T lymphocytes (CTL). Genetically engineered F proteins and nested sets of synthetic peptides spanning the F protein were used to determine sequences of F recognized by a number of F-specific CTL clones. Combined N- and C-terminal deletions of the respective peptides revealed that human HLA class I and HLA class II-restricted CTL efficiently recognize nonapeptides or decapeptides representing epitopes of F. Three distinct sequences recognized by three different HLA class II (DQw1, DR2, and DR4/w53)-restricted CTL clones appear to cluster between amino acids 379 and 466 of F, thus defining an important T-cell epitope area of F. Within this same region, a nonamer peptide of F was found to be recognized by an HLA-B27-restricted CTL clone, as expected on the basis of the structural homology between this peptide and other known HLA-B27 binding peptides. PMID:7680390

  3. Two Novel Class II Hydrophobins from Trichoderma spp. Stimulate Enzymatic Hydrolysis of Poly(Ethylene Terephthalate) when Expressed as Fusion Proteins

    PubMed Central

    Espino-Rammer, Liliana; Ribitsch, Doris; Przylucka, Agnieszka; Marold, Annemarie; Greimel, Katrin J.; Herrero Acero, Enrique; Guebitz, Georg M.; Kubicek, Christian P.

    2013-01-01

    Poly(ethylene terephthalate) (PET) can be functionalized and/or recycled via hydrolysis by microbial cutinases. The rate of hydrolysis is however low. Here, we tested whether hydrophobins (HFBs), small secreted fungal proteins containing eight positionally conserved cysteine residues, are able to enhance the rate of enzymatic hydrolysis of PET. Species of the fungal genus Trichoderma have the most proliferated arsenal of class II hydrophobin-encoding genes among fungi. To this end, we studied two novel class II HFBs (HFB4 and HFB7) of Trichoderma. HFB4 and HFB7, produced in Escherichia coli as fusions to the C terminus of glutathione S-transferase, exhibited subtle structural differences reflected in hydrophobicity plots that correlated with unequal hydrophobicity and hydrophily, respectively, of particular amino acid residues. Both proteins exhibited a dosage-dependent stimulation effect on PET hydrolysis by cutinase from Humicola insolens, with HFB4 displaying an adsorption isotherm-like behavior, whereas HFB7 was active only at very low concentrations and was inhibitory at higher concentrations. We conclude that class II HFBs can stimulate the activity of cutinases on PET, but individual HFBs can display different properties. The present findings suggest that hydrophobins can be used in the enzymatic hydrolysis of aromatic-aliphatic polyesters such as PET. PMID:23645195

  4. HIV-1 Fusion Assay

    PubMed Central

    Cavrois, Marielle; Neidleman, Jason; Greene, Warner C.

    2016-01-01

    The HIV-1 fusion assay measures all steps in the HIV-1 life cycle up to and including viral fusion. It relies on the incorporation of a β-lactamase Vpr (BlaM-Vpr) protein chimera into the virion and the subsequent transfer of this chimera into the target cell by fusion (Figure 1). The transfer is monitored by the enzymatic cleavage of CCF2, a fluorescent dye substrate of β-lactamase, loaded into the target cells. Cleavage of the β-lactam ring in CCF2 by β-lactamase changes the fluorescence emission spectrum of the dye from green (520 nm) to blue (447 nm). This change reflects virion fusion and can be detected by flow cytometry (Figure 2).

  5. Viral diseases and pathogenesis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    It includes classification of viral infection. It describes common ways of virus entry, replication, and transmission. It introduces the routes of viral invasion and molecular basis for viral pathogenesis....

  6. Safety Assessment for Inertial Fusion Energy Power Plants: Methodology and Application to the Analysis of the HYLIFE-II and SOMBRERO Conceptual Designs

    NASA Astrophysics Data System (ADS)

    Reyes, S.; Latkowski, J. F.; Sanz, J.; Gomez del Rio, J.

    2001-06-01

    Although the safety and environmental (S & E) characteristics of fusion energy have long been emphasized, these benefits are not automatically achieved. To maximize the potential S & E attractiveness of the inertial fusion energy (IFE), analyses must be performed early in the designs so that lessons can be learned and intelligent decisions made. In this work we have introduced for the first time heat transfer and thermal-hydraulics calculations as part of a state-of-the-art set of codes and libraries in order to establish an updated methodology for IFE safety analysis. We have focused our efforts primarily on two IFE power plant conceptual designs: HYLIFE-II and SOMBRERO. To some degree, these designs represent the extremes in IFE power plant designs. Also, a preliminary safety assessment has been performed for a generic target fabrication facility producing various types of targets and using various production techniques. Although this study cannot address all issues and hazards posed by an IFE power plant, it advances our understanding of radiological safety of such facilities. This will enable better comparisons between IFE designs and competing technologies from the safety point of view.

  7. Stochastic models of viral infection

    NASA Astrophysics Data System (ADS)

    Chou, Tom

    2009-03-01

    We develop biophysical models of viral infections from a stochastic process perspective. The entry of enveloped viruses is treated as a stochastic multiple receptor and coreceptor engagement process that can lead to membrane fusion or endocytosis. The probabilities of entry via fusion and endocytosis are computed as functions of the receptor/coreceptor engagement rates. Since membrane fusion and endocytosis entry pathways can lead to very different infection outcomes, we delineate the parameter regimes conducive to each entry pathway. After entry, viral material is biochemically processed and degraded as it is transported towards the nucleus. Productive infections occur only when the material reaches the nucleus in the proper biochemical state. Thus, entry into the nucleus in an infectious state requires the proper timing of the cytoplasmic transport process. We compute the productive infection probability and show its nonmonotonic dependence on both transport speeds and biochemical transformation rates. Our results carry subtle consequences on the dosage and efficacy of antivirals such as reverse transcription inhibitors.

  8. Integrated operations plan for the MFTF-B Mirror Fusion Test Facility. Volume II. Integrated operations plan

    SciTech Connect

    Not Available

    1981-12-01

    This document defines an integrated plan for the operation of the Lawrence Livermore National Laboratory (LLNL) Mirror Fusion Test Facility (MFTF-B). The plan fulfills and further delineates LLNL policies and provides for accomplishing the functions required by the program. This plan specifies the management, operations, maintenance, and engineering support responsibilities. It covers phasing into sustained operations as well as the sustained operations themselves. Administrative and Plant Engineering support, which are now being performed satisfactorily, are not part of this plan unless there are unique needs.

  9. Viral evolution

    PubMed Central

    Nasir, Arshan; Kim, Kyung Mo; Caetano-Anollés, Gustavo

    2012-01-01

    Explaining the origin of viruses remains an important challenge for evolutionary biology. Previous explanatory frameworks described viruses as founders of cellular life, as parasitic reductive products of ancient cellular organisms or as escapees of modern genomes. Each of these frameworks endow viruses with distinct molecular, cellular, dynamic and emergent properties that carry broad and important implications for many disciplines, including biology, ecology and epidemiology. In a recent genome-wide structural phylogenomic analysis, we have shown that large-to-medium-sized viruses coevolved with cellular ancestors and have chosen the evolutionary reductive route. Here we interpret these results and provide a parsimonious hypothesis for the origin of viruses that is supported by molecular data and objective evolutionary bioinformatic approaches. Results suggest two important phases in the evolution of viruses: (1) origin from primordial cells and coexistence with cellular ancestors, and (2) prolonged pressure of genome reduction and relatively late adaptation to the parasitic lifestyle once virions and diversified cellular life took over the planet. Under this evolutionary model, new viral lineages can evolve from existing cellular parasites and enhance the diversity of the world’s virosphere. PMID:23550145

  10. Viral Parkinsonism

    PubMed Central

    Jang, Haeman; Boltz, David A.; Webster, Robert G.; Smeyne, Richard Jay

    2015-01-01

    Parkinson's disease is a debilitating neurological disorder characterized that affects 1-2% of the adult population over 55 years of age. For the vast majority of cases, the etiology of this disorder is unknown, although it is generally accepted that there is a genetic susceptibility to any number of environmental agents. One such agent may be viruses. It has been shown that numerous viruses can enter the nervous system, i.e. they are neurotropic, and induce a number of encephalopathies. One of the secondary consequences of these encephalopathies can be parkinsonism, that is both transient as well as permanent. One of the most highlighted and controversial cases of viral parkinsonism is that which followed the 1918 influenza outbreak and the subsequent induction of von Economo's encephalopathy. In this review, we discuss the neurological sequelae of infection by influenza virus as well as that of other viruses known to induce parkinsonism including Coxsackie, Japanese encephalitis B, St. Louis, West Nile and HIV viruses. PMID:18760350

  11. Viral entry mechanisms: the increasing diversity of paramyxovirus entry

    PubMed Central

    Smith, Everett Clinton; Popa, Andreea; Chang, Andres; Masante, Cyril; Dutch, Rebecca Ellis

    2009-01-01

    The paramyxovirus family contains established human pathogens such as measles virus and human respiratory syncytial virus, and emerging pathogens including the Hendra and Nipah viruses and the recently identified human metapneumovirus. Two major envelope glycoproteins, the attachment protein and the fusion protein, promote the processes of viral attachment and virus-cell membrane fusion required for entry. While common mechanisms of fusion protein proteolytic activation and the mechanism of membrane fusion promotion have been shown in recent years, considerable diversity exists in the family related to receptor binding and the potential mechanisms of fusion triggering. PMID:19878307

  12. Paramyxovirus fusion and entry: multiple paths to a common end.

    PubMed

    Chang, Andres; Dutch, Rebecca E

    2012-04-01

    The paramyxovirus family contains many common human pathogenic viruses, including measles, mumps, the parainfluenza viruses, respiratory syncytial virus, human metapneumovirus, and the zoonotic henipaviruses, Hendra and Nipah. While the expression of a type 1 fusion protein and a type 2 attachment protein is common to all paramyxoviruses, there is considerable variation in viral attachment, the activation and triggering of the fusion protein, and the process of viral entry. In this review, we discuss recent advances in the understanding of paramyxovirus F protein-mediated membrane fusion, an essential process in viral infectivity. We also review the role of the other surface glycoproteins in receptor binding and viral entry, and the implications for viral infection. Throughout, we concentrate on the commonalities and differences in fusion triggering and viral entry among the members of the family. Finally, we highlight key unanswered questions and how further studies can identify novel targets for the development of therapeutic treatments against these human pathogens. PMID:22590688

  13. Targeting of a Nuclease to Murine Leukemia Virus Capsids Inhibits Viral Multiplication

    NASA Astrophysics Data System (ADS)

    Natsoulis, Georges; Seshaiah, Partha; Federspiel, Mark J.; Rein, Alan; Hughes, Stephen H.; Boeke, Jef D.

    1995-01-01

    Capsid-targeted viral inactivation is an antiviral strategy in which toxic fusion proteins are targeted to virions, where they inhibit viral multiplication by destroying viral components. These fusion proteins consist of a virion structural protein moiety and an enzymatic moiety such as a nuclease. Such fusion proteins can severely inhibit transposition of yeast retrotransposon Ty1, an element whose transposition mechanistically resembles retroviral multiplication. We demonstrate that expression of a murine retrovirus capsid-staphylococcal nuclease fusion protein inhibits multiplication of the corresponding murine leukemia virus by 30- to 100-fold. Staphylococcal nuclease is apparently inactive intracellularly and hence nontoxic to the host cell, but it is active extracellularly because of its requirement for high concentrations of Ca2+ ions. Virions assembled in and shed from cells expressing the fusion protein contain very small amounts of intact viral RNA, as would be predicted for nuclease-mediated inhibition of viral multiplication.

  14. RAB-5- and DYNAMIN-1-Mediated Endocytosis of EFF-1 Fusogen Controls Cell-Cell Fusion.

    PubMed

    Smurova, Ksenia; Podbilewicz, Benjamin

    2016-02-16

    Cell-cell fusion plays essential roles during fertilization and organogenesis. Previous studies in C. elegans led to the identification of the eukaryotic fusion protein (EFF-1 fusogen), which has structural homology to class II viral fusogens. Transcriptional repression of EFF-1 ensures correct fusion fates, and overexpression of EFF-1 results in embryonic lethality. EFF-1 must be expressed on the surface of both fusing cells; however, little is known regarding how cells regulate EFF-1 surface exposure. Here, we report that EFF-1 is actively removed from the plasma membrane of epidermal cells by dynamin- and RAB-5-dependent endocytosis and accumulates in early endosomes. EFF-1 was transiently localized to apical domains of fusion-competent cells. Effective cell-cell fusion occurred only between pairs of cell membranes in which EFF-1 localized. Downregulation of dynamin or RAB-5 caused EFF-1 mislocalization to all apical membrane domains and excessive fusion. Thus, internalization of EFF-1 is a safety mechanism preventing excessive cell fusion. PMID:26854231

  15. RAB-5- and DYNAMIN-1-Mediated Endocytosis of EFF-1 Fusogen Controls Cell-Cell Fusion

    PubMed Central

    Smurova, Ksenia; Podbilewicz, Benjamin

    2016-01-01

    Summary Cell-cell fusion plays essential roles during fertilization and organogenesis. Previous studies in C. elegans led to the identification of the eukaryotic fusion protein (EFF-1 fusogen), which has structural homology to class II viral fusogens. Transcriptional repression of EFF-1 ensures correct fusion fates, and overexpression of EFF-1 results in embryonic lethality. EFF-1 must be expressed on the surface of both fusing cells; however, little is known regarding how cells regulate EFF-1 surface exposure. Here, we report that EFF-1 is actively removed from the plasma membrane of epidermal cells by dynamin- and RAB-5-dependent endocytosis and accumulates in early endosomes. EFF-1 was transiently localized to apical domains of fusion-competent cells. Effective cell-cell fusion occurred only between pairs of cell membranes in which EFF-1 localized. Downregulation of dynamin or RAB-5 caused EFF-1 mislocalization to all apical membrane domains and excessive fusion. Thus, internalization of EFF-1 is a safety mechanism preventing excessive cell fusion. PMID:26854231

  16. Crystal Structure of West Nile Virus Envelope Glycoprotein Reveals Viral Surface Epitopes

    SciTech Connect

    Kanai,R.; Kar, K.; Anthony, K.; Gould, L.; Ledizet, M.; Fikrig, E.; Marasco, W.; Koski, R.; Modis, Y.

    2006-01-01

    West Nile virus, a member of the Flavivirus genus, causes fever that can progress to life-threatening encephalitis. The major envelope glycoprotein, E, of these viruses mediates viral attachment and entry by membrane fusion. We have determined the crystal structure of a soluble fragment of West Nile virus E. The structure adopts the same overall fold as that of the E proteins from dengue and tick-borne encephalitis viruses. The conformation of domain II is different from that in other prefusion E structures, however, and resembles the conformation of domain II in postfusion E structures. The epitopes of neutralizing West Nile virus-specific antibodies map to a region of domain III that is exposed on the viral surface and has been implicated in receptor binding. In contrast, we show that certain recombinant therapeutic antibodies, which cross-neutralize West Nile and dengue viruses, bind a peptide from domain I that is exposed only during the membrane fusion transition. By revealing the details of the molecular landscape of the West Nile virus surface, our structure will assist the design of antiviral vaccines and therapeutics.

  17. Viral Quasispecies Evolution

    PubMed Central

    Sheldon, Julie; Perales, Celia

    2012-01-01

    Summary: Evolution of RNA viruses occurs through disequilibria of collections of closely related mutant spectra or mutant clouds termed viral quasispecies. Here we review the origin of the quasispecies concept and some biological implications of quasispecies dynamics. Two main aspects are addressed: (i) mutant clouds as reservoirs of phenotypic variants for virus adaptability and (ii) the internal interactions that are established within mutant spectra that render a virus ensemble the unit of selection. The understanding of viruses as quasispecies has led to new antiviral designs, such as lethal mutagenesis, whose aim is to drive viruses toward low fitness values with limited chances of fitness recovery. The impact of quasispecies for three salient human pathogens, human immunodeficiency virus and the hepatitis B and C viruses, is reviewed, with emphasis on antiviral treatment strategies. Finally, extensions of quasispecies to nonviral systems are briefly mentioned to emphasize the broad applicability of quasispecies theory. PMID:22688811

  18. Role of sequence and structure of the Hendra fusion protein fusion peptide in membrane fusion.

    PubMed

    Smith, Everett Clinton; Gregory, Sonia M; Tamm, Lukas K; Creamer, Trevor P; Dutch, Rebecca Ellis

    2012-08-24

    Viral fusion proteins are intriguing molecular machines that undergo drastic conformational changes to facilitate virus-cell membrane fusion. During fusion a hydrophobic region of the protein, termed the fusion peptide (FP), is inserted into the target host cell membrane, with subsequent conformational changes culminating in membrane merger. Class I fusion proteins contain FPs between 20 and 30 amino acids in length that are highly conserved within viral families but not between. To examine the sequence dependence of the Hendra virus (HeV) fusion (F) protein FP, the first eight amino acids were mutated first as double, then single, alanine mutants. Mutation of highly conserved glycine residues resulted in inefficient F protein expression and processing, whereas substitution of valine residues resulted in hypofusogenic F proteins despite wild-type surface expression levels. Synthetic peptides corresponding to a portion of the HeV F FP were shown to adopt an α-helical secondary structure in dodecylphosphocholine micelles and small unilamellar vesicles using circular dichroism spectroscopy. Interestingly, peptides containing point mutations that promote lower levels of cell-cell fusion within the context of the whole F protein were less α-helical and induced less membrane disorder in model membranes. These data represent the first extensive structure-function relationship of any paramyxovirus FP and demonstrate that the HeV F FP and potentially other paramyxovirus FPs likely require an α-helical structure for efficient membrane disordering and fusion. PMID:22761418

  19. Global transcriptomic profiling of bovine endometrial immune response in vitro. II. Effect of bovine viral diarrhea virus on the endometrial response to lipopolysaccharide.

    PubMed

    Oguejiofor, Chike F; Cheng, Zhangrui; Abudureyimu, Ayimuguli; Anstaett, Olivia L; Brownlie, Joe; Fouladi-Nashta, Ali A; Wathes, D Claire

    2015-10-01

    Infection with noncytopathic bovine viral diarrhea virus (ncpBVDV) is associated with uterine disease and infertility. This study investigated the influence of ncpBVDV on immune functions of the bovine endometrium by testing the response to bacterial lipopolysaccharide (LPS). Primary cultures of mixed epithelial and stromal cells were divided into four treatment groups (control [CONT], BVDV, CONT+LPS, and BVDV+LPS) and infected with ncpBVDV for 4 days followed by treatment with LPS for 6 h. Whole-transcriptomic gene expression was measured followed by Ingenuity Pathway Analysis. Differential expression of 184 genes was found between CONT and BVDV treatments, showing interplay between induction and inhibition of responses. Up-regulation of TLR3, complement, and chemotactic and TRIM factors by ncpBVDV all suggested an ongoing immune response to viral infection. Down-regulation of inflammatory cytokines, chemokines, CXCR4, and serine proteinase inhibitors suggested mechanisms by which ncpBVDV may simultaneously counter the host response. Comparison between BVDV+LPS and CONT+LPS treatments showed 218 differentially expressed genes. Canonical pathway analysis identified the key importance of interferon signaling. Top down-regulated genes were RSAD2, ISG15, BST2, MX2, OAS1, USP18, IFIT3, IFI27, SAMD9, IFIT1, and DDX58, whereas TRIM56, C3, and OLFML1 were most up-regulated. Many of these genes are also regulated by IFNT during maternal recognition of pregnancy. Many innate immune genes that typically respond to LPS were inhibited by ncpBVDV, including those involved in pathogen recognition, inflammation, interferon response, chemokines, tissue remodeling, cell migration, and cell death/survival. Infection with ncpBVDV can thus compromise immune function and pregnancy recognition, thereby potentially predisposing infected cows to postpartum bacterial endometritis and reduced fertility. PMID:26353892

  20. Cellular and humoral immune reactions in chronic active liver disease. II. Lymphocyte subsets and viral antigens in liver biopsies of patients with acute and chronic hepatitis B.

    PubMed Central

    Eggink, H F; Houthoff, H J; Huitema, S; Wolters, G; Poppema, S; Gips, C H

    1984-01-01

    The characteristics and distribution of the inflammatory infiltrate in liver biopsies of 25 patients with hepatitis B viral (HBV) infection were studied in relation to the distribution and expression of HBV antigens. Mononuclear subsets were characterized with monoclonal (OKT, OKM, Leu) antibodies to surface antigens. For the demonstration of viral antigens directly conjugated antibodies to surface (HBsAg), core (HBcAg) and 'e' (HBeAg) antigen were used. For the study of mutual relations all methods were performed on serial cut tissue sections. In chronic active hepatitis B (CAH-B, n = 12) OKT8+ lymphocytes of T cell origin were the only cell type present in areas with liver cell degeneration and T cell cytotoxicity appears to be the only immune mechanism. In chronic persistent hepatitis B (CPH-B, n = 7) the only conspicuous feature was the presence of many Leu 3+ lymphocytes of the helper/inducer population in the portal tracts. In acute hepatitis B (AHB, n = 6) OKT8+ cells of non-T origin (OKT1-,3-) and Leu 7+ cells of presumed natural killer (NK) potential predominated in the areas with liver cell necrosis, and non-T cell cytotoxicity appears to be the predominant immune mechanism. In none of these disease entities a positive spatial relation could be established between the cytotoxic cells and the demonstrable expression of HBV antigens in hepatocytes. It is concluded that differences in immunological reaction pattern may explain the different course in the three forms of HBV infection studied. Images Fig. 1 Fig. 2 PMID:6713726

  1. Viral Skin Diseases.

    PubMed

    Ramdass, Priya; Mullick, Sahil; Farber, Harold F

    2015-12-01

    In the vast world of skin diseases, viral skin disorders account for a significant percentage. Most viral skin diseases present with an exanthem (skin rash) and, oftentimes, an accompanying enanthem (lesions involving the mucosal membrane). In this article, the various viral skin diseases are explored, including viral childhood exanthems (measles, rubella, erythema infectiosum, and roseola), herpes viruses (herpes simplex virus, varicella zoster virus, Kaposi sarcoma herpes virus, viral zoonotic infections [orf, monkeypox, ebola, smallpox]), and several other viral skin diseases, such as human papilloma virus, hand, foot, and mouth disease, molluscum contagiosum, and Gianotti-Crosti syndrome. PMID:26612372

  2. A dendritic nano-sized hexanuclear ruthenium(II) complex as a one- and two-photon luminescent tracking non-viral gene vector

    PubMed Central

    Qiu, Kangqiang; Yu, Bole; Huang, Huaiyi; Zhang, Pingyu; Huang, Juanjuan; Zou, Shanshan; Chen, Yu; Ji, Liangnian; Chao, Hui

    2015-01-01

    Fluorescent tracking gene delivery could provide us with a better understanding of the critical steps in the transfection process. However, for in vivo tracking applications, a small diameter (<10 nm) is one of the rigorous requirements for tracking vectors. Herein, we have demonstrated a new paradigm for two-photon tracking gene delivery based on a dendritic nano-sized hexanuclear ruthenium(II) polypyridyl complex. Because this metallodendrimer has a multivalent periphery, the complex, which is 6.1 nm, showed high stability and excellent dispersibility and could stepwise condense DNA in vitro. With the outstanding photochemical properties of Ru(II) polypyridyl, this complex could track gene delivery in vivo using one- and two-photon imaging. PMID:26185052

  3. Human keratinocytes restrict chikungunya virus replication at a post-fusion step

    SciTech Connect

    Bernard, Eric; Simmons, Graham; Chazal, Nathalie; 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.

  4. Fusion of Erythrocytes by Sendai Virus Studied by Immuno-Freeze-Etching

    PubMed Central

    Bächi, Thomas; Aguet, Michel; Howe, Calderon

    1973-01-01

    Extensive fusion of human erythrocytes agglutinated by Sendai virus was observed after 30 s of incubation at 37 C. Electron microscopy of thin sections failed to reveal the presence of virions, viral fragments, or discrete viral antigens reactive with ferritin-labeled antibody at the sites of fusion. Immuno-freezeetching of membrane surfaces demonstrated the dispersal of viral envelope antigens from what appeared to be original sites of viral attachment. Virus-induced clustering of membrane glycoproteins was interpreted as resulting from interaction of viral antigens with membrane receptor proteins and forming the structural basis for fusion of membranes with one another. Images PMID:4351454

  5. Vaccines for viral and bacterial pathogens causing acute gastroenteritis: Part II: Vaccines for Shigella, Salmonella, enterotoxigenic E. coli (ETEC) enterohemorragic E. coli (EHEC) and Campylobacter jejuni.

    PubMed

    O'Ryan, Miguel; Vidal, Roberto; del Canto, Felipe; Carlos Salazar, Juan; Montero, David

    2015-01-01

    In Part II we discuss the following bacterial pathogens: Shigella, Salmonella (non-typhoidal), diarrheogenic E. coli (enterotoxigenic and enterohemorragic) and Campylobacter jejuni. In contrast to the enteric viruses and Vibrio cholerae discussed in Part I of this series, for the bacterial pathogens described here there is only one licensed vaccine, developed primarily for Vibrio cholerae and which provides moderate protection against enterotoxigenic E. coli (ETEC) (Dukoral(®)), as well as a few additional candidates in advanced stages of development for ETEC and one candidate for Shigella spp. Numerous vaccine candidates in earlier stages of development are discussed. PMID:25715096

  6. Vaccines for viral and bacterial pathogens causing acute gastroenteritis: Part II: Vaccines for Shigella, Salmonella, enterotoxigenic E. coli (ETEC) enterohemorragic E. coli (EHEC) and Campylobacter jejuni

    PubMed Central

    O’Ryan, Miguel; Vidal, Roberto; del Canto, Felipe; Carlos Salazar, Juan; Montero, David

    2015-01-01

    In Part II we discuss the following bacterial pathogens: Shigella, Salmonella (non-typhoidal), diarrheogenic E. coli (enterotoxigenic and enterohemorragic) and Campylobacter jejuni. In contrast to the enteric viruses and Vibrio cholerae discussed in Part I of this series, for the bacterial pathogens described here there is only one licensed vaccine, developed primarily for Vibrio cholerae and which provides moderate protection against enterotoxigenic E. coli (ETEC) (Dukoral®), as well as a few additional candidates in advanced stages of development for ETEC and one candidate for Shigella spp. Numerous vaccine candidates in earlier stages of development are discussed. PMID:25715096

  7. Results of a phase I/II open-label, safety and efficacy trial of coagulation factor IX (recombinant), albumin fusion protein in haemophilia B patients

    PubMed Central

    Martinowitz, U; Lissitchkov, T; Lubetsky, A; Jotov, G; Barazani-Brutman, T; Voigt, C; Jacobs, I; Wuerfel, T; Santagostino, E

    2015-01-01

    Introduction rIX-FP is a coagulation factor IX (recombinant), albumin fusion protein with more than fivefold half-life prolongation over other standard factor IX (FIX) products available on the market. Aim This prospective phase II, open-label study evaluated the safety and efficacy of rIX-FP for the prevention of bleeding episodes during weekly prophylaxis and assessed the haemostatic efficacy for on-demand treatment of bleeding episodes in previously treated patients with haemophilia B. Methods The study consisted of a 10–14 day evaluation of rIX-FP pharmacokinetics (PK), and an 11 month safety and efficacy evaluation period with subjects receiving weekly prophylaxis treatment. Safety was evaluated by the occurrence of related adverse events, and immunogenic events, including development of inhibitors. Efficacy was evaluated by annualized spontaneous bleeding rate (AsBR), and the number of injections to achieve haemostasis. Results Seventeen subjects participated in the study, 13 received weekly prophylaxis and 4 received episodic treatment only. No inhibitors were detected in any subject. The mean and median AsBR were 1.25, and 1.13 respectively in the weekly prophylaxis arm. All bleeding episodes were treated with 1 or 2 injections of rIX-FP. Three prophylaxis subjects who were treated on demand prior to study entry had >85% reduction in AsBR compared to the bleeding rate prior to study entry. Conclusion This study demonstrated the efficacy for weekly routine prophylaxis of rIX-FP to prevent spontaneous bleeding episodes and for the treatment of bleeding episodes. In addition no safety issues were detected during the study and an improved PK profile was demonstrated. PMID:25990590

  8. Rho GTPase activity modulates paramyxovirus fusion protein-mediated cell-cell fusion

    SciTech Connect

    Schowalter, Rachel M.; Wurth, Mark A.; Aguilar, Hector C.; Lee, Benhur; Moncman, Carole L.; McCann, Richard O.; Dutch, Rebecca Ellis . E-mail: rdutc2@uky.edu

    2006-07-05

    The paramyxovirus fusion protein (F) promotes fusion of the viral envelope with the plasma membrane of target cells as well as cell-cell fusion. The plasma membrane is closely associated with the actin cytoskeleton, but the role of actin dynamics in paramyxovirus F-mediated membrane fusion is unclear. We examined cell-cell fusion promoted by two different paramyxovirus F proteins in three cell types in the presence of constitutively active Rho family GTPases, major cellular coordinators of actin dynamics. Reporter gene and syncytia assays demonstrated that expression of either Rac1{sup V12} or Cdc42{sup V12} could increase cell-cell fusion promoted by the Hendra or SV5 glycoproteins, though the effect was dependent on the cell type expressing the viral glycoproteins. In contrast, RhoA{sup L63} decreased cell-cell fusion promoted by Hendra glycoproteins but had little affect on SV5 F-mediated fusion. Also, data suggested that GTPase activation in the viral glycoprotein-containing cell was primarily responsible for changes in fusion. Additionally, we found that activated Cdc42 promoted nuclear rearrangement in syncytia.

  9. Viral load, gene expression and mapping of viral integration sites in HPV16-associated HNSCC cell lines.

    PubMed

    Olthof, Nadine C; Huebbers, Christian U; Kolligs, Jutta; Henfling, Mieke; Ramaekers, Frans C S; Cornet, Iris; van Lent-Albrechts, Josefa A; Stegmann, Alexander P A; Silling, Steffi; Wieland, Ulrike; Carey, Thomas E; Walline, Heather M; Gollin, Susanne M; Hoffmann, Thomas K; de Winter, Johan; Kremer, Bernd; Klussmann, Jens P; Speel, Ernst-Jan M

    2015-03-01

    HPV-related HNSCC generally have a better prognosis than HPV-negative HNSCC. However, a subgroup of HPV-positive tumors with poor prognosis has been recognized, particularly related to smoking, EGFR overexpression and chromosomal instability. Viral integration into the host genome might contribute to carcinogenesis, as is shown for cervical carcinomas. Therefore, all HPV16-positive HNSCC cell lines currently available have been carefully analyzed for viral and host genome parameters. The viral integration status, viral load, viral gene expression and the presence of aneusomies was evaluated in the cell lines UD-SCC-2, UM-SCC-047, UM-SCC-104, UPCI:SCC090, UPCI:SCC152, UPCI:SCC154 and 93VU147T. HPV integration was examined using FISH, APOT-PCR and DIPS-PCR. Viral load and the expression of the viral genes E2, E6 and E7 were determined via quantitative PCR. All cell lines showed integration-specific staining patterns and signals indicating transcriptional activity using FISH. APOT- and DIPS-PCR identified integration-derived fusion products in six cell lines and only episomal products for UM-SCC-104. Despite the observed differences in viral load and the number of viral integration sites, this did not relate to the identified viral oncogene expression. Furthermore, cell lines exhibited EGFR expression and aneusomy (except UPCI:SCC154). In conclusion, all HPV16-positive HNSCC cell lines showed integrated and/or episomal viral DNA that is transcriptionally active, although viral oncogene expression was independent of viral copy number and the number of viral integration sites. Because these cell lines also contain EGFR expression and aneusomy, which are parameters of poor prognosis, they should be considered suitable model systems for the development of new antiviral therapies. PMID:25082736

  10. Line tension at lipid phase boundaries as driving force for HIV fusion peptide-mediated fusion

    NASA Astrophysics Data System (ADS)

    Yang, Sung-Tae; Kiessling, Volker; Tamm, Lukas K.

    2016-04-01

    Lipids and proteins are organized in cellular membranes in clusters, often called `lipid rafts'. Although raft-constituent ordered lipid domains are thought to be energetically unfavourable for membrane fusion, rafts have long been implicated in many biological fusion processes. For the case of HIV gp41-mediated membrane fusion, this apparent contradiction can be resolved by recognizing that the interfaces between ordered and disordered lipid domains are the predominant sites of fusion. Here we show that line tension at lipid domain boundaries contributes significant energy to drive gp41-fusion peptide-mediated fusion. This energy, which depends on the hydrophobic mismatch between ordered and disordered lipid domains, may contribute tens of kBT to fusion, that is, it is comparable to the energy required to form a lipid stalk intermediate. Line-active compounds such as vitamin E lower line tension in inhomogeneous membranes, thereby inhibit membrane fusion, and thus may be useful natural viral entry inhibitors.

  11. Line tension at lipid phase boundaries as driving force for HIV fusion peptide-mediated fusion.

    PubMed

    Yang, Sung-Tae; Kiessling, Volker; Tamm, Lukas K

    2016-01-01

    Lipids and proteins are organized in cellular membranes in clusters, often called 'lipid rafts'. Although raft-constituent ordered lipid domains are thought to be energetically unfavourable for membrane fusion, rafts have long been implicated in many biological fusion processes. For the case of HIV gp41-mediated membrane fusion, this apparent contradiction can be resolved by recognizing that the interfaces between ordered and disordered lipid domains are the predominant sites of fusion. Here we show that line tension at lipid domain boundaries contributes significant energy to drive gp41-fusion peptide-mediated fusion. This energy, which depends on the hydrophobic mismatch between ordered and disordered lipid domains, may contribute tens of kBT to fusion, that is, it is comparable to the energy required to form a lipid stalk intermediate. Line-active compounds such as vitamin E lower line tension in inhomogeneous membranes, thereby inhibit membrane fusion, and thus may be useful natural viral entry inhibitors. PMID:27113279

  12. Structural Basis for Broad Detection of Genogroup II Noroviruses by a Monoclonal Antibody That Binds to a Site Occluded in the Viral Particle

    SciTech Connect

    Hansmana, Grant S.; Taylor, David W.; Smith, Thomas J.; McLellan, Jason S.; Georgiev, Ivelin; Tame, Jeremy R.H.; Park, Sam-Yong; Yamazaki, Makoto; Gondaira, Fumio; Miki, Motohiro; Katayama, Kazuhiko; Murata, Kazuyoshi; Kwong, Peter D.

    2012-03-13

    Human noroviruses are genetically and antigenically highly divergent. Monoclonal antibodies raised in mice against one kind of norovirus virus-like particle (VLP), however, were found to have broad recognition. In this study, we present the crystal structure of the antigen-binding fragment (Fab) for one of these broadly reactive monoclonal antibodies, 5B18, in complex with the capsid-protruding domain from a genogroup II genotype 10 (GII.10) norovirus at 3.3-{angstrom} resolution and, also, the cryo-electron microscopy structure of the GII.10 VLP at {approx}10-{angstrom} resolution. The GII.10 VLP structure was more similar in overall architecture to the GV.1 murine norovirus virion than to the prototype GI.1 human norovirus VLP, with the GII.10 protruding domain raised {approx}15 {angstrom} off the shell domain and rotated {approx}40{sup o} relative to the GI.1 protruding domain. In the crystal structure, the 5B18 Fab bound to a highly conserved region of the protruding domain. Based on the VLP structure, this region is involved in interactions with other regions of the capsid and is buried in the virus particle. Despite the occluded nature of the recognized epitope in the VLP structure, enzyme-linked immunosorbent assay (ELISA) binding suggested that the 5B18 antibody was able to capture intact VLPs. Together, the results provide evidence that the norovirus particle is capable of extreme conformational flexibility, which may allow for antibody recognition of conserved surfaces that would otherwise be buried on intact particles.

  13. A Review of Data Fusion Techniques

    PubMed Central

    2013-01-01

    The integration of data and knowledge from several sources is known as data fusion. This paper summarizes the state of the data fusion field and describes the most relevant studies. We first enumerate and explain different classification schemes for data fusion. Then, the most common algorithms are reviewed. These methods and algorithms are presented using three different categories: (i) data association, (ii) state estimation, and (iii) decision fusion. PMID:24288502

  14. Exosomes in Viral Disease.

    PubMed

    Anderson, Monique R; Kashanchi, Fatah; Jacobson, Steven

    2016-07-01

    Viruses have evolved many mechanisms by which to evade and subvert the immune system to ensure survival and persistence. However, for each method undertaken by the immune system for pathogen removal, there is a counteracting mechanism utilized by pathogens. The new and emerging role of microvesicles in immune intercellular communication and function is no different. Viruses across many different families have evolved to insert viral components in exosomes, a subtype of microvesicle, with many varying downstream effects. When assessed cumulatively, viral antigens in exosomes increase persistence through cloaking viral genomes, decoying the immune system, and even by increasing viral infection in uninfected cells. Exosomes therefore represent a source of viral antigen that can be used as a biomarker for disease and targeted for therapy in the control and eradication of these disorders. With the rise in the persistence of new and reemerging viruses like Ebola and Zika, exploring the role of exosomes become more important than ever. PMID:27324390

  15. Paramyxovirus membrane fusion: Lessons from the F and HN atomic structures

    SciTech Connect

    Lamb, Robert A. . E-mail: ralamb@northwestern.edu; Paterson, Reay G.; Jardetzky, Theodore S.

    2006-01-05

    Paramyxoviruses enter cells by fusion of their lipid envelope with the target cell plasma membrane. Fusion of the viral membrane with the plasma membrane allows entry of the viral genome into the cytoplasm. For paramyxoviruses, membrane fusion occurs at neutral pH, but the trigger mechanism that controls the viral entry machinery such that it occurs at the right time and in the right place remains to be elucidated. Two viral glycoproteins are key to the infection process-an attachment protein that varies among different paramyxoviruses and the fusion (F) protein, which is found in all paramyxoviruses. For many of the paramyxoviruses (parainfluenza viruses 1-5, mumps virus, Newcastle disease virus and others), the attachment protein is the hemagglutinin/neuraminidase (HN) protein. In the last 5 years, atomic structures of paramyxovirus F and HN proteins have been reported. The knowledge gained from these structures towards understanding the mechanism of viral membrane fusion is described.

  16. The Dark Side of Cell Fusion

    PubMed Central

    Bastida-Ruiz, Daniel; Van Hoesen, Kylie; Cohen, Marie

    2016-01-01

    Cell fusion is a physiological cellular process essential for fertilization, viral entry, muscle differentiation and placental development, among others. In this review, we will highlight the different cancer cell-cell fusions and the advantages obtained by these fusions. We will specially focus on the acquisition of metastatic features by cancer cells after fusion with bone marrow-derived cells. The mechanism by which cancer cells fuse with other cells has been poorly studied thus far, but the presence in several cancer cells of syncytin, a trophoblastic fusogen, leads us to a cancer cell fusion mechanism similar to the one used by the trophoblasts. The mechanism by which cancer cells perform the cell fusion could be an interesting target for cancer therapy. PMID:27136533

  17. Vaccination with a Fusion Protein That Introduces HIV-1 Gag Antigen into a Multitrimer CD40L Construct Results in Enhanced CD8+ T Cell Responses and Protection from Viral Challenge by Vaccinia-Gag

    PubMed Central

    Gupta, Sachin; Termini, James M.; Raffa, Francesca N.; Williams, Cindi-Ann; Kornbluth, Richard S.

    2014-01-01

    CD40 ligand (CD40L, CD154) is a membrane protein that is important for the activation of dendritic cells (DCs) and DC-induced CD8+ T cell responses. To be active, CD40L must cluster CD40 receptors on responding cells. To produce a soluble form of CD40L that clusters CD40 receptors necessitates the use of a multitrimer construct. With this in mind, a tripartite fusion protein was made from surfactant protein D (SPD), HIV-1 Gag as a test antigen, and CD40L, where SPD serves as a scaffold for the multitrimer protein complex. This SPD-Gag-CD40L protein activated CD40-bearing cells and bone marrow-derived DCs in vitro. Compared to a plasmid for Gag antigen alone (pGag), DNA vaccination of mice with pSPD-Gag-CD40L induced an increased number of Gag-specific CD8+ T cells with increased avidity for major histocompatibility complex class I-restricted Gag peptide and improved vaccine-induced protection from challenge by vaccinia-Gag virus. The importance of the multitrimeric nature of the complex was shown using a plasmid lacking the N terminus of SPD that produced a single trimer fusion protein. This plasmid, pTrimer-Gag-CD40L, was only weakly active on CD40-bearing cells and did not elicit strong CD8+ T cell responses or improve protection from vaccinia-Gag challenge. An adenovirus 5 (Ad5) vaccine incorporating SPD-Gag-CD40L was much stronger than Ad5 expressing Gag alone (Ad5-Gag) and induced complete protection (i.e., sterilizing immunity) from vaccinia-Gag challenge. Overall, these results show the potential of a new vaccine design in which antigen is introduced into a construct that expresses a multitrimer soluble form of CD40L, leading to strongly protective CD8+ T cell responses. PMID:24227853

  18. Fusion breeder

    SciTech Connect

    Moir, R.W.

    1982-04-20

    The fusion breeder is a fusion reactor designed with special blankets to maximize the transmutation by 14 MeV neutrons of uranium-238 to plutonium or thorium to uranium-233 for use as a fuel for fission reactors. Breeding fissile fuels has not been a goal of the US fusion energy program. This paper suggests it is time for a policy change to make the fusion breeder a goal of the US fusion program and the US nuclear energy program. The purpose of this paper is to suggest this policy change be made and tell why it should be made, and to outline specific research and development goals so that the fusion breeder will be developed in time to meet fissile fuel needs.

  19. The Art of Engineering Viral Nanoparticles

    PubMed Central

    Pokorski, Jonathan K.; Steinmetz, Nicole F.

    2011-01-01

    Viral nanotechnology is an emerging and highly interdisciplinary field in which viral nanoparticles (VNPs) are applied in diverse areas such as electronics, energy and next-generation medical devices. VNPs have been developed as candidates for novel materials, and are often described as “programmable” because they can be modified and functionalized using a number of techniques. In this review, we discuss the concepts and methods that allow VNPs to be engineered, including (i) bioconjugation chemistries, (ii) encapsulation techniques, (iii) mineralization strategies, and (iv) film and hydrogel development. With all these techniques in hand, the potential applications of VNPs are limited only by the imagination. PMID:21047140

  20. Fusion Implementation

    SciTech Connect

    J.A. Schmidt

    2002-02-20

    If a fusion DEMO reactor can be brought into operation during the first half of this century, fusion power production can have a significant impact on carbon dioxide production during the latter half of the century. An assessment of fusion implementation scenarios shows that the resource demands and waste production associated with these scenarios are manageable factors. If fusion is implemented during the latter half of this century it will be one element of a portfolio of (hopefully) carbon dioxide limiting sources of electrical power. It is time to assess the regional implications of fusion power implementation. An important attribute of fusion power is the wide range of possible regions of the country, or countries in the world, where power plants can be located. Unlike most renewable energy options, fusion energy will function within a local distribution system and not require costly, and difficult, long distance transmission systems. For example, the East Coast of the United States is a prime candidate for fusion power deployment by virtue of its distance from renewable energy sources. As fossil fuels become less and less available as an energy option, the transmission of energy across bodies of water will become very expensive. On a global scale, fusion power will be particularly attractive for regions separated from sources of renewable energy by oceans.

  1. Mechanistic Study of Broadly Neutralizing Human Monoclonal Antibodies against Dengue Virus That Target the Fusion Loop

    PubMed Central

    Costin, Joshua M.; Zaitseva, Elena; Kahle, Kristen M.; Nicholson, Cindo O.; Rowe, Dawne K.; Graham, Amanda S.; Bazzone, Lindsey E.; Hogancamp, Greg; Figueroa Sierra, Marielys; Fong, Rachel H.; Yang, Sung-Tae; Lin, Li; Robinson, James E.; Doranz, Benjamin J.; Chernomordik, Leonid V.; Michael, Scott F.; Schieffelin, John S.

    2013-01-01

    There are no available vaccines for dengue, the most important mosquito-transmitted viral disease. Mechanistic studies with anti-dengue virus (DENV) human monoclonal antibodies (hMAbs) provide a rational approach to identify and characterize neutralizing epitopes on DENV structural proteins that can serve to inform vaccine strategies. Here, we report a class of hMAbs that is likely to be an important determinant in the human humoral response to DENV infection. In this study, we identified and characterized three broadly neutralizing anti-DENV hMAbs: 4.8A, D11C, and 1.6D. These antibodies were isolated from three different convalescent patients with distinct histories of DENV infection yet demonstrated remarkable similarities. All three hMAbs recognized the E glycoprotein with high affinity, neutralized all four serotypes of DENV, and mediated antibody-dependent enhancement of infection in Fc receptor-bearing cells at subneutralizing concentrations. The neutralization activities of these hMAbs correlated with a strong inhibition of virus-liposome and intracellular fusion, not virus-cell binding. We mapped epitopes of these antibodies to the highly conserved fusion loop region of E domain II. Mutations at fusion loop residues W101, L107, and/or G109 significantly reduced the binding of the hMAbs to E protein. The results show that hMAbs directed against the highly conserved E protein fusion loop block viral entry downstream of virus-cell binding by inhibiting E protein-mediated fusion. Characterization of hMAbs targeting this region may provide new insights into DENV vaccine and therapeutic strategies. PMID:23077306

  2. Viruses and viral proteins

    PubMed Central

    Verdaguer, Nuria; Ferrero, Diego; Murthy, Mathur R. N.

    2014-01-01

    For more than 30 years X-ray crystallography has been by far the most powerful approach for determining the structures of viruses and viral proteins at atomic resolution. The information provided by these structures, which covers many important aspects of the viral life cycle such as cell-receptor recognition, viral entry, nucleic acid transfer and genome replication, has extensively enriched our vision of the virus world. Many of the structures available correspond to potential targets for antiviral drugs against important human pathogens. This article provides an overview of the current knowledge of different structural aspects of the above-mentioned processes. PMID:25485129

  3. Splicing of cauliflower mosaic virus 35S RNA is essential for viral infectivity.

    PubMed Central

    Kiss-László, Z; Blanc, S; Hohn, T

    1995-01-01

    A splicing event essential for the infectivity of a plant pararetrovirus has been characterized. Transient expression experiments using reporter constructs revealed a splice donor site in the leader sequence of the cauliflower mosaic virus (CaMV) 35S RNA and three additional splice donor sites within open reading frame (ORF) I. All four donors use the same splice acceptor within ORF II. Splicing between the leader and ORF II produces an mRNA from which ORF III and, in the presence of the CaMV translational transactivator, ORF IV can be translated efficiently. The other three splicing events produce RNAs encoding ORF I-II in-frame fusions. All four spliced CaMV RNAs were detected in CaMV-infected plants. Virus mutants in which the splice acceptor site in ORF II is inactivated are not infectious, indicating that splicing plays an essential role in the CaMV life cycle. The results presented here suggest a model for viral gene expression in which RNA splicing is required to provide appropriate substrate mRNAs for the specialized translation mechanisms of CaMV. Images PMID:7628455

  4. Induction of cross-priming of naive CD8+ T lymphocytes by recombinant bacillus Calmette-Guerin that secretes heat shock protein 70-major membrane protein-II fusion protein.

    PubMed

    Mukai, Tetsu; Maeda, Yumi; Tamura, Toshiki; Matsuoka, Masanori; Tsukamoto, Yumiko; Makino, Masahiko

    2009-11-15

    Because Mycobacterium bovis bacillus Calmette-Guérin (BCG) unconvincingly activates human naive CD8(+) T cells, a rBCG (BCG-70M) that secretes a fusion protein comprising BCG-derived heat shock protein (HSP)70 and Mycobacterium leprae-derived major membrane protein (MMP)-II, one of the immunodominant Ags of M. leprae, was newly constructed to potentiate the ability of activating naive CD8(+) T cells through dendritic cells (DC). BCG-70M secreted HSP70-MMP-II fusion protein in vitro, which stimulated DC to produce IL-12p70 through TLR2. BCG-70M-infected DC activated not only memory and naive CD8(+) T cells, but also CD4(+) T cells of both types to produce IFN-gamma. The activation of these naive T cells by BCG-70M was dependent on the MHC and CD86 molecules on BCG-70M-infected DC, and was significantly inhibited by pretreatment of DC with chloroquine. Both brefeldin A and lactacystin significantly inhibited the activation of naive CD8(+) T cells by BCG-70M through DC. Thus, the CD8(+) T cell activation may be induced by cross-presentation of Ags through a TAP- and proteosome-dependent cytosolic pathway. When naive CD8(+) T cells were stimulated by BCG-70M-infected DC in the presence of naive CD4(+) T cells, CD62L(low)CD8(+) T cells and perforin-producing CD8(+) T cells were efficiently produced. MMP-II-reactive CD4(+) and CD8(+) memory T cells were efficiently produced in C57BL/6 mice by infection with BCG-70M. These results indicate that BCG-70M activated DC, CD4(+) T cells, and CD8(+) T cells, and the combination of HSP70 and MMP-II may be useful for inducing better T cell activation. PMID:19846882

  5. Image fusion

    NASA Technical Reports Server (NTRS)

    Pavel, M.

    1993-01-01

    The topics covered include the following: a system overview of the basic components of a system designed to improve the ability of a pilot to fly through low-visibility conditions such as fog; the role of visual sciences; fusion issues; sensor characterization; sources of information; image processing; and image fusion.

  6. Structural characterization of Mumps virus fusion protein core

    SciTech Connect

    Liu Yueyong; Xu Yanhui; Lou Zhiyong; Zhu Jieqing; Hu Xuebo; Gao, George F.; Qiu Bingsheng . E-mail: Qiubs@sun.im.ac.cn; Rao Zihe . E-mail: raozh@xtal.tsinghua.edu.cn; Tien, Po . E-mail: tienpo@sun.im.ac.cn

    2006-09-29

    The fusion proteins of enveloped viruses mediating the fusion between the viral and cellular membranes comprise two discontinuous heptad repeat (HR) domains located at the ectodomain of the enveloped glycoproteins. The crystal structure of the fusion protein core of Mumps virus (MuV) was determined at 2.2 A resolution. The complex is a six-helix bundle in which three HR1 peptides form a central highly hydrophobic coiled-coil and three HR2 peptides pack against the hydrophobic grooves on the surface of central coiled-coil in an oblique antiparallel manner. Fusion core of MuV, like those of simian virus 5 and human respiratory syncytium virus, forms typical 3-4-4-4-3 spacing. The similar charecterization in HR1 regions, as well as the existence of O-X-O motif in extended regions of HR2 helix, suggests a basic rule for the formation of the fusion core of viral fusion proteins.

  7. VIRAL INFECTIONS DURING PREGNANCY

    PubMed Central

    Silasi, Michelle; Cardenas, Ingrid; Racicot, Karen; Kwon, Ja-Young; Aldo, Paula; Mor, Gil

    2015-01-01

    Viral infections during pregnancy have long been considered benign conditions with a few notable exceptions, such as herpes virus. The recent Ebola outbreak and other viral epidemics and pandemics show how pregnant women suffer worse outcomes (such as preterm labor and adverse fetal outcomes) than the general population and non-pregnant women. New knowledge about the ways the maternal-fetal interface and placenta interact with the maternal immune system may explain these findings. Once thought to be “immunosuppressed”, the pregnant woman actually undergoes an immunological transformation, where the immune system is necessary to promote and support the pregnancy and growing fetus. When this protection is breached, as in a viral infection, this security is weakened and infection with other microorganisms can then propagate and lead to outcomes, such as preterm labor. In this manuscript, we review the major viral infections relevant to pregnancy, and offer potential mechanisms for the associated adverse pregnancy outcomes. PMID:25582523

  8. Viral Hemorrhagic Fevers

    MedlinePlus

    ... Related Links About VSPB (Viral Special Pathogens Branch) File Formats Help: How do I view different file formats (PDF, DOC, PPT, MPEG) on this site? Adobe PDF file Microsoft PowerPoint file Microsoft Word file Microsoft Excel ...

  9. HIV and Viral Hepatitis

    MedlinePlus

    ... prevalent among blacks as among whites. Viral Hepatitis Transmission People can be infected with the three most ... risk for HAV. • • New data suggest that sexual transmission of HCV among MSM with HIV occurs more ...

  10. Viral quasispecies complexity measures.

    PubMed

    Gregori, Josep; Perales, Celia; Rodriguez-Frias, Francisco; Esteban, Juan I; Quer, Josep; Domingo, Esteban

    2016-06-01

    Mutant spectrum dynamics (changes in the related mutants that compose viral populations) has a decisive impact on virus behavior. The several platforms of next generation sequencing (NGS) to study viral quasispecies offer a magnifying glass to study viral quasispecies complexity. Several parameters are available to quantify the complexity of mutant spectra, but they have limitations. Here we critically evaluate the information provided by several population diversity indices, and we propose the introduction of some new ones used in ecology. In particular we make a distinction between incidence, abundance and function measures of viral quasispecies composition. We suggest a multidimensional approach (complementary information contributed by adequately chosen indices), propose some guidelines, and illustrate the use of indices with a simple example. We apply the indices to three clinical samples of hepatitis C virus that display different population heterogeneity. Areas of virus biology in which population complexity plays a role are discussed. PMID:27060566

  11. Antibodies to envelope glycoprotein of dengue virus during the natural course of infection are predominantly cross-reactive and recognize epitopes containing highly conserved residues at the fusion loop of domain II.

    PubMed

    Lai, Chih-Yun; Tsai, Wen-Yang; Lin, Su-Ru; Kao, Chuan-Liang; Hu, Hsien-Ping; King, Chwan-Chuen; Wu, Han-Chung; Chang, Gwong-Jen; Wang, Wei-Kung

    2008-07-01

    The antibody response to the envelope (E) glycoprotein of dengue virus (DENV) is known to play a critical role in both protection from and enhancement of disease, especially after primary infection. However, the relative amounts of homologous and heterologous anti-E antibodies and their epitopes remain unclear. In this study, we examined the antibody responses to E protein as well as to precursor membrane (PrM), capsid, and nonstructural protein 1 (NS1) of four serotypes of DENV by Western blot analysis of DENV serotype 2-infected patients with different disease severity and immune status during an outbreak in southern Taiwan in 2002. Based on the early-convalescent-phase sera tested, the rates of antibody responses to PrM and NS1 proteins were significantly higher in patients with secondary infection than in those with primary infection. A blocking experiment and neutralization assay showed that more than 90% of anti-E antibodies after primary infection were cross-reactive and nonneutralizing against heterologous serotypes and that only a minor proportion were type specific, which may account for the type-specific neutralization activity. Moreover, the E-binding activity in sera of 10 patients with primary infection was greatly reduced by amino acid replacements of three fusion loop residues, tryptophan at position 101, leucine at position 107, and phenylalanine at position 108, but not by replacements of those outside the fusion loop of domain II, suggesting that the predominantly cross-reactive anti-E antibodies recognized epitopes involving the highly conserved residues at the fusion loop of domain II. These findings have implications for our understanding of the pathogenesis of dengue and for the future design of subunit vaccine against DENV as well. PMID:18448542

  12. Viral miRNAs.

    PubMed

    Plaisance-Bonstaff, Karlie; Renne, Rolf

    2011-01-01

    Since 2004, more than 200 microRNAs (miRNAs) have been discovered in double-stranded DNA viruses, mainly herpesviruses and polyomaviruses (Nucleic Acids Res 32:D109-D111, 2004). miRNAs are short 22  ±  3 nt RNA molecules that posttranscriptionally regulate gene expression by binding to 3'-untranslated regions (3'UTR) of target mRNAs, thereby inducing translational silencing and/or transcript degradation (Nature 431:350-355, 2004; Cell 116:281-297, 2004). Since miRNAs require only limited complementarity for binding, miRNA targets are difficult to determine (Mol Cell 27:91-105, 2007). To date, targets have only been experimentally verified for relatively few viral miRNAs, which either target viral or host cellular gene expression: For example, SV40 and related polyomaviruses encode miRNAs which target viral large T antigen expression (Nature 435:682-686, 2005; J Virol 79:13094-13104, 2005; Virology 383:183-187, 2009; J Virol 82:9823-9828, 2008) and miRNAs of α-, β-, and γ-herpesviruses have been implicated in regulating the transition from latent to lytic gene expression, a key step in the herpesvirus life cycle. Viral miRNAs have also been shown to target various host cellular genes. Although this field is just beginning to unravel the multiple roles of viral miRNA in biology and pathogenesis, the current data strongly suggest that virally encoded miRNAs are able to regulate fundamental biological processes such as immune recognition, promotion of cell survival, angiogenesis, proliferation, and cell differentiation. This chapter aims to summarize our current knowledge of viral miRNAs, their targets and function, and the challenges lying ahead to decipher their role in viral biology, pathogenesis, and for γ-herepsvirus-encoded miRNAs, potentially tumorigenesis. PMID:21431678

  13. Immigration and viral hepatitis.

    PubMed

    Sharma, Suraj; Carballo, Manuel; Feld, Jordan J; Janssen, Harry L A

    2015-08-01

    WHO estimates reveal that the global prevalence of viral hepatitis may be as high as 500 million, with an annual mortality rate of up to 1.3 million individuals. The majority of this global burden of disease is borne by nations of the developing world with high rates of vertical and iatrogenic transmission of HBV and HCV, as well as poor access to healthcare. In 2013, 3.2% of the global population (231 million individuals) migrated into a new host nation. Migrants predominantly originate from the developing countries of the south, into the developed economies of North America and Western Europe. This mass migration of individuals from areas of high-prevalence of viral hepatitis poses a unique challenge to the healthcare systems of the host nations. Due to a lack of universal standards for screening, vaccination and treatment of viral hepatitis, the burden of chronic liver disease and hepatocellular carcinoma continues to increase among migrant populations globally. Efforts to increase case identification and treatment among migrants have largely been limited to small outreach programs in urban centers, such that the majority of migrants with viral hepatitis continue to remain unaware of their infection. This review summarizes the data on prevalence of viral hepatitis and burden of chronic liver disease among migrants, current standards for screening and treatment of immigrants and refugees, and efforts to improve the identification and treatment of viral hepatitis among migrants. PMID:25962882

  14. Conceptual design of a laser-fusion power plant. Part II. Two technical options: 1. JADE reactor; 2. Heat transfer by heat pipes

    SciTech Connect

    Not Available

    1981-07-01

    A laser fusion reactor concept is described that employs liquid metal walls. The concept envisions a porous medium, called the JADE, of specific geometry lining the reactor cavity. Some advantages and disadvantages of the concept are pointed out. The possibility of using heat pipes for passive cooling in ICF reactors is discussed. Some of the problems are outlined. (MOW)

  15. A generic screening platform for inhibitors of virus induced cell fusion using cellular electrical impedance.

    PubMed

    Watterson, Daniel; Robinson, Jodie; Chappell, Keith J; Butler, Mark S; Edwards, David J; Fry, Scott R; Bermingham, Imogen M; Cooper, Matthew A; Young, Paul R

    2016-01-01

    Fusion of the viral envelope with host cell membranes is an essential step in the life cycle of all enveloped viruses. Despite such a clear target for antiviral drug development, few anti-fusion drugs have progressed to market. One significant hurdle is the absence of a generic, high-throughput, reproducible fusion assay. Here we report that real time, label-free measurement of cellular electrical impedance can quantify cell-cell fusion mediated by either individually expressed recombinant viral fusion proteins, or native virus infection. We validated this approach for all three classes of viral fusion and demonstrated utility in quantifying fusion inhibition using antibodies and small molecule inhibitors specific for dengue virus and respiratory syncytial virus. PMID:26976324

  16. Reciprocal Regulation of AKT and MAP Kinase Dictates Virus-Host Cell Fusion

    PubMed Central

    Sharma, Nishi R.; Mani, Prashant; Nandwani, Neha; Mishra, Rajakishore; Rana, Ajay; Sarkar, Debi P.

    2010-01-01

    Viruses of the Paramyxoviridae family bind to their host cells by using hemagglutinin-neuraminidase (HN), which enhances fusion protein (F)-mediated membrane fusion. Although respiratory syncytial virus and parainfluenza virus 5 of this family are suggested to trigger host cell signaling during infection, the virus-induced intracellular signals dictating virus-cell fusion await elucidation. Using an F- or HN-F-containing reconstituted envelope of Sendai virus, another paramyxovirus, we revealed the role and regulation of AKT1 and Raf/MEK/ERK cascades during viral fusion with liver cells. Our observation that extracellular signal-regulated kinase (ERK) activation promotes viral fusion via ezrin-mediated cytoskeletal rearrangements, whereas AKT1 attenuates fusion by promoting phosphorylation of F protein, indicates a counteractive regulation of viral fusion by reciprocal activation of AKT1 and mitogen-activated protein kinase (MAPK) cascades, establishing a novel conceptual framework for a therapeutic strategy. PMID:20164223

  17. A generic screening platform for inhibitors of virus induced cell fusion using cellular electrical impedance

    PubMed Central

    Watterson, Daniel; Robinson, Jodie; Chappell, Keith J.; Butler, Mark S.; Edwards, David J.; Fry, Scott R.; Bermingham, Imogen M.; Cooper, Matthew A.; Young, Paul R.

    2016-01-01

    Fusion of the viral envelope with host cell membranes is an essential step in the life cycle of all enveloped viruses. Despite such a clear target for antiviral drug development, few anti-fusion drugs have progressed to market. One significant hurdle is the absence of a generic, high-throughput, reproducible fusion assay. Here we report that real time, label-free measurement of cellular electrical impedance can quantify cell-cell fusion mediated by either individually expressed recombinant viral fusion proteins, or native virus infection. We validated this approach for all three classes of viral fusion and demonstrated utility in quantifying fusion inhibition using antibodies and small molecule inhibitors specific for dengue virus and respiratory syncytial virus. PMID:26976324

  18. Viral suppressors of RNA-based viral immunity: Host targets

    PubMed Central

    Wu, Qingfa; Wang, Xianbing

    2010-01-01

    Discovery of diverse plant and animal viral proteins as suppressors of RNA silencing has provided strong support for an RNA-based viral immunity (RVI), which is now known to specifically destroy viral RNAs by RNA interference in fungi, plants and invertebrates. Here we review several recent studies that have revealed new mechanistic insights into plant and insect viral suppressors of RVI or suggested a role for RNA silencing suppression during mammalian viral infection. PMID:20638637

  19. Fragments of Target Cells are Internalized into Retroviral Envelope Protein-Expressing Cells during Cell-Cell Fusion by Endocytosis

    PubMed Central

    Izumida, Mai; Kamiyama, Haruka; Suematsu, Takashi; Honda, Eri; Koizumi, Yosuke; Yasui, Kiyoshi; Hayashi, Hideki; Ariyoshi, Koya; Kubo, Yoshinao

    2016-01-01

    Retroviruses enter into host cells by fusion between viral and host cell membranes. Retroviral envelope glycoprotein (Env) induces the membrane fusion, and also mediates cell-cell fusion. There are two types of cell-cell fusions induced by the Env protein. Fusion-from-within is induced by fusion between viral fusogenic Env protein-expressing cells and susceptible cells, and virions induce fusion-from-without by fusion between adjacent cells. Although entry of ecotropic murine leukemia virus (E-MLV) requires host cell endocytosis, the involvement of endocytosis in cell fusion is unclear. By fluorescent microscopic analysis of the fusion-from-within, we found that fragments of target cells are internalized into Env-expressing cells. Treatment of the Env-expressing cells with an endocytosis inhibitor more significantly inhibited the cell fusion than that of the target cells, indicating that endocytosis in Env-expressing cells is required for the cell fusion. The endocytosis inhibitor also attenuated the fusion-from-without. Electron microscopic analysis suggested that the membrane fusion resulting in fusion-from-within initiates in endocytic membrane dents. This study shows that two types of the viral cell fusion both require endocytosis, and provides the cascade of fusion-from-within. PMID:26834711

  20. Stochastic Fusion Simulations and Experiments Suggest Passive and Active Roles of Hemagglutinin during Membrane Fusion

    PubMed Central

    Lee, Donald W.; Thapar, Vikram; Clancy, Paulette; Daniel, Susan

    2014-01-01

    Influenza enters the host cell cytoplasm by fusing the viral and host membrane together. Fusion is mediated by hemagglutinin (HA) trimers that undergo conformational change when acidified in the endosome. It is currently debated how many HA trimers, w, and how many conformationally changed HA trimers, q, are minimally required for fusion. Conclusions vary because there are three common approaches for determining w and q from fusion data. One approach correlates the fusion rate with the fraction of fusogenic HA trimers and leads to the conclusion that one HA trimer is required for fusion. A second approach correlates the fusion rate with the total concentration of fusogenic HA trimers and indicates that more than one HA trimer is required. A third approach applies statistical models to fusion rate data obtained at a single HA density to establish w or q and suggests that more than one HA trimer is required. In this work, all three approaches are investigated through stochastic fusion simulations and experiments to elucidate the roles of HA and its ability to bend the target membrane during fusion. We find that the apparent discrepancies among the results from the various approaches may be resolved if nonfusogenic HA participates in fusion through interactions with a fusogenic HA. Our results, based on H3 and H1 serotypes, suggest that three adjacent HA trimers and one conformationally changed HA trimer are minimally required to induce membrane fusion (w = 3 and q = 1). PMID:24559987

  1. Fusion Power.

    ERIC Educational Resources Information Center

    Dingee, David A.

    1979-01-01

    Discusses the extraordinary potential, the technical difficulties, and the financial problems that are associated with research and development of fusion power plants as a major source of energy. (GA)

  2. Inertial electrostatic confinement and nuclear fusion in the interelectrode plasma of a nanosecond vacuum discharge. II: Particle-in-cell simulations

    NASA Astrophysics Data System (ADS)

    Kurilenkov, Yu. K.; Tarakanov, V. P.; Gus'kov, S. Yu.

    2010-12-01

    Results of particle-in-sell simulations of ion acceleration by using the KARAT code in a cylindrical geometry in the problem formulation corresponding to an actual experiment with a low-energy vacuum discharge with a hollow cathode are presented. The fundamental role of the formed virtual cathode is analyzed. The space-time dynamics of potential wells related to the formation of the virtual cathode is discussed. Quasi-steady potential wells (with a depth of ˜80% of the applied voltage) cause acceleration of deuterium ions to energies about the electron beam energy (˜50 keV). In the well, a quasi-isotropic velocity distribution function of fast ions forms. The results obtained are compared with available data on inertial electrostatic confinement fusion (IECF). In particular, similar correlations between the structure of potential wells and the neutron yield, as well as the scaling of the fusion power density, which increases with decreasing virtual cathode radius and increasing potential well depth, are considered. The chosen electrode configuration and potential well parameters provide power densities of nuclear DD fusion in a nanosecond vacuum discharge noticeably higher than those achieved in other similar IECF systems.

  3. Modeling Viral Capsid Assembly

    PubMed Central

    2014-01-01

    I present a review of the theoretical and computational methodologies that have been used to model the assembly of viral capsids. I discuss the capabilities and limitations of approaches ranging from equilibrium continuum theories to molecular dynamics simulations, and I give an overview of some of the important conclusions about virus assembly that have resulted from these modeling efforts. Topics include the assembly of empty viral shells, assembly around single-stranded nucleic acids to form viral particles, and assembly around synthetic polymers or charged nanoparticles for nanotechnology or biomedical applications. I present some examples in which modeling efforts have promoted experimental breakthroughs, as well as directions in which the connection between modeling and experiment can be strengthened. PMID:25663722

  4. Viral hepatitis: Indian scenario.

    PubMed

    Satsangi, Sandeep; Chawla, Yogesh K

    2016-07-01

    Viral hepatitis is a cause for major health care burden in India and is now equated as a threat comparable to the "big three" communicable diseases - HIV/AIDS, malaria and tuberculosis. Hepatitis A virus and Hepatitis E virus are predominantly enterically transmitted pathogens and are responsible to cause both sporadic infections and epidemics of acute viral hepatitis. Hepatitis B virus and Hepatitis C virus are predominantly spread via parenteral route and are notorious to cause chronic hepatitis which can lead to grave complications including cirrhosis of liver and hepatocellular carcinoma. Around 400 million people all over the world suffer from chronic hepatitis and the Asia-Pacific region constitutes the epicentre of this epidemic. The present article would aim to cover the basic virologic aspects of these viruses and highlight the present scenario of viral hepatitis in India. PMID:27546957

  5. [Viral hepatitis in travellers].

    PubMed

    Abreu, Cândida

    2007-01-01

    Considering the geographical asymmetric distribution of viral hepatitis A, B and E, having a much higher prevalence in the less developed world, travellers from developed countries are exposed to a considerable and often underestimated risk of hepatitis infection. In fact a significant percentage of viral hepatitis occurring in developed countries is travel related. This results from globalization and increased mobility from tourism, international work, humanitarian and religious missions or other travel related activities. Several studies published in Europe and North America shown that more than 50% of reported cases of hepatitis A are travel related. On the other hand frequent outbreaks of hepatitis A and E in specific geographic areas raise the risk of infection in these restricted zones and that should be clearly identified. Selected aspects related with the distribution of hepatitis A, B and E are reviewed, particularly the situation in Portugal according to the published studies, as well as relevant clinical manifestations and differential diagnosis of viral hepatitis. Basic prevention rules considering enteric transmitted hepatitis (hepatitis A and hepatitis E) and parenteral transmitted (hepatitis B) are reviewed as well as hepatitis A and B immunoprophylaxis. Common clinical situations and daily practice "pre travel" advice issues are discussed according to WHO/CDC recommendations and the Portuguese National Vaccination Program. Implications from near future availability of a hepatitis E vaccine, a currently in phase 2 trial, are highlighted. Potential indications for travellers to endemic countries like India, Nepal and some regions of China, where up to 30% of sporadic cases of acute viral hepatitis are caused by hepatitis E virus, are considered. Continued epidemiological surveillance for viral hepatitis is essential to recognize and control possible outbreaks, but also to identify new viral hepatitis agents that may emerge as important global health

  6. Failure of Viral Shells

    NASA Astrophysics Data System (ADS)

    Klug, William S.; Bruinsma, Robijn F.; Michel, Jean-Philippe; Knobler, Charles M.; Ivanovska, Irena L.; Schmidt, Christoph F.; Wuite, Gijs J. L.

    2006-12-01

    We report a combined theoretical and experimental study of the structural failure of viral shells under mechanical stress. We find that discontinuities in the force-indentation curve associated with failure should appear when the so-called Föppl von Kármán (FvK) number exceeds a critical value. A nanoindentation study of a viral shell subject to a soft-mode instability, where the stiffness of the shell decreases with increasing pH, confirms the predicted onset of failure as a function of the FvK number.

  7. Control of mechanically activated polymersome fusion: Factors affecting fusion

    DOE PAGESBeta

    Henderson, Ian M.; Paxton, Walter F.

    2014-12-15

    Previously we have studied the mechanically-activated fusion of extruded (200 nm) polymer vesicles into giant polymersomes using agitation in the presence of salt. In this study we have investigated several factors contributing to this phenomenon, including the effects of (i) polymer vesicle concentration, (ii) agitation speed and duration, and iii) variation of the salt and its concentration. It was found that increasing the concentration of the polymer dramatically increases the production of giant vesicles through the increased collisions of polymersomes. Our investigations also found that increasing the frequency of agitation increased the efficiency of fusion, though ultimately limited the sizemore » of vesicle which could be produced due to the high shear involved. Finally it was determined that salt-mediation of the fusion process was not limited to NaCl, but is instead a general effect facilitated by the presence of solvated ionic compounds, albeit with different salts initiating fusion at different concentration.« less

  8. Control of mechanically activated polymersome fusion: Factors affecting fusion

    SciTech Connect

    Henderson, Ian M.; Paxton, Walter F.

    2014-12-15

    Previously we have studied the mechanically-activated fusion of extruded (200 nm) polymer vesicles into giant polymersomes using agitation in the presence of salt. In this study we have investigated several factors contributing to this phenomenon, including the effects of (i) polymer vesicle concentration, (ii) agitation speed and duration, and iii) variation of the salt and its concentration. It was found that increasing the concentration of the polymer dramatically increases the production of giant vesicles through the increased collisions of polymersomes. Our investigations also found that increasing the frequency of agitation increased the efficiency of fusion, though ultimately limited the size of vesicle which could be produced due to the high shear involved. Finally it was determined that salt-mediation of the fusion process was not limited to NaCl, but is instead a general effect facilitated by the presence of solvated ionic compounds, albeit with different salts initiating fusion at different concentration.

  9. Viral diseases of the rabbit.

    PubMed

    Krogstad, Aric P; Simpson, Janet E; Korte, Scott W

    2005-01-01

    Viral disease in the rabbit is encountered infrequently by the clinical practitioner; however, several viral diseases were reported to occur in this species. Viral diseases that are described in the rabbit primarily may affect the integument, gastrointestinal tract or, central nervous system or maybe multi-systemic in nature. Rabbit viral diseases range from oral papillomatosis, with benign clinical signs, to rabbit hemorrhagic disease and myxomatosis, which may result in significant clinical disease and mortality. The wild rabbit may serve as a reservoir for disease transmission for many of these viral agents. In general, treatment of viral disease in the rabbit is supportive in nature. PMID:15585192

  10. WATERBORNE VIRAL GASTROENTERITIS

    EPA Science Inventory

    In the study of human gastroenteritis, the use of electron microscopy and related techniques has led to the identification of new viral agents which had previously escaped detection by routine cell-culture procedures. Efforts to characterize and further study these agents are cur...

  11. BOVINE VIRAL DIARRHEA VIRUSES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bovine viral diarrhea virus (BVDV) is an umbrella term for two species of viruses, BVDV1 and BVDV2, within the Pestivirus genus of the Flavivirus family. BVDV viruses are further subclassified as cytopathic and noncytopathic based on their activity in cultured epithelial cells. Noncytopathic BVDV p...

  12. BIOMARKERS OF VIRAL EXPOSURE

    EPA Science Inventory

    Viral and protozoan pathogens associated with raw sludge can cause encephalitis, gastroenteritis, hepatitis, myocarditis, and a number of other diseases. Raw sludge that has been treated to reduce these pathogens can be used for land application according to the regulations spec...

  13. Leafhopper viral pathogens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Four newly discovered viral pathogens in leafhopper vectors of Pierce’s disease of grapes, have been shown to replicate in sharpshooter leafhoppers; the glassy-winged sharpshooter, GWSS, Homalodisca vitripennis, and Oncometopia nigricans (Hemiptera: Cicadellidae). The viruses were classified as memb...

  14. Transport of viral specimens.

    PubMed Central

    Johnson, F B

    1990-01-01

    The diagnosis of viral infections by culture relies on the collection of proper specimens, proper care to protect the virus in the specimens from environmental damage, and use of an adequate transport system to maintain virus activity. Collection of specimens with swabs that are toxic to either virus or cell culture should be avoided. A variety of transport media have been formulated, beginning with early bacteriological transport media. Certain swab-tube combinations have proven to be both effective and convenient. Of the liquid transport media, sucrose-based and broth-based media appear to be the most widely accepted and used. Studies on virus stability show that most viruses tested are sufficiently stable in transport media to withstand a transport time of 1 to 3 days. Some viruses may withstand longer transport times. In many cases, it is not necessary to store virus specimens in a refrigerator or send them to the laboratory on wet ice or frozen on dry ice. However, the specimen should not be exposed to environmental extremes. Modern viral transport media allow for more effective use of viral culture and culture enhancement techniques for the diagnosis of human viral infections. PMID:2187591

  15. Bovine viral diarrhea viruses

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Infections with bovine viral diarrhea viruses (BVDV) result in significant economic losses for beef and dairy producers worldwide. BVDV is actually an umbrella term for two species of viruses, BVDV1 and BVDV2, within the Pestivirus genus of the Flavivirus family. While denoted as a bovine pathogen...

  16. Multiepitope fusion antigen induces broadly protective antibodies that prevent adherence of Escherichia coli strains expressing colonization factor antigen I (CFA/I), CFA/II, and CFA/IV.

    PubMed

    Ruan, Xiaosai; Knudsen, David E; Wollenberg, Katie M; Sack, David A; Zhang, Weiping

    2014-02-01

    Diarrhea is the second leading cause of death in children younger than 5 years and continues to be a major threat to global health. Enterotoxigenic Escherichia coli (ETEC) strains are the most common bacteria causing diarrhea in developing countries. ETEC strains are able to attach to host small intestinal epithelial cells by using bacterial colonization factor antigen (CFA) adhesins. This attachment helps to initiate the diarrheal disease. Vaccines that induce antiadhesin immunity to block adherence of ETEC strains that express immunologically heterogeneous CFA adhesins are expected to protect against ETEC diarrhea. In this study, we created a CFA multiepitope fusion antigen (MEFA) carrying representative epitopes of CFA/I, CFA/II (CS1, CS2, and CS3), and CFA/IV (CS4, CS5, and CS6), examined its immunogenicity in mice, and assessed the potential of this MEFA as an antiadhesin vaccine against ETEC. Mice intraperitoneally immunized with this CFA MEFA exhibited no adverse effects and developed immune responses to CFA/I, CFA/II, and CFA/IV adhesins. Moreover, after incubation with serum of the immunized mice, ETEC or E. coli strains expressing CFA/I, CFA/II, or CFA/IV adhesins were significantly inhibited in adherence to Caco-2 cells. Our results indicated this CFA MEFA elicited antibodies that not only cross-reacted to CFA/I, CFA/II and CFA/IV adhesins but also broadly inhibited adherence of E. coli strains expressing these seven adhesins and suggested that this CFA MEFA could be a candidate to induce broad-spectrum antiadhesin protection against ETEC diarrhea. Additionally, this antigen construction approach (creating an MEFA) may be generally used in vaccine development against heterogenic pathogens. PMID:24351757

  17. Laser fusion

    SciTech Connect

    Smit, W.A.; Boskma, P.

    1980-12-01

    Unrestricted laser fusion offers nations an opportunity to circumvent arms control agreements and develop thermonuclear weapons. Early laser weapons research sought a clean radiation-free bomb to replace the fission bomb, but this was deceptive because a fission bomb was needed to trigger the fusion reaction and additional radioactivity was induced by generating fast neutrons. As laser-implosion experiments focused on weapons physics, simulating weapons effects, and applications for new weapons, the military interest shifted from developing a laser-ignited hydrogen bomb to more sophisticated weapons and civilian applications for power generation. Civilian and military research now overlap, making it possible for several countries to continue weapons activities and permitting proliferation of nuclear weapons. These countries are reluctant to include inertial confinement fusion research in the Non-Proliferation Treaty. 16 references. (DCK)

  18. The actin cytoskeleton inhibits pore expansion during PIV5 fusion protein-promoted cell-cell fusion

    SciTech Connect

    Wurth, Mark A.; Schowalter, Rachel M.; Smith, Everett Clinton; Moncman, Carole L.; Ellis Dutch, Rebecca; McCann, Richard O.

    2010-08-15

    Paramyxovirus fusion (F) proteins promote both virus-cell fusion, required for viral entry, and cell-cell fusion, resulting in syncytia formation. We used the F-actin stabilizing drug, jasplakinolide, and the G-actin sequestrant, latrunculin A, to examine the role of actin dynamics in cell-cell fusion mediated by the parainfluenza virus 5 (PIV5) F protein. Jasplakinolide treatment caused a dose-dependent increase in cell-cell fusion as measured by both syncytia and reporter gene assays, and latrunculin A treatment also resulted in fusion stimulation. Treatment with jasplakinolide or latrunculin A partially rescued a fusion pore opening defect caused by deletion of the PIV5 F protein cytoplasmic tail, but these drugs had no effect on fusion inhibited at earlier stages by either temperature arrest or by a PIV5 heptad repeat peptide. These data suggest that the cortical actin cytoskeleton is an important regulator of fusion pore enlargement, an energetically costly stage of viral fusion protein-mediated membrane merger.

  19. HIV Entry and Envelope Glycoprotein-mediated Fusion*

    PubMed Central

    Blumenthal, Robert; Durell, Stewart; Viard, Mathias

    2012-01-01

    HIV entry involves binding of the trimeric viral envelope glycoprotein (Env) gp120/gp41 to cell surface receptors, which triggers conformational changes in Env that drive the membrane fusion reaction. The conformational landscape that the lipids and Env navigate en route to fusion has been examined by biophysical measurements on the microscale, whereas electron tomography, x-rays, and NMR have provided insights into the process on the nanoscale and atomic scale. However, the coupling between the lipid and protein pathways that give rise to fusion has not been resolved. Here, we discuss the known and unknown about the overall HIV Env-mediated fusion process. PMID:23043104

  20. Plasma Potential Measurements by the Heavy Ion Beam Probe Diagnostic in Fusion Plasmas: Biasing Experiments in the TJ-II Stellarator and T-10 Tokamak

    SciTech Connect

    Melnikov, A.V.; Hidalgo, C.; Eliseev, L.G.

    2004-09-15

    The effect of edge biasing on plasma potential was investigated in the TJ-II stellarator and the T-10 tokamak. The Heavy Ion Beam Probe (HIBP) diagnostic, a unique tool for studying the core potential directly, was used in both machines. Experiments in TJ-II show that it is possible to modify the global confinement and edge plasma parameters with limiter biasing, illustrating the direct impact of radial electric fields on TJ-II confinement properties. For the first time it was shown that the plasma column in a stellarator can be charged as a whole for a hot, near-reactor-relevant plasma. The plasma potential and electric fields evolve on two different characteristic time scales. Although the experimental conditions in the two machines have many important differences, the basic features of plasma potential behavior have some similarities: The potential response has the same polarity and scale as the biasing voltage, and the fluctuations are suppressed near the electrode/limiter region. However, whereas both edge and core plasma potential are affected by biasing in TJ-II, the potential changes mainly near the biased electrode in T-10.

  1. Viral Membrane Scission

    PubMed Central

    Rossman, Jeremy S.; Lamb, Robert A.

    2014-01-01

    Virus budding is a complex, multistep process in which viral proteins make specific alterations in membrane curvature. Many different viral proteins can deform the membrane and form a budding virion, but very few can mediate membrane scission to complete the budding process. As a result, enveloped viruses have developed numerous ways of facilitating membrane scission, including hijacking host cellular scission machinery and expressing their own scission proteins. These proteins mediate scission in very different ways, though the biophysical mechanics underlying their actions may be similar. In this review, we explore the mechanisms of membrane scission and the ways in which enveloped viruses use these systems to mediate the release of budding virions. PMID:24099087

  2. Retrovirus Epidemiology Donor Study-II (REDS-II)

    ClinicalTrials.gov

    2016-04-14

    Acquired Immunodeficiency Syndrome; Blood Donors; Blood Transfusion; HIV Infections; HIV-1; HIV-2; HTLV-I; HTLV-II; Retroviridae Infections; Hepatitis, Viral, Human; Hepatitis B; Hepacivirus; West Nile Virus

  3. Optimizing Viral Discovery in Bats

    PubMed Central

    Young, Cristin C. W.; Olival, Kevin J.

    2016-01-01

    Viral discovery studies in bats have increased dramatically over the past decade, yet a rigorous synthesis of the published data is lacking. We extract and analyze data from 93 studies published between 2007–2013 to examine factors that increase success of viral discovery in bats, and specific trends and patterns of infection across host taxa and viral families. Over the study period, 248 novel viruses from 24 viral families have been described. Using generalized linear models, at a study level we show the number of host species and viral families tested best explained number of viruses detected. We demonstrate that prevalence varies significantly across viral family, specimen type, and host taxonomy, and calculate mean PCR prevalence by viral family and specimen type across all studies. Using a logistic model, we additionally identify factors most likely to increase viral detection at an individual level for the entire dataset and by viral families with sufficient sample sizes. Our analysis highlights major taxonomic gaps in recent bat viral discovery efforts and identifies ways to improve future viral pathogen detection through the design of more efficient and targeted sample collection and screening approaches. PMID:26867024

  4. Optimizing Viral Discovery in Bats.

    PubMed

    Young, Cristin C W; Olival, Kevin J

    2016-01-01

    Viral discovery studies in bats have increased dramatically over the past decade, yet a rigorous synthesis of the published data is lacking. We extract and analyze data from 93 studies published between 2007-2013 to examine factors that increase success of viral discovery in bats, and specific trends and patterns of infection across host taxa and viral families. Over the study period, 248 novel viruses from 24 viral families have been described. Using generalized linear models, at a study level we show the number of host species and viral families tested best explained number of viruses detected. We demonstrate that prevalence varies significantly across viral family, specimen type, and host taxonomy, and calculate mean PCR prevalence by viral family and specimen type across all studies. Using a logistic model, we additionally identify factors most likely to increase viral detection at an individual level for the entire dataset and by viral families with sufficient sample sizes. Our analysis highlights major taxonomic gaps in recent bat viral discovery efforts and identifies ways to improve future viral pathogen detection through the design of more efficient and targeted sample collection and screening approaches. PMID:26867024

  5. Fusion Activity of HIV gp41 Fusion Domain is Related to its Secondary Structure and Depth of Membrane Insertion in a Cholesterol-Dependent Fashion

    PubMed Central

    Lai, Alex L.; Moorthy, Anna Eswara; Li, Yinling; Tamm, Lukas K.

    2013-01-01

    The HIV gp41 fusion domain plays a critical role in membrane fusion during viral entry. A thorough understanding of the relationship between the structure and activity of the fusion domain in different lipid environments helps to formulate mechanistic models on how it might function in mediating membrane fusion. The secondary structure of the fusion domain in small liposomes composed of different lipid mixtures was investigated by circular dichroism spectroscopy. In membranes containing less than 30 mol% cholesterol the fusion domain formed an α-helix and in membranes containing equal to or more than 30 mol% cholesterol the fusion domain formed β-sheet secondary structure. EPR spectra of spin-labeled fusion domains also indicated different conformations in membranes with and without cholesterol. Power saturation EPR data were further used to determine the orientation and depth of α-helical fusion domains in lipid bilayers. Fusion and membrane perturbation activities of the gp41 fusion domain were measured by lipid mixing and contents leakage. The fusion domain fused membranes in both its helical and β-sheet forms. High cholesterol, which induced β-sheet, promoted fusion, but acidic lipids, which promoted relatively deep membrane insertion as an α-helix, also induced fusion. The results indicate that the structure of the HIV gp41 fusion domain is plastic and depends critically on the lipid environment. Provided their membrane insertion is deep, α-helical and β-sheet conformations contribute to membrane fusion. PMID:22343048

  6. Cold fusion, Alchemist's dream

    SciTech Connect

    Clayton, E.D.

    1989-09-01

    In this report the following topics relating to cold fusion are discussed: muon catalysed cold fusion; piezonuclear fusion; sundry explanations pertaining to cold fusion; cosmic ray muon catalysed cold fusion; vibrational mechanisms in excited states of D{sub 2} molecules; barrier penetration probabilities within the hydrogenated metal lattice/piezonuclear fusion; branching ratios of D{sub 2} fusion at low energies; fusion of deuterons into {sup 4}He; secondary D+T fusion within the hydrogenated metal lattice; {sup 3}He to {sup 4}He ratio within the metal lattice; shock induced fusion; and anomalously high isotopic ratios of {sup 3}He/{sup 4}He.

  7. Fusion Power Demonstration III

    SciTech Connect

    Lee, J.D.

    1985-07-01

    This is the third in the series of reports covering the Fusion Power Demonstration (FPD) design study. This volume considers the FPD-III configuration that incorporates an octopole end plug. As compared with the quadrupole end-plugged designs of FPD-I and FPD-II, this octopole configuration reduces the number of end cell magnets and shortens the minimum ignition length of the central cell. The end-cell plasma length is also reduced, which in turn reduces the size and cost of the end cell magnets and shielding. As a contiuation in the series of documents covering the FPD, this report does not stand alone as a design description of FPD-III. Design details of FPD-III subsystems that do not differ significantly from those of the FPD-II configuration are not duplicated in this report.

  8. The role of cholesterol in membrane fusion.

    PubMed

    Yang, Sung-Tae; Kreutzberger, Alex J B; Lee, Jinwoo; Kiessling, Volker; Tamm, Lukas K

    2016-09-01

    Cholesterol modulates the bilayer structure of biological membranes in multiple ways. It changes the fluidity, thickness, compressibility, water penetration and intrinsic curvature of lipid bilayers. In multi-component lipid mixtures, cholesterol induces phase separations, partitions selectively between different coexisting lipid phases, and causes integral membrane proteins to respond by changing conformation or redistribution in the membrane. But, which of these often overlapping properties are important for membrane fusion?-Here we review a range of recent experiments that elucidate the multiple roles that cholesterol plays in SNARE-mediated and viral envelope glycoprotein-mediated membrane fusion. PMID:27179407

  9. Viral insertion in Evi12 causes expression of aberrant Grp94 mRNAs containing the viral gag myristylation motif

    SciTech Connect

    Akker, Eric van den; Aarts, Lambertus H.J.; Delwel, Ruud

    2007-09-30

    Ecotropic Virus Integration site 12 (Evi12) is a common virus insertion site (cVIS) in retrovirally induced murine models of leukemia and lymphoma, suggesting an important role for this locus in these hematopoietic disorders. Evi12 is located near the promoter of the ER chaperone protein and Hsp90 family member Grp94. Here we show that viral insertion in Evi12 results in the expression of aberrant Grp94 transcripts in Cas-Br-MuLV as well as in AKXD induced hematopoietic tumors, demonstrating that Grp94 is a common viral target gene. While most transcripts encode for truncated forms of Grp94, transcripts containing viral gag sequences were detected in the leukemia cell line NFS107. Interestingly, these fusion transcripts encode for myristylated viral-Grp94 fusion proteins that localize to the plasma membrane. Combined with recent evidence that myristylated forms of Hsp90 transform cells, our data suggest that myristylation of target genes may be an important mechanism in retrovirally mediated oncogenesis. Since retroviral insertion in Evi12 also affects the expression of a recently identified novel gene Grp94 neighboring nucleotidase (Gnn), located at the other side of Evi12, it appears that proviral insertion can lead to deregulation of two genes present in the same locus.

  10. Assembly of Influenza Hemagglutinin Fusion Peptides in a Phospholipid Bilayer by Coarse-grained Computer Simulations

    PubMed Central

    Collu, Francesca; Spiga, Enrico; Lorenz, Christian D.; Fraternali, Franca

    2015-01-01

    Membrane fusion is critical to eukaryotic cellular function and crucial to the entry of enveloped viruses such as influenza and human immunodeficiency virus. Influenza viral entry in the host cell is mediated by a 20–23 amino acid long sequence, called the fusion peptide (FP). Recently, possible structures for the fusion peptide (ranging from an inverted V shaped α-helical structure to an α-helical hairpin, or to a complete α-helix) and their implication in the membrane fusion initiation have been proposed. Despite the large number of studies devoted to the structure of the FP, the mechanism of action of this peptide remains unclear with several mechanisms having been suggested, including the induction of local disorder, promoting membrane curvature, and/or altering local membrane composition. In recent years, several research groups have employed atomistic and/or coarse-grained molecular dynamics (MD) simulations to investigate the matter. In all previous works, the behavior of a single FP monomer was studied, while in this manuscript, we use a simplified model of a tripeptide (TP) monomer of FP (TFP) instead of a single FP monomer because each Influenza Hemagglutinin contains three FP molecules in the biological system. In this manuscript we report findings targeted at understanding the fusogenic properties and the collective behavior of these trimers of FP peptides on a 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine model membrane. Here we show how the TFP monomers self-assemble into differently sized oligomers in the presence of the membrane. We measure the perturbation to the structure of the phospholipid membrane caused by the presence of these TFP oligomers. Our work (i) shows how self-assembly of TFP in the presence of the membrane induces non negligible deformation to the membrane and (ii) could be a useful starting point to stimulate discussion and further work targeted to fusion pore formation. PMID:26636093

  11. Combating emerging viral threats

    PubMed Central

    Bekerman, Elena; Einav, Shirit

    2015-01-01

    Synopsis Most approved antiviral therapeutics selectively inhibit proteins encoded by a single virus, thereby providing a “one drug-one bug” solution. As a result of this narrow spectrum of coverage and the high cost of drug development, therapies are currently approved for fewer than ten viruses out of the hundreds known to cause human disease. This perspective summarizes progress and challenges in the development of broad-spectrum antiviral therapies. These strategies include targeting enzymatic functions shared by multiple viruses and host cell machinery by newly discovered compounds or by repurposing approved drugs. These approaches offer new practical means for developing therapeutics against existing and emerging viral threats. PMID:25883340

  12. Equine viral arteritis.

    PubMed

    Balasuriya, Udeni B R

    2014-12-01

    Equine arteritis virus (EAV), the causative agent of equine viral arteritis (EVA), is a respiratory and reproductive disease that occurs throughout the world. EAV infection is highly species-specific and exclusively limited to members of the family Equidae, which includes horses, donkeys, mules, and zebras. EVA is an economically important disease and outbreaks could cause significant losses to the equine industry. The primary objective of this article is to summarize current understanding of EVA, specifically the disease, pathogenesis, epidemiology, host immune response, vaccination and treatment strategies, prevention and control measures, and future directions. PMID:25441113

  13. Viral surveillance and discovery

    PubMed Central

    Lipkin, Walter Ian; Firth, Cadhla

    2014-01-01

    The field of virus discovery has burgeoned with the advent of high throughput sequencing platforms and bioinformatics programs that enable rapid identification and molecular characterization of known and novel agents, investments in global microbial surveillance that include wildlife and domestic animals as well as humans, and recognition that viruses may be implicated in chronic as well as acute diseases. Here we review methods for viral surveillance and discovery, strategies and pitfalls in linking discoveries to disease, and identify opportunities for improvements in sequencing instrumentation and analysis, the use of social media and medical informatics that will further advance clinical medicine and public health. PMID:23602435

  14. Complement and Viral Pathogenesis

    PubMed Central

    Stoermer, Kristina A.; Morrison, Thomas E.

    2011-01-01

    The complement system functions as an immune surveillance system that rapidly responds to infection. Activation of the complement system by specific recognition pathways triggers a protease cascade, generating cleavage products that function to eliminate pathogens, regulate inflammatory responses, and shape adaptive immune responses. However, when dysregulated, these powerful functions can become destructive and the complement system has been implicated as a pathogenic effector in numerous diseases, including infectious diseases. This review highlights recent discoveries that have identified critical roles for the complement system in the pathogenesis of viral infection. PMID:21292294

  15. The Human Metapneumovirus Fusion Protein Mediates Entry via an Interaction with RGD-Binding Integrins

    PubMed Central

    Cox, Reagan G.; Livesay, S. Brent; Johnson, Monika; Ohi, Melanie D.

    2012-01-01

    Paramyxoviruses use a specialized fusion protein to merge the viral envelope with cell membranes and initiate infection. Most paramyxoviruses require the interaction of two viral proteins to enter cells; an attachment protein binds cell surface receptors, leading to the activation of a fusion (F) protein that fuses the viral envelope and host cell plasma membrane. In contrast, human metapneumovirus (HMPV) expressing only the F protein is replication competent, suggesting a primary role for HMPV F in attachment and fusion. We previously identified an invariant arginine-glycine-aspartate (RGD) motif in the HMPV F protein and showed that the RGD-binding integrin αVβ1-promoted HMPV infection. Here we show that both HMPV F-mediated binding and virus entry depend upon multiple RGD-binding integrins and that HMPV F can mediate binding and fusion in the absence of the viral attachment (G) protein. The invariant F-RGD motif is critical for infection, as an F-RAE virus was profoundly impaired. Further, F-integrin binding is required for productive viral RNA transcription, indicating that RGD-binding integrins serve as receptors for the HMPV fusion protein. Thus, HMPV F is triggered to induce virus-cell fusion by interactions with cellular receptors in a manner that is independent of the viral G protein. These results suggest a stepwise mechanism of HMPV entry mediated by the F protein through its interactions with cellular receptors, including RGD-binding integrins. PMID:22933271

  16. Cryomicroscopy provides structural snapshots of influenza virus membrane fusion.

    PubMed

    Calder, Lesley J; Rosenthal, Peter B

    2016-09-01

    The lipid-enveloped influenza virus enters host cells during infection by binding cell-surface receptors and, after receptor-mediated endocytosis, fusing with the membrane of the endosome and delivering the viral genome and transcription machinery into the host cell. These events are mediated by the hemagglutinin (HA) surface glycoprotein. At the low pH of the endosome, an irreversible conformational change in the HA, including the exposure of the hydrophobic fusion peptide, activates membrane fusion. Here we used electron cryomicroscopy and cryotomography to image the fusion of influenza virus with target membranes at low pH. We visualized structural intermediates of HA and their interactions with membranes during the course of membrane fusion as well as ultrastructural changes in the virus that accompany membrane fusion. Our observations are relevant to a wide range of protein-mediated membrane-fusion processes and demonstrate how dynamic membrane events may be studied by cryomicroscopy. PMID:27501535

  17. A Mechanistic Paradigm for Broad-Spectrum Antivirals that Target Virus-Cell Fusion

    PubMed Central

    Hollmann, Axel; Tanner, Lukas B.; Akyol Ataman, Zeynep; Yun, Tatyana; Shui, Guanghou; Aguilar, Hector C.; Zhang, Dong; Meriwether, David; Roman-Sosa, Gleyder; Robinson, Lindsey R.; Juelich, Terry L.; Buczkowski, Hubert; Chou, Sunwen; Castanho, Miguel A. R. B.; Wolf, Mike C.; Smith, Jennifer K.; Banyard, Ashley; Kielian, Margaret; Reddy, Srinivasa; Wenk, Markus R.; Selke, Matthias; Santos, Nuno C.; Freiberg, Alexander N.; Jung, Michael E.; Lee, Benhur

    2013-01-01

    LJ001 is a lipophilic thiazolidine derivative that inhibits the entry of numerous enveloped viruses at non-cytotoxic concentrations (IC50≤0.5 µM), and was posited to exploit the physiological difference between static viral membranes and biogenic cellular membranes. We now report on the molecular mechanism that results in LJ001's specific inhibition of virus-cell fusion. The antiviral activity of LJ001 was light-dependent, required the presence of molecular oxygen, and was reversed by singlet oxygen (1O2) quenchers, qualifying LJ001 as a type II photosensitizer. Unsaturated phospholipids were the main target modified by LJ001-generated 1O2. Hydroxylated fatty acid species were detected in model and viral membranes treated with LJ001, but not its inactive molecular analog, LJ025. 1O2-mediated allylic hydroxylation of unsaturated phospholipids leads to a trans-isomerization of the double bond and concurrent formation of a hydroxyl group in the middle of the hydrophobic lipid bilayer. LJ001-induced 1O2-mediated lipid oxidation negatively impacts on the biophysical properties of viral membranes (membrane curvature and fluidity) critical for productive virus-cell membrane fusion. LJ001 did not mediate any apparent damage on biogenic cellular membranes, likely due to multiple endogenous cytoprotection mechanisms against phospholipid hydroperoxides. Based on our understanding of LJ001's mechanism of action, we designed a new class of membrane-intercalating photosensitizers to overcome LJ001's limitations for use as an in vivo antiviral agent. Structure activity relationship (SAR) studies led to a novel class of compounds (oxazolidine-2,4-dithiones) with (1) 100-fold improved in vitro potency (IC50<10 nM), (2) red-shifted absorption spectra (for better tissue penetration), (3) increased quantum yield (efficiency of 1O2 generation), and (4) 10–100-fold improved bioavailability. Candidate compounds in our new series moderately but significantly (p≤0.01) delayed the

  18. Viral infections of rabbits.

    PubMed

    Kerr, Peter J; Donnelly, Thomas M

    2013-05-01

    Viral diseases of rabbits have been used historically to study oncogenesis (e.g. rabbit fibroma virus, cottontail rabbit papillomavirus) and biologically to control feral rabbit populations (e.g. myxoma virus). However, clinicians seeing pet rabbits in North America infrequently encounter viral diseases although myxomatosis may be seen occasionally. The situation is different in Europe and Australia, where myxomatosis and rabbit hemorrhagic disease are endemic. Advances in epidemiology and virology have led to detection of other lapine viruses that are now recognized as agents of emerging infectious diseases. Rabbit caliciviruses, related to rabbit hemorrhagic disease, are generally avirulent, but lethal variants are being identified in Europe and North America. Enteric viruses including lapine rotavirus, rabbit enteric coronavirus and rabbit astrovirus are being acknowledged as contributors to the multifactorial enteritis complex of juvenile rabbits. Three avirulent leporid herpesviruses are found in domestic rabbits. A fourth highly pathogenic virus designated leporid herpesvirus 4 has been described in Canada and Alaska. This review considers viruses affecting rabbits by their clinical significance. Viruses of major and minor clinical significance are described, and viruses of laboratory significance are mentioned. PMID:23642871

  19. [Emergent viral infections].

    PubMed

    Galama, J M

    2001-03-31

    The emergence and re-emergence of viral infections is an ongoing process. Large-scale vaccination programmes led to the eradication or control of some viral infections in the last century, but new viruses are always emerging. Increased travel is leading to a rise in the importation of exotic infections such as dengue and hepatitis E, but also of hepatitis A, which is no longer endemic. Apart from import diseases new viruses have appeared (Nipah-virus and transfusion-transmitted virus). Existing viruses may suddenly cause more severe diseases, e.g. infection by enterovirus 71. The distribution area of a virus may change, e.g. in case of West Nile virus, an Egyptian encephalitis virus that appears to have established itself in the USA. Furthermore, there is no such thing as a completely new virus; it is always an existing virus that has adapted itself to another host or that was already present in humans but has only recently been discovered. A number of factors facilitate the emergence of new infectious diseases. These include intensive animal husbandry and the transport of animals. The unexpected appearance of West Nile virus in the western hemisphere was possibly due to animal transportation. PMID:11305210

  20. Human viral gastroenteritis.

    PubMed Central

    Christensen, M L

    1989-01-01

    During the last 15 years, several different groups of fastidious viruses that are responsible for a large proportion of acute viral gastroenteritis cases have been discovered by the electron microscopic examination of stool specimens. This disease is one of the most prevalent and serious clinical syndromes seen around the world, especially in children. Rotaviruses, in the family Reoviridae, and fastidious fecal adenoviruses account for much of the viral gastroenteritis in infants and young children, whereas the small caliciviruses and unclassified astroviruses, and possibly enteric coronaviruses, are responsible for significantly fewer cases overall. In addition to electron microscopy, enzyme immunoassays and other rapid antigen detection systems have been developed to detect rotaviruses and fastidious fecal adenoviruses in the stool specimens of both nonhospitalized patients and those hospitalized for dehydration and electrolyte imbalance. Experimental rotavirus vaccines have also been developed, due to the prevalence and seriousness of rotavirus infection. The small, unclassified Norwalk virus and morphologically similar viruses are responsible for large and small outbreaks of acute gastroenteritis in older children, adolescents, and adults. Hospitalization of older patients infected with these viruses is usually not required, and their laboratory diagnoses have been limited primarily to research laboratories. Images PMID:2644024

  1. Line tension at lipid phase boundaries as driving force for HIV fusion peptide-mediated fusion

    PubMed Central

    Yang, Sung-Tae; Kiessling, Volker; Tamm, Lukas K.

    2016-01-01

    Lipids and proteins are organized in cellular membranes in clusters, often called ‘lipid rafts'. Although raft-constituent ordered lipid domains are thought to be energetically unfavourable for membrane fusion, rafts have long been implicated in many biological fusion processes. For the case of HIV gp41-mediated membrane fusion, this apparent contradiction can be resolved by recognizing that the interfaces between ordered and disordered lipid domains are the predominant sites of fusion. Here we show that line tension at lipid domain boundaries contributes significant energy to drive gp41-fusion peptide-mediated fusion. This energy, which depends on the hydrophobic mismatch between ordered and disordered lipid domains, may contribute tens of kBT to fusion, that is, it is comparable to the energy required to form a lipid stalk intermediate. Line-active compounds such as vitamin E lower line tension in inhomogeneous membranes, thereby inhibit membrane fusion, and thus may be useful natural viral entry inhibitors. PMID:27113279

  2. Multi-unit inertial fusion plants based on HYLIFE-II, with shared heavy-ion RIA driver and target factory, producing electricity and hydrogen fuel

    SciTech Connect

    Logan, G.; Moir, R.; Hoffman, M.

    1994-05-05

    Following is a modification of the IFEFUEL systems code, called IFEFUEL2, to treat specifically the HYLIFE-II target chamber concept. The same improved Recirculating Induction Accelerator (RIA) energy scaling model developed recently by Bieri is used in this survey of the economics of multi-unit IFE plants producing both electricity and hydrogen fuel. Reference cases will assume conventional HI-indirect target gains for a 2 mm spot, and improved HYLIFE-II BoP models as per Hoffman. Credits for improved plant availability and lower operating costs due to HYLIFE-II`s 30-yr target chamber lifetime are included, as well as unit cost reductions suggested by Delene to credit greater {open_quotes}learning curve{close_quotes} benefits for the duplicated portions of a multi-unit plant. To illustrate the potential impact of more advanced assumptions, additional {open_quotes}advanced{close_quotes} cases will consider the possible benefits of an MHD + Steam BoP, where direct MHD conversion of plasma from baseball-size LiH target blanket shells is assumed to be possible in a new (as yet undesigned) liquid Flibe-walled target chamber, together and separately, with advanced, higher-gain heavy-ion targets with Fast Ignitors. These runs may help decide the course of a possible future {open_quotes}HYLIFE-III{close_quotes} IFE study. Beam switchyard and final focusing system costs per target chamber are assumed to be consistent with single-sided illumination, for either {open_quotes}conventional{close_quotes} or {open_quotes}advanced{close_quotes} indirect target gain assumptions. Target costs are scaled according to the model by Woodworth. In all cases, the driver energy and rep rate for each chosen number of target chambers and total plant output will be optimized to minimize the cost of electricity (CoE) and the associated cost of hydrogen (CoH), using a relationship between CoE and CoH to be presented in the next section.

  3. Distinct structural rearrangements of the VSV glycoprotein drive membrane fusion

    PubMed Central

    Libersou, Sonia; Albertini, Aurélie A.V.; Ouldali, Malika; Maury, Virginie; Maheu, Christine; Raux, Hélène; de Haas, Felix; Roche, Stéphane

    2010-01-01

    The entry of enveloped viruses into cells requires the fusion of viral and cellular membranes, driven by conformational changes in viral glycoproteins. Many studies have shown that fusion involves the cooperative action of a large number of these glycoproteins, but the underlying mechanisms are unknown. We used electron microscopy and tomography to study the low pH–induced fusion reaction catalyzed by vesicular stomatitis virus glycoprotein (G). Pre- and post-fusion crystal structures were observed on virions at high and low pH, respectively. Individual fusion events with liposomes were also visualized. Fusion appears to be driven by two successive structural rearrangements of G at different sites on the virion. Fusion is initiated at the flat base of the particle. Glycoproteins located outside the contact zone between virions and liposomes then reorganize into regular arrays. We suggest that the formation of these arrays, which have been shown to be an intrinsic property of the G ectodomain, induces membrane constraints, achieving the fusion reaction. PMID:20921141

  4. Viral noncoding RNAs: more surprises

    PubMed Central

    Tycowski, Kazimierz T.; Guo, Yang Eric; Lee, Nara; Moss, Walter N.; Vallery, Tenaya K.; Xie, Mingyi

    2015-01-01

    Eukaryotic cells produce several classes of long and small noncoding RNA (ncRNA). Many DNA and RNA viruses synthesize their own ncRNAs. Like their host counterparts, viral ncRNAs associate with proteins that are essential for their stability, function, or both. Diverse biological roles—including the regulation of viral replication, viral persistence, host immune evasion, and cellular transformation—have been ascribed to viral ncRNAs. In this review, we focus on the multitude of functions played by ncRNAs produced by animal viruses. We also discuss their biogenesis and mechanisms of action. PMID:25792595

  5. Comprehensive analysis of HPV16 integration in OSCC reveals no significant impact of physical status on viral oncogene and virally disrupted human gene expression.

    PubMed

    Olthof, Nadine C; Speel, Ernst-Jan M; Kolligs, Jutta; Haesevoets, Annick; Henfling, Mieke; Ramaekers, Frans C S; Preuss, Simon F; Drebber, Uta; Wieland, Ulrike; Silling, Steffi; Lam, Wan L; Vucic, Emily A; Kremer, Bernd; Klussmann, Jens-P; Huebbers, Christian U

    2014-01-01

    Infection with high-risk human papillomavirus (HPV) type 16 is an independent risk factor for the development of oropharyngeal squamous cell carcinomas (OSCC). However, it is unclear whether viral integration is an essential hallmark in the carcinogenic process of OSCC and whether HPV integration correlates with the level of viral gene transcription and influences the expression of disrupted host genes. We analyzed 75 patients with OSCC. HPV16-positivity was proven by p16(INK4A) immunohistochemistry, PCR and FISH. Viral integration was examined using DIPS- as well as APOT-PCR. Viral E2, E6 and E7 gene expression levels were quantified by quantitative reverse transcriptase (RT-q)PCR. Expression levels of 7 human genes disrupted by the virus were extracted from mRNA expression profiling data of 32 OSCCs. Viral copy numbers were assessed by qPCR in 73 tumors. We identified 37 HPV16-human fusion products indicating viral integration in 29 (39%) OSCC. In the remaining tumors (61%) only episome-derived PCR products were detected. When comparing OSCC with or without an integration-derived fusion product, we did not find significant differences in the mean RNA expression of viral genes E2, E6 and E7 or the viral copy numbers per cell, nor did the RNA expression of the HPV-disrupted genes differ from either group of OSCC. In conclusion, our data do not support the hypothesis that integration affects the levels of viral and/or HPV-disrupted human gene transcripts. Thus constitutive, rather than a high level, of expression of oncogene transcripts appears to be required in HPV-related OSCC. PMID:24586376

  6. Structural and Nonstructural Viral Proteins Are Targets of T-Helper Immune Response against Human Respiratory Syncytial Virus.

    PubMed

    Lorente, Elena; Barriga, Alejandro; Barnea, Eilon; Mir, Carmen; Gebe, John A; Admon, Arie; López, Daniel

    2016-06-01

    Proper antiviral humoral and cellular immune responses require previous recognition of viral antigenic peptides that are bound to HLA class II molecules, which are exposed on the surface of antigen-presenting cells. The helper immune response is critical for the control and the clearance of human respiratory syncytial virus (HRSV) infection, a virus with severe health risk in infected pediatric, immunocompromised, and elderly populations. In this study, using a mass spectrometry analysis of complex HLA class II-bound peptide pools that were isolated from large amounts of HRSV-infected cells, 19 naturally processed HLA-DR ligands, most of them included in a complex nested set of peptides, were identified. Both the immunoprevalence and the immunodominance of the HLA class II response to HRSV were focused on one nonstructural (NS1) and two structural (matrix and mainly fusion) proteins of the infective virus. These findings have clear implications for analysis of the helper immune response as well as for antiviral vaccine design. PMID:27090790

  7. Nuclear targeting of viral and non-viral DNA.

    PubMed

    Chowdhury, E H

    2009-07-01

    The nuclear envelope presents a major barrier to transgene delivery and expression using a non-viral vector. Virus is capable of overcoming the barrier to deliver their genetic materials efficiently into the nucleus by virtue of the specialized protein components with the unique amino acid sequences recognizing cellular nuclear transport machinery. However, considering the safety issues in the clinical gene therapy for treating critical human diseases, non-viral systems are highly promising compared with their viral counterparts. This review summarizes the progress on exploring the nuclear traffic mechanisms for the prominent viral vectors and the technological innovations for the nuclear delivery of non-viral DNA by mimicking those natural processes evolved for the viruses as well as for many cellular proteins. PMID:19552613

  8. Exosome Biogenesis, Regulation, and Function in Viral Infection

    PubMed Central

    Alenquer, Marta; Amorim, Maria João

    2015-01-01

    Exosomes are extracellular vesicles released upon fusion of multivesicular bodies (MVBs) with the cellular plasma membrane. They originate as intraluminal vesicles (ILVs) during the process of MVB formation. Exosomes were shown to contain selectively sorted functional proteins, lipids, and RNAs, mediating cell-to-cell communications and hence playing a role in the physiology of the healthy and diseased organism. Challenges in the field include the identification of mechanisms sustaining packaging of membrane-bound and soluble material to these vesicles and the understanding of the underlying processes directing MVBs for degradation or fusion with the plasma membrane. The investigation into the formation and roles of exosomes in viral infection is in its early years. Although still controversial, exosomes can, in principle, incorporate any functional factor, provided they have an appropriate sorting signal, and thus are prone to viral exploitation. This review initially focuses on the composition and biogenesis of exosomes. It then explores the regulatory mechanisms underlying their biogenesis. Exosomes are part of the endocytic system, which is tightly regulated and able to respond to several stimuli that lead to alterations in the composition of its sub-compartments. We discuss the current knowledge of how these changes affect exosomal release. We then summarize how different viruses exploit specific proteins of endocytic sub-compartments and speculate that it could interfere with exosome function, although no direct link between viral usage of the endocytic system and exosome release has yet been reported. Many recent reports have ascribed functions to exosomes released from cells infected with a variety of animal viruses, including viral spread, host immunity, and manipulation of the microenvironment, which are discussed. Given the ever-growing roles and importance of exosomes in viral infections, understanding what regulates their composition and levels, and

  9. [Update chronic viral hepatitis].

    PubMed

    Ziegenhagen, D J

    2016-03-01

    More than 500,000 people in Germany have chronic viral hepatitis. The interferon-based treatments formerly used in hepatitis B have been widely replaced by life-long oral medication with nucleoside or nucleotide analogues. Treatment for chronic hepatitis C has been improved substantially by the development of new and very expensive drug combinations. Up to 90% of patients can now be cured with certainty, and one to two years after successful treatment there is no relevant risk of recurrence. These individuals expect to receive insurance cover under appropriate conditions. Vaccination programmes are very efficient at decreasing the incidence of hepatitis B, but no vaccine against hepatitis C is likely to become available in the next decade. PMID:27111951

  10. Dengue viral infections

    PubMed Central

    Malavige, G; Fernando, S; Fernando, D; Seneviratne, S

    2004-01-01

    Dengue viral infections are one of the most important mosquito borne diseases in the world. They may be asymptomatic or may give rise to undifferentiated fever, dengue fever, dengue haemorrhagic fever (DHF), or dengue shock syndrome. Annually, 100 million cases of dengue fever and half a million cases of DHF occur worldwide. Ninety percent of DHF subjects are children less than 15 years of age. At present, dengue is endemic in 112 countries in the world. No vaccine is available for preventing this disease. Early recognition and prompt initiation of appropriate treatment are vital if disease related morbidity and mortality are to be limited. This review outlines aspects of the epidemiology of dengue infections, the dengue virus and its mosquito vector, clinical features and pathogenesis of dengue infections, and the management and control of these infections. PMID:15466994

  11. Viral Hemorrhagic Fever Diagnostics.

    PubMed

    Racsa, Lori D; Kraft, Colleen S; Olinger, Gene G; Hensley, Lisa E

    2016-01-15

    There are 4 families of viruses that cause viral hemorrhagic fever (VHF), including Filoviridae. Ebola virus is one virus within the family Filoviridae and the cause of the current outbreak of VHF in West Africa. VHF-endemic areas are found throughout the world, yet traditional diagnosis of VHF has been performed in large reference laboratories centered in Europe and the United States. The large amount of capital needed, as well as highly trained and skilled personnel, has limited the availability of diagnostics in endemic areas except in conjunction with governmental and nongovernmental entities. However, rapid diagnosis of VHF is essential to efforts that will limit outbreaks. In addition, increased global travel suggests VHF diagnoses may be made outside of the endemic areas. Thus, understanding how to diagnose VHF is imperative for laboratories worldwide. This article reviews traditional and current diagnostic modalities for VHF. PMID:26354968

  12. Fusion activity of influenza virus. A comparison between biological and artificial target membrane vesicles.

    PubMed

    Stegmann, T; Hoekstra, D; Scherphof, G; Wilschut, J

    1986-08-25

    We have investigated the pH-dependent fusion activity of influenza virus toward human erythrocyte ghosts, utilizing a recently developed fluorescence assay, which permits continuous monitoring of the fusion reaction. The rate of fusion is negligible at neutral pH but shows a sharp increase at pH values just below 5.5. This pH dependence profile closely corresponds to that of virus-induced hemolysis. Fusion is rapidly inactivated by a low-pH preincubation of the virus alone either at 37 or at 0 degrees C. The presence of ghosts during this low-pH preincubation, carried out at 0 degree C under which condition there is hardly any fusion, causes a significant protection of the viral fusion activity against inactivation. Fusion initiated at low pH can be arrested instantaneously by readjustment of the pH to neutral. The characteristics of fusion of influenza virus with ghosts deviate from those of fusion with cardiolipin liposomes (Stegmann, T., Hoekstra, D., Scherphof, G., and Wilschut, J. (1985) Biochemistry 24, 3107-3113). Fusion with ghosts is consistent with a requirement of the well-documented pH-dependent conformational change in the viral hemagglutinin, whereas fusion with cardiolipin liposomes does not exhibit a strict dependence on the conformational change. Rather, the negative surface charge on the liposomes plays a critical role, as zwitterionic liposomes containing gangliosides show fusion behavior similar to that of erythrocyte ghosts. PMID:3733744

  13. Public Relations on Fusion in Europe

    NASA Astrophysics Data System (ADS)

    Ongena, J.; van Oost, G.; Paris, P. J.

    2000-10-01

    A summary will be presented of PR efforts on fusion energy research in Europe. A 3-D movie of a fusion research experimental reactor has been realized at the start of this year. It has been made entirely on virtual animation basis. Two versions exists, a short version of 3 min., as a video clip, and a longer version of nearly 8 min. Both could be viewed in 3D, using special projections and passive glasses or in normal VHS video projections. A new CD-ROM for individual and classroom use will be presented, discussing (i) the different energy forms, (ii) general principles of fusion, (iii) current research efforts and (iv) future prospects of fusion. This CD-ROM is now produced in English, German, French, Spanish, Italian and Portuguese Several new brochures and leaflets intended to increase the public awareness on fusion in Europe will be on display.

  14. Efforts in Public Relations on Fusion in Europe

    NASA Astrophysics Data System (ADS)

    Ongena, J.; van Oost, G.

    2001-10-01

    An overview will be given of different published materials currently in use in Europe for public relations on fusion. We will also present a CD-ROM for individual and classroom use, containing (i) a general background on different energy forms, (ii) general principles of fusion, (iii) current research efforts and (iv) future prospects of fusion. This CD-ROM is currently in English, German, French, Spanish, Portuguese and Italian. Fusion posters developed in collaboration with CPEP in Dutch, French, German, Italian, Spanish and Portuguese will be shown. Several new brochures and leaflets intended to increase the public awareness on fusion in Europe will be on display.

  15. Role of the synaptobrevin C terminus in fusion pore formation

    PubMed Central

    Ngatchou, Annita N.; Kisler, Kassandra; Fang, Qinghua; Walter, Alexander M.; Zhao, Ying; Bruns, Dieter; Sørensen, Jakob B.; Lindau, Manfred

    2010-01-01

    Neurotransmitter release is mediated by the SNARE proteins synaptobrevin II (sybII, also known as VAMP2), syntaxin, and SNAP-25, generating a force transfer to the membranes and inducing fusion pore formation. However, the molecular mechanism by which this force leads to opening of a fusion pore remains elusive. Here we show that the ability of sybII to support exocytosis is inhibited by addition of one or two residues to the sybII C terminus depending on their energy of transfer from water to the membrane interface, following a Boltzmann distribution. These results suggest that following stimulation, the SNARE complex pulls the C terminus of sybII deeper into the vesicle membrane. We propose that this movement disrupts the vesicular membrane continuity leading to fusion pore formation. In contrast to current models, the experiments suggest that fusion pore formation begins with molecular rearrangements at the intravesicular membrane leaflet and not between the apposed cytoplasmic leaflets. PMID:20937897

  16. Exploiting viral natural history for vaccine development.

    PubMed

    Barry, Peter A

    2015-06-01

    The partial successes of the Phase 2 gB-based vaccine trials for HCMV highlight the very real likelihood that vaccine-mediated induction of antibodies that neutralize the fusion pathway of fibroblast infection is not sufficient as a singular strategy to confer protective efficacy against primary HCMV infection. Alternative strategies that serve as adjuncts to gB-based vaccines are likely required to target different aspects of the complex lifecycle of HCMV infection. There has been considerable recent interest in targeting the gH/gL/UL128/UL130/UL131 pentamer complex (gH/gL-PC) to neutralize the endocytic pathway of HCMV infection of epithelial and endothelial cells. Since both cell types are critical during primary mucosal infection, intrahost spread, and shedding of HCMV in an infected host, the gH/gL-PC represents a high-value target for vaccination to interrupt the HCMV lifecycle. The natural history of HCMV is exceedingly complex and incompletely resolved, and the protective efficacy generated by gH/gL-PC remains to be validated in clinical trials. Yet, there are salient aspects of its lifecycle that offer clues about how other novel vaccine strategies can be targeted to especially susceptible parts of the viral proteome to significantly disrupt HCMV's ability to infect susceptible hosts. In particular, the protracted evolution of Herpesvirales has endowed HCMV with two remarkable properties of its natural history: (1) lifelong persistence within immune hosts that develop extraordinarily large antiviral immune responses and (2) the ability to reinfect those with prior immunity. The latter phenotype strongly implies that, if HCMV can overcome prior immunity to initiate a new infection, it is likely irrelevant whether prior immunity derives from prior infection or prior vaccination. Both phenotypes are unified by the extensive devotion of the HCMV coding repertoire (~50%) to viral proteins that modulate host cell signaling, trafficking, activation, antigen

  17. Viral Hepatitis: A through E and Beyond

    MedlinePlus

    Viral Hepatitis: A through E and Beyond NATIONAL INSTITUTES OF HEALTH U.S. Department of Health and Human Services National Digestive Diseases Information Clearinghouse What is viral hepatitis? Viral hepatitis is inflammation of the liver caused ...

  18. Universal antibodies against the highly conserved influenza fusion peptide cross-neutralize several subtypes of influenza A virus

    SciTech Connect

    Hashem, Anwar M.; Van Domselaar, Gary; Li, Changgui; Wang, Junzhi; She, Yi-Min; Cyr, Terry D.; Sui, Jianhua; He, Runtao; Marasco, Wayne A.; Li, Xuguang

    2010-12-10

    Research highlights: {yields} The fusion peptide is the only universally conserved epitope in all influenza viral hemagglutinins. {yields} Anti-fusion peptide antibodies are universal antibodies that cross-react with all influenza HA subtypes. {yields} The universal antibodies cross-neutralize different influenza A subtypes. {yields} The universal antibodies inhibit the fusion process between the viruses and the target cells. -- Abstract: The fusion peptide of influenza viral hemagglutinin plays a critical role in virus entry by facilitating membrane fusion between the virus and target cells. As the fusion peptide is the only universally conserved epitope in all influenza A and B viruses, it could be an attractive target for vaccine-induced immune responses. We previously reported that antibodies targeting the first 14 amino acids of the N-terminus of the fusion peptide could bind to virtually all influenza virus strains and quantify hemagglutinins in vaccines produced in embryonated eggs. Here we demonstrate that these universal antibodies bind to the viral hemagglutinins in native conformation presented in infected mammalian cell cultures and neutralize multiple subtypes of virus by inhibiting the pH-dependant fusion of viral and cellular membranes. These results suggest that this unique, highly-conserved linear sequence in viral hemagglutinin is exposed sufficiently to be attacked by the antibodies during the course of infection and merits further investigation because of potential importance in the protection against diverse strains of influenza viruses.

  19. Evolution of the proportions of two sigma viral types in experimental populations of Drosophila melanogaster in the absence of the allele that is restrictive of viral multiplication.

    PubMed Central

    Fleuriet, A

    1999-01-01

    A minority of flies in natural populations of Drosophila melanogaster are endemically infected by a rhabdovirus, sigma. The virus is vertically transmitted through male and female gametes. Two alleles of a fly locus, the ref(2)P locus, are present as a polymorphism in all populations: O permissive, and P restrictive for viral multiplication and transmission. Two viral types are known, Type I, which is very sensitive to the P allele, and Type II, which is more resistant. Previous observations have shown that, in presence of the P allele, viral Type II is selected for, in both natural and experimental populations. The aim of the present study was to determine whether, in the absence of P, Type I is selected for, or whether the two types are equivalent. For this purpose, experimental populations deprived of the P allele and differing in the initial proportions of the two viral types were established. After several generations, and despite a possible bias toward Type I, the frequencies of Type I and Type II clones differed in the various populations, depending on their initial values. These findings do not rule out selective advantage of viral Type I in the absence of P, but suggest that, if any, this advantage is in no way comparable to that displayed by viral Type II in the presence of P. PMID:10581286

  20. Theoretical basis of a beneficial role for vitamin D in viral hepatitis

    PubMed Central

    Lương, Khanh vinh quốc; Nguyễn, Lan Thi Hoàng

    2012-01-01

    Abnormal bone metabolism and dysfunction of the calcium-parathyroid hormone-vitamin D axis have been reported in patients with viral hepatitis. Some studies suggested a relationship between vitamin D and viral hepatitis. Genetic studies have provided an opportunity to identify the proteins that link vitamin D to the pathology of viral hepatitis (i.e., the major histocompatibility complex class II molecules, the vitamin D receptor, cytochrome P450, the renin-angiotensin system, apolipoprotein E, liver X receptor, toll-like receptor, and the proteins regulated by the Sp1 promoter gene). Vitamin D also exerts its effects on viral hepatitis via non-genomic factors, i.e., matrix metalloproteinase, endothelial vascular growth factor, prostaglandins, cyclooxygenase-2, and oxidative stress. In conclusion, vitamin D could have a beneficial role in viral hepatitis. Calcitriol is best used for viral hepatitis because it is the active form of the vitamin D3 metabolite. PMID:23082050

  1. Endosome-to-cytosol transport of viral nucleocapsids.

    PubMed

    Le Blanc, Isabelle; Luyet, Pierre-Philippe; Pons, Véronique; Ferguson, Charles; Emans, Neil; Petiot, Anne; Mayran, Nathalie; Demaurex, Nicolas; Fauré, Julien; Sadoul, Rémy; Parton, Robert G; Gruenberg, J

    2005-07-01

    During viral infection, fusion of the viral envelope with endosomal membranes and nucleocapsid release were thought to be concomitant events. We show here that for the vesicular stomatitis virus they occur sequentially, at two successive steps of the endocytic pathway. Fusion already occurs in transport intermediates between early and late endosomes, presumably releasing the nucleocapsid within the lumen of intra-endosomal vesicles, where it remains hidden. Transport to late endosomes is then required for the nucleocapsid to be delivered to the cytoplasm. This last step, which initiates infection, depends on the late endosomal lipid lysobisphosphatidic acid (LBPA) and its putative effector Alix/AIP1, and is regulated by phosphatidylinositol-3-phosphate (PtdIns3P) signalling via the PtdIns3P-binding protein Snx16. We conclude that the nucleocapsid is exported into the cytoplasm after the back-fusion of internal vesicles with the limiting membrane of late endosomes, and that this process is controlled by the phospholipids LBPA and PtdIns3P and their effectors. PMID:15951806

  2. Viral infection, inflammation and schizophrenia

    PubMed Central

    Kneeland, Rachel E.; Fatemi, S. Hossein

    2012-01-01

    Schizophrenia is a severe neurodevelopmental disorder with genetic and environmental etiologies. Prenatal viral/bacterial infections and inflammation play major roles in the genesis of schizophrenia. In this review, we describe a viral model of schizophrenia tested in mice whereby the offspring of mice prenatally infected with influenza at E7, E9, E16, and E18 show significant gene, protein, and brain structural abnormalities postnatally. Similarly, we describe data on rodents exposed to bacterial infection or injected with a synthetic viral mimic (PolyI:C) also demonstrating brain structural and behavioral abnormalities. Moreover, human serologic data has been indispensible in supporting the viral theory of schizophrenia. Individuals born seropositive for bacterial and viral agents are at a significantly elevated risk of developing schizophrenia. While the specific mechanisms of prenatal viral/bacterial infections and brain disorder are unclear, recent findings suggest that the maternal inflammatory response may be associated with fetal brain injury. Preventive and therapeutic treatment options are also proposed. This review presents data related to epidemiology, human serology, and experimental animal models which support the viral model of schizophrenia. PMID:22349576

  3. Visualizing viral protein structures in cells using genetic probes for correlated light and electron microscopy.

    PubMed

    Ou, Horng D; Deerinck, Thomas J; Bushong, Eric; Ellisman, Mark H; O'Shea, Clodagh C

    2015-11-15

    Structural studies of viral proteins most often use high-resolution techniques such as X-ray crystallography, nuclear magnetic resonance, single particle negative stain, or cryo-electron microscopy (EM) to reveal atomic interactions of soluble, homogeneous viral proteins or viral protein complexes. Once viral proteins or complexes are separated from their host's cellular environment, their natural in situ structure and details of how they interact with other cellular components may be lost. EM has been an invaluable tool in virology since its introduction in the late 1940's and subsequent application to cells in the 1950's. EM studies have expanded our knowledge of viral entry, viral replication, alteration of cellular components, and viral lysis. Most of these early studies were focused on conspicuous morphological cellular changes, because classic EM metal stains were designed to highlight classes of cellular structures rather than specific molecular structures. Much later, to identify viral proteins inducing specific structural configurations at the cellular level, immunostaining with a primary antibody followed by colloidal gold secondary antibody was employed to mark the location of specific viral proteins. This technique can suffer from artifacts in cellular ultrastructure due to compromises required to provide access to the immuno-reagents. Immunolocalization methods also require the generation of highly specific antibodies, which may not be available for every viral protein. Here we discuss new methods to visualize viral proteins and structures at high resolutions in situ using correlated light and electron microscopy (CLEM). We discuss the use of genetically encoded protein fusions that oxidize diaminobenzidine (DAB) into an osmiophilic polymer that can be visualized by EM. Detailed protocols for applying the genetically encoded photo-oxidizing protein MiniSOG to a viral protein, photo-oxidation of the fusion protein to yield DAB polymer staining, and

  4. Pushing the Envelope: Dengue Viral Membrane Coaxed into Shape by Molecular Simulations.

    PubMed

    Marzinek, Jan K; Holdbrook, Daniel A; Huber, Roland G; Verma, Chandra; Bond, Peter J

    2016-08-01

    Dengue virus is a flavivirus responsible for millions of infections per year. Its surface contains a phospholipid bilayer, within which are embedded the envelope (E) and membrane (M) proteins, arranged with icosahedral geometry. Exposure to low pH triggers the E proteins to undergo conformational changes, which precede fusion with the host cell membrane and release of the viral genome. The flavivirus membrane exhibits significant local curvature and deformation, as revealed by cryoelectron microscopy (cryo-EM), but its precise structure and interactions with envelope components remain unclear. We now report simulations of the dengue viral particle that refine its envelope structure in unprecedented detail. Our final models are morphologically consistent with cryo-EM data, and reveal the structural basis for membrane curvature. Electrostatic interactions increased envelope complex stability; this coupling has potential functional significance in the context of the viral fusion mechanism and infective states. PMID:27396828

  5. Insulated Foamy Viral Vectors.

    PubMed

    Browning, Diana L; Collins, Casey P; Hocum, Jonah D; Leap, David J; Rae, Dustin T; Trobridge, Grant D

    2016-03-01

    Retroviral vector-mediated gene therapy is promising, but genotoxicity has limited its use in the clinic. Genotoxicity is highly dependent on the retroviral vector used, and foamy viral (FV) vectors appear relatively safe. However, internal promoters may still potentially activate nearby genes. We developed insulated FV vectors, using four previously described insulators: a version of the well-studied chicken hypersensitivity site 4 insulator (650cHS4), two synthetic CCCTC-binding factor (CTCF)-based insulators, and an insulator based on the CCAAT box-binding transcription factor/nuclear factor I (7xCTF/NF1). We directly compared these insulators for enhancer-blocking activity, effect on FV vector titer, and fidelity of transfer to both proviral long terminal repeats. The synthetic CTCF-based insulators had the strongest insulating activity, but reduced titers significantly. The 7xCTF/NF1 insulator did not reduce titers but had weak insulating activity. The 650cHS4-insulated FV vector was identified as the overall most promising vector. Uninsulated and 650cHS4-insulated FV vectors were both significantly less genotoxic than gammaretroviral vectors. Integration sites were evaluated in cord blood CD34(+) cells and the 650cHS4-insulated FV vector had fewer hotspots compared with an uninsulated FV vector. These data suggest that insulated FV vectors are promising for hematopoietic stem cell gene therapy. PMID:26715244

  6. DENGUE VIRAL INFECTIONS

    PubMed Central

    Gurugama, Padmalal; Garg, Pankaj; Perera, Jennifer; Wijewickrama, Ananda; Seneviratne, Suranjith L

    2010-01-01

    Dengue viral infections are one of the most important mosquito-borne diseases in the world. Presently dengue is endemic in 112 countries in the world. It has been estimated that almost 100 million cases of dengue fever and half a million cases of dengue hemorrhagic fever (DHF) occur worldwide. An increasing proportion of DHF is in children less than 15 years of age, especially in South East and South Asia. The unique structure of the dengue virus and the pathophysiologic responses of the host, different serotypes, and favorable conditions for vector breeding have led to the virulence and spread of the infections. The manifestations of dengue infections are protean from being asymptomatic to undifferentiated fever, severe dengue infections, and unusual complications. Early recognition and prompt initiation of appropriate supportive treatment are often delayed resulting in unnecessarily high morbidity and mortality. Attempts are underway for the development of a vaccine for preventing the burden of this neglected disease. This review outlines the epidemiology, clinical features, pathophysiologic mechanisms, management, and control of dengue infections. PMID:20418983

  7. Tight Junctions Go Viral!

    PubMed Central

    Torres-Flores, Jesús M.; Arias, Carlos F.

    2015-01-01

    Tight junctions (TJs) are highly specialized membrane domains involved in many important cellular processes such as the regulation of the passage of ions and macromolecules across the paracellular space and the establishment of cell polarity in epithelial cells. Over the past few years there has been increasing evidence that different components of the TJs can be hijacked by viruses in order to complete their infectious cycle. Viruses from at least nine different families of DNA and RNA viruses have been reported to use TJ proteins in their benefit. For example, TJ proteins such as JAM-A or some members of the claudin family of proteins are used by members of the Reoviridae family and hepatitis C virus as receptors or co-receptors during their entry into their host cells. Reovirus, in addition, takes advantage of the TJ protein Junction Adhesion Molecule-A (JAM-A) to achieve its hematogenous dissemination. Some other viruses are capable of regulating the expression or the localization of TJ proteins to induce cell transformation or to improve the efficiency of their exit process. This review encompasses the importance of TJs for viral entry, replication, dissemination, and egress, and makes a clear statement of the importance of studying these proteins to gain a better understanding of the replication strategies used by viruses that infect epithelial and/or endothelial cells. PMID:26404354

  8. Viral BLIP dynamics during HAART.

    SciTech Connect

    Markowitz, M.; Louie, M.; Hurley, A.; Ho, David D.; Perelson, Alan S.,; Di Mascio, M.

    2001-01-01

    Intermittent episodes of low-level viremia (blips) are often observed in well-suppressed, HAART-treated patients. It has been reported that viral blips do not correlate with the emergence of new HAART-related mutations; however, increased frequency of blips correlates with slower decay of latently infected cells. Since blips are transient and unpredictable, detailed knowledge about them is difficult to obtain. We present an analysis of the dynamics of viral blips from viral load (VL) measurements on 123 patients for a period of 809k480d (21-1817d) and sampled every 31{+-}12d for a total of 26{+-}15 samples per patient.

  9. Pseudorabies Virus Glycoprotein M Inhibits Membrane Fusion

    PubMed Central

    Klupp, Barbara G.; Nixdorf, Ralf; Mettenleiter, Thomas C.

    2000-01-01

    A transient transfection-fusion assay was established to investigate membrane fusion mediated by pseudorabies virus (PrV) glycoproteins. Plasmids expressing PrV glycoproteins under control of the immediate-early 1 promoter-enhancer of human cytomegalovirus were transfected into rabbit kidney cells, and the extent of cell fusion was quantitated 27 to 42 h after transfection. Cotransfection of plasmids encoding PrV glycoproteins B (gB), gD, gH, and gL resulted in formation of polykaryocytes, as has been shown for homologous proteins of herpes simplex virus type 1 (HSV-1) (A. Turner, B. Bruun, T. Minson, and H. Browne, J. Virol. 72:873–875, 1998). However, in contrast to HSV-1, fusion was also observed when the gD-encoding plasmid was omitted, which indicates that PrV gB, gH, and gL are sufficient to mediate fusion. Fusogenic activity was enhanced when a carboxy-terminally truncated version of gB (gB-008) lacking the C-terminal 29 amino acids was used instead of wild-type gB. With gB-008, only gH was required in addition for fusion. A very rapid and extended fusion was observed after cotransfection of plasmids encoding gB-008 and gDH, a hybrid protein consisting of the N-terminal 271 amino acids of gD fused to the 590 C-terminal amino acids of gH. This protein has been shown to substitute for gH, gD, and gL function in the respective viral mutants (B. G. Klupp and T. C. Mettenleiter, J. Virol. 73:3014–3022, 1999). Cotransfection of plasmids encoding PrV gC, gE, gI, gK, and UL20 with gB-008 and gDH had no effect on fusion. However, inclusion of a gM-expressing plasmid strongly reduced the extent of fusion. An inhibitory effect was also observed after inclusion of plasmids encoding gM homologs of equine herpesvirus 1 or infectious laryngotracheitis virus but only in conjunction with expression of the gM complex partner, the gN homolog. Inhibition by PrV gM was not limited to PrV glycoprotein-mediated fusion but also affected fusion induced by the F protein of bovine

  10. A Phase II Comparative Study of Gross Tumor Volume Definition With or Without PET/CT Fusion in Dosimetric Planning for Non-Small-Cell Lung Cancer (NSCLC): Primary Analysis of Radiation Therapy Oncology Group (RTOG) 0515

    SciTech Connect

    Bradley, Jeffrey; Bae, Kyounghwa; Choi, Noah; Forster, Ken; Siegel, Barry A.; Brunetti, Jacqueline; Purdy, James; Faria, Sergio; Vu, Toni; Thorstad, Wade; Choy, Hak

    2012-01-01

    Background: Radiation Therapy Oncology Group (RTOG) 0515 is a Phase II prospective trial designed to quantify the impact of positron emission tomography (PET)/computed tomography (CT) compared with CT alone on radiation treatment plans (RTPs) and to determine the rate of elective nodal failure for PET/CT-derived volumes. Methods: Each enrolled patient underwent definitive radiation therapy for non-small-cell lung cancer ({>=}60 Gy) and had two RTP datasets generated: gross tumor volume (GTV) derived with CT alone and with PET/CT. Patients received treatment using the PET/CT-derived plan. The primary end point, the impact of PET/CT fusion on treatment plans was measured by differences of the following variables for each patient: GTV, number of involved nodes, nodal station, mean lung dose (MLD), volume of lung exceeding 20 Gy (V20), and mean esophageal dose (MED). Regional failure rate was a secondary end point. The nonparametric Wilcoxon matched-pairs signed-ranks test was used with Bonferroni adjustment for an overall significance level of 0.05. Results: RTOG 0515 accrued 52 patients, 47 of whom are evaluable. The follow-up time for all patients is 12.9 months (2.7-22.2). Tumor staging was as follows: II = 6%; IIIA = 40%; and IIIB = 54%. The GTV was statistically significantly smaller for PET/CT-derived volumes (98.7 vs. 86.2 mL; p < 0.0001). MLDs for PET/CT plans were slightly lower (19 vs. 17.8 Gy; p = 0.06). There was no significant difference in the number of involved nodes (2.1 vs. 2.4), V20 (32% vs. 30.8%), or MED (28.7 vs. 27.1 Gy). Nodal contours were altered by PET/CT for 51% of patients. One patient (2%) has developed an elective nodal failure. Conclusions: PET/CT-derived tumor volumes were smaller than those derived by CT alone. PET/CT changed nodal GTV contours in 51% of patients. The elective nodal failure rate for GTVs derived by PET/CT is quite low, supporting the RTOG standard of limiting the target volume to the primary tumor and involved nodes.

  11. Viral vector-mediated expression of K+ channels regulates electrical excitability in skeletal muscle.

    PubMed

    Falk, T; Kilani, R K; Yool, A J; Sherman, S J

    2001-09-01

    Modification of K+ currents by exogenous gene expression may lead to therapeutic interventions in skeletal muscle diseases characterized by alterations in electrical excitability. In order to study the specific effects of increasing outward K+ currents, we expressed a modified voltage-dependent K+ channel in primary cultured rat skeletal muscle cells. The rat Kv1.4 channel was expressed as an N-terminal fusion protein containing a bioluminescent marker (green fluorescent protein). Transgene expression was carried out using the helper-dependent herpes simplex 1 amplicon system. Transduced myoballs, identified using fluorescein optics and studied electrophysiologically with single-cell patch clamp, exhibited a greater than two-fold increase in K+ conductance by 20-30 h after infection. This increase in K+ current led to a decrease in membrane resistance and a 10-fold increase in the current threshold for action potential generation. Electrical hyperexcitability induced by the Na+ channel toxin anemone toxin II (1 microM) was effectively counteracted by overexpression of Kv1.4 at 30-32 h after transduction. Thus, virally induced overexpression of a voltage-gated K+ channel in skeletal muscle has a powerful effect in reducing electrical excitability. PMID:11571576

  12. Cytokines and persistent viral infections.

    PubMed

    Beltra, Jean-Christophe; Decaluwe, Hélène

    2016-06-01

    Intracellular pathogens such as the human immunodeficiency virus, hepatitis C and B or Epstein-Barr virus often cause chronic viral infections in humans. Persistence of these viruses in the host is associated with a dramatic loss of T-cell immune response due to functional T-cell exhaustion. Developing efficient immunotherapeutic approaches to prevent viral persistence and/or to restore a highly functional T-cell mediated immunity remains a major challenge. During the last two decades, numerous studies aimed to identify relevant host-derived factors that could be modulated to achieve this goal. In this review, we focus on recent advances in our understanding of the role of cytokines in preventing or facilitating viral persistence. We concentrate on the impact of multiple relevant cytokines in T-cell dependent immune response to chronic viral infection and the potential for using cytokines as therapeutic agents in mice and humans. PMID:26907634

  13. Fusion energy

    NASA Astrophysics Data System (ADS)

    1990-09-01

    The main purpose of the International Thermonuclear Experimental Reactor (ITER) is to develop an experimental fusion reactor through the united efforts of many technologically advanced countries. The ITER terms of reference, issued jointly by the European Community, Japan, the USSR, and the United States, call for an integrated international design activity and constitute the basis of current activities. Joint work on ITER is carried out under the auspices of the International Atomic Energy Agency (IAEA), according to the terms of quadripartite agreement reached between the European Community, Japan, the USSR, and the United States. The site for joint technical work sessions is at the Max Planck Institute of Plasma Physics. Garching, Federal Republic of Germany. The ITER activities have two phases: a definition phase performed in 1988 and the present design phase (1989 to 1990). During the definition phase, a set of ITER technical characteristics and supporting research and development (R and D) activities were developed and reported. The present conceptual design phase of ITER lasts until the end of 1990. The objectives of this phase are to develop the design of ITER, perform a safety and environmental analysis, develop site requirements, define future R and D needs, and estimate cost, manpower, and schedule for construction and operation. A final report will be submitted at the end of 1990. This paper summarizes progress in the ITER program during the 1989 design phase.

  14. Fusion energy

    SciTech Connect

    Not Available

    1990-09-01

    The main purpose of the International Thermonuclear Experimental Reactor (ITER) is to develop an experimental fusion reactor through the united efforts of many technologically advanced countries. The ITER terms of reference, issued jointly by the European Community, Japan, the USSR, and the United States, call for an integrated international design activity and constitute the basis of current activities. Joint work on ITER is carried out under the auspices of the International Atomic Energy Agency (IAEA), according to the terms of quadripartite agreement reached between the European Community, Japan, the USSR, and the United States. The site for joint technical work sessions is at the MaxPlanck Institute of Plasma Physics. Garching, Federal Republic of Germany. The ITER activities have two phases: a definition phase performed in 1988 and the present design phase (1989--1990). During the definition phase, a set of ITER technical characteristics and supporting research and development (R D) activities were developed and reported. The present conceptual design phase of ITER lasts until the end of 1990. The objectives of this phase are to develop the design of ITER, perform a safety and environmental analysis, develop site requirements, define future R D needs, and estimate cost, manpower, and schedule for construction and operation. A final report will be submitted at the end of 1990. This paper summarizes progress in the ITER program during the 1989 design phase.

  15. Neuroanatomy goes viral!

    PubMed

    Nassi, Jonathan J; Cepko, Constance L; Born, Richard T; Beier, Kevin T

    2015-01-01

    The nervous system is complex not simply because of the enormous number of neurons it contains but by virtue of the specificity with which they are connected. Unraveling this specificity is the task of neuroanatomy. In this endeavor, neuroanatomists have traditionally exploited an impressive array of tools ranging from the Golgi method to electron microscopy. An ideal method for studying anatomy would label neurons that are interconnected, and, in addition, allow expression of foreign genes in these neurons. Fortuitously, nature has already partially developed such a method in the form of neurotropic viruses, which have evolved to deliver their genetic material between synaptically connected neurons while largely eluding glia and the immune system. While these characteristics make some of these viruses a threat to human health, simple modifications allow them to be used in controlled experimental settings, thus enabling neuroanatomists to trace multi-synaptic connections within and across brain regions. Wild-type neurotropic viruses, such as rabies and alpha-herpes virus, have already contributed greatly to our understanding of brain connectivity, and modern molecular techniques have enabled the construction of recombinant forms of these and other viruses. These newly engineered reagents are particularly useful, as they can target genetically defined populations of neurons, spread only one synapse to either inputs or outputs, and carry instructions by which the targeted neurons can be made to express exogenous proteins, such as calcium sensors or light-sensitive ion channels, that can be used to study neuronal function. In this review, we address these uniquely powerful features of the viruses already in the neuroanatomist's toolbox, as well as the aspects of their biology that currently limit their utility. Based on the latter, we consider strategies for improving viral tracing methods by reducing toxicity, improving control of transsynaptic spread, and extending

  16. Neuroanatomy goes viral!

    PubMed Central

    Nassi, Jonathan J.; Cepko, Constance L.; Born, Richard T.; Beier, Kevin T.

    2015-01-01

    The nervous system is complex not simply because of the enormous number of neurons it contains but by virtue of the specificity with which they are connected. Unraveling this specificity is the task of neuroanatomy. In this endeavor, neuroanatomists have traditionally exploited an impressive array of tools ranging from the Golgi method to electron microscopy. An ideal method for studying anatomy would label neurons that are interconnected, and, in addition, allow expression of foreign genes in these neurons. Fortuitously, nature has already partially developed such a method in the form of neurotropic viruses, which have evolved to deliver their genetic material between synaptically connected neurons while largely eluding glia and the immune system. While these characteristics make some of these viruses a threat to human health, simple modifications allow them to be used in controlled experimental settings, thus enabling neuroanatomists to trace multi-synaptic connections within and across brain regions. Wild-type neurotropic viruses, such as rabies and alpha-herpes virus, have already contributed greatly to our understanding of brain connectivity, and modern molecular techniques have enabled the construction of recombinant forms of these and other viruses. These newly engineered reagents are particularly useful, as they can target genetically defined populations of neurons, spread only one synapse to either inputs or outputs, and carry instructions by which the targeted neurons can be made to express exogenous proteins, such as calcium sensors or light-sensitive ion channels, that can be used to study neuronal function. In this review, we address these uniquely powerful features of the viruses already in the neuroanatomist’s toolbox, as well as the aspects of their biology that currently limit their utility. Based on the latter, we consider strategies for improving viral tracing methods by reducing toxicity, improving control of transsynaptic spread, and

  17. Inhibition of Sendai virus fusion with phospholipid vesicles and human erythrocyte membranes by hydrophobic peptides

    SciTech Connect

    Kelsey, D.R.; Flanagan, T.D.; Young, J.E.; Yeagle, P.L. )

    1991-06-01

    Hydrophobic di- and tripeptides which are capable of inhibiting enveloped virus infection of cells are also capable of inhibiting at least three different types of membrane fusion events. Large unilamellar vesicles (LUV) of N-methyl dioleoylphosphatidylethanolamine (N-methyl DOPE), containing encapsulated 1-aminonaphthalene-3,6,8-trisulfonic acid (ANTS) and/or p-xylene bis(pyridinium bromide) (DPX), were formed by extrusion. Vesicle fusion and leakage were then monitored with the ANTS/DPX fluorescence assay. Sendai virus fusion with lipid vesicles and Sendai virus fusion with human erythrocyte membranes were measured by following the relief of fluorescence quenching of virus labeled with octadecylrhodamine B chloride (R18). This study found that the effectiveness of the peptides carbobenzoxy-L-Phe-L-Phe (Z-L-Phe-L-Phe), Z-L-Phe, Z-D-Phe, and Z-Gly-L-Phe-L-Phe in inhibiting N-methyl DOPE LUV fusion or fusion of virus with N-methyl DOPE LUV also paralleled their reported ability to block viral infectivity. Furthermore, Z-D-Phe-L-PheGly and Z-Gly-L-Phe inhibited Sendai virus fusion with human erythrocyte membranes with the same relative potency with which they inhibited vesicle-vesicle and virus-vesicle fusion. The evidence suggests a mechanism by which these peptides exert their inhibition of plaque formation by enveloped viruses. This class of inhibitors apparently acts by inhibiting fusion of the viral envelope with the target cell membrane, thereby preventing viral infection. The physical pathway by which these peptides inhibit membrane fusion was investigated. {sup 31}P nuclear magnetic resonance (NMR) of proposed intermediates in the pathway for membrane fusion in LUV revealed that the potent fusion inhibitor Z-D-Phe-L-PheGly selectively altered the structure (or dynamics) of the hypothesized fusion intermediates and that the poor inhibitor Z-Gly-L-Phe did not.

  18. HIV-Infected Dendritic Cells Present Endogenous MHC Class II-Restricted Antigens to HIV-Specific CD4+ T Cells.

    PubMed

    Coulon, Pierre-Grégoire; Richetta, Clémence; Rouers, Angéline; Blanchet, Fabien P; Urrutia, Alejandra; Guerbois, Mathilde; Piguet, Vincent; Theodorou, Ioannis; Bet, Anne; Schwartz, Olivier; Tangy, Frédéric; Graff-Dubois, Stéphanie; Cardinaud, Sylvain; Moris, Arnaud

    2016-07-15

    It is widely assumed that CD4(+) T cells recognize antigenic peptides (epitopes) derived solely from incoming, exogenous, viral particles or proteins. However, alternative sources of MHC class II (MHC-II)-restricted Ags have been described, in particular epitopes derived from newly synthesized proteins (so-called endogenous). In this study, we show that HIV-infected dendritic cells (DC) present MHC-II-restricted endogenous viral Ags to HIV-specific (HS) CD4(+) T cells. This endogenous pathway functions independently of the exogenous route for HIV Ag presentation and offers a distinct possibility for the immune system to activate HS CD4(+) T cells. We examined the implication of autophagy, which plays a crucial role in endogenous viral Ag presentation and thymic selection of CD4(+) T cells, in HIV endogenous presentation. We show that infected DC do not use autophagy to process MHC-II-restricted HIV Ags. This is unlikely to correspond to a viral escape from autophagic degradation, as infecting DC with Nef- or Env-deficient HIV strains did not impact HS T cell activation. However, we demonstrate that, in DC, specific targeting of HIV Ags to autophagosomes using a microtubule-associated protein L chain 3 (LC3) fusion protein effectively enhances and broadens HS CD4(+) T cell responses, thus favoring an endogenous MHC-II-restricted presentation. In summary, in DC, multiple endogenous presentation pathways lead to the activation of HS CD4(+) T cell responses. These findings will help in designing novel strategies to activate HS CD4(+) T cells that are required for CTL activation/maintenance and B cell maturation. PMID:27288536

  19. Viral RNAs Are Unusually Compact

    PubMed Central

    Gopal, Ajaykumar; Egecioglu, Defne E.; Yoffe, Aron M.; Ben-Shaul, Avinoam; Rao, Ayala L. N.; Knobler, Charles M.; Gelbart, William M.

    2014-01-01

    A majority of viruses are composed of long single-stranded genomic RNA molecules encapsulated by protein shells with diameters of just a few tens of nanometers. We examine the extent to which these viral RNAs have evolved to be physically compact molecules to facilitate encapsulation. Measurements of equal-length viral, non-viral, coding and non-coding RNAs show viral RNAs to have among the smallest sizes in solution, i.e., the highest gel-electrophoretic mobilities and the smallest hydrodynamic radii. Using graph-theoretical analyses we demonstrate that their sizes correlate with the compactness of branching patterns in predicted secondary structure ensembles. The density of branching is determined by the number and relative positions of 3-helix junctions, and is highly sensitive to the presence of rare higher-order junctions with 4 or more helices. Compact branching arises from a preponderance of base pairing between nucleotides close to each other in the primary sequence. The density of branching represents a degree of freedom optimized by viral RNA genomes in response to the evolutionary pressure to be packaged reliably. Several families of viruses are analyzed to delineate the effects of capsid geometry, size and charge stabilization on the selective pressure for RNA compactness. Compact branching has important implications for RNA folding and viral assembly. PMID:25188030

  20. Sequential conformational rearrangements in flavivirus membrane fusion

    PubMed Central

    Chao, Luke H; Klein, Daryl E; Schmidt, Aaron G; Peña, Jennifer M; Harrison, Stephen C

    2014-01-01

    The West Nile Virus (WNV) envelope protein, E, promotes membrane fusion during viral cell entry by undergoing a low-pH triggered conformational reorganization. We have examined the mechanism of WNV fusion and sought evidence for potential intermediates during the conformational transition by following hemifusion of WNV virus-like particles (VLPs) in a single particle format. We have introduced specific mutations into E, to relate their influence on fusion kinetics to structural features of the protein. At the level of individual E subunits, trimer formation and membrane engagement of the threefold clustered fusion loops are rate-limiting. Hemifusion requires at least two adjacent trimers. Simulation of the kinetics indicates that availability of competent monomers within the contact zone between virus and target membrane makes trimerization a bottleneck in hemifusion. We discuss the implications of the model we have derived for mechanisms of membrane fusion in other contexts. DOI: http://dx.doi.org/10.7554/eLife.04389.001 PMID:25479384

  1. Inhibition of HIV-1 endocytosis allows lipid mixing at the plasma membrane, but not complete fusion

    PubMed Central

    2011-01-01

    Background We recently provided evidence that HIV-1 enters HeLa-derived TZM-bl and lymphoid CEMss cells by fusing with endosomes, whereas its fusion with the plasma membrane does not proceed beyond the lipid mixing step. The mechanism of restriction of HIV-1 fusion at the cell surface and/or the factors that aid the virus entry from endosomes remain unclear. Results We examined HIV-1 fusion with a panel of target cells lines and with primary CD4+ T cells. Kinetic measurements of fusion combined with time-resolved imaging of single viruses further reinforced the notion that HIV-1 enters the cells via endocytosis and fusion with endosomes. Furthermore, we attempted to deliberately redirect virus fusion to the plasma membrane, using two experimental strategies. First, the fusion reaction was synchronized by pre-incubating the viruses with cells at reduced temperature to allow CD4 and coreceptors engagement, but not the virus uptake or fusion. Subsequent shift to a physiological temperature triggered accelerated virus uptake followed by entry from endosomes, but did not permit fusion at the cell surface. Second, blocking HIV-1 endocytosis by a small-molecule dynamin inhibitor, dynasore, resulted in transfer of viral lipids to the plasma membrane without any detectable release of the viral content into the cytosol. We also found that a higher concentration of dynasore is required to block the HIV-endosome fusion compared to virus internalization. Conclusions Our results further support the notion that HIV-1 enters disparate cell types through fusion with endosomes. The block of HIV-1 fusion with the plasma membrane at a post-lipid mixing stage shows that this membrane is not conducive to fusion pore formation and/or enlargement. The ability of dynasore to interfere with the virus-endosome fusion suggests that dynamin could be involved in two distinct steps of HIV-1 entry - endocytosis and fusion within intracellular compartments. PMID:22145853

  2. Structural changes of envelope proteins during alphavirus fusion

    SciTech Connect

    Li, Long; Jose, Joyce; Xiang, Ye; Kuhn, Richard J.; Rossmann, Michael G.

    2010-12-08

    Alphaviruses are enveloped RNA viruses that have a diameter of about 700 {angstrom} and can be lethal human pathogens. Entry of virus into host cells by endocytosis is controlled by two envelope glycoproteins, E1 and E2. The E2-E1 heterodimers form 80 trimeric spikes on the icosahedral virus surface, 60 with quasi-three-fold symmetry and 20 coincident with the icosahedral three-fold axes arranged with T = 4 quasi-symmetry. The E1 glycoprotein has a hydrophobic fusion loop at one end and is responsible for membrane fusion. The E2 protein is responsible for receptor binding and protects the fusion loop at neutral pH. The lower pH in the endosome induces the virions to undergo an irreversible conformational change in which E2 and E1 dissociate and E1 forms homotrimers, triggering fusion of the viral membrane with the endosomal membrane and then releasing the viral genome into the cytoplasm. Here we report the structure of an alphavirus spike, crystallized at low pH, representing an intermediate in the fusion process and clarifying the maturation process. The trimer of E2-E1 in the crystal structure is similar to the spikes in the neutral pH virus except that the E2 middle region is disordered, exposing the fusion loop. The amino- and carboxy-terminal domains of E2 each form immunoglobulin-like folds, consistent with the receptor attachment properties of E2.

  3. Visualization of Content Release from Cell Surface-Attached Single HIV-1 Particles Carrying an Extra-Viral Fluorescent pH-Sensor

    PubMed Central

    Sood, Chetan; Marin, Mariana; Mason, Caleb S.; Melikyan, Gregory B.

    2016-01-01

    HIV-1 fusion leading to productive entry has long been thought to occur at the plasma membrane. However, our previous single virus imaging data imply that, after Env engagement of CD4 and coreceptors at the cell surface, the virus enters into and fuses with intracellular compartments. We were unable to reliably detect viral fusion at the plasma membrane. Here, we implement a novel virus labeling strategy that biases towards detection of virus fusion that occurs in a pH-neutral environment—at the plasma membrane or, possibly, in early pH-neutral vesicles. Virus particles are co-labeled with an intra-viral content marker, which is released upon fusion, and an extra-viral pH sensor consisting of ecliptic pHluorin fused to the transmembrane domain of ICAM-1. This sensor fully quenches upon virus trafficking to a mildly acidic compartment, thus precluding subsequent detection of viral content release. As an interesting secondary observation, the incorporation of the pH-sensor revealed that HIV-1 particles occasionally shuttle between neutral and acidic compartments in target cells expressing CD4, suggesting a small fraction of viral particles is recycled to the plasma membrane and re-internalized. By imaging viruses bound to living cells, we found that HIV-1 content release in neutral-pH environment was a rare event (~0.4% particles). Surprisingly, viral content release was not significantly reduced by fusion inhibitors, implying that content release was due to spontaneous formation of viral membrane defects occurring at the cell surface. We did not measure a significant occurrence of HIV-1 fusion at neutral pH above this defect-mediated background loss of content, suggesting that the pH sensor may destabilize the membrane of the HIV-1 pseudovirus and, thus, preclude reliable detection of single virus fusion events at neutral pH. PMID:26863211

  4. Visualization of Content Release from Cell Surface-Attached Single HIV-1 Particles Carrying an Extra-Viral Fluorescent pH-Sensor.

    PubMed

    Sood, Chetan; Marin, Mariana; Mason, Caleb S; Melikyan, Gregory B

    2016-01-01

    HIV-1 fusion leading to productive entry has long been thought to occur at the plasma membrane. However, our previous single virus imaging data imply that, after Env engagement of CD4 and coreceptors at the cell surface, the virus enters into and fuses with intracellular compartments. We were unable to reliably detect viral fusion at the plasma membrane. Here, we implement a novel virus labeling strategy that biases towards detection of virus fusion that occurs in a pH-neutral environment-at the plasma membrane or, possibly, in early pH-neutral vesicles. Virus particles are co-labeled with an intra-viral content marker, which is released upon fusion, and an extra-viral pH sensor consisting of ecliptic pHluorin fused to the transmembrane domain of ICAM-1. This sensor fully quenches upon virus trafficking to a mildly acidic compartment, thus precluding subsequent detection of viral content release. As an interesting secondary observation, the incorporation of the pH-sensor revealed that HIV-1 particles occasionally shuttle between neutral and acidic compartments in target cells expressing CD4, suggesting a small fraction of viral particles is recycled to the plasma membrane and re-internalized. By imaging viruses bound to living cells, we found that HIV-1 content release in neutral-pH environment was a rare event (~0.4% particles). Surprisingly, viral content release was not significantly reduced by fusion inhibitors, implying that content release was due to spontaneous formation of viral membrane defects occurring at the cell surface. We did not measure a significant occurrence of HIV-1 fusion at neutral pH above this defect-mediated background loss of content, suggesting that the pH sensor may destabilize the membrane of the HIV-1 pseudovirus and, thus, preclude reliable detection of single virus fusion events at neutral pH. PMID:26863211

  5. Viral metagenomics and blood safety.

    PubMed

    Sauvage, V; Eloit, M

    2016-02-01

    The characterization of the human blood-associated viral community (also called blood virome) is essential for epidemiological surveillance and to anticipate new potential threats for blood transfusion safety. Currently, the risk of blood-borne agent transmission of well-known viruses (HBV, HCV, HIV and HTLV) can be considered as under control in high-resource countries. However, other viruses unknown or unsuspected may be transmitted to recipients by blood-derived products. This is particularly relevant considering that a significant proportion of transfused patients are immunocompromised and more frequently subjected to fatal outcomes. Several measures to prevent transfusion transmission of unknown viruses have been implemented including the exclusion of at-risk donors, leukocyte reduction of donor blood, and physicochemical treatment of the different blood components. However, up to now there is no universal method for pathogen inactivation, which would be applicable for all types of blood components and, equally effective for all viral families. In addition, among available inactivation procedures of viral genomes, some of them are recognized to be less effective on non-enveloped viruses, and inadequate to inactivate higher viral titers in plasma pools or derivatives. Given this, there is the need to implement new methodologies for the discovery of unknown viruses that may affect blood transfusion. Viral metagenomics combined with High Throughput Sequencing appears as a promising approach for the identification and global surveillance of new and/or unexpected viruses that could impair blood transfusion safety. PMID:26778104

  6. Inhibition of cdk9 during Herpes Simplex Virus 1 Infection Impedes Viral Transcription

    PubMed Central

    Ou, Mark; Sandri-Goldin, Rozanne M.

    2013-01-01

    During herpes simplex virus 1 (HSV-1) infection there is a loss of the serine-2 phosphorylated form of RNA polymerase II (RNAP II) found in elongation complexes. This occurs in part because RNAP II undergoes ubiquitination and proteasomal degradation during times of highly active viral transcription, which may result from stalled elongating complexes. In addition, a viral protein, ICP22, was reported to trigger a loss of serine-2 RNAP II. These findings have led to some speculation that the serine-2 phosphorylated form of RNAP II may not be required for HSV-1 transcription, although this form is required for cellular transcription elongation and RNA processing. Cellular kinase cdk9 phosphorylates serine-2 in the C-terminal domain (CTD) of RNAP II. To determine if serine-2 phosphorylated RNAP II is required for HSV-1 transcription, we inhibited cdk9 during HSV-1 infection and measured viral gene expression. Inhibition was achieved by adding cdk9 inhibitors 5,6-dichlorobenzimidazone-1-β-D-ribofuranoside (DRB) or flavopiridol (FVP) or by expression of a dominant–negative cdk9 or HEXIM1, which in conjunction with 7SK snRNA inhibits cdk9 in complex with cyclin 1. Here we report that inhibition of cdk9 resulted in decreased viral yields and levels of late proteins, poor formation of viral transcription-replication compartments, reduced levels of poly(A)+ mRNA and decreased RNA synthesis as measured by uptake of 5-bromouridine into nascent RNA. Importantly, a global reduction in viral mRNAs was seen as determined by microarray analysis. We conclude that serine-2 phosphorylation of the CTD of RNAP II is required for HSV-1 transcription. PMID:24205359

  7. Bone graft substitutes for spine fusion: A brief review

    PubMed Central

    Gupta, Ashim; Kukkar, Nitin; Sharif, Kevin; Main, Benjamin J; Albers, Christine E; El-Amin III, Saadiq F

    2015-01-01

    Bone graft substitutes are widely used in the field of orthopedics and are extensively used to promote vertebral fusion. Fusion is the most common technique in spine surgery and is used to treat morbidities and relieve discomfort. Allograft and autograft bone substitutes are currently the most commonly used bone grafts to promote fusion. These approaches pose limitations and present complications to the patient. Numerous alternative bone graft substitutes are on the market or have been developed and proposed for application. These options have attempted to promote spine fusion by enhancing osteogenic properties. In this review, we reviewed biology of spine fusion and the current advances in biomedical materials and biological strategies for application in surgical spine fusion. Our findings illustrate that, while many bone graft substitutes perform well as bone graft extenders, only osteoinductive proteins (recombinant bone morphogenetic proteins-2 and osteogenic protein-1) provide evidence for use as both bone enhancers and bone substitutes for specific types of spinal fusion. Tissue engineered hydrogels, synthetic polymer composites and viral based gene therapy also holds the potential to be used for spine fusion in future, though warrants further investigation to be used in clinical practice. PMID:26191491

  8. Bone graft substitutes for spine fusion: A brief review.

    PubMed

    Gupta, Ashim; Kukkar, Nitin; Sharif, Kevin; Main, Benjamin J; Albers, Christine E; El-Amin Iii, Saadiq F

    2015-07-18

    Bone graft substitutes are widely used in the field of orthopedics and are extensively used to promote vertebral fusion. Fusion is the most common technique in spine surgery and is used to treat morbidities and relieve discomfort. Allograft and autograft bone substitutes are currently the most commonly used bone grafts to promote fusion. These approaches pose limitations and present complications to the patient. Numerous alternative bone graft substitutes are on the market or have been developed and proposed for application. These options have attempted to promote spine fusion by enhancing osteogenic properties. In this review, we reviewed biology of spine fusion and the current advances in biomedical materials and biological strategies for application in surgical spine fusion. Our findings illustrate that, while many bone graft substitutes perform well as bone graft extenders, only osteoinductive proteins (recombinant bone morphogenetic proteins-2 and osteogenic protein-1) provide evidence for use as both bone enhancers and bone substitutes for specific types of spinal fusion. Tissue engineered hydrogels, synthetic polymer composites and viral based gene therapy also holds the potential to be used for spine fusion in future, though warrants further investigation to be used in clinical practice. PMID:26191491

  9. Viral vectors for vaccine applications

    PubMed Central

    Choi, Youngjoo

    2013-01-01

    Traditional approach of inactivated or live-attenuated vaccine immunization has resulted in impressive success in the reduction and control of infectious disease outbreaks. However, many pathogens remain less amenable to deal with the traditional vaccine strategies, and more appropriate vaccine strategy is in need. Recent discoveries that led to increased understanding of viral molecular biology and genetics has rendered the used of viruses as vaccine platforms and as potential anti-cancer agents. Due to their ability to effectively induce both humoral and cell-mediated immune responses, viral vectors are deemed as an attractive alternative to the traditional platforms to deliver vaccine antigens as well as to specifically target and kill tumor cells. With potential targets ranging from cancers to a vast number of infectious diseases, the benefits resulting from successful application of viral vectors to prevent and treat human diseases can be immense. PMID:23858400

  10. Noncoding RNPs of Viral Origin

    PubMed Central

    Steitz, Joan; Borah, Sumit; Cazalla, Demian; Fok, Victor; Lytle, Robin; Mitton-Fry, Rachel; Riley, Kasandra; Samji, Tasleem

    2011-01-01

    SUMMARY Like their host cells, many viruses produce noncoding (nc)RNAs. These show diversity with respect to time of expression during viral infection, length and structure, protein-binding partners and relative abundance compared with their host-cell counterparts. Viruses, with their limited genomic capacity, presumably evolve or acquire ncRNAs only if they selectively enhance the viral life cycle or assist the virus in combating the host’s response to infection. Despite much effort, identifying the functions of viral ncRNAs has been extremely challenging. Recent technical advances and enhanced understanding of host-cell ncRNAs promise accelerated insights into the RNA warfare mounted by this fascinating class of RNPs. PMID:20719877

  11. Noncoding RNPs of viral origin.

    PubMed

    Steitz, Joan; Borah, Sumit; Cazalla, Demian; Fok, Victor; Lytle, Robin; Mitton-Fry, Rachel; Riley, Kasandra; Samji, Tasleem

    2011-03-01

    Like their host cells, many viruses produce noncoding (nc)RNAs. These show diversity with respect to time of expression during viral infection, length and structure, protein-binding partners and relative abundance compared with their host-cell counterparts. Viruses, with their limited genomic capacity, presumably evolve or acquire ncRNAs only if they selectively enhance the viral life cycle or assist the virus in combating the host's response to infection. Despite much effort, identifying the functions of viral ncRNAs has been extremely challenging. Recent technical advances and enhanced understanding of host-cell ncRNAs promise accelerated insights into the RNA warfare mounted by this fascinating class of RNPs. PMID:20719877

  12. Viral IAPs, then and now.

    PubMed

    Clem, Rollie J

    2015-03-01

    The identification, now more than 20 years ago, of the first iap genes in baculoviruses subsequently led to many important discoveries concerning the regulation of apoptosis and other important biological processes in insects and mammals. Currently there are more than 200 known viral IAP homologs in baculoviruses and other families of invertebrate DNA viruses. This review begins with a personal account of the events leading up to the discovery of the first iap genes, followed by a summary of what is currently known about the different types of viral IAPs and their functions in regulating apoptosis, and possibly other cellular processes. PMID:25652775

  13. Conformation-specific antibodies targeting the trimer-of-hairpins motif of the human T-cell leukemia virus type 1 transmembrane glycoprotein recognize the viral envelope but fail to neutralize viral entry.

    PubMed

    Mirsaliotis, Antonis; Nurkiyanova, Kulpash; Lamb, Daniel; Woof, Jenny M; Brighty, David W

    2007-06-01

    Human T-cell leukemia virus type 1 (HTLV-1) entry into cells is dependent upon the viral envelope glycoprotein-catalyzed fusion of the viral and cellular membranes. Following receptor activation of the envelope, the transmembrane glycoprotein (TM) is thought to undergo a series of fusogenic conformational transitions through a rod-like prehairpin intermediate to a compact trimer-of-hairpins structure. Importantly, synthetic peptides that interfere with the conformational changes of TM are potent inhibitors of membrane fusion and HTLV-1 entry, suggesting that TM is a valid target for antiviral therapy. To assess the utility of TM as a vaccine target and to explore further the function of TM in HTLV-1 pathogenesis, we have begun to examine the immunological properties of TM. Here we demonstrate that a recombinant trimer-of-hairpins form of the TM ectodomain is strongly immunogenic. Monoclonal antibodies raised against the TM immunogen specifically bind to trimeric forms of TM, including structures thought to be important for membrane fusion. Importantly, these antibodies recognize the envelope on virally infected cells but, surprisingly, fail to neutralize envelope-mediated membrane fusion or infection by pseudotyped viral particles. Our data imply that, even in the absence of overt membrane fusion, there are multiple forms of TM on virally infected cells and that some of these display fusion-associated structures. Finally, we demonstrate that many of the antibodies possess the ability to recruit complement to TM, suggesting that envelope-derived immunogens capable of eliciting a combination of neutralizing and complement-fixing antibodies would be of value as subunit vaccines for intervention in HTLV infections. PMID:17376912

  14. Bacterial CRISPR/Cas DNA endonucleases: A revolutionary technology that could dramatically impact viral research and treatment

    SciTech Connect

    Kennedy, Edward M.; Cullen, Bryan R.

    2015-05-15

    CRISPR/Cas systems mediate bacterial adaptive immune responses that evolved to protect bacteria from bacteriophage and other horizontally transmitted genetic elements. Several CRISPR/Cas systems exist but the simplest variant, referred to as Type II, has a single effector DNA endonuclease, called Cas9, which is guided to its viral DNA target by two small RNAs, the crRNA and the tracrRNA. Initial efforts to adapt the CRISPR/Cas system for DNA editing in mammalian cells, which focused on the Cas9 protein from Streptococcus pyogenes (Spy), demonstrated that Spy Cas9 can be directed to DNA targets in mammalian cells by tracrRNA:crRNA fusion transcripts called single guide RNAs (sgRNA). Upon binding, Cas9 induces DNA cleavage leading to mutagenesis as a result of error prone non-homologous end joining (NHEJ). Recently, the Spy Cas9 system has been adapted for high throughput screening of genes in human cells for their relevance to a particular phenotype and, more generally, for the targeted inactivation of specific genes, in cell lines and in vivo in a number of model organisms. The latter aim seems likely to be greatly enhanced by the recent development of Cas9 proteins from bacterial species such as Neisseria meningitidis and Staphyloccus aureus that are small enough to be expressed using adeno-associated (AAV)-based vectors that can be readily prepared at very high titers. The evolving Cas9-based DNA editing systems therefore appear likely to not only impact virology by allowing researchers to screen for human genes that affect the replication of pathogenic human viruses of all types but also to derive clonal human cell lines that lack individual gene products that either facilitate or restrict viral replication. Moreover, high titer AAV-based vectors offer the possibility of directly targeting DNA viruses that infect discrete sites in the human body, such as herpes simplex virus and hepatitis B virus, with the hope that the entire population of viral DNA genomes

  15. Magneto-Inertial Fusion

    DOE PAGESBeta

    Wurden, G. A.; Hsu, S. C.; Intrator, T. P.; Grabowski, T. C.; Degnan, J. H.; Domonkos, M.; Turchi, P. J.; Campbell, E. M.; Sinars, D. B.; Herrmann, M. C.; et al

    2015-11-17

    In this community white paper, we describe an approach to achieving fusion which employs a hybrid of elements from the traditional magnetic and inertial fusion concepts, called magneto-inertial fusion (MIF). The status of MIF research in North America at multiple institutions is summarized including recent progress, research opportunities, and future plans.

  16. Slow liner fusion

    SciTech Connect

    Shaffer, M.J.

    1997-08-01

    {open_quotes}Slow{close_quotes} liner fusion ({approximately}10 ms compression time) implosions are nondestructive and make repetitive ({approximately} 1 Hz) pulsed liner fusion reactors possible. This paper summarizes a General Atomics physics-based fusion reactor study that showed slow liner feasibility, even with conservative open-line axial magnetic field confinement and Bohm radial transport.

  17. Cold fusion research

    SciTech Connect

    1989-11-01

    I am pleased to forward to you the Final Report of the Cold Fusion Panel. This report reviews the current status of cold fusion and includes major chapters on Calorimetry and Excess Heat, Fusion Products and Materials Characterization. In addition, the report makes a number of conclusions and recommendations, as requested by the Secretary of Energy.

  18. Cluster-impact fusion

    SciTech Connect

    Echenique, P.M.; Manson, J.R.; Ritchie, R.H. )

    1990-03-19

    We present a model for the cluster-impact-fusion experiments of Buehler, Friedlander, and Friedman, Calculated fusion rates as a function of bombarding energy for constant cluster size agree well with experiment. The dependence of the fusion rate on cluster size at fixed bombarding energy is explained qualitatively. The role of correlated, coherent collisions in enhanced energy loss by clusters is emphasized.

  19. Molecular mechanism of respiratory syncytial virus fusion inhibitors

    PubMed Central

    Battles, Michael B; Langedijk, Johannes P; Furmanova-Hollenstein, Polina; Chaiwatpongsakorn, Supranee; Costello, Heather M; Kwanten, Leen; Vranckx, Luc; Vink, Paul; Jaensch, Steffen; Jonckers, Tim H M; Koul, Anil; Arnoult, Eric; Peeples, Mark E; Roymans, Dirk; McLellan, Jason S

    2016-01-01

    Respiratory syncytial virus (RSV) is a leading cause of pneumonia and bronchiolitis in young children and the elderly. Therapeutic small molecules have been developed that bind the RSV F glycoprotein and inhibit membrane fusion, yet their binding sites and molecular mechanisms of action remain largely unknown. Here we show that these inhibitors bind to a three-fold-symmetric pocket within the central cavity of the metastable prefusion conformation of RSV F. Inhibitor binding stabilizes this conformation by tethering two regions that must undergo a structural rearrangement to facilitate membrane fusion. Inhibitor-escape mutations occur in residues that directly contact the inhibitors or are involved in the conformational rearrangements required to accommodate inhibitor binding. Resistant viruses do not propagate as well as wild-type RSV in vitro, indicating a fitness cost for inhibitor escape. Collectively, these findings provide new insight into class I viral fusion proteins and should facilitate development of optimal RSV fusion inhibitors. PMID:26641933

  20. Molecular mechanism of respiratory syncytial virus fusion inhibitors.

    PubMed

    Battles, Michael B; Langedijk, Johannes P; Furmanova-Hollenstein, Polina; Chaiwatpongsakorn, Supranee; Costello, Heather M; Kwanten, Leen; Vranckx, Luc; Vink, Paul; Jaensch, Steffen; Jonckers, Tim H M; Koul, Anil; Arnoult, Eric; Peeples, Mark E; Roymans, Dirk; McLellan, Jason S

    2016-02-01

    Respiratory syncytial virus (RSV) is a leading cause of pneumonia and bronchiolitis in young children and the elderly. Therapeutic small molecules have been developed that bind the RSV F glycoprotein and inhibit membrane fusion, yet their binding sites and molecular mechanisms of action remain largely unknown. Here we show that these inhibitors bind to a three-fold-symmetric pocket within the central cavity of the metastable prefusion conformation of RSV F. Inhibitor binding stabilizes this conformation by tethering two regions that must undergo a structural rearrangement to facilitate membrane fusion. Inhibitor-escape mutations occur in residues that directly contact the inhibitors or are involved in the conformational rearrangements required to accommodate inhibitor binding. Resistant viruses do not propagate as well as wild-type RSV in vitro, indicating a fitness cost for inhibitor escape. Collectively, these findings provide new insight into class I viral fusion proteins and should facilitate development of optimal RSV fusion inhibitors. PMID:26641933

  1. MFR, a Putative Receptor Mediating the Fusion of Macrophages

    PubMed Central

    Saginario, Charles; Sterling, Hyacinth; Beckers, Cornelius; Kobayashi, Ruji; Solimena, Michele; Ullu, Elisabetta; Vignery, Agnès

    1998-01-01

    We had previously identified a macrophage surface protein whose expression is highly induced, transient, and specific, as it is restricted to actively fusing macrophages in vitro and in vivo. This protein is recognized by monoclonal antibodies that block macrophage fusion. We have now purified this protein and cloned its corresponding cDNA. This protein belongs to the superfamily of immunoglobulins and is similar to immune antigen receptors such as the T-cell receptor, B-cell receptor, and viral receptors such as CD4. We have therefore named this protein macrophage fusion receptor (MFR). We show that the extracellular domain of MFR prevents fusion of macrophages in vitro and therefore propose that MFR belongs to the fusion machinery of macrophages. MFR is identical to SHPS-1 and BIT and is a homologue of P84, SIRPα, and MyD-1, all of which have been recently cloned and implicated in cell signaling and cell-cell interaction events. PMID:9774638

  2. Methodologies in the study of cell-cell fusion.

    PubMed

    Cohen, F S; Melikyan, G B

    1998-10-01

    The process of membrane fusion has been profitably studied by fusing cells that express fusion proteins on their surfaces to the membranes of target cells. Primary methods for monitoring the occurrence of fusion between cells are measurement of formation of heterokaryons, measurement of activation of reporter genes, measurement of transfer of lipidic and aqueous fluorescent dyes, and electrophysiological recording of fusion pores. Fluorescence and electrical methods have been well developed for fusion of a nucleated cell expressing viral fusion proteins to red blood cell targets. These techniques are now being extended to the study of fusion between two nucleated cells. Microscopic observation of spread of fluorescent dyes from one cell to another is a sensitive and convenient means of detecting fusion on the level of single events. In such studies, both the membrane and the aqueous continuities that occur as a result of fusion can be measured in the same experiment. By following spread of aqueous dyes of different sizes from one cell to another, the growth of a fusion pore can also be followed. By labeling cells with fluorescent probes, a state of hemifusion can be identified if probes in outer membrane leaflets transfer but probes in inner leaflets or aqueous spaces do not. Electrical measurements-both capacitance and double-whole-cell voltage-clamp techniques-are the most sensitive methods yet developed for detecting the formation of pores and for quantifying their growth. These powerful single-event methodologies should be directly applicable to further advances in expressing nonviral fusion proteins on cell surfaces. PMID:9790869

  3. Functional analysis of the transmembrane domain in paramyxovirus F protein-mediated membrane fusion

    PubMed Central

    Bissonnette, Mei Lin Z.; Donald, Jason E.; DeGrado, William F.; Jardetzky, Theodore S.; Lamb, Robert A.

    2009-01-01

    To enter cells enveloped viruses use fusion-mediating glycoproteins to facilitate the merger of the viral and host cell membranes. These glycoproteins undergo large-scale irreversible refolding during membrane fusion. The paramyxovirus parainfluenza virus 5 (PIV5) mediates membrane merger through its fusion protein (F). The transmembrane (TM) domains of viral fusion proteins are typically required for fusion. The TM domain of F is particularly interesting in that it is potentially unusually long; multiple calculations suggest a TM helix length between 25 and 48 residues. Oxidative cross-linking of single cysteine substitutions indicates the F TM trimer forms a helical bundle within the membrane. To assess the functional role of the PIV5 F protein TM domain, alanine scanning mutagenesis was performed. Two residues located in the outer leaflet of the bilayer are critical for fusion. Multiple amino acid substitutions at these positions indicate the physical properties of the side chain play a critical role in supporting or blocking fusion. Analysis of intermediate steps in F protein refolding indicated that the mutants were not trapped at the open stalk intermediate or the prehairpin intermediate. Incorporation of a known F protein destabilizing mutation that causes a hyperfusogenic phenotype restored fusion activity to the mutants. Further, altering the curvature of the lipid bilayer by addition of oleic acid promoted fusion of the F protein mutants. In aggregate, these data indicate that the TM domain plays a functional role in fusion beyond merely anchoring the protein in the viral envelope and that it can affect the structures and steady-state concentrations of the various conformational intermediates en route to the final postfusion state. We suggest that the unusual length of this TM helix might allow it to serve as a template for formation of or specifically stabilize the lipid stalk intermediate in fusion. PMID:19121325

  4. Enhanced chemical weapon warning via sensor fusion

    NASA Astrophysics Data System (ADS)

    Flaherty, Michael; Pritchett, Daniel; Cothren, Brian; Schwaiger, James

    2011-05-01

    Torch Technologies Inc., is actively involved in chemical sensor networking and data fusion via multi-year efforts with Dugway Proving Ground (DPG) and the Defense Threat Reduction Agency (DTRA). The objective of these efforts is to develop innovative concepts and advanced algorithms that enhance our national Chemical Warfare (CW) test and warning capabilities via the fusion of traditional and non-traditional CW sensor data. Under Phase I, II, and III Small Business Innovative Research (SBIR) contracts with DPG, Torch developed the Advanced Chemical Release Evaluation System (ACRES) software to support non real-time CW sensor data fusion. Under Phase I and II SBIRs with DTRA in conjunction with the Edgewood Chemical Biological Center (ECBC), Torch is using the DPG ACRES CW sensor data fuser as a framework from which to develop the Cloud state Estimation in a Networked Sensor Environment (CENSE) data fusion system. Torch is currently developing CENSE to implement and test innovative real-time sensor network based data fusion concepts using CW and non-CW ancillary sensor data to improve CW warning and detection in tactical scenarios.

  5. Detection of viral infections using colloidal quantum dots

    NASA Astrophysics Data System (ADS)

    Bentzen, Elizabeth L.; House, Frances S.; Utley, Thomas J.; Crowe, James E., Jr.; Wright, David W.

    2006-02-01

    Fluorescence is a tool widely employed in biological assays. Fluorescent semiconducting nanocrystals, quantum dots (QDs), are beginning to find their way into the tool box of many biologist, chemist and biochemist. These quantum dots are an attractive alternative to the traditional organic dyes due to their broad excitation spectra, narrow emission spectra and photostability. Quantum dots were used to detect and monitor the progession of viral glycoproteins, F (fusion) and G (attachment), from Respiratory Syncytial Virus (RSV) in HEp-2 cells. Additionally, oligo-Qdot RNA probes have been developed for identification and detection of mRNA of the N(nucleocapsid) protein for RSV. The use of quantum dot-FISH probes provides another confirmatory route to diagnostics as well as a new class of probes for monitoring the flux and fate of viral RNA RSV is the most common cause of lower respiratory tract infection in children worldwide and the most common cause of hospitalization of infants in the US. Antiviral therapy is available for treatment of RSV but is only effective if given within the first 48 hours of infection. Existing test methods require a virus level of at least 1000-fold of the amount needed for infection of most children and require several days to weeks to obtain results. The use of quantum dots may provide an early, rapid method for detection and provide insight into the trafficking of viral proteins during the course of infection.

  6. The Paradigm of Viral Communication.

    ERIC Educational Resources Information Center

    Welker, Carl B.

    2002-01-01

    Introduces the concepts of idea viruses and viral communication, a technology-based communication that spreads ideas quickly. Explains its applicability in the area of direct marketing and discusses a technology platform that provides the opportunity of sending a message to a large number of people and emotional or pecuniary incentives to…

  7. Asian citrus psyllid viral pathogen

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A newly discovered viral pathogen of Asian citrus psyllid, AsCP, Diaphorina citri, Kuwayama (Psyllidae: Hemiptera) was classified as a Reoviridae. This virus may serve as a biological control agent for AsCP. The AsCP is an efficient vector of the plant-infecting bacterium (Candidatus Liberibacter as...

  8. Viral obesity: fact or fiction?

    PubMed

    Mitra, A K; Clarke, K

    2010-04-01

    The aetiology of obesity is multifactorial. An understanding of the contributions of various causal factors is essential for the proper management of obesity. Although it is primarily thought of as a condition brought on by lifestyle choices, recent evidence shows there is a link between obesity and viral infections. Numerous animal models have documented an increased body weight and a number of physiologic changes, including increased insulin sensitivity, increased glucose uptake and decreased leptin secretion that contribute to an increase in body fat in adenovirus-36 infection. Other viral agents associated with increasing obesity in animals included canine distemper virus, rous-associated virus 7, scrapie, Borna disease virus, SMAM-1 and other adenoviruses. This review attempted to determine if viral infection is a possible cause of obesity. Also, this paper discussed mechanisms by which viruses might produce obesity. Based on the evidence presented in this paper, it can be concluded that a link between obesity and viral infections cannot be ruled out. Further epidemiologic studies are needed to establish a causal link between the two, and determine if these results can be used in future management and prevention of obesity. PMID:19874530

  9. Viral Subversion of Nucleocytoplasmic Trafficking

    PubMed Central

    Yarbrough, Melanie L.; Mata, Miguel A.; Sakthivel, Ramanavelan; Fontoura, Beatriz M. A.

    2014-01-01

    Trafficking of proteins and RNA into and out of the nucleus occurs through the nuclear pore complex (NPC). Due to its critical function in many cellular processes, the NPC and transport factors are common targets of several viruses that disrupt key constituents of the machinery to facilitate viral replication. Many viruses such as poliovirus and severe acute respiratory syndrome (SARS) virus inhibit protein import into the nucleus, while viruses such as influenza A virus target and disrupt host mRNA nuclear export. Current evidence indicates that these viruses may employ such strategies to avert the host immune response. Conversely, many viruses co-opt nucleocytoplasmic trafficking to facilitate transport of viral RNAs. Since viral proteins interact with key regulators of the host nuclear transport machinery, viruses have served as invaluable tools of discovery that led to the identification of novel constituents of nuclear transport pathways. In addition, this review explores the importance of nucleocytoplasmic trafficking to viral pathogenesis as these studies revealed new antiviral therapeutic strategies and exposed previously unknown cellular mechanisms. Further understanding of nuclear transport pathways will determine whether such therapeutics will be useful treatments for important human pathogens. PMID:24289861

  10. Nosocomial Spread of Viral Disease

    PubMed Central

    Aitken, Celia; Jeffries, Donald J.

    2001-01-01

    Viruses are important causes of nosocomial infection, but the fact that hospital outbreaks often result from introduction(s) from community-based epidemics, together with the need to initiate specific laboratory testing, means that there are usually insufficient data to allow the monitoring of trends in incidences. The most important defenses against nosocomial transmission of viruses are detailed and continuing education of staff and strict adherence to infection control policies. Protocols must be available to assist in the management of patients with suspected or confirmed viral infection in the health care setting. In this review, we present details on general measures to prevent the spread of viral infection in hospitals and other health care environments. These include principles of accommodation of infected patients and approaches to good hygiene and patient management. They provide detail on individual viral diseases accompanied in each case with specific information on control of the infection and, where appropriate, details of preventive and therapeutic measures. The important areas of nosocomial infection due to blood-borne viruses have been extensively reviewed previously and are summarized here briefly, with citation of selected review articles. Human prion diseases, which present management problems very different from those of viral infection, are not included. PMID:11432812

  11. Herbal medicines for viral myocarditis

    PubMed Central

    Liu, Zhao Lan; Liu, Zhi Jun; Liu, Jian Ping; Yang, Min; Kwong, Joey

    2012-01-01

    Background Herbal medicines are being used for treating viral diseases including viral myocarditis, and many controlled trials have been done to investigate their efficacy. Objectives To assess the effects of herbal medicines on clinical and indirect outcomes in patients with viral myocarditis. Search strategy We searched the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library Issue 3, 2009, MEDLINE (January 1966 - July 2009), EMBASE (January 1998 - July 2009), Chinese Biomedical Database (1979 - 2009), China National Knowledge Infrastructure (1979 - 2009), Chinese VIP Information (1989 - 2009), Chinese Academic Conference Papers Database and Chinese Dissertation Database (1980 - 2009), AMED (1985 - 2009), LILACS accessed in July 2009 and the trials register of the Cochrane Complementary Medicine Field. We handsearched Chinese journals and conference proceedings. No language restrictions were applied. Selection criteria Randomised controlled trials of herbal medicines (with a minimum of seven days treatment duration) compared with placebo, no intervention, or conventional interventions were included. Trials of herbal medicine plus conventional drug versus drug alone were also included. Only trials that reported adequate description of allocation sequence generation were included. Data collection and analysis Two review authors independently extracted data and evaluated trial quality. Adverse effects information was collected from the trials. Main results Fourteen randomised trials involving 1463 people were included. All trials were conducted and published in China. Quality of the trials was assessed to be low. No trial had diagnosis of viral myocarditis confirmed histologically, and only a few trials attempted to establish viral aetiology. Nine different herbal medicines were tested in the included trials. The trials reported electrocardiogram results, level of myocardial enzymes, cardiac function, symptoms, and adverse effects

  12. Herbal medicines for viral myocarditis

    PubMed Central

    Liu, Zhao Lan; Liu, Zhi Jun; Liu, Jian Ping; Yang, Min; Kwong, Joey

    2011-01-01

    Background Herbal medicines are being used for treating viral diseases including viral myocarditis, and many controlled trials have been done to investigate their efficacy. Objectives To assess the effects of herbal medicines on clinical and indirect outcomes in patients with viral myocarditis. Search methods We searched the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library Issue 3, 2009, MEDLINE (January 1966 - July 2009), EMBASE (January 1998 - July 2009), Chinese Biomedical Database (1979 - 2009), China National Knowledge Infrastructure (1979 - 2009), Chinese VIP Information (1989 - 2009), Chinese Academic Conference Papers Database and Chinese Dissertation Database (1980 - 2009), AMED (1985 - 2009), LILACS accessed in July 2009 and the trials register of the Cochrane Complementary Medicine Field. We handsearched Chinese journals and conference proceedings. No language restrictions were applied. Selection criteria Randomised controlled trials of herbal medicines (with a minimum of seven days treatment duration) compared with placebo, no intervention, or conventional interventions were included. Trials of herbal medicine plus conventional drug versus drug alone were also included. Only trials that reported adequate description of allocation sequence generation were included. Data collection and analysis Two review authors independently extracted data and evaluated trial quality. Adverse effects information was collected from the trials. Results Fourteen randomised trials involving 1463 people were included. All trials were conducted and published in China. Quality of the trials was assessed to be low. No trial had diagnosis of viral myocarditis confirmed histologically, and only a few trials attempted to establish viral aetiology. Nine different herbal medicines were tested in the included trials. The trials reported electrocardiogram results, level of myocardial enzymes, cardiac function, symptoms, and adverse effects. Astragalus

  13. Magnetic fusion energy plasma interactive and high heat flux components. Volume II. Technical assessment of the critical issues and problem areas in high heat flux materials and component development

    SciTech Connect

    Abdou, M.A.; Boyd, R.D.; Easor, J.R.; Gauster, W.B.; Gordon, J.D.; Mattas, R.F.; Morgan, G.D.; Ulrickson, M.A,; Watson, R.D.; Wolfer, W.G,

    1984-06-01

    A technical assessment of the critical issues and problem areas for high heat flux materials and components (HHFMC) in magnetic fusion devices shows these problems to be of critical importance for the successful operation of near-term fusion experiments and for the feasibility and attractiveness of long-term fusion reactors. A number of subgroups were formed to assess the critical HHFMC issues along the following major lines: (1) source conditions, (2) systems integration, (3) materials and processes, (4) thermal hydraulics, (5) thermomechanical response, (6) electromagnetic response, (7) instrumentation and control, and (8) test facilities. The details of the technical assessment are presented in eight chapters. The primary technical issues and needs for each area are highlighted.

  14. The fusion breeder

    NASA Astrophysics Data System (ADS)

    Moir, Ralph W.

    1982-10-01

    The fusion breeder is a fusion reactor designed with special blankets to maximize the transmutation by 14 MeV neutrons of uranium-238 to plutonium or thorium to uranium-233 for use as a fuel for fission reactors. Breeding fissile fuels has not been a goal of the U.S. fusion energy program. This paper suggests it is time for a policy change to make the fusion breeder a goal of the U.S. fusion program and the U.S. nuclear energy program. There is wide agreement that many approaches will work and will produce fuel for five equal-sized LWRs, and some approach as many as 20 LWRs at electricity costs within 20% of those at today's price of uranium (30/lb of U3O8). The blankets designed to suppress fissioning, called symbiotes, fusion fuel factories, or just fusion breeders, will have safety characteristics more like pure fusion reactors and will support as many as 15 equal power LWRs. The blankets designed to maximize fast fission of fertile material will have safety characteristics more like fission reactors and will support 5 LWRs. This author strongly recommends development of the fission suppressed blanket type, a point of view not agreed upon by everyone. There is, however, wide agreement that, to meet the market price for uranium which would result in LWR electricity within 20% of today's cost with either blanket type, fusion components can cost severalfold more than would be allowed for pure fusion to meet the goal of making electricity alone at 20% over today's fission costs. Also widely agreed is that the critical-path-item for the fusion breeder is fusion development itself; however, development of fusion breeder specific items (blankets, fuel cycle) should be started now in order to have the fusion breeder by the time the rise in uranium prices forces other more costly choices.

  15. Inborn errors of anti-viral interferon immunity in humans

    PubMed Central

    Sancho-Shimizu, Vanessa; de Diego, Rebeca Perez; Jouanguy, Emmanuelle; Zhang, Shen-Ying; Casanova, Jean-Laurent

    2011-01-01

    The three types of interferon (IFNs) are essential for immunity against at least some viruses in the mouse model of experimental infections, type I IFNs displaying the broadest and strongest anti-viral activity. Consistently, human genetic studies have shown that type II IFN is largely redundant for immunity against viruses in the course of natural infections. The precise contributions of human type I and III IFNs remain undefined. However, various inborn errors of anti-viral IFN immunity have been described, which can result in either broad or narrow immunological and viral phenotypes. The broad disorders impair the response to (STAT1, TYK2) or the production of at least type I and type III IFNs following multiple stimuli (NEMO), resulting in multiple viral infections at various sites, including herpes simplex encephalitis (HSE). The narrow disorders impair exclusively (TLR3) or mostly (UNC-93B, TRIF, TRAF3) the TLR3-dependent induction of type I and III IFNs, leading to HSE in apparently otherwise healthy individuals. These recent discoveries highlight the importance of human type I and III IFNs in protective immunity against viruses, including the TLR3-IFN pathway in protection against HSE. PMID:22347990

  16. Viral mediated gene transfer to sprouting blood vessels during angiogenesis.

    PubMed

    Alian, Akram; Eldor, Amiram; Falk, Haya; Panet, Amos

    2002-08-01

    Several experimental systems have been applied to investigate the development of new blood vessels. Angiogenesis can be followed ex-vivo by culturing explants of rat aorta 'rings' in biomatrix gels. This angiogenesis system was modified for the study of viral vector mediated gene transfer, using adenovirus, vaccinia- and retroviral vectors. Two modifications were introduced to the model in order to facilitate efficient viral mediated gene transfer, (i) placing the aorta ring on top of a thin layer of collagen such that the angiogenic tissue will be accessible to the viral vector; and (ii) infection of the aorta rings prior to embedding them into the collagen matrix. While adenovirus and vaccinia vectors infected efficiently the aorta rings they induced cell death. Subsequent gene transfer experiments were, therefore, carried with retroviral vectors containing vascular endothelial growth factor (VEGF) and the beta-interferon (IFN) genes. Overexpression of VEGF enhanced significantly microvessel sprouting, while overexpression of IFN-beta induced an antiviral effect. The experimental system described in this study can facilitate the application of other viral vectors to the study of genes that may regulate the complex angiogenic process and thereby open new avenues for vascular gene therapy. PMID:12176137

  17. Measuring Experiential Avoidance in Adults: The Avoidance and Fusion Questionnaire

    ERIC Educational Resources Information Center

    Schmalz, Jonathan E.; Murrell, Amy R.

    2010-01-01

    To date, general levels of experiential avoidance are primarily measured by the Acceptance and Action Questionnaire-II (AAQ-II), but it includes items of questionable comprehensibility. The Avoidance and Fusion Questionnaire for Youth (AFQ-Y), previously validated as a measure of experiential avoidance with children and adolescents, was…

  18. FUSION-COMPETENT STATE INDUCED BY A C-TERMINAL HIV-1 FUSION PEPTIDE IN CHOLESTEROL-RICH MEMBRANES

    PubMed Central

    Apellániz, Beatriz; Nieva, José L.

    2015-01-01

    The replicative cycle of the Human Immunodeficiency Virus type-1 begins after fusion of the viral and target-cell membranes. The envelope glycoprotein gp41 transmembrane subunit contains conserved hydrophobic domains that engage and perturb the merging lipid bilayers. In this work, we have characterized the fusion-committed state generated in vesicles by CpreTM, a synthetic peptide derived from the sequence connecting the membrane-proximal external region (MPER) and the transmembrane domain (TMD) of gp41. Pre-loading cholesterol-rich vesicles with CpreTM rendered them competent for subsequent lipid-mixing with fluorescently-labeled target vesicles. Highlighting the physiological relevance of the lasting fusion-competent state, the broadly neutralizing antibody 4E10 bound to the CpreTM-primed vesicles and inhibited lipid-mixing. Heterotypic fusion assays disclosed dependence on the lipid composition of the vesicles that acted either as virus or cell membrane surrogates. Lipid-mixing exhibited above all a critical dependence on the cholesterol content in those experiments. We infer that the fusion-competent state described herein resembles bona-fide perturbations generated by the pre-hairpin MPER-TMD connection within the viral membrane. PMID:25617671

  19. Fusion and quality analysis for remote sensing images using contourlet transform

    NASA Astrophysics Data System (ADS)

    Choi, Yoonsuk; Sharifahmadian, Ershad; Latifi, Shahram

    2013-05-01

    Recent developments in remote sensing technologies have provided various images with high spatial and spectral resolutions. However, multispectral images have low spatial resolution and panchromatic images have low spectral resolution. Therefore, image fusion techniques are necessary to improve the spatial resolution of spectral images by injecting spatial details of high-resolution panchromatic images. The objective of image fusion is to provide useful information by improving the spatial resolution and the spectral information of the original images. The fusion results can be utilized in various applications, such as military, medical imaging, and remote sensing. This paper addresses two issues in image fusion: i) image fusion method and ii) quality analysis of fusion results. First, a new contourlet-based image fusion method is presented, which is an improvement over the wavelet-based fusion. This fusion method is then applied to a case study to demonstrate its fusion performance. Fusion framework and scheme used in the study are discussed in detail. Second, quality analysis for the fusion results is discussed. We employed various quality metrics in order to analyze the fusion results both spatially and spectrally. Our results indicate that the proposed contourlet-based fusion method performs better than the conventional wavelet-based fusion methods.

  20. Materials research for fusion

    NASA Astrophysics Data System (ADS)

    Knaster, J.; Moeslang, A.; Muroga, T.

    2016-05-01

    Fusion materials research started in the early 1970s following the observation of the degradation of irradiated materials used in the first commercial fission reactors. The technological challenges of fusion energy are intimately linked with the availability of suitable materials capable of reliably withstanding the extremely severe operational conditions of fusion reactors. Although fission and fusion materials exhibit common features, fusion materials research is broader. The harder mono-energetic spectrum associated with the deuterium-tritium fusion neutrons (14.1 MeV compared to <2 MeV on average for fission neutrons) releases significant amounts of hydrogen and helium as transmutation products that might lead to a (at present undetermined) degradation of structural materials after a few years of operation. Overcoming the historical lack of a fusion-relevant neutron source for materials testing is an essential pending step in fusion roadmaps. Structural materials development, together with research on functional materials capable of sustaining unprecedented power densities during plasma operation in a fusion reactor, have been the subject of decades of worldwide research efforts underpinning the present maturity of the fusion materials research programme.

  1. Test design description for the Fusion Materials Open Test Assembly (Fusion MOTA-2A): Volume 1A, Part 1

    SciTech Connect

    Bauer, R.E.

    1988-11-01

    This document encompasses the test requirements, hardware design, fabrication, and safety analysis for the Fusion Materials Open Test Assembly experiment for irradiation in FFTF Cycle 11 (Fusion MOTA-2A). Fusion MOTA is equally shared by the US Fusion Material (DOE), Japanese Fusion Materials (MONBUSHO), and BEATRIX-II (IEA) programs. In the interest of providing optimum use of the irradiation space in the Fusion MOTA-2A and LMR MOTA-1G, eight of the Fusion MOTA canisters will be placed in MOTA-1G and an equal number of LMR canisters placed in Fusion MOTA-2A (Powell/Doran 1988). This eliminates the need to process Fusion MOTA-2A through the IEM cell prior to insertion for FFTF Cycle 11A. The LMR MOTA design and safety analysis (Greenslade 1984) is the basis for much of this design and safety analysis report. This design description and safety analysis for the Fusion MOTA-2A is presented per the outline given in Chapter IV of the FTR User`s Guide (Taylor 1978). 35 refs., 17 figs., 9 tabs.

  2. Structure of the uncleaved ectodomain of the paramyxovirus (hPIV3) fusion protein

    SciTech Connect

    Yin, Hsien-Sheng; Paterson, Reay G.; Wen, Xiaolin; Lamb, Robert A.; Jardetzky, Theodore S.

    2010-03-08

    Class I viral fusion proteins share common mechanistic and structural features but little sequence similarity. Structural insights into the protein conformational changes associated with membrane fusion are based largely on studies of the influenza virus hemagglutinin in pre- and postfusion conformations. Here, we present the crystal structure of the secreted, uncleaved ectodomain of the paramyxovirus, human parainfluenza virus 3 fusion (F) protein, a member of the class I viral fusion protein group. The secreted human parainfluenza virus 3 F forms a trimer with distinct head, neck, and stalk regions. Unexpectedly, the structure reveals a six-helix bundle associated with the postfusion form of F, suggesting that the anchor-minus ectodomain adopts a conformation largely similar to the postfusion state. The transmembrane anchor domains of F may therefore profoundly influence the folding energetics that establish and maintain a metastable, prefusion state.

  3. Structure of the uncleaved ectodomain of the paramyxovirus (hPIV3) fusion protein

    PubMed Central

    Yin, Hsien-Sheng; Paterson, Reay G.; Wen, Xiaolin; Lamb, Robert A.; Jardetzky, Theodore S.

    2005-01-01

    Class I viral fusion proteins share common mechanistic and structural features but little sequence similarity. Structural insights into the protein conformational changes associated with membrane fusion are based largely on studies of the influenza virus hemagglutinin in pre- and postfusion conformations. Here, we present the crystal structure of the secreted, uncleaved ectodomain of the paramyxovirus, human parainfluenza virus 3 fusion (F) protein, a member of the class I viral fusion protein group. The secreted human parainfluenza virus 3 F forms a trimer with distinct head, neck, and stalk regions. Unexpectedly, the structure reveals a six-helix bundle associated with the postfusion form of F, suggesting that the anchor-minus ectodomain adopts a conformation largely similar to the postfusion state. The transmembrane anchor domains of F may therefore profoundly influence the folding energetics that establish and maintain a metastable, prefusion state. PMID:15964978

  4. An Anti-Influenza Virus Antibody Inhibits Viral Infection by Reducing Nucleus Entry of Influenza Nucleoprotein

    PubMed Central

    Yoon, Aerin; Yi, Kye Sook; Chang, So Young; Kim, Sung Hwan; Song, Manki; Choi, Jung Ah; Bourgeois, Melissa; Hossain, M. Jaber; Chen, Li-Mei; Donis, Ruben O.; Kim, Hyori; Lee, Yujean; Hwang, Do Been; Min, Ji-Young; Chang, Shin Jae; Chung, Junho

    2015-01-01

    To date, four main mechanisms mediating inhibition of influenza infection by anti-hemagglutinin antibodies have been reported. Anti-globular-head-domain antibodies block either influenza virus receptor binding to the host cell or progeny virion release from the host cell. Anti-stem region antibodies hinder the membrane fusion process or induce antibody-dependent cytotoxicity to infected cells. In this study we identified a human monoclonal IgG1 antibody (CT302), which does not inhibit both the receptor binding and the membrane fusion process but efficiently reduced the nucleus entry of viral nucleoprotein suggesting a novel inhibition mechanism of viral infection by antibody. This antibody binds to the subtype-H3 hemagglutinin globular head domain of group-2 influenza viruses circulating throughout the population between 1997 and 2007. PMID:26512723

  5. An Anti-Influenza Virus Antibody Inhibits Viral Infection by Reducing Nucleus Entry of Influenza Nucleoprotein.

    PubMed

    Yoon, Aerin; Yi, Kye Sook; Chang, So Young; Kim, Sung Hwan; Song, Manki; Choi, Jung Ah; Bourgeois, Melissa; Hossain, M Jaber; Chen, Li-Mei; Donis, Ruben O; Kim, Hyori; Lee, Yujean; Hwang, Do Been; Min, Ji-Young; Chang, Shin Jae; Chung, Junho

    2015-01-01

    To date, four main mechanisms mediating inhibition of influenza infection by anti-hemagglutinin antibodies have been reported. Anti-globular-head-domain antibodies block either influenza virus receptor binding to the host cell or progeny virion release from the host cell. Anti-stem region antibodies hinder the membrane fusion process or induce antibody-dependent cytotoxicity to infected cells. In this study we identified a human monoclonal IgG1 antibody (CT302), which does not inhibit both the receptor binding and the membrane fusion process but efficiently reduced the nucleus entry of viral nucleoprotein suggesting a novel inhibition mechanism of viral infection by antibody. This antibody binds to the subtype-H3 hemagglutinin globular head domain of group-2 influenza viruses circulating throughout the population between 1997 and 2007. PMID:26512723

  6. The heads of the measles virus attachment protein move to transmit the fusion-triggering signal

    PubMed Central

    Navaratnarajah, Chanakha K; Oezguen, Numan; Rupp, Levi; Kay, Leah; Leonard, Vincent HJ; Braun, Werner; Cattaneo, Roberto

    2010-01-01

    The measles virus entry system, constituted of attachment (hemagglutinin, H) and fusion proteins, operates based on a variety of natural and targeted receptors. However, the mechanism triggering fusion of the viral envelope with the plasma membrane is not understood. Here we tested a model considering that the two heads of an H-dimer, which are covalently linked at their base, after binding two receptor molecules, move relative to each other to transmit the fusion-triggering signal. Indeed, stabilizing the H-dimer interface by additional inter-molecular disulfide bonds prevented membrane fusion, an effect reversed by a reducing agent. Moreover, a membrane-anchored designated receptor efficiently triggered fusion, provided it engaged the H-dimer at locations proximal to where the natural receptors bind, and distal to the H-dimer interface. We discuss how receptors may force H-heads to switch partners and transmit the fusion-triggering signal. PMID:21217701

  7. Fusion peptide of HIV-1 as a site of vulnerability to neutralizing antibody.

    PubMed

    Kong, Rui; Xu, Kai; Zhou, Tongqing; Acharya, Priyamvada; Lemmin, Thomas; Liu, Kevin; Ozorowski, Gabriel; Soto, Cinque; Taft, Justin D; Bailer, Robert T; Cale, Evan M; Chen, Lei; Choi, Chang W; Chuang, Gwo-Yu; Doria-Rose, Nicole A; Druz, Aliaksandr; Georgiev, Ivelin S; Gorman, Jason; Huang, Jinghe; Joyce, M Gordon; Louder, Mark K; Ma, Xiaochu; McKee, Krisha; O'Dell, Sijy; Pancera, Marie; Yang, Yongping; Blanchard, Scott C; Mothes, Walther; Burton, Dennis R; Koff, Wayne C; Connors, Mark; Ward, Andrew B; Kwong, Peter D; Mascola, John R

    2016-05-13

    The HIV-1 fusion peptide, comprising 15 to 20 hydrophobic residues at the N terminus of the Env-gp41 subunit, is a critical component of the virus-cell entry machinery. Here, we report the identification of a neutralizing antibody, N123-VRC34.01, which targets the fusion peptide and blocks viral entry by inhibiting conformational changes in gp120 and gp41 subunits of Env required for entry. Crystal structures of N123-VRC34.01 liganded to the fusion peptide, and to the full Env trimer, revealed an epitope consisting of the N-terminal eight residues of the gp41 fusion peptide and glycan N88 of gp120, and molecular dynamics showed that the N-terminal portion of the fusion peptide can be solvent-exposed. These results reveal the fusion peptide to be a neutralizing antibody epitope and thus a target for vaccine design. PMID:27174988

  8. Replication of parainfluenza (Sendai) virus in isolated rat pulmonary type II alveolar epithelial cells.

    PubMed Central

    Castleman, W. L.; Northrop, P. J.; McAllister, P. K.

    1989-01-01

    The major objectives of this study were to determine whether alveolar type II epithelial cells isolated from rat lung and maintained in tissue culture would support productive replication of parainfluenza type 1 (Sendai) virus and to determine whether isolated type II cells from neonatal (5-day-old) rats that are more susceptible to viral-induced alveolar dysplasia supported viral replication to a greater extent than those from weanling (25-day-old) rats. Isolated and cultured type II cells from neonatal and weanling rats that were inoculated with Sendai virus supported productive replication as indicated by ultrastructural identification of budding virions and viral nucleocapsids in type II cells and by demonstration of rising titers of infectious virus from inoculated type II cell cultures. Alveolar macrophages from neonatal and weanling rats also supported viral replication, although infectious viral titers in macrophage cultures were lower than those from type II cell cultures. Only minor differences were detected between viral titers from neonatal and weanling type II epithelial cell cultures. Higher densities of viral nucleocapsids were observed in neonatal type II cells than in those from weanling rats. The results indicate that isolated type II alveolar epithelial cells support productive replication of parainfluenza virus and that type II cells are probably more efficient in supporting productive viral replication than are alveolar macrophages. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 PMID:2541612

  9. Performance analysis of image fusion methods in transform domain

    NASA Astrophysics Data System (ADS)

    Choi, Yoonsuk; Sharifahmadian, Ershad; Latifi, Shahram

    2013-05-01

    Image fusion involves merging two or more images in such a way as to retain the most desirable characteristics of each. There are various image fusion methods and they can be classified into three main categories: i) Spatial domain, ii) Transform domain, and iii) Statistical domain. We focus on the transform domain in this paper as spatial domain methods are primitive and statistical domain methods suffer from a significant increase of computational complexity. In the field of image fusion, performance analysis is important since the evaluation result gives valuable information which can be utilized in various applications, such as military, medical imaging, remote sensing, and so on. In this paper, we analyze and compare the performance of fusion methods based on four different transforms: i) wavelet transform, ii) curvelet transform, iii) contourlet transform and iv) nonsubsampled contourlet transform. Fusion framework and scheme are explained in detail, and two different sets of images are used in our experiments. Furthermore, various performance evaluation metrics are adopted to quantitatively analyze the fusion results. The comparison results show that the nonsubsampled contourlet transform method performs better than the other three methods. During the experiments, we also found out that the decomposition level of 3 showed the best fusion performance, and decomposition levels beyond level-3 did not significantly affect the fusion results.

  10. In vivo imaging of alphaherpesvirus infection reveals synchronized activity dependent on axonal sorting of viral proteins

    PubMed Central

    Granstedt, Andrea E.; Bosse, Jens B.; Thiberge, Stephan Y.; Enquist, Lynn W.

    2013-01-01

    A clinical hallmark of human alphaherpesvirus infections is peripheral pain or itching. Pseudorabies virus (PRV), a broad host range alphaherpesvirus, causes violent pruritus in many different animals, but the mechanism is unknown. Previous in vitro studies have shown that infected, cultured peripheral nervous system (PNS) neurons exhibited aberrant electrical activity after PRV infection due to the action of viral membrane fusion proteins, yet it is unclear if such activity occurs in infected PNS ganglia in living animals and if it correlates with disease symptoms. Using two-photon microscopy, we imaged autonomic ganglia in living mice infected with PRV strains expressing GCaMP3, a genetically encoded calcium indicator, and used the changes in calcium flux to monitor the activity of many neurons simultaneously with single-cell resolution. Infection with virulent PRV caused these PNS neurons to fire synchronously and cyclically in highly correlated patterns among infected neurons. This activity persisted even when we severed the presynaptic axons, showing that infection-induced firing is independent of input from presynaptic brainstem neurons. This activity was not observed after infections with an attenuated PRV recombinant used for circuit tracing or with PRV mutants lacking either viral glycoprotein B, required for membrane fusion, or viral membrane protein Us9, required for sorting virions and viral glycoproteins into axons. We propose that the viral fusion proteins produced by virulent PRV infection induce electrical coupling in unmyelinated axons in vivo. This action would then give rise to the synchronous and cyclical activity in the ganglia and contribute to the characteristic peripheral neuropathy. PMID:23980169

  11. Muon Catalyzed Fusion

    NASA Technical Reports Server (NTRS)

    Armour, Edward A.G.

    2007-01-01

    Muon catalyzed fusion is a process in which a negatively charged muon combines with two nuclei of isotopes of hydrogen, e.g, a proton and a deuteron or a deuteron and a triton, to form a muonic molecular ion in which the binding is so tight that nuclear fusion occurs. The muon is normally released after fusion has taken place and so can catalyze further fusions. As the muon has a mean lifetime of 2.2 microseconds, this is the maximum period over which a muon can participate in this process. This article gives an outline of the history of muon catalyzed fusion from 1947, when it was first realised that such a process might occur, to the present day. It includes a description of the contribution that Drachrnan has made to the theory of muon catalyzed fusion and the influence this has had on the author's research.

  12. Recycling Endosomes and Viral Infection

    PubMed Central

    Vale-Costa, Sílvia; Amorim, Maria João

    2016-01-01

    Many viruses exploit specific arms of the endomembrane system. The unique composition of each arm prompts the development of remarkably specific interactions between viruses and sub-organelles. This review focuses on the viral–host interactions occurring on the endocytic recycling compartment (ERC), and mediated by its regulatory Ras-related in brain (Rab) GTPase Rab11. This protein regulates trafficking from the ERC and the trans-Golgi network to the plasma membrane. Such transport comprises intricate networks of proteins/lipids operating sequentially from the membrane of origin up to the cell surface. Rab11 is also emerging as a critical factor in an increasing number of infections by major animal viruses, including pathogens that provoke human disease. Understanding the interplay between the ERC and viruses is a milestone in human health. Rab11 has been associated with several steps of the viral lifecycles by unclear processes that use sophisticated diversified host machinery. For this reason, we first explore the state-of-the-art on processes regulating membrane composition and trafficking. Subsequently, this review outlines viral interactions with the ERC, highlighting current knowledge on viral-host binding partners. Finally, using examples from the few mechanistic studies available we emphasize how ERC functions are adjusted during infection to remodel cytoskeleton dynamics, innate immunity and membrane composition. PMID:27005655

  13. Induction of Cell-Cell Fusion by Ebola Virus Glycoprotein: Low pH Is Not a Trigger.

    PubMed

    Markosyan, Ruben M; Miao, Chunhui; Zheng, Yi-Min; Melikyan, Gregory B; Liu, Shan-Lu; Cohen, Fredric S

    2016-01-01

    Ebola virus (EBOV) is a highly pathogenic filovirus that causes hemorrhagic fever in humans and animals. Currently, how EBOV fuses its envelope membrane within an endosomal membrane to cause infection is poorly understood. We successfully measure cell-cell fusion mediated by the EBOV fusion protein, GP, assayed by the transfer of both cytoplasmic and membrane dyes. A small molecule fusion inhibitor, a neutralizing antibody, as well as mutations in EBOV GP known to reduce viral infection, all greatly reduce fusion. By monitoring redistribution of small aqueous dyes between cells and by electrical capacitance measurements, we discovered that EBOV GP-mediated fusion pores do not readily enlarge-a marked difference from the behavior of other viral fusion proteins. EBOV GP must be cleaved by late endosome-resident cathepsins B or L in order to become fusion-competent. Cleavage of cell surface-expressed GP appears to occur in endosomes, as evidenced by the fusion block imposed by cathepsin inhibitors, agents that raise endosomal pH, or an inhibitor of anterograde trafficking. Treating effector cells with a recombinant soluble cathepsin B or thermolysin, which cleaves GP into an active form, increases the extent of fusion, suggesting that a fraction of surface-expressed GP is not cleaved. Whereas the rate of fusion is increased by a brief exposure to acidic pH, fusion does occur at neutral pH. Importantly, the extent of fusion is independent of external pH in experiments in which cathepsin activity is blocked and EBOV GP is cleaved by thermolysin. These results imply that low pH promotes fusion through the well-known pH-dependent activity of cathepsins; fusion induced by cleaved EBOV GP is a process that is fundamentally independent of pH. The cell-cell fusion system has revealed some previously unappreciated features of EBOV entry, which could not be readily elucidated in the context of endosomal entry. PMID:26730950

  14. Induction of Cell-Cell Fusion by Ebola Virus Glycoprotein: Low pH Is Not a Trigger

    PubMed Central

    Zheng, Yi-Min; Melikyan, Gregory B.; Liu, Shan-Lu; Cohen, Fredric S.

    2016-01-01

    Ebola virus (EBOV) is a highly pathogenic filovirus that causes hemorrhagic fever in humans and animals. Currently, how EBOV fuses its envelope membrane within an endosomal membrane to cause infection is poorly understood. We successfully measure cell-cell fusion mediated by the EBOV fusion protein, GP, assayed by the transfer of both cytoplasmic and membrane dyes. A small molecule fusion inhibitor, a neutralizing antibody, as well as mutations in EBOV GP known to reduce viral infection, all greatly reduce fusion. By monitoring redistribution of small aqueous dyes between cells and by electrical capacitance measurements, we discovered that EBOV GP-mediated fusion pores do not readily enlarge—a marked difference from the behavior of other viral fusion proteins. EBOV GP must be cleaved by late endosome-resident cathepsins B or L in order to become fusion-competent. Cleavage of cell surface-expressed GP appears to occur in endosomes, as evidenced by the fusion block imposed by cathepsin inhibitors, agents that raise endosomal pH, or an inhibitor of anterograde trafficking. Treating effector cells with a recombinant soluble cathepsin B or thermolysin, which cleaves GP into an active form, increases the extent of fusion, suggesting that a fraction of surface-expressed GP is not cleaved. Whereas the rate of fusion is increased by a brief exposure to acidic pH, fusion does occur at neutral pH. Importantly, the extent of fusion is independent of external pH in experiments in which cathepsin activity is blocked and EBOV GP is cleaved by thermolysin. These results imply that low pH promotes fusion through the well-known pH-dependent activity of cathepsins; fusion induced by cleaved EBOV GP is a process that is fundamentally independent of pH. The cell-cell fusion system has revealed some previously unappreciated features of EBOV entry, which could not be readily elucidated in the context of endosomal entry. PMID:26730950

  15. A combination HIV reporter virus system for measuring post-entry event efficiency and viral outcome in primary CD4+ T cell subsets.

    PubMed

    Tilton, Carisa A; Tabler, Caroline O; Lucera, Mark B; Marek, Samantha L; Haqqani, Aiman A; Tilton, John C

    2014-01-01

    Fusion between the viral membrane of human immunodeficiency virus (HIV) and the host cell marks the end of the HIV entry process and the beginning of a series of post-entry events including uncoating, reverse transcription, integration, and viral gene expression. The efficiency of post-entry events can be modulated by cellular factors including viral restriction factors and can lead to several distinct outcomes: productive, latent, or abortive infection. Understanding host and viral proteins impacting post-entry event efficiency and viral outcome is critical for strategies to reduce HIV infectivity and to optimize transduction of HIV-based gene therapy vectors. Here, we report a combination reporter virus system measuring both membrane fusion and viral promoter-driven gene expression. This system enables precise determination of unstimulated primary CD4+ T cell subsets targeted by HIV, the efficiency of post-entry viral events, and viral outcome and is compatible with high-throughput screening and cell-sorting methods. PMID:24025341

  16. Magnetic-confinement fusion

    NASA Astrophysics Data System (ADS)

    Ongena, J.; Koch, R.; Wolf, R.; Zohm, H.

    2016-05-01

    Our modern society requires environmentally friendly solutions for energy production. Energy can be released not only from the fission of heavy nuclei but also from the fusion of light nuclei. Nuclear fusion is an important option for a clean and safe solution for our long-term energy needs. The extremely high temperatures required for the fusion reaction are routinely realized in several magnetic-fusion machines. Since the early 1990s, up to 16 MW of fusion power has been released in pulses of a few seconds, corresponding to a power multiplication close to break-even. Our understanding of the very complex behaviour of a magnetized plasma at temperatures between 150 and 200 million °C surrounded by cold walls has also advanced substantially. This steady progress has resulted in the construction of ITER, a fusion device with a planned fusion power output of 500 MW in pulses of 400 s. ITER should provide answers to remaining important questions on the integration of physics and technology, through a full-size demonstration of a tenfold power multiplication, and on nuclear safety aspects. Here we review the basic physics underlying magnetic fusion: past achievements, present efforts and the prospects for future production of electrical energy. We also discuss questions related to the safety, waste management and decommissioning of a future fusion power plant.

  17. Henipavirus mediated membrane fusion, virus entry and targeted therapeutics.

    PubMed

    Steffen, Deborah L; Xu, Kai; Nikolov, Dimitar B; Broder, Christopher C

    2012-02-01

    The Paramyxoviridae genus Henipavirus is presently represented by the type species Hendra and Nipah viruses which are both recently emerged zoonotic viral pathogens responsible for repeated outbreaks associated with high morbidity and mortality in Australia, Southeast Asia, India and Bangladesh. These enveloped viruses bind and enter host target cells through the coordinated activities of their attachment (G) and class I fusion (F) envelope glycoproteins. The henipavirus G glycoprotein interacts with host cellular B class ephrins, triggering conformational alterations in G that lead to the activation of the F glycoprotein, which facilitates the membrane fusion process. Using the recently published structures of HeV-G and NiV-G and other paramyxovirus glycoproteins, we review the features of the henipavirus envelope glycoproteins that appear essential for mediating the viral fusion process, including receptor binding, G-F interaction, F activation, with an emphasis on G and the mutations that disrupt viral infectivity. Finally, recent candidate therapeutics for henipavirus-mediated disease are summarized in light of their ability to inhibit HeV and NiV entry by targeting their G and F glycoproteins. PMID:22470837

  18. Henipavirus Mediated Membrane Fusion, Virus Entry and Targeted Therapeutics

    PubMed Central

    Steffen, Deborah L.; Xu, Kai; Nikolov, Dimitar B.; Broder, Christopher C.

    2012-01-01

    The Paramyxoviridae genus Henipavirus is presently represented by the type species Hendra and Nipah viruses which are both recently emerged zoonotic viral pathogens responsible for repeated outbreaks associated with high morbidity and mortality in Australia, Southeast Asia, India and Bangladesh. These enveloped viruses bind and enter host target cells through the coordinated activities of their attachment (G) and class I fusion (F) envelope glycoproteins. The henipavirus G glycoprotein interacts with host cellular B class ephrins, triggering conformational alterations in G that lead to the activation of the F glycoprotein, which facilitates the membrane fusion process. Using the recently published structures of HeV-G and NiV-G and other paramyxovirus glycoproteins, we review the features of the henipavirus envelope glycoproteins that appear essential for mediating the viral fusion process, including receptor binding, G-F interaction, F activation, with an emphasis on G and the mutations that disrupt viral infectivity. Finally, recent candidate therapeutics for henipavirus-mediated disease are summarized in light of their ability to inhibit HeV and NiV entry by targeting their G and F glycoproteins. PMID:22470837

  19. The Role of Phlebovirus Glycoproteins in Viral Entry, Assembly and Release

    PubMed Central

    Spiegel, Martin; Plegge, Teresa; Pöhlmann, Stefan

    2016-01-01

    Bunyaviruses are enveloped viruses with a tripartite RNA genome that can pose a serious threat to animal and human health. Members of the Phlebovirus genus of the family Bunyaviridae are transmitted by mosquitos and ticks to humans and include highly pathogenic agents like Rift Valley fever virus (RVFV) and severe fever with thrombocytopenia syndrome virus (SFTSV) as well as viruses that do not cause disease in humans, like Uukuniemi virus (UUKV). Phleboviruses and other bunyaviruses use their envelope proteins, Gn and Gc, for entry into target cells and for assembly of progeny particles in infected cells. Thus, binding of Gn and Gc to cell surface factors promotes viral attachment and uptake into cells and exposure to endosomal low pH induces Gc-driven fusion of the viral and the vesicle membranes. Moreover, Gn and Gc facilitate virion incorporation of the viral genome via their intracellular domains and Gn and Gc interactions allow the formation of a highly ordered glycoprotein lattice on the virion surface. Studies conducted in the last decade provided important insights into the configuration of phlebovirus Gn and Gc proteins in the viral membrane, the cellular factors used by phleboviruses for entry and the mechanisms employed by phlebovirus Gc proteins for membrane fusion. Here, we will review our knowledge on the glycoprotein biogenesis and the role of Gn and Gc proteins in the phlebovirus replication cycle. PMID:27455305

  20. The Role of Phlebovirus Glycoproteins in Viral Entry, Assembly and Release.

    PubMed

    Spiegel, Martin; Plegge, Teresa; Pöhlmann, Stefan

    2016-01-01

    Bunyaviruses are enveloped viruses with a tripartite RNA genome that can pose a serious threat to animal and human health. Members of the Phlebovirus genus of the family Bunyaviridae are transmitted by mosquitos and ticks to humans and include highly pathogenic agents like Rift Valley fever virus (RVFV) and severe fever with thrombocytopenia syndrome virus (SFTSV) as well as viruses that do not cause disease in humans, like Uukuniemi virus (UUKV). Phleboviruses and other bunyaviruses use their envelope proteins, Gn and Gc, for entry into target cells and for assembly of progeny particles in infected cells. Thus, binding of Gn and Gc to cell surface factors promotes viral attachment and uptake into cells and exposure to endosomal low pH induces Gc-driven fusion of the viral and the vesicle membranes. Moreover, Gn and Gc facilitate virion incorporation of the viral genome via their intracellular domains and Gn and Gc interactions allow the formation of a highly ordered glycoprotein lattice on the virion surface. Studies conducted in the last decade provided important insights into the configuration of phlebovirus Gn and Gc proteins in the viral membrane, the cellular factors used by phleboviruses for entry and the mechanisms employed by phlebovirus Gc proteins for membrane fusion. Here, we will review our knowledge on the glycoprotein biogenesis and the role of Gn and Gc proteins in the phlebovirus replication cycle. PMID:27455305

  1. Development of a cost-effective oral vaccination method against viral disease in fish.

    PubMed

    Companjen, A R; Florack, D E A; Bastiaans, J H M W; Matos, C I; Bosch, D; Rombout, J H W M

    2005-01-01

    Different vaccination methods have been applied to protect fish against the detrimental effects of various pathogens. Several studies have shown the potentials of oral vaccination. In theory oral vaccination is an effortless and stress-free method which can be applied at almost any age. In general, however, the vaccine has to be protected to avoid digestion, which results in high costs for application in aquaculture. In this paper we introduce a cost-effective oral vaccination strategy for viral diseases of fish. The vaccines discussed here include fusion proteins consisting of a gut adhesion molecule and a viral peptide expressed in plants. The adhesion molecule mediates binding to and uptake from the gut, whereas the viral peptide functions as vaccine antigen mediating the induction of a humoral immune response. The first pilot studies using a fusion of the gut adhesion molecule and well-characterised heterologous linear B- and T-cell viral epitopes, produced in potato tubers, showed a promising binding and subsequent uptake in the end gut of carp. The results further indicated that a specific humoral immune response was evoked. PMID:15962477

  2. Viral-templated Palladium Nanocatalysts

    NASA Astrophysics Data System (ADS)

    Yang, Cuixian

    Despite recent progress on nanocatalysis, there exist several critical challenges in simple and readily controllable nanocatalyst synthesis including the unpredictable particle growth, deactivation of catalytic activity, cumbersome catalyst recovery and lack of in-situ reaction monitoring. In this dissertation, two novel approaches are presented for the fabrication of viral-templated palladium (Pd) nanocatalysts, and their catalytic activities for dichromate reduction reaction and Suzuki Coupling reaction were thoroughly studied. In the first approach, viral template based bottom-up assembly is employed for the Pd nanocatalyst synthesis in a chip-based format. Specifically, genetically displayed cysteine residues on each coat protein of Tobacco Mosaic Virus (TMV) templates provide precisely spaced thiol functionalities for readily controllable surface assembly and enhanced formation of catalytically active Pd nanoparticles. Catalysts with the chip-based format allow for simple separation and in-situ monitoring of the reaction extent. Thorough examination of synthesis-structure-activity relationship of Pd nanoparticles formed on surface-assembled viral templates shows that Pd nanoparticle size, catalyst loading density and catalytic activity of viral-templated Pd nanocatalysts can be readily controlled simply by tuning the synthesis conditions. The viral-templated Pd nanocatalysts with optimized synthesis conditions are shown to have higher catalytic activity per unit Pd mass than the commercial Pd/C catalysts. Furthermore, tunable and selective surface assembly of TMV biotemplates is exploited to control the loading density and location of Pd nanocatalysts on solid substrates via preferential electroless deposition. In addition, the catalytic activities of surface-assembled TMV-templated Pd nanocatalysts were also investigated for the ligand-free Suzuki Coupling reaction under mild reaction conditions. The chip-based format enables simple catalyst separation and

  3. Sulfated polysaccharide, curdlan sulfate, efficiently prevents entry/fusion and restricts antibody-dependent enhancement of dengue virus infection in vitro: a possible candidate for clinical application.

    PubMed

    Ichiyama, Koji; Gopala Reddy, Sindhoora Bhargavi; Zhang, Li Feng; Chin, Wei Xin; Muschin, Tegshi; Heinig, Lars; Suzuki, Youichi; Nanjundappa, Haraprasad; Yoshinaka, Yoshiyuki; Ryo, Akihide; Nomura, Nobuo; Ooi, Eng Eong; Vasudevan, Subhash G; Yoshida, Takashi; Yamamoto, Naoki

    2013-01-01

    Curdlan sulfate (CRDS), a sulfated 1→3-β-D glucan, previously shown to be a potent HIV entry inhibitor, is characterized in this study as a potent inhibitor of the Dengue virus (DENV). CRDS was identified by in silico blind docking studies to exhibit binding potential to the envelope (E) protein of the DENV. CRDS was shown to inhibit the DENV replication very efficiently in different cells in vitro. Minimal effective concentration of CRDS was as low as 0.1 µg/mL in LLC-MK2 cells, and toxicity was observed only at concentrations over 10 mg/mL. CRDS can also inhibit DENV-1, 3, and 4 efficiently. CRDS did not inhibit the replication of DENV subgenomic replicon. Time of addition experiments demonstrated that the compound not only inhibited viral infection at the host cell binding step, but also at an early post-attachment step of entry (membrane fusion). The direct binding of CRDS to DENV was suggested by an evident reduction in the viral titers after interaction of the virus with CRDS following an ultrafiltration device separation, as well as after virus adsorption to an alkyl CRDS-coated membrane filter. The electron microscopic features also showed that CRDS interacted directly with the viral envelope, and caused changes to the viral surface. CRDS also potently inhibited DENV infection in DC-SIGN expressing cells as well as the antibody-dependent enhancement of DENV-2 infection. Based on these data, a probable binding model of CRDS to DENV E protein was constructed by a flexible receptor and ligand docking study. The binding site of CRDS was predicted to be at the interface between domains II and III of E protein dimer, which is unique to this compound, and is apparently different from the β-OG binding site. Since CRDS has already been tested in humans without serious side effects, its clinical application can be considered. PMID:23658845

  4. Sulfated Polysaccharide, Curdlan Sulfate, Efficiently Prevents Entry/Fusion and Restricts Antibody-Dependent Enhancement of Dengue Virus Infection In Vitro: A Possible Candidate for Clinical Application

    PubMed Central

    Zhang, Li Feng; Chin, Wei Xin; Muschin, Tegshi; Heinig, Lars; Suzuki, Youichi; Nanjundappa, Haraprasad; Yoshinaka, Yoshiyuki; Ryo, Akihide; Nomura, Nobuo; Ooi, Eng Eong; Vasudevan, Subhash G.; Yoshida, Takashi; Yamamoto, Naoki

    2013-01-01

    Curdlan sulfate (CRDS), a sulfated 1→3-β-D glucan, previously shown to be a potent HIV entry inhibitor, is characterized in this study as a potent inhibitor of the Dengue virus (DENV). CRDS was identified by in silico blind docking studies to exhibit binding potential to the envelope (E) protein of the DENV. CRDS was shown to inhibit the DENV replication very efficiently in different cells in vitro. Minimal effective concentration of CRDS was as low as 0.1 µg/mL in LLC-MK2 cells, and toxicity was observed only at concentrations over 10 mg/mL. CRDS can also inhibit DENV-1, 3, and 4 efficiently. CRDS did not inhibit the replication of DENV subgenomic replicon. Time of addition experiments demonstrated that the compound not only inhibited viral infection at the host cell binding step, but also at an early post-attachment step of entry (membrane fusion). The direct binding of CRDS to DENV was suggested by an evident reduction in the viral titers after interaction of the virus with CRDS following an ultrafiltration device separation, as well as after virus adsorption to an alkyl CRDS-coated membrane filter. The electron microscopic features also showed that CRDS interacted directly with the viral envelope, and caused changes to the viral surface. CRDS also potently inhibited DENV infection in DC-SIGN expressing cells as well as the antibody-dependent enhancement of DENV-2 infection. Based on these data, a probable binding model of CRDS to DENV E protein was constructed by a flexible receptor and ligand docking study. The binding site of CRDS was predicted to be at the interface between domains II and III of E protein dimer, which is unique to this compound, and is apparently different from the β-OG binding site. Since CRDS has already been tested in humans without serious side effects, its clinical application can be considered. PMID:23658845

  5. Observation of incomplete fusion reactions at l < l {sub crit}

    SciTech Connect

    Yadav, Abhishek Sharma, Vijay R. Singh, Devendra P. Unnati,; Singh, B. P.; Prasad, R.; Singh, Pushpendra P.; Bala, Indu; Kumar, R.; Muralithar, S.; Singh, R. P.; Sharma, M. K.

    2014-08-14

    In order to understand the presence of incomplete fusion at low energies i.e. 4-7MeV/nucleon and also to study its dependence on various entrance-channel parameters, the two type of measurements (i) excitation function for {sup 12}C+{sup 159}Tb, and (ii) forward recoil ranges for {sup 12}C+{sup 159}Tb systems have been performed. The experimentally measured excitation functions have been analyzed within the framework of compound nucleus decay using statistical model code PACE4. Analysis of data suggests the production of xn/px)n-channels via complete fusion, as these are found to be well reproduced by PACE4 predictions, while, a significant enhancement in the excitation functions of α-emitting channels has been observed over the theoretical ones, which has been attributed due to the incomplete fusion processes. Further, the incomplete fusion events observed in case of forward recoil range measurements have been explained on the basis of the breakup fusion model, where these events may be attributed to the fusion of {sup 8}Be and/or {sup 4}He from {sup 12}C projectile to the target nucleus. In the present work, the SUMRULE model calculations are found to highly underestimate the observed incomplete fusion cross-sections which indicate that the l-values lower than l {sub crit} (limit of complete fusion) significantly contribute to the incomplete fusion reactions.

  6. Detection and Tracking of Dual-Labeled HIV Particles Using Wide-Field Live Cell Imaging to Follow Viral Core Integrity.

    PubMed

    Mamede, João I; Hope, Thomas J

    2016-01-01

    Live cell imaging is a valuable technique that allows the characterization of the dynamic processes of the HIV-1 life cycle. Here, we present a method of production and imaging of dual-labeled HIV viral particles that allows the visualization of two events. Varying release of the intravirion fluid phase marker reveals virion fusion and the loss of the integrity of HIV viral cores with the use of live wide-field fluorescent microscopy. PMID:26714704

  7. Myristoylated and non-myristoylated forms of the pH sensor protein hisactophilin II: intracellular shuttling to plasma membrane and nucleus monitored in real time by a fusion with green fluorescent protein.

    PubMed Central

    Hanakam, F; Albrecht, R; Eckerskorn, C; Matzner, M; Gerisch, G

    1996-01-01

    Hisactophilins are myristoylated proteins that are rich in histidine residues and known to exist in Dictyostelium cells in a plasma membrane-bound and a soluble cytoplasmic state. Intracellular translocation of these proteins in response to pH changes was monitored using hisactophilin fusions with green fluorescent protein (GFP) and confocal laser scanning microscopy. Both the normal and a mutated non-myristoylated fusion protein shuffled within the cells in a pH-dependent manner. After lowering the pH, these proteins translocated within minutes between the cytoplasm, the plasma membrane and the nucleus. The role of histidine clusters on the surface of hisactophilin molecules in binding of the proteins to the plasma membrane and in their transfer to the nucleus is discussed on the basis of a pH switch mechanism. Images PMID:8670794

  8. The relationship of the lunar regolith less than 10-microns fraction and agglutinates. II - Chemical composition of agglutinate glass as a test of the 'fusion of the finest fraction' /F3/ model

    NASA Technical Reports Server (NTRS)

    Walker, R. J.; Papike, J. J.

    1982-01-01

    Agglutinate glasses from nine Apollo soils have been studied using an automated electron microprobe technique in order to test the fusion of the finest fraction model proposed by Papike (1981). The nine average agglutinate glass compositions are compared with the calculated fused-soil-free compositions, the bulk compositions and the 90-20 micron fraction compositions of the soils in which they are found. It is found that the agglutinate glass data are consistent with the composition of most of the fractions finer than 10 microns, allowing for the volatile loss of K2O and Na2O; some inconsistencies that do arise may result from the degree of soil maturity and the amount of material finer than 10 microns. It is concluded that the fusion of the finest fraction model is a good first approximation of mechanisms affecting the formation of agglutinate glass.

  9. Profiling of Viral Proteins Expressed from the Genomic RNA of Japanese Encephalitis Virus Using a Panel of 15 Region-Specific Polyclonal Rabbit Antisera: Implications for Viral Gene Expression

    PubMed Central

    Yun, Sang-Im; Yun, Gil-Nam; Byun, Sung-June; Lee, Young-Min

    2015-01-01

    Japanese encephalitis virus (JEV), a mosquito-borne flavivirus, is closely related to West Nile (WN), yellow fever (YF), and dengue (DEN) viruses. Its plus-strand genomic RNA carries a single open reading frame encoding a polyprotein that is cleaved into three structural (C, prM/M, and E) and at least seven nonstructural (NS1/NS1', NS2A, NS2B, NS3, NS4A, NS4B, and NS5) proteins, based on previous work with WNV, YFV, and DENV. Here, we aimed to profile experimentally all the viral proteins found in JEV-infected cells. We generated a collection of 15 JEV-specific polyclonal antisera covering all parts of the viral protein-coding regions, by immunizing rabbits with 14 bacterially expressed glutathione-S-transferase fusion proteins (for all nine viral proteins except NS2B) or with a chemically synthesized oligopeptide (for NS2B). In total lysates of JEV-infected BHK-21 cells, immunoblotting with these antisera revealed: (i) three mature structural proteins (~12-kDa C, ~8-kDa M, and ~53-kDa E), a precursor of M (~24-kDa prM) and three other M-related proteins (~10-14 kDa); (ii) the predicted ~45-kDa NS1 and its frameshift product, ~58-kDa NS1', with no evidence of the predicted ~25-kDa NS2A; (iii) the predicted but hardly detectable ~14-kDa NS2B and an unexpected but predominant ~12-kDa NS2B-related protein; (iv) the predicted ~69-kDa NS3 plus two major cleavage products (~34-kDa NS3N-term and ~35-kDa NS3C-term), together with at least nine minor proteins of ~16-52 kDa; (v) the predicted ~14-kDa NS4A; (vi) two NS4B-related proteins (~27-kDa NS4B and ~25-kDa NS4B'); and (vii) the predicted ~103-kDa NS5 plus at least three other NS5-related proteins (~15 kDa, ~27 kDa, and ~90 kDa). Combining these data with confocal microscopic imaging of the proteins’ intracellular localization, our study is the first to provide a solid foundation for the study of JEV gene expression, which is crucial for elucidating the regulatory mechanisms of JEV genome replication and pathobiology

  10. Autophagy-associated dengue vesicles promote viral transmission avoiding antibody neutralization.

    PubMed

    Wu, Yan-Wei; Mettling, Clément; Wu, Shang-Rung; Yu, Chia-Yi; Perng, Guey-Chuen; Lin, Yee-Shin; Lin, Yea-Lih

    2016-01-01

    One of the major defense mechanisms against virus spread in vivo is the blocking of viral infectibility by neutralizing antibodies. We describe here the identification of infectious autophagy-associated dengue vesicles released from infected cells. These vesicles contain viral proteins E, NS1, prM/M, and viral RNA, as well as host lipid droplets and LC3-II, an autophagy marker. The viral RNA can be protected within the autophagic organelles since anti-dengue neutralizing antibodies do not have an effect on the vesicle-mediated transmission that is able to initiate a new round of infection in target cells. Importantly, such infectious vesicles were also detected in a patient serum. Our study suggests that autophagy machinery plays a new role in dengue virus transmission. This discovery explains the inefficiency of neutralizing antibody upon dengue infection as a potential immune evasion mechanism in vivo. PMID:27558165

  11. Autophagy-associated dengue vesicles promote viral transmission avoiding antibody neutralization

    PubMed Central

    Wu, Yan-Wei; Mettling, Clément; Wu, Shang-Rung; Yu, Chia-Yi; Perng, Guey-Chuen; Lin, Yee-Shin; Lin, Yea-Lih

    2016-01-01

    One of the major defense mechanisms against virus spread in vivo is the blocking of viral infectibility by neutralizing antibodies. We describe here the identification of infectious autophagy-associated dengue vesicles released from infected cells. These vesicles contain viral proteins E, NS1, prM/M, and viral RNA, as well as host lipid droplets and LC3-II, an autophagy marker. The viral RNA can be protected within the autophagic organelles since anti-dengue neutralizing antibodies do not have an effect on the vesicle-mediated transmission that is able to initiate a new round of infection in target cells. Importantly, such infectious vesicles were also detected in a patient serum. Our study suggests that autophagy machinery plays a new role in dengue virus transmission. This discovery explains the inefficiency of neutralizing antibody upon dengue infection as a potential immune evasion mechanism in vivo. PMID:27558165

  12. Cdc42 controls the dilation of the exocytotic fusion pore by regulating membrane tension

    PubMed Central

    Bretou, Marine; Jouannot, Ouardane; Fanget, Isabelle; Pierobon, Paolo; Larochette, Nathanaël; Gestraud, Pierre; Guillon, Marc; Emiliani, Valentina; Gasman, Stéphane; Desnos, Claire; Lennon-Duménil, Ana-Maria; Darchen, François

    2014-01-01

    Membrane fusion underlies multiple processes, including exocytosis of hormones and neurotransmitters. Membrane fusion starts with the formation of a narrow fusion pore. Radial expansion of this pore completes the process and allows fast release of secretory compounds, but this step remains poorly understood. Here we show that inhibiting the expression of the small GTPase Cdc42 or preventing its activation with a dominant negative Cdc42 construct in human neuroendocrine cells impaired the release process by compromising fusion pore enlargement. Consequently the mode of vesicle exocytosis was shifted from full-collapse fusion to kiss-and-run. Remarkably, Cdc42-knockdown cells showed reduced membrane tension, and the artificial increase of membrane tension restored fusion pore enlargement. Moreover, inhibiting the motor protein myosin II by blebbistatin decreased membrane tension, as well as fusion pore dilation. We conclude that membrane tension is the driving force for fusion pore dilation and that Cdc42 is a key regulator of this force. PMID:25143404

  13. Viral proteases as targets for drug design.

    PubMed

    Skoreński, Marcin; Sieńczyk, Marcin

    2013-01-01

    In order to productively infect a host, viruses must enter the cell and force host cell replication mechanisms to produce new infectious virus particles. The success of this process unfortunately results in disease progression and, in the case of infection with many viral species, may cause mortality. The discoveries of Louis Pasteur and Edward Jenner led to one of the greatest advances in modern medicine - the development of vaccines that generate long-lasting memory immune responses to combat viral infection. Widespread use of vaccines has reduced mortality and morbidity associated with viral infection and, in some cases, has completely eradicated virus from the human population. Unfortunately, several viral species maintain a significant ability to mutate and "escape" vaccine-induced immune responses. Thus, novel anti-viral agents are required for treatment and prevention of viral disease. Targeting proteases that are crucial in the viral life cycle has proven to be an effective method to control viral infection, and this avenue of investigation continues to generate anti-viral treatments. Herein, we provide the reader with a brief history as well as a comprehensive review of the most recent advances in the design and synthesis of viral protease inhibitors. PMID:23016690

  14. Two Horizons of Fusion

    ERIC Educational Resources Information Center

    Lo, Mun Ling; Chik, Pakey Pui Man

    2016-01-01

    In this paper, we aim to differentiate the internal and external horizons of "fusion." "Fusion" in the internal horizon relates to the structure and meaning of the object of learning as experienced by the learner. It clarifies the interrelationships among an object's critical features and aspects. It also illuminates the…

  15. Fusion Science Education Outreach

    NASA Astrophysics Data System (ADS)

    Danielson, C. A.; DIII-D Education Group

    1996-11-01

    This presentation will focus on education outreach activities at General Atomics that have been expanded to include the general population on science education with a focus on fusion energy. Outreach materials are distributed upon request both nationally and internationally. These materials include a notebook containing copies of DIII--D tour panels, fusion poster, new fusion energy video, new fusion energy brochure, and the electromagnetic spectrum curriculum. The 1996 Fusion Forum (held in the House Caucus Room) included a student/ teacher lunch with Energy Secretary Hazel O'Leary and a private visit to the Forum exhibits. The continuing partnership with Kearny High School includes lectures, job shadowing, internship, equipment donations and an award-winning electric car-racing program. Development of distribution by CD of the existing interactive fusion energy kiosk and a virtual reality tour of the DIII--D facility are underway. The DIII--D fusion education WWW site includes e-mail addresses to ``Ask the Wizard,'' and/or receive GA's outreach materials. Steve Rodecker, a local science teacher, aided by DIII--D fusion staff, won his second Tapestry Award; he also was named the ``1995 National Science Teacher of the Year'' and will be present to share his experiences with the DIII--D educational outreach program.

  16. Controlled Nuclear Fusion.

    ERIC Educational Resources Information Center

    Glasstone, Samuel

    This publication is one of a series of information booklets for the general public published by The United States Atomic Energy Commission. Among the topics discussed are: Importance of Fusion Energy; Conditions for Nuclear Fusion; Thermonuclear Reactions in Plasmas; Plasma Confinement by Magnetic Fields; Experiments With Plasmas; High-Temperature…

  17. Crystal structure of glycoprotein E2 from bovine viral diarrhea virus

    PubMed Central

    Li, Yue; Wang, Jimin; Kanai, Ryuta; Modis, Yorgo

    2013-01-01

    Pestiviruses, including bovine viral diarrhea virus, are important animal pathogens and are closely related to hepatitis C virus, which remains a major global health threat. They have an outer lipid envelope bearing two glycoproteins, E1 and E2, required for cell entry. They deliver their genome into the host cell cytoplasm by fusion of their envelope with a cellular membrane. The crystal structure of bovine viral diarrhea virus E2 reveals a unique protein architecture consisting of two Ig-like domains followed by an elongated β-stranded domain with a new fold. E2 forms end-to-end homodimers with a conserved C-terminal motif rich in aromatic residues at the contact. A disulfide bond across the interface explains the acid resistance of pestiviruses and their requirement for a redox activation step to initiate fusion. From the structure of E2, we propose alternative possible membrane fusion mechanisms. We expect the pestivirus fusion apparatus to be conserved in hepatitis C virus. PMID:23569276

  18. Drug Sanctuaries, Low Steady State Viral Loads and Viral Blips.

    SciTech Connect

    Perelson, Alan S.,; Callaway, D.; Pomerantz, R. J.; Chen, H. Y.; Markowitz, M.; Ho, David D.; Di Mascio, M.

    2002-01-01

    Patients on HAART for long periods of time obtain viral loads (VLs) below 50 copies/ml. Ultrasensitive VL assays show that some of these patients obtain a low steady state VL, while others continue to exhibit VL declines to below 5 copies/ml. Low steady states can be explained by two-compartment models that incorporate a drug sanctuary. Interestingly, when patients exhibit continued declines below 50 copies/ml the rate of decline has a half-life of {approx} 6 months, consistent with some estimates of the rate of latent cell decline. Some patients, despite having sustained undetectable VLs show periods of transient viremia (blips). I will present some statistical characterization of the blips observed in a set of 123 patients, suggesting that blips are generated largely by random processes, that blips tend to correspond to periods of a few weeks in which VLs are elevated, and that VL decay from the peak of a blip may have two-phases. Using new results suggesting that the viral burst size, N {approx} 5 x 10{sup 4}, we estimate the number of cells needed to produce a blip.

  19. Reversible conformational changes and fusion activity of rabies virus glycoprotein.

    PubMed Central

    Gaudin, Y; Tuffereau, C; Segretain, D; Knossow, M; Flamand, A

    1991-01-01

    In an attempt to understand the implication of the rabies virus glycoprotein (G) in the first steps of the viral cycle, we studied the pH dependence of virus-induced fusion and hemagglutination, as well as modifications of the structure and properties of the viral glycoprotein following pH acidification. Our results suggest that the G protein adopts at least three distinct configurations, each associated with different properties. At neutral pH, G did not fuse membranes or hemagglutinate erythrocytes. It was insensitive to digestion with bromelain and trypsin. At pH 6.4, the glycoprotein became sensitive to proteases. Hemagglutination was at its maximum and then sharply decreased with the pH. No fusion was detected. Aggregation of virus was also observed. The third configuration, at below pH 6.1, was associated with the appearance of fusion. Some neutralizing monoclonal antibodies were able to differentiate these three configurations. Preincubation of the virus at below pH 6 inhibited fusion, but this inhibition, like the structural modifications of the glycoprotein, was reversible when G was reincubated at neutral pH. Images PMID:1870204

  20. Characterization of Potent Fusion Inhibitors of Influenza Virus

    PubMed Central

    Rowse, Michael; Qiu, Shihong; Tsao, Jun; Xian, Tongmei; Khawaja, Sarah; Yamauchi, Yohei; Yang, Zhen; Wang, Guoxin; Luo, Ming

    2015-01-01

    New inhibitors of influenza viruses are needed to combat the potential emergence of novel human influenza viruses. We have identified a class of small molecules that inhibit replication of influenza virus at picomolar concentrations in plaque reduction assays. The compound also inhibits replication of vesicular stomatitis virus. Time of addition and dilution experiments with influenza virus indicated that an early time point of infection was blocked and that inhibitor 136 tightly bound to virions. Using fluorescently labeled influenza virus, inhibition of viral fusion to cellular membranes by blocked lipid mixing was established as the mechanism of action for this class of inhibitors. Stabilization of the neutral pH form of hemagglutinin (HA) was ruled out by trypsin digestion studies in vitro and with conformation specific HA antibodies within cells. Direct visualization of 136 treated influenza virions at pH 7.5 or acidified to pH 5.0 showed that virions remain intact and that glycoproteins become disorganized as expected when HA undergoes a conformational change. This suggests that exposure of the fusion peptide at low pH is not inhibited but lipid mixing is inhibited, a different mechanism than previously reported fusion inhibitors. We hypothesize that this new class of inhibitors intercalate into the virus envelope altering the structure of the viral envelope required for fusion to cellular membranes. PMID:25803288

  1. Characterization of potent fusion inhibitors of influenza virus.

    PubMed

    Rowse, Michael; Qiu, Shihong; Tsao, Jun; Xian, Tongmei; Khawaja, Sarah; Yamauchi, Yohei; Yang, Zhen; Wang, Guoxin; Luo, Ming

    2015-01-01

    New inhibitors of influenza viruses are needed to combat the potential emergence of novel human influenza viruses. We have identified a class of small molecules that inhibit replication of influenza virus at picomolar concentrations in plaque reduction assays. The compound also inhibits replication of vesicular stomatitis virus. Time of addition and dilution experiments with influenza virus indicated that an early time point of infection was blocked and that inhibitor 136 tightly bound to virions. Using fluorescently labeled influenza virus, inhibition of viral fusion to cellular membranes by blocked lipid mixing was established as the mechanism of action for this class of inhibitors. Stabilization of the neutral pH form of hemagglutinin (HA) was ruled out by trypsin digestion studies in vitro and with conformation specific HA antibodies within cells. Direct visualization of 136 treated influenza virions at pH 7.5 or acidified to pH 5.0 showed that virions remain intact and that glycoproteins become disorganized as expected when HA undergoes a conformational change. This suggests that exposure of the fusion peptide at low pH is not inhibited but lipid mixing is inhibited, a different mechanism than previously reported fusion inhibitors. We hypothesize that this new class of inhibitors intercalate into the virus envelope altering the structure of the viral envelope required for fusion to cellular membranes. PMID:25803288

  2. Integrated systems for pulsed-power driven inertial fusion energy

    NASA Astrophysics Data System (ADS)

    Cuneo, M. E.; Slutz, S. A.; Stygar, W. A.; Herrmann, M. C.; Sinars, D. B.; McBride, R. D.; Vesey, R. A.; Sefkow, A. B.; Mazarakis, M. G.; Vandevender, J. P.; Waisman, E. M.; Hansen, D. L.; Owen, A. C.; Jones, J. F.; Romero, J. A.; McKenney, J.

    2011-10-01

    Pulsed power fusion concepts integrate: (i) directly-magnetically-driven fusion targets that absorb large energies (10 MJ), (ii) efficient, rep-rated driver modules, (iii) compact, scalable, integrated driver architectures, (iv) driver-to-target coupling techniques with standoff and driver protection, and (v) long lifetime fusion chambers shielded by vaporizing blankets and thick liquid walls. Large fusion yields (3-30 GJ) and low rep-rates (0.1-1 Hz) may be an attractive path for IFE. Experiments on the ZR facility are validating physics issues for magnetically driven targets. Scientific breakeven (fusion energy = fuel energy) may be possible in the next few years. Plans for system development and integration will be discussed. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  3. An FPGA-based heterogeneous image fusion system design method

    NASA Astrophysics Data System (ADS)

    Song, Le; Lin, Yu-chi; Chen, Yan-hua; Zhao, Mei-rong

    2011-08-01

    Taking the advantages of FPGA's low cost and compact structure, an FPGA-based heterogeneous image fusion platform is established in this study. Altera's Cyclone IV series FPGA is adopted as the core processor of the platform, and the visible light CCD camera and infrared thermal imager are used as the image-capturing device in order to obtain dualchannel heterogeneous video images. Tailor-made image fusion algorithms such as gray-scale weighted averaging, maximum selection and minimum selection methods are analyzed and compared. VHDL language and the synchronous design method are utilized to perform a reliable RTL-level description. Altera's Quartus II 9.0 software is applied to simulate and implement the algorithm modules. The contrast experiments of various fusion algorithms show that, preferably image quality of the heterogeneous image fusion can be obtained on top of the proposed system. The applied range of the different fusion algorithms is also discussed.

  4. Decomposition of incomplete fusion

    SciTech Connect

    Sobotka, L.B.; Sarantities, D.G.; Stracener, D.W.; Majka, Z.; Abenante, V.; Semkow, T.M.; Hensley, D.C.; Beene, J.R.; Halbert, M.L.

    1989-01-01

    The velocity distribution of fusion-like products formed in the reaction 701 MeV /sup 28/Si+/sup 100/Mo is decomposed into 26 incomplete fusion channels. The momentum deficit of the residue per nonevaporative mass unit is approximately equal to the beam momentum per nucleon. The yields of the incomplete fusion channels correlate with the Q-value for projectile fragmentation rather than that for incomplete fusion. The backward angle multiplicities of light particles and heavy ions increase with momentum transfer, however, the heavy ion multiplicities also depend on the extent of the fragmentation of the incomplete fusion channel. These data indicate that at fixed linear momentum transfer, increased fragmentation of the unfused component is related to a reduced transferred angular momentum. 22 refs., 6 figs., 1 tab.

  5. Bacterial CRISPR/Cas DNA endonucleases: A revolutionary technology that could dramatically impact viral research and treatment

    PubMed Central

    Kennedy, Edward M.; Cullen, Bryan R.

    2015-01-01

    CRISPR/Cas systems mediate bacterial adaptive immune responses that evolved to protect bacteria from bacteriophage and other horizontally transmitted genetic elements. Several CRISPR/Cas systems exist but the simplest variant, referred to as Type II, has a single effector DNA endonuclease, called Cas9, which is guided to its viral DNA target by two small RNAs, the crRNA and the tracrRNA. Initial efforts to adapt the CRISPR/Cas system for DNA editing in mammalian cells, which focused on the Cas9 protein from Streptococcus pyogenes (Spy), demonstrated that Spy Cas9 can be directed to DNA targets in mammalian cells by tracrRNA:crRNA fusion transcripts called single guide RNAs (sgRNA). Upon binding, Cas9 induces DNA cleavage leading to mutagenesis as a result of error prone non-homologous end joining (NHEJ). Recently, the Spy Cas9 system has been adapted for high throughput screening of genes in human cells for their relevance to a particular phenotype and, more generally, for the targeted inactivation of specific genes, in cell lines and in vivo in a number of model organisms. The latter aim seems likely to be greatly enhanced by the recent development of Cas9 proteins from bacterial species such as Neisseria meningitidis and Staphyloccus aureus that are small enough to be expressed using adeno-associated (AAV)-based vectors that can be readily prepared at very high titers. The evolving Cas9-based DNA editing systems therefore appear likely to not only impact virology by allowing researchers to screen for human genes that affect the replication of pathogenic human viruses of all types but also to derive clonal human cell lines that lack individual gene products that either facilitate or restrict viral replication. Moreover, high titer AAV-based vectors offer the possibility of directly targeting DNA viruses that infect discrete sites in the human body, such as herpes simplex virus and hepatitis B virus, with the hope that the entire population of viral DNA genomes

  6. Bacterial CRISPR/Cas DNA endonucleases: A revolutionary technology that could dramatically impact viral research and treatment.

    PubMed

    Kennedy, Edward M; Cullen, Bryan R

    2015-05-01

    CRISPR/Cas systems mediate bacterial adaptive immune responses that evolved to protect bacteria from bacteriophage and other horizontally transmitted genetic elements. Several CRISPR/Cas systems exist but the simplest variant, referred to as Type II, has a single effector DNA endonuclease, called Cas9, which is guided to its viral DNA target by two small RNAs, the crRNA and the tracrRNA. Initial efforts to adapt the CRISPR/Cas system for DNA editing in mammalian cells, which focused on the Cas9 protein from Streptococcus pyogenes (Spy), demonstrated that Spy Cas9 can be directed to DNA targets in mammalian cells by tracrRNA:crRNA fusion transcripts called single guide RNAs (sgRNA). Upon binding, Cas9 induces DNA cleavage leading to mutagenesis as a result of error prone non-homologous end joining (NHEJ). Recently, the Spy Cas9 system has been adapted for high throughput screening of genes in human cells for their relevance to a particular phenotype and, more generally, for the targeted inactivation of specific genes, in cell lines and in vivo in a number of model organisms. The latter aim seems likely to be greatly enhanced by the recent development of Cas9 proteins from bacterial species such as Neisseria meningitidis and Staphyloccus aureus that are small enough to be expressed using adeno-associated (AAV)-based vectors that can be readily prepared at very high titers. The evolving Cas9-based DNA editing systems therefore appear likely to not only impact virology by allowing researchers to screen for human genes that affect the replication of pathogenic human viruses of all types but also to derive clonal human cell lines that lack individual gene products that either facilitate or restrict viral replication. Moreover, high titer AAV-based vectors offer the possibility of directly targeting DNA viruses that infect discrete sites in the human body, such as herpes simplex virus and hepatitis B virus, with the hope that the entire population of viral DNA genomes

  7. NLRs, inflammasomes, and viral infection

    PubMed Central

    Jacobs, Sarah R.; Damania, Blossom

    2012-01-01

    NLR proteins are innate immune sensors that respond to microbial infection. Upon pathogen infection, some NLR proteins form large complexes, called inflammasomes, which activate caspase-1 and induce the production of active IL-1β and IL-18. Activation of inflammasomes can also lead to an inflammatory cell death program, named pyroptosis. In this review, we will discuss the role of various NLR proteins in sensing different viral infections, as well as the strategies used by several RNA and DNA viruses to counteract the antiviral effects of NLR-dependent inflammasomes. PMID:22581934

  8. Endogenized viral sequences in mammals.

    PubMed

    Parrish, Nicholas F; Tomonaga, Keizo

    2016-06-01

    Reverse-transcribed RNA molecules compose a significant portion of the human genome. Many of these RNA molecules were retrovirus genomes either infecting germline cells or having done so in a previous generation but retaining transcriptional activity. This mechanism itself accounts for a quarter of the genomic sequence information of mammals for which there is data. We understand relatively little about the causes and consequences of retroviral endogenization. This review highlights functions ascribed to sequences of viral origin endogenized into mammalian genomes and suggests some of the most pressing questions raised by these observations. PMID:27128186

  9. [Microbiological diagnosis of viral hepatitis].

    PubMed

    Alonso, Roberto; Aguilera, Antonio; Córdoba, Juan; Fuertes, Antonio

    2015-11-01

    Liver inflammation or hepatitis has many different causes, both infectious and non-infectious. Among the former, viral infection is responsible for at least half of all hepatitis worldwide. Different viruses have been described with primary tropism for liver tissue. These microorganisms have been successively named with letters of the alphabet: A, B, C, D, E and G. The aim of this paper is to review this heterogeneous group of viruses in its most basic aspects, including clinical implications, treatment, main control, and prophylactic measures and, of special interest, diagnostic approaches, both serological and molecular, which are used for their detection, quantification and characterization. PMID:25742731

  10. Viral diseases of marine invertebrates

    NASA Astrophysics Data System (ADS)

    Johnson, P. T.

    1984-03-01

    Approximately 40 viruses are known from marine sponges; turbellarian and monogenetic flatworms; cephalopod, bivalve, and gastropod mollusks; nereid polychaetes; and isopod and decapod crustaceans. Most of the viruses can be tentatively assigned to the Herpesviridae, Baculoviridae, Iridoviridae, Adenoviridae, Papovaviridae, Reoviridae, “Birnaviridae”, Bunyaviridae, Rhabdoviridae, and Picornaviridae. Viruslike particles found in oysters might be representatives of the Togaviridae and Retroviridae. Enveloped single-stranded RNA viruses from crustaceans have developmental and morphological characteristics intermediate between families, and some show evidence of relationships to the Paramyxoviridae as well as the Bunyaviridae or Rhabdoviridae. Certain small viruses of shrimp cannot be assigned, even tentatively, to a particular family. Some viruses cause disease in wild and captive hosts, others are associated with disease states but may not be primary instigators, and many occur in apparently normal animals. The frequency of viral disease in natural populations of marine invertebrates is unknown. Several viruses that cause disease in captive animals, with or without experimental intervention, have also been found in diseased wild hosts, including herpeslike viruses of crabs and oysters, iridovirus of octopus, and reolike and bunyalike viruses of crabs. Iridolike viruses have been implicated in massive mortalities of cultured oysters. Baculoviruses, and IHHN virus, which is of uncertain affinities, cause economically damaging diseases in cultured penaeid shrimp. Double or multiple viral infection is common in crabs. For example, a reolike virus and associated rhabdolike virus act synergistically to cause paralytic and fatal disease in Callinectes sapidus. Information on host range, most susceptible stage, and viral latency is available only for viruses of shrimp. One baculovirus attacks five species of New World penaeid shrimp. IHHN virus infects three species of

  11. ConnesFusionTensorProduct/Photon GluonFusion in Mitochondria

    NASA Astrophysics Data System (ADS)

    Wh-Maksoed, Prodi Of Physics Ui, Depok 16415-Indonesia; Ssi, Wh-Maksoed

    2016-05-01

    As in AJ Wassermann distinguished of classical invariant theory & quantum invariant theory subfactor, in S. Palcoux:``From Neveu-Schwarz Subfactors & Connes Fusion'' described the subfactor theory & Witt-algebra whereas Andreas Thom's explanation about ConnesFusionTensorProduct/CFTP related Connes fusion to composition of homomorphism (i). classical tensor product O-X adds the changes,(ii). Relative tensor product H-X preserve the changes. For photonGluonFusion/PGF defined:''photon is the gauge boson of QED, the simplest of all boson'' devotes to CFT as ``quantum field theory which are invariant under conformal transformation & in 2D there are infinite dimensional algebra. Alain Connes states theirselves Connes fusion as ``associative tensor operation'' to be in coincidences with ``their dynamic behavior driven by the balance in mitochondrial fusion & fission (Carveney, 2007) from Peter Alexander Williams: ``Retinal neuronal remodeling in a model of Optic Atrophy'', Dec, 2011. Great acknowledged to the VicePresident of the R.I, HE.Mr. Drs. M. JUSUF KALLA.

  12. Canine distemper virus envelope protein interactions modulated by hydrophobic residues in the fusion protein globular head.

    PubMed

    Avila, Mislay; Khosravi, Mojtaba; Alves, Lisa; Ader-Ebert, Nadine; Bringolf, Fanny; Zurbriggen, Andreas; Plemper, Richard K; Plattet, Philippe

    2015-01-15

    Membrane fusion for morbillivirus cell entry relies on critical interactions between the viral fusion (F) and attachment (H) envelope glycoproteins. Through extensive mutagenesis of an F cavity recently proposed to contribute to F's interaction with the H protein, we identified two neighboring hydrophobic residues responsible for severe F-to-H binding and fusion-triggering deficiencies when they were mutated in combination. Since both residues reside on one side of the F cavity, the data suggest that H binds the F globular head domain sideways. PMID:25355896

  13. Physics of laser fusion. Vol. I. Theory of the coronal plasma in laser-fusion targets

    SciTech Connect

    Max, C.E.

    1981-12-01

    This monograph deals with the physics of the coronal region in laser fusion targets. The corona consists of hot plasma which has been evaporated from the initially solid target during laser heating. It is in the corona that the laser light is absorbed by the target, and the resulting thermal energy is conducted toward cold high-density regions, where ablation occurs. The topics to be discussed are theoretical mechanisms for laser light absorption and reflection, hot-electron production, and the physics of heat conduction in laser-produced plasmas. An accompanying monograph by H. Ahlstrom (Vol.II) reviews the facilities, diagnostics, and data from recent laser fusion experiments.

  14. Viral Infection in Renal Transplant Recipients

    PubMed Central

    Cukuranovic, Jovana; Ugrenovic, Sladjana; Jovanovic, Ivan; Visnjic, Milan; Stefanovic, Vladisav

    2012-01-01

    Viruses are among the most common causes of opportunistic infection after transplantation. The risk for viral infection is a function of the specific virus encountered, the intensity of immune suppression used to prevent graft rejection, and other host factors governing susceptibility. Although cytomegalovirus is the most common opportunistic pathogen seen in transplant recipients, numerous other viruses have also affected outcomes. In some cases, preventive measures such as pretransplant screening, prophylactic antiviral therapy, or posttransplant viral monitoring may limit the impact of these infections. Recent advances in laboratory monitoring and antiviral therapy have improved outcomes. Studies of viral latency, reactivation, and the cellular effects of viral infection will provide clues for future strategies in prevention and treatment of viral infections. This paper will summarize the major viral infections seen following transplant and discuss strategies for prevention and management of these potential pathogens. PMID:22654630

  15. Update on Alcohol and Viral Hepatitis

    PubMed Central

    Gitto, Stefano; Vitale, Giovanni; Villa, Erica; Andreone, Pietro

    2014-01-01

    Alcohol consumption is often associated with viral hepatitis. Although alcohol is known to worsen viral liver disease, the interactions between alcohol and viral hepatitis are not fully understood. Molecular alterations in the liver due to alcohol and viral hepatitis include effects on viral replication, increased oxidative stress, cytotoxicity, and a weakened immune response. Clinically, alcohol enhances disease progression and favors induction of primitive liver neoplasm. The use of new antivirals for hepatitis C and well-established drugs for hepatitis B will determine how viral hepatitis can be controlled in a large percentage of these patients. However, alcohol-related liver disease continues to represent a barrier for access to antivirals, and it remains an unresolved health issue. PMID:26356547

  16. Cell-based analysis of Chikungunya virus E1 protein in membrane fusion

    PubMed Central

    2012-01-01

    Background Chikungunya fever is a pandemic disease caused by the mosquito-borne Chikungunya virus (CHIKV). E1 glycoprotein mediation of viral membrane fusion during CHIKV infection is a crucial step in the release of viral genome into the host cytoplasm for replication. How the E1 structure determines membrane fusion and whether other CHIKV structural proteins participate in E1 fusion activity remain largely unexplored. Methods A bicistronic baculovirus expression system to produce recombinant baculoviruses for cell-based assay was used. Sf21 insect cells infected by recombinant baculoviruses bearing wild type or single-amino-acid substitution of CHIKV E1 and EGFP (enhanced green fluorescence protein) were employed to investigate the roles of four E1 amino acid residues (G91, V178, A226, and H230) in membrane fusion activity. Results Western blot analysis revealed that the E1 expression level and surface features in wild type and mutant substituted cells were similar. However, cell fusion assay found that those cells infected by CHIKV E1-H230A mutant baculovirus showed little fusion activity, and those bearing CHIKV E1-G91D mutant completely lost the ability to induce cell-cell fusion. Cells infected by recombinant baculoviruses of CHIKV E1-A226V and E1-V178A mutants exhibited the same membrane fusion capability as wild type. Although the E1 expression level of cells bearing monomeric-E1-based constructs (expressing E1 only) was greater than that of cells bearing 26S-based constructs (expressing all structural proteins), the sizes of syncytial cells induced by infection of baculoviruses containing 26S-based constructs were larger than those from infections having monomeric-E1 constructs, suggesting that other viral structure proteins participate or regulate E1 fusion activity. Furthermore, membrane fusion in cells infected by baculovirus bearing the A226V mutation constructs exhibited increased cholesterol-dependences and lower pH thresholds. Cells bearing the V178

  17. Sequencing Needs for Viral Diagnostics

    SciTech Connect

    Gardner, S N; Lam, M; Mulakken, N J; Torres, C L; Smith, J R; Slezak, T

    2004-01-26

    We built a system to guide decisions regarding the amount of genomic sequencing required to develop diagnostic DNA signatures, which are short sequences that are sufficient to uniquely identify a viral species. We used our existing DNA diagnostic signature prediction pipeline, which selects regions of a target species genome that are conserved among strains of the target (for reliability, to prevent false negatives) and unique relative to other species (for specificity, to avoid false positives). We performed simulations, based on existing sequence data, to assess the number of genome sequences of a target species and of close phylogenetic relatives (''near neighbors'') that are required to predict diagnostic signature regions that are conserved among strains of the target species and unique relative to other bacterial and viral species. For DNA viruses such as variola (smallpox), three target genomes provide sufficient guidance for selecting species-wide signatures. Three near neighbor genomes are critical for species specificity. In contrast, most RNA viruses require four target genomes and no near neighbor genomes, since lack of conservation among strains is more limiting than uniqueness. SARS and Ebola Zaire are exceptional, as additional target genomes currently do not improve predictions, but near neighbor sequences are urgently needed. Our results also indicate that double stranded DNA viruses are more conserved among strains than are RNA viruses, since in most cases there was at least one conserved signature candidate for the DNA viruses and zero conserved signature candidates for the RNA viruses.

  18. Population Dynamics of Viral Inactivation

    NASA Astrophysics Data System (ADS)

    Freeman, Krista; Li, Dong; Behrens, Manja; Streletzky, Kiril; Olsson, Ulf; Evilevitch, Alex

    We have investigated the population dynamics of viral inactivation in vitrousing time-resolved cryo electron microscopy combined with light and X-ray scattering techniques. Using bacteriophage λ as a model system for pressurized double-stranded DNA viruses, we found that virions incubated with their cell receptor eject their genome in a stochastic triggering process. The triggering of DNA ejection occurs in a non synchronized manner after the receptor addition, resulting in an exponential decay of the number of genome-filled viruses with time. We have explored the characteristic time constant of this triggering process at different temperatures, salt conditions, and packaged genome lengths. Furthermore, using the temperature dependence we determined an activation energy for DNA ejections. The dependences of the time constant and activation energy on internal DNA pressure, affected by salt conditions and encapsidated genome length, suggest that the triggering process is directly dependent on the conformational state of the encapsidated DNA. The results of this work provide insight into how the in vivo kinetics of the spread of viral infection are influenced by intra- and extra cellular environmental conditions. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship under Grant No. DGE-1252522.

  19. Viral Subversion of the Nuclear Pore Complex

    PubMed Central

    Le Sage, Valerie; Mouland, Andrew J.

    2013-01-01

    The nuclear pore complex (NPC) acts as a selective barrier between the nucleus and the cytoplasm and is responsible for mediating communication by regulating the transport of RNA and proteins. Numerous viral pathogens have evolved different mechanisms to hijack the NPC in order to regulate trafficking of viral proteins, genomes and even capsids into and out of the nucleus thus promoting virus replication. The present review examines the different strategies and the specific nucleoporins utilized during viral infections as a means of promoting their life cycle and inhibiting host viral defenses. PMID:23959328

  20. Snapshots: Chromatin Control of Viral Infection

    PubMed Central

    Knipe, David M.; Lieberman, Paul M.; Jung, Jae U.; McBride, Alison A.; Morris, Kevin V.; Ott, Melanie; Margolis, David; Nieto, Amelia; Nevels, Michael; Parks, Robin J.; Kristie, Thomas M.

    2012-01-01

    Like their cellular host counterparts, many invading viral pathogens must contend with, modulate, and utilize the host cell’s chromatin machinery to promote efficient lytic infection or control persistent-latent states. While not intended to be comprehensive, this review represents a compilation of conceptual snapshots of the dynamic interplay of viruses with the chromatin environment. Contributions focus on chromatin dynamics during infection, viral circumvention of cellular chromatin repression, chromatin organization of large DNA viruses, tethering and persistence, viral interactions with cellular chromatin modulation machinery, and control of viral latency-reactivation cycles. PMID:23217624

  1. RTNS-II: irradiations at the Rotating Target Neutron Source-II. 1983 annual report

    SciTech Connect

    Not Available

    1983-01-01

    This is the second annual report summarizing irradiation experiments and operations at RTNS-II. It covers calendar year 1983 and includes reports on all irradiations, non-fusion as well as fusion, and on utilization of Monbusho's transmission electron microscope (TEM) a RTNS-II. Each summary article has been submitted by the investigator and has been altered only to meet the style and format requirements of this report.

  2. Globin mRNAs are primers for the transcription of influenza viral RNA in vitro

    PubMed Central

    Bouloy, Michele; Plotch, Stephen J.; Krug, Robert M.

    1978-01-01

    Because influenza viral RNA transcription in vitro is greatly enhanced by the addition of a primer dinucleotide, ApG or GpG, we have proposed that viral RNA transcription in vivo requires initiation by primer RNAs synthesized by the host cell, specifically by RNA polymerase II, thereby explaining the α-amanitin sensitivity of viral RNA transcription in vivo. Here, we identify such primer RNAs, initially in reticulocyte extracts, where they are shown to be globin mRNAs. Purified globin mRNAs very effectively stimulated viral RNA transcription in vitro, and the resulting transcripts directed the synthesis of all the nonglycosylated virus-specific proteins in micrococcal nuclease-treated L cell extracts. The viral RNA transcripts synthesized in vitro primed by ApG also directed the synthesis of the nonglycosylated virus-specific proteins, but the globin mRNA-primed transcripts were translated about 3 times more efficiently. The translation of the globin mRNA-primed, but not the ApG-primed, viral RNA transcripts was inhibited by 7-methylguanosine 5′-phosphate in the presence of S-adenosylhomocysteine, suggesting that the globin mRNA-primed transcripts contained a 5′-terminal methylated cap structure. We propose that this cap was transferred from the globin mRNA primer to the newly synthesized viral RNA transcripts, because no detectable de novo synthesis of a methylated cap occurred during globin mRNA-primed viral RNA transcription. Preliminary experiments indicate that other purified eukaryotic mRNAs also stimulate influenza viral RNA transcription in vitro. Images PMID:283399

  3. Fusion Studies in Japan

    NASA Astrophysics Data System (ADS)

    Ogawa, Yuichi

    2016-05-01

    A new strategic energy plan decided by the Japanese Cabinet in 2014 strongly supports the steady promotion of nuclear fusion development activities, including the ITER project and the Broader Approach activities from the long-term viewpoint. Atomic Energy Commission (AEC) in Japan formulated the Third Phase Basic Program so as to promote an experimental fusion reactor project. In 2005 AEC has reviewed this Program, and discussed on selection and concentration among many projects of fusion reactor development. In addition to the promotion of ITER project, advanced tokamak research by JT-60SA, helical plasma experiment by LHD, FIREX project in laser fusion research and fusion engineering by IFMIF were highly prioritized. Although the basic concept is quite different between tokamak, helical and laser fusion researches, there exist a lot of common features such as plasma physics on 3-D magnetic geometry, high power heat load on plasma facing component and so on. Therefore, a synergetic scenario on fusion reactor development among various plasma confinement concepts would be important.

  4. Histone deacetylase 6 inhibition enhances oncolytic viral replication in glioma

    PubMed Central

    Nakashima, Hiroshi; Kaufmann, Johanna K.; Wang, Pin-Yi; Nguyen, Tran; Speranza, Maria-Carmela; Kasai, Kazue; Okemoto, Kazuo; Otsuki, Akihiro; Nakano, Ichiro; Fernandez, Soledad; Goins, William F.; Grandi, Paola; Glorioso, Joseph C.; Lawler, Sean; Cripe, Timothy P.; Chiocca, E. Antonio

    2015-01-01

    Oncolytic viral (OV) therapy, which uses genetically engineered tumor-targeting viruses, is being increasingly used in cancer clinical trials due to the direct cytolytic effects of this treatment that appear to provoke a robust immune response against the tumor. As OVs enter tumor cells, intrinsic host defenses have the potential to hinder viral replication and spread within the tumor mass. In this report, we show that histone deacetylase 6 (HDAC6) in tumor cells appears to alter the trafficking of post-entry OVs from the nucleus toward lysosomes. In glioma cell lines and glioma-stem–like cells, HDAC6 inhibition (HDAC6i) by either pharmacologic or genetic means substantially increased replication of oncolytic herpes simplex virus type 1 (oHSV). Moreover, HDAC6i increased shuttling of post-entry oHSV to the nucleus. In addition, electron microscopic analysis revealed that post-entry oHSVs are preferentially taken up into glioma cells through the endosomal pathway rather than via fusion at the cell surface. Together, these findings illustrate a mechanism of glioma cell defense against an incoming infection by oHSV and identify possible approaches to enhance oHSV replication and subsequent lysis of tumor cells. PMID:26524593

  5. A Sorting Signal Suppresses IFITM1 Restriction of Viral Entry*

    PubMed Central

    Li, Kun; Jia, Rui; Li, Minghua; Zheng, Yi-Min; Miao, Chunhui; Yao, Yunfang; Ji, Hong-Long; Geng, Yunqi; Qiao, Wentao; Albritton, Lorraine M.; Liang, Chen; Liu, Shan-Lu

    2015-01-01

    The interferon-induced transmembrane proteins (IFITMs) broadly inhibit virus infections, particularly at the viral entry level. However, despite this shared ability to inhibit fusion, IFITMs differ in the potency and breadth of viruses restricted, an anomaly that is not fully understood. Here, we show that differences in the range of viruses restricted by IFITM1 are regulated by a C-terminal non-canonical dibasic sorting signal KRXX that suppresses restriction of some viruses by governing its intracellular distribution. Replacing the two basic residues with alanine (KR/AA) increased restriction of jaagsiekte sheep retrovirus and 10A1 amphotropic murine leukemia virus. Deconvolution microscopy revealed an altered subcellular distribution for KR/AA, with fewer molecules in LAMP1-positive lysosomes balanced by increased levels in CD63-positive multivesicular bodies, where jaagsiekte sheep retrovirus pseudovirions are colocalized. IFITM1 binds to cellular adaptor protein complex 3 (AP-3), an association that is lost when the dibasic motif is altered. Although knockdown of AP-3 itself decreases some virus entry, expression of parental IFITM1, but not its KR/AA mutant, potentiates inhibition of viral infections in AP-3 knockdown cells. By using the substituted cysteine accessibility method, we provide evidence that IFITM1 adopts more than one membrane topology co-existing in cellular membranes. Because the C-terminal dibasic sorting signal is unique to human IFITM1, our results provide novel insight into understanding the species- and virus-specific antiviral effect of IFITMs. PMID:25527505

  6. Histone deacetylase 6 inhibition enhances oncolytic viral replication in glioma.

    PubMed

    Nakashima, Hiroshi; Kaufmann, Johanna K; Wang, Pin-Yi; Nguyen, Tran; Speranza, Maria-Carmela; Kasai, Kazue; Okemoto, Kazuo; Otsuki, Akihiro; Nakano, Ichiro; Fernandez, Soledad; Goins, William F; Grandi, Paola; Glorioso, Joseph C; Lawler, Sean; Cripe, Timothy P; Chiocca, E Antonio

    2015-11-01

    Oncolytic viral (OV) therapy, which uses genetically engineered tumor-targeting viruses, is being increasingly used in cancer clinical trials due to the direct cytolytic effects of this treatment that appear to provoke a robust immune response against the tumor. As OVs enter tumor cells, intrinsic host defenses have the potential to hinder viral replication and spread within the tumor mass. In this report, we show that histone deacetylase 6 (HDAC6) in tumor cells appears to alter the trafficking of post-entry OVs from the nucleus toward lysosomes. In glioma cell lines and glioma-stem-like cells, HDAC6 inhibition (HDAC6i) by either pharmacologic or genetic means substantially increased replication of oncolytic herpes simplex virus type 1 (oHSV). Moreover, HDAC6i increased shuttling of post-entry oHSV to the nucleus. In addition, electron microscopic analysis revealed that post-entry oHSVs are preferentially taken up into glioma cells through the endosomal pathway rather than via fusion at the cell surface. Together, these findings illustrate a mechanism of glioma cell defense against an incoming infection by oHSV and identify possible approaches to enhance oHSV replication and subsequent lysis of tumor cells. PMID:26524593

  7. A sorting signal suppresses IFITM1 restriction of viral entry.

    PubMed

    Li, Kun; Jia, Rui; Li, Minghua; Zheng, Yi-Min; Miao, Chunhui; Yao, Yunfang; Ji, Hong-Long; Geng, Yunqi; Qiao, Wentao; Albritton, Lorraine M; Liang, Chen; Liu, Shan-Lu

    2015-02-13

    The interferon-induced transmembrane proteins (IFITMs) broadly inhibit virus infections, particularly at the viral entry level. However, despite this shared ability to inhibit fusion, IFITMs differ in the potency and breadth of viruses restricted, an anomaly that is not fully understood. Here, we show that differences in the range of viruses restricted by IFITM1 are regulated by a C-terminal non-canonical dibasic sorting signal KRXX that suppresses restriction of some viruses by governing its intracellular distribution. Replacing the two basic residues with alanine (KR/AA) increased restriction of jaagsiekte sheep retrovirus and 10A1 amphotropic murine leukemia virus. Deconvolution microscopy revealed an altered subcellular distribution for KR/AA, with fewer molecules in LAMP1-positive lysosomes balanced by increased levels in CD63-positive multivesicular bodies, where jaagsiekte sheep retrovirus pseudovirions are colocalized. IFITM1 binds to cellular adaptor protein complex 3 (AP-3), an association that is lost when the dibasic motif is altered. Although knockdown of AP-3 itself decreases some virus entry, expression of parental IFITM1, but not its KR/AA mutant, potentiates inhibition of viral infections in AP-3 knockdown cells. By using the substituted cysteine accessibility method, we provide evidence that IFITM1 adopts more than one membrane topology co-existing in cellular membranes. Because the C-terminal dibasic sorting signal is unique to human IFITM1, our results provide novel insight into understanding the species- and virus-specific antiviral effect of IFITMs. PMID:25527505

  8. Magnetic systems for fusion devices

    SciTech Connect

    Henning, C.D.

    1985-02-01

    Mirror experiments have led the way in applying superconductivity to fusion research because of unique requirements for high and steady magnetic fields. The first significant applications were Baseball II at LLNL and IMP at ORNL. More recently, the MFTF-B yin-yang coil was successfully tested and the entire tandem configuration is nearing completion. Tokamak magnets have also enjoyed recent success with the large coil project tests at ORNL, preceded by single coil tests in Japan and Germany. In the USSR, the T-7 Tokamak has been operational for many years and the T-15 Tokamak is under construction, with the TF coils nearing completion. Also the Tore Supra is being built in France.

  9. HIV fusion peptide penetrates, disorders, and softens T-cell membrane mimics.

    PubMed

    Tristram-Nagle, Stephanie; Chan, Rob; Kooijman, Edgar; Uppamoochikkal, Pradeep; Qiang, Wei; Weliky, David P; Nagle, John F

    2010-09-10

    This work investigates the interaction of N-terminal gp41 fusion peptide (FP) of human immunodeficiency virus type 1 (HIV-1) with model membranes in order to elucidate how FP leads to fusion of HIV and T-cell membranes. FP constructs were (i) wild-type FP23 (23 N-terminal amino acids of gp41), (ii) water-soluble monomeric FP that adds six lysines on the C-terminus of FP23 (FPwsm), and (iii) the C-terminus covalently linked trimeric version (FPtri) of FPwsm. Model membranes were (i) LM3 (a T-cell mimic), (ii) 1,2-dioleoyl-sn-glycero-3-phosphocholine, (iii) 1,2-dioleoyl-sn-glycero-3-phosphocholine/30 mol% cholesterol, (iv) 1,2-dierucoyl-sn-glycero-3-phosphocholine, and (v) 1,2-dierucoyl-sn-glycero-3-phosphocholine/30 mol% cholesterol. Diffuse synchrotron low-angle x-ray scattering from fully hydrated samples, supplemented by volumetric data, showed that FP23 and FPtri penetrate into the hydrocarbon region and cause membranes to thin. Depth of penetration appears to depend upon a complex combination of factors including bilayer thickness, presence of cholesterol, and electrostatics. X-ray data showed an increase in curvature in hexagonal phase 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine, which further indicates that FP23 penetrates into the hydrocarbon region rather than residing in the interfacial headgroup region. Low-angle x-ray scattering data also yielded the bending modulus K(C), a measure of membrane stiffness, and wide-angle x-ray scattering yielded the S(xray) orientational order parameter. Both FP23 and FPtri decreased K(C) and S(xray) considerably, while the weak effect of FPwsm suggests that it did not partition strongly into LM3 model membranes. Our results are consistent with the HIV FP disordering and softening the T-cell membrane, thereby lowering the activation energy for viral membrane fusion. PMID:20655315

  10. Electrostatic Architecture of the Infectious Salmon Anemia Virus (ISAV) Core Fusion Protein Illustrates a Carboxyl-Carboxylate pH Sensor*

    PubMed Central

    Cook, Jonathan D.; Soto-Montoya, Hazel; Korpela, Markus K.; Lee, Jeffrey E.

    2015-01-01

    Segment 5, ORF 1 of the infectious salmon anemia virus (ISAV) genome, encodes for the ISAV F protein, which is responsible for viral-host endosomal membrane fusion during a productive ISAV infection. The entry machinery of ISAV is composed of a complex of the ISAV F and ISAV hemagglutinin esterase (HE) proteins in an unknown stoichiometry prior to receptor engagement by ISAV HE. Following binding of the receptor to ISAV HE, dissociation of the ISAV F protein from HE, and subsequent endocytosis, the ISAV F protein resolves into a fusion-competent oligomeric state. Here, we present a 2.1 Å crystal structure of the fusion core of the ISAV F protein determined at low pH. This structure has allowed us to unambiguously demonstrate that the ISAV entry machinery exhibits typical class I viral fusion protein architecture. Furthermore, we have determined stabilizing factors that accommodate the pH-dependent mode of ISAV transmission, and our structure has allowed the identification of a central coil that is conserved across numerous and varied post-fusion viral glycoprotein structures. We then discuss a mechanistic model of ISAV fusion that parallels the paramyxoviral class I fusion strategy wherein attachment and fusion are relegated to separate proteins in a similar fashion to ISAV fusion. PMID:26082488

  11. The stability analysis of a general viral infection model with distributed delays and multi-staged infected progression

    NASA Astrophysics Data System (ADS)

    Wang, Jinliang; Liu, Shengqiang

    2015-01-01

    We investigate an in-host model with general incidence and removal rate, as well as distributed delays in virus infections and in productions. By employing Lyapunov functionals and LaSalle's invariance principle, we define and prove the basic reproductive number R0 as a threshold quantity for stability of equilibria. It is shown that if R0 > 1 , then the infected equilibrium is globally asymptotically stable, while if R0 ⩽ 1 , then the infection free equilibrium is globally asymptotically stable under some reasonable assumptions. Moreover, n + 1 distributed delays describe (i) the time between viral entry and the transcription of viral RNA, (ii) the n - 1 -stage time needed for activated infected cells between viral RNA transcription and viral release, and (iii) the time necessary for the newly produced viruses to be infectious (maturation), respectively. The model can describe the viral infection dynamics of many viruses such as HIV-1, HCV and HBV.

  12. Spherical torus fusion reactor

    DOEpatents

    Martin Peng, Y.K.M.

    1985-10-03

    The object of this invention is to provide a compact torus fusion reactor with dramatic simplification of plasma confinement design. Another object of this invention is to provide a compact torus fusion reactor with low magnetic field and small aspect ratio stable plasma confinement. In accordance with the principles of this invention there is provided a compact toroidal-type plasma confinement fusion reactor in which only the indispensable components inboard of a tokamak type of plasma confinement region, mainly a current conducting medium which carries electrical current for producing a toroidal magnet confinement field about the toroidal plasma region, are retained.

  13. HIV gp41-Mediated Membrane Fusion Occurs at Edges of Cholesterol-Rich Lipid Domains

    PubMed Central

    Yang, Sung-Tae; Kiessling, Volker; Simmons, James A.; White, Judith M.; Tamm, Lukas K.

    2015-01-01

    Lipid rafts in plasma membranes have emerged as possible platforms for entry of HIV and other viruses into cells. However, how lipid phase heterogeneity contributes to viral entry is little known due to the fine-grained and still poorly understood complexity of biological membranes. We used model systems mimicking HIV envelopes and T-cell membranes and showed that raft-like (Lo phase) lipid domains are necessary and sufficient for efficient membrane targeting and fusion. Interestingly, membrane binding and fusion was low in homogeneous Ld and Lo phase membranes, indicating that lipid phase heterogeneity is essential. The HIV fusion peptide preferentially targeted to Lo/Ld boundary regions and promoted full fusion at the interface between ordered and disordered lipids. Ld phase vesicles proceeded only to hemifusion. Thus, we propose that the edges, but not the areas of raft-like ordered lipid domains are vital for HIV entry and membrane fusion. PMID:25915200

  14. Fusion for Space Propulsion

    NASA Technical Reports Server (NTRS)

    Thio, Y. C. Francis; Schafer, Charles (Technical Monitor)

    2001-01-01

    There is little doubt that humans will attempt to explore and develop the solar system in this century. A large amount of energy will be required for accomplishing this. The need for fusion propulsion is discussed. For a propulsion system, there are three important thermodynamical attributes: (1) The absolute amount of energy available, (2) the propellant exhaust velocity, and (3) the jet power per unit mass of the propulsion system (specific power). For human exploration and development of the solar system, propellant exhaust velocity in excess of 100 km/s and specific power in excess of 10 kW/kg are required. Chemical combustion can produce exhaust velocity up to about 5 km/s. Nuclear fission processes typically result in producing energy in the form of heat that needs to be manipulated at temperatures limited by materials to about 2,800 K. Using the energy to heat a hydrogen propellant increases the exhaust velocity by only a factor of about two. Alternatively the energy can be converted into electricity which is then used to accelerate particles to high exhaust velocity. The necessary power conversion and conditioning equipment, however, increases the mass of the propulsion system for the same jet power by more than two orders of magnitude over chemical system, thus greatly limits the thrust-to-weight ratio attainable. The principal advantage of the fission process is that its development is relatively mature and is available right now. If fusion can be developed, fusion appears to have the best of all worlds in terms of propulsion - it can provide the absolute amount, the propellant exhaust velocity, and the high specific jet power. An intermediate step towards pure fusion propulsion is a bimodal system in which a fission reactor is used to provide some of the energy to drive a fusion propulsion unit. The technical issues related to fusion for space propulsion are discussed. The technical priorities for developing and applying fusion for propulsion are

  15. New Small Molecule Entry Inhibitors Targeting Hemagglutinin-Mediated Influenza A Virus Fusion

    PubMed Central

    Antanasijevic, Aleksandar; Wang, Minxiu; Li, Bing; Mills, Debra M.; Ames, Jessica A.; Nash, Peter J.; Williams, John D.; Peet, Norton P.; Moir, Donald T.; Prichard, Mark N.; Keith, Kathy A.; Barnard, Dale L.; Caffrey, Michael; Rong, Lijun; Bowlin, Terry L.

    2014-01-01

    Influenza viruses are a major public health threat worldwide, and options for antiviral therapy are limited by the emergence of drug-resistant virus strains. The influenza virus glycoprotein hemagglutinin (HA) plays critical roles in the early stage of virus infection, including receptor binding and membrane fusion, making it a potential target for the development of anti-influenza drugs. Using pseudotype virus-based high-throughput screens, we have identified several new small molecules capable of inhibiting influenza virus entry. We prioritized two novel inhibitors, MBX2329 and MBX2546, with aminoalkyl phenol ether and sulfonamide scaffolds, respectively, that specifically inhibit HA-mediated viral entry. The two compounds (i) are potent (50% inhibitory concentration [IC50] of 0.3 to 5.9 μM); (ii) are selective (50% cytotoxicity concentration [CC50] of >100 μM), with selectivity index (SI) values of >20 to 200 for different influenza virus strains; (iii) inhibit a wide spectrum of influenza A viruses, which includes the 2009 pandemic influenza virus A/H1N1/2009, highly pathogenic avian influenza (HPAI) virus A/H5N1, and oseltamivir-resistant A/H1N1 strains; (iv) exhibit large volumes of synergy with oseltamivir (36 and 331 μM2 % at 95% confidence); and (v) have chemically tractable structures. Mechanism-of-action studies suggest that both MBX2329 and MBX2546 bind to HA in a nonoverlapping manner. Additional results from HA-mediated hemolysis of chicken red blood cells (cRBCs), competition assays with monoclonal antibody (MAb) C179, and mutational analysis suggest that the compounds bind in the stem region of the HA trimer and inhibit HA-mediated fusion. Therefore, MBX2329 and MBX2546 represent new starting points for chemical optimization and have the potential to provide valuable future therapeutic options and research tools to study the HA-mediated entry process. PMID:24198411

  16. Viral ancestors of antiviral systems.

    PubMed

    Villarreal, Luis P

    2011-10-01

    All life must survive their corresponding viruses. Thus antiviral systems are essential in all living organisms. Remnants of virus derived information are also found in all life forms but have historically been considered mostly as junk DNA. However, such virus derived information can strongly affect host susceptibility to viruses. In this review, I evaluate the role viruses have had in the origin and evolution of host antiviral systems. From Archaea through bacteria and from simple to complex eukaryotes I trace the viral components that became essential elements of antiviral immunity. I conclude with a reexamination of the 'Big Bang' theory for the emergence of the adaptive immune system in vertebrates by horizontal transfer and note how viruses could have and did provide crucial and coordinated features. PMID:22069523

  17. Addressing viral resistance through vaccines

    PubMed Central

    Laughlin, Catherine; Schleif, Amanda; Heilman, Carole A

    2015-01-01

    Antimicrobial resistance is a serious healthcare concern affecting millions of people around the world. Antiviral resistance has been viewed as a lesser threat than antibiotic resistance, but it is important to consider approaches to address this growing issue. While vaccination is a logical strategy, and has been shown to be successful many times over, next generation viral vaccines with a specific goal of curbing antiviral resistance will need to clear several hurdles including vaccine design, evaluation and implementation. This article suggests that a new model of vaccination may need to be considered: rather than focusing on public health, this model would primarily target sectors of the population who are at high risk for complications from certain infections. PMID:26604979

  18. Viral haemorrhagic fever in children.

    PubMed

    MacDermott, Nathalie E; De, Surjo; Herberg, Jethro A

    2016-05-01

    Viral haemorrhagic fevers (VHFs) are currently at the forefront of the world's attention due to the recentZaire ebolavirusepidemic in West Africa. This epidemic has highlighted the frailty of the world's public health response mechanisms and demonstrated the potential risks to nations around the world of imported cases of epidemic diseases. While imported cases in children are less likely, the potential for such a scenario remains. It is therefore essential that paediatricians are aware of and prepared for potential imported cases of tropical diseases, VHFs being of particular importance due to their propensity to cause nosocomial spread. Examining the four families of viruses-Filoviridae,Arenaviridae,BunyaviridaeandFlaviviridae, we describe the different types of VHFs, with emphasis on differentiation from other diseases through detailed history-taking, their presentation and management from a paediatric perspective. PMID:26787609

  19. Viral Ancestors of Antiviral Systems

    PubMed Central

    Villarreal, Luis P.

    2011-01-01

    All life must survive their corresponding viruses. Thus antiviral systems are essential in all living organisms. Remnants of virus derived information are also found in all life forms but have historically been considered mostly as junk DNA. However, such virus derived information can strongly affect host susceptibility to viruses. In this review, I evaluate the role viruses have had in the origin and evolution of host antiviral systems. From Archaea through bacteria and from simple to complex eukaryotes I trace the viral components that became essential elements of antiviral immunity. I conclude with a reexamination of the ‘Big Bang’ theory for the emergence of the adaptive immune system in vertebrates by horizontal transfer and note how viruses could have and did provide crucial and coordinated features. PMID:22069523

  20. Viral hepatitis vaccination during pregnancy.

    PubMed

    Zhao, Yueyuan; Jin, Hui; Zhang, Xuefeng; Wang, Bei; Liu, Pei

    2016-04-01

    Viral hepatitis is a serious global public health problem. It is also a common cause of jaundice and gestational complications in pregnant women. Moreover, infected mothers can transmit the virus to their fetus or neonate, which may increase disease burden and decrease quality of life. To date, commercial vaccines have been developed for hepatitis A, B, and E and are available to the general population. The Advisory Committee on Immunization Practices currently accepts emergency vaccination against hepatitis A and B during pregnancy due to benefits that overweight the potential risks. While there are limited data from trials with limited numbers of samples that suggest the efficacy or safety of hepatitis B and E vaccines in pregnant women, additional data are necessary to provide evidence of vaccination during pregnancy. PMID:26833263

  1. Viral-associated thrombotic microangiopathies.

    PubMed

    Lopes da Silva, Rodrigo

    2011-01-01

    Thrombotic microangiopathies encompass a group of disorders characterized by microangiopathic hemolytic anemia, thrombocytopenia associated with hyaline thrombi (comprised primarily of platelet aggregates in the microcirculation), and varying degrees of end-organ failure. Many primary (genetic) and secondary etiological predisposing factors have been described-namely pregnancy, autoimmune disorders, cancer, drugs and antineoplastic therapy, bone marrow transplantation/solid organ transplantation, and infections. In the setting of infectious diseases, the association with Shiga or Shiga-like exotoxin of Escherichia coli 0157:h7 or Shigella dysenteriae type 1-induced typical hemolytic uremic syndrome is well known. Recently however, an increasing body of evidence suggests that viruses may also play an important role as trigger factors in the pathogenesis of thrombotic microangiopathies. This is a comprehensive review focusing on the current understanding of viral associated/induced endothelial stimulation and damage that ultimately leads to the development of this life-threatening multisystemic disorder. PMID:21727765

  2. Label fusion strategy selection.

    PubMed

    Robitaille, Nicolas; Duchesne, Simon

    2012-01-01

    Label fusion is used in medical image segmentation to combine several different labels of the same entity into a single discrete label, potentially more accurate, with respect to the exact, sought segmentation, than the best input element. Using simulated data, we compared three existing label fusion techniques-STAPLE, Voting, and Shape-Based Averaging (SBA)-and observed that none could be considered superior depending on the dissimilarity between the input elements. We thus developed an empirical, hybrid technique called SVS, which selects the most appropriate technique to apply based on this dissimilarity. We evaluated the label fusion strategies on two- and three-dimensional simulated data and showed that SVS is superior to any of the three existing methods examined. On real data, we used SVS to perform fusions of 10 segmentations of the hippocampus and amygdala in 78 subjects from the ICBM dataset. SVS selected SBA in almost all cases, which was the most appropriate method overall. PMID:22518113

  3. Fusion power demonstration

    SciTech Connect

    Henning, C.D.; Logan, B.G.

    1983-09-01

    As a satellite to the MARS (Mirror Advanced Reactor Study) a smaller, near-term device has been scoped, called the FPD (Fusion Power Demonstration). Envisioned as the next logical step toward a power reactor, it would advance the mirror fusion program beyond MFTF-B and provide an intermediate step toward commercial fusion power. Breakeven net electric power capability would be the goal such that no net utility power would be required to sustain the operation. A phased implementation is envisioned, with a deuterium checkout first to verify the plasma systems before significant neutron activation has occurred. Major tritium-related facilities would be installed with the second phase to produce sufficient fusion power to supply the recirculating power to maintain the neutral beams, ECRH, magnets and other auxiliary equipment.

  4. Laser-Driven Fusion.

    ERIC Educational Resources Information Center

    Gibson, A. F.

    1980-01-01

    Discusses the present status and future prospects of laser-driven fusion. Current research (which is classified under three main headings: laser-matter interaction processes, compression, and laser development) is also presented. (HM)

  5. Progress toward fusion energy

    SciTech Connect

    Thomassen, K.I.

    1981-03-11

    This paper summarizes the basis for the present optimism in the magnetic fusion program, and describes some of the remaining tasks leading to a demonstration power reactor and the primary technologies necessary for that endeavor.

  6. Localization of a Region in the Fusion Protein of Avian Metapneumovirus That Modulates Cell-Cell Fusion

    PubMed Central

    Wei, Yongwei; Feng, Kurtis; Yao, Xiangjie; Cai, Hui; Li, Junan; Mirza, Anne M.; Iorio, Ronald M.

    2012-01-01

    The genus Metapneumovirus within the subfamily Pneumovirinae of the family Paramyxoviridae includes two members, human metapneumovirus (hMPV) and avian metapneumovirus (aMPV), causing respiratory tract infections in humans and birds, respectively. Paramyxoviruses enter host cells by fusing the viral envelope with a host cell membrane. Membrane fusion of hMPV appears to be unique, in that fusion of some hMPV strains requires low pH. Here, we show that the fusion (F) proteins of aMPV promote fusion in the absence of the attachment protein and low pH is not required. Furthermore, there are notable differences in cell-cell fusion among aMPV subtypes. Trypsin was required for cell-cell fusion induced by subtype B but not subtypes A and C. The F protein of aMPV subtype A was highly fusogenic, whereas those from subtypes B and C were not. By construction and evaluation of chimeric F proteins composed of domains from the F proteins of subtypes A and B, we localized a region composed of amino acid residues 170 to 338 in the F protein that is responsible for the hyperfusogenic phenotype of the F from subtype A. Further mutagenesis analysis revealed that residues R295, G297, and K323 in this region collectively contributed to the hyperfusogenicity. Taken together, we have identified a region in the aMPV F protein that modulates the extent of membrane fusion. A model for fusion consistent with these data is presented. PMID:22915815

  7. Cold nuclear fusion

    SciTech Connect

    Tsyganov, E. N.

    2012-02-15

    Recent accelerator experiments on fusion of various elements have clearly demonstrated that the effective cross-sections of these reactions depend on what material the target particle is placed in. In these experiments, there was a significant increase in the probability of interaction when target nuclei are imbedded in a conducting crystal or are a part of it. These experiments open a new perspective on the problem of so-called cold nuclear fusion.

  8. Glossary of fusion energy

    SciTech Connect

    Whitson, M.O.

    1985-02-01

    The Glossary of Fusion Energy is an attempt to present a concise, yet comprehensive collection of terms that may be beneficial to scientists and laymen who are directly or tangentially concerned with this burgeoning energy enterprise. Included are definitions of terms in theoretical plasma physics, controlled thermonuclear fusion, and some related physics concepts. Also, short descriptions of some of the major thermonuclear experiments currently under way in the world today are included.

  9. Advances in fusion technology

    NASA Astrophysics Data System (ADS)

    Baker, Charles C.

    2000-12-01

    The US fusion technology program is an essential element in the development of the knowledge base for an attractive fusion power source. The technology program incorporates both near and long term R&D, contributes to material and engineering sciences as well as technology development, ranges from hardware production to theory and modeling, contributes significantly to spin-off applications, and performs global systems assessments and focused design studies.

  10. Viral kinetic modeling: state of the art

    SciTech Connect

    Canini, Laetitia; Perelson, Alan S.

    2014-06-25

    Viral kinetic modeling has led to increased understanding of the within host dynamics of viral infections and the effects of therapy. Here we review recent developments in the modeling of viral infection kinetics with emphasis on two infectious diseases: hepatitis C and influenza. We review how viral kinetic modeling has evolved from simple models of viral infections treated with a drug or drug cocktail with an assumed constant effectiveness to models that incorporate drug pharmacokinetics and pharmacodynamics, as well as phenomenological models that simply assume drugs have time varying-effectiveness. We also discuss multiscale models that include intracellular events in viral replication, models of drug-resistance, models that include innate and adaptive immune responses and models that incorporate cell-to-cell spread of infection. Overall, viral kinetic modeling has provided new insights into the understanding of the disease progression and the modes of action of several drugs. In conclusion, we expect that viral kinetic modeling will be increasingly used in the coming years to optimize drug regimens in order to improve therapeutic outcomes and treatment tolerability for infectious diseases.

  11. Macrophages and the Viral Dissemination Super Highway

    PubMed Central

    Klepper, Arielle; Branch, Andrea D

    2016-01-01

    Monocytes and macrophages are key components of the innate immune system yet they are often the victims of attack by infectious agents. This review examines the significance of viral infection of macrophages. The central hypothesis is that macrophage tropism enhances viral dissemination and persistence, but these changes may come at the cost of reduced replication in cells other than macrophages. PMID:26949751

  12. Mitochondria Apply the Brake to Viral Immunity.

    PubMed

    Ashton-Rickardt, Philip G

    2016-06-14

    The development and function of cytotoxic CD8 T cells (CTLs), which provide immunity to viral infections, are regulated by changes in mitochondrial respiration. Champagne et al. (2016) describe a new mechanism through which mitochondrial metabolism controls production of ATP required for the secretion of critical anti-viral molecules by CTLs. PMID:27304497

  13. Molecular biology of bovine viral diarrhea virus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bovine viral diarrhea viruses (BVDV) are arguably the most important viral pathogen of ruminants worldwide and can cause severe economic loss. Clinical symptoms of the disease caused by BVDV range from subclinical to severe acute hemorrhagic syndrome, with the severity of disease being strain depend...

  14. Magnetized Target Fusion

    NASA Technical Reports Server (NTRS)

    Griffin, Steven T.

    2002-01-01

    Magnetized target fusion (MTF) is under consideration as a means of building a low mass, high specific impulse, and high thrust propulsion system for interplanetary travel. This unique combination is the result of the generation of a high temperature plasma by the nuclear fusion process. This plasma can then be deflected by magnetic fields to provide thrust. Fusion is initiated by a small traction of the energy generated in the magnetic coils due to the plasma's compression of the magnetic field. The power gain from a fusion reaction is such that inefficiencies due to thermal neutrons and coil losses can be overcome. Since the fusion reaction products are directly used for propulsion and the power to initiate the reaction is directly obtained from the thrust generation, no massive power supply for energy conversion is required. The result should be a low engine mass, high specific impulse and high thrust system. The key is to successfully initiate fusion as a proof-of-principle for this application. Currently MSFC is implementing MTF proof-of-principle experiments. This involves many technical details and ancillary investigations. Of these, selected pertinent issues include the properties, orientation and timing of the plasma guns and the convergence and interface development of the "pusher" plasma. Computer simulations of the target plasma's behavior under compression and the convergence and mixing of the gun plasma are under investigation. This work is to focus on the gun characterization and development as it relates to plasma initiation and repeatability.

  15. ITER Fusion Energy

    ScienceCinema

    Dr. Norbert Holtkamp

    2010-01-08

    ITER (in Latin ?the way?) is designed to demonstrate the scientific and technological feasibility of fusion energy. Fusion is the process by which two light atomic nuclei combine to form a heavier over one and thus release energy. In the fusion process two isotopes of hydrogen ? deuterium and tritium ? fuse together to form a helium atom and a neutron. Thus fusion could provide large scale energy production without greenhouse effects; essentially limitless fuel would be available all over the world. The principal goals of ITER are to generate 500 megawatts of fusion power for periods of 300 to 500 seconds with a fusion power multiplication factor, Q, of at least 10. Q ? 10 (input power 50 MW / output power 500 MW). The ITER Organization was officially established in Cadarache, France, on 24 October 2007. The seven members engaged in the project ? China, the European Union, India, Japan, Korea, Russia and the United States ? represent more than half the world?s population. The costs for ITER are shared by the seven members. The cost for the construction will be approximately 5.5 billion Euros, a similar amount is foreseen for the twenty-year phase of operation and the subsequent decommissioning.

  16. The conserved glycine residues in the transmembrane domain of the Semliki Forest virus fusion protein are not required for assembly and fusion

    SciTech Connect

    Liao Maofu; Kielian, Margaret . E-mail: kielian@aecom.yu.edu

    2005-02-05

    The alphavirus Semliki Forest virus (SFV) infects cells via a low pH-triggered fusion reaction mediated by the viral E1 protein. Both the E1 fusion peptide and transmembrane (TM) domain are essential for membrane fusion, but the functional requirements for the TM domain are poorly understood. Here we explored the role of the five TM domain glycine residues, including the highly conserved glycine pair at E1 residues 415/416. SFV mutants with alanine substitutions for individual or all five glycine residues (5G/A) showed growth kinetics and fusion pH dependence similar to those of wild-type SFV. Mutants with increasing substitution of glycine residues showed an increasingly more stringent requirement for cholesterol during fusion. The 5G/A mutant showed decreased fusion kinetics and extent in fluorescent lipid mixing assays. TM domain glycine residues thus are not required for efficient SFV fusion or assembly but can cause subtle effects on the properties of membrane fusion.

  17. Human Metapneumovirus Is Capable of Entering Cells by Fusion with Endosomal Membranes

    PubMed Central

    Cox, Reagan G.; Mainou, Bernardo A.; Johnson, Monika; Hastings, Andrew K.; Schuster, Jennifer E.; Dermody, Terence S.; Williams, John V.

    2015-01-01

    Human metapneumovirus (HMPV), a member of the Paramyxoviridae family, is a leading cause of lower respiratory illness. Although receptor binding is thought to initiate fusion at the plasma membrane for paramyxoviruses, the entry mechanism for HMPV is largely uncharacterized. Here we sought to determine whether HMPV initiates fusion at the plasma membrane or following internalization. To study the HMPV entry process in human bronchial epithelial (BEAS-2B) cells, we used fluorescence microscopy, an R18-dequenching fusion assay, and developed a quantitative, fluorescence microscopy assay to follow virus binding, internalization, membrane fusion, and visualize the cellular site of HMPV fusion. We found that HMPV particles are internalized into human bronchial epithelial cells before fusing with endosomes. Using chemical inhibitors and RNA interference, we determined that HMPV particles are internalized via clathrin-mediated endocytosis in a dynamin-dependent manner. HMPV fusion and productive infection are promoted by RGD-binding integrin engagement, internalization, actin polymerization, and dynamin. Further, HMPV fusion is pH-independent, although infection with rare strains is modestly inhibited by RNA interference or chemical inhibition of endosomal acidification. Thus, HMPV can enter via endocytosis, but the viral fusion machinery is not triggered by low pH. Together, our results indicate that HMPV is capable of entering host cells by multiple pathways, including membrane fusion from endosomal compartments. PMID:26629703

  18. Integrin αvβ1 Modulation Affects Subtype B Avian Metapneumovirus Fusion Protein-mediated Cell-Cell Fusion and Virus Infection.

    PubMed

    Yun, Bing-Ling; Guan, Xiao-Lu; Liu, Yong-Zhen; Zhang, Yao; Wang, Yong-Qiang; Qi, Xiao-Le; Cui, Hong-Yu; Liu, Chang-Jun; Zhang, Yan-Ping; Gao, Hong-Lei; Gao, Li; Li, Kai; Gao, Yu-Long; Wang, Xiao-Mei

    2016-07-01

    Avian metapneumovirus (aMPV) fusion (F) protein mediates virus-cell membrane fusion to initiate viral infection, which requires F protein binding to its receptor(s) on the host cell surface. However, the receptor(s) for aMPV F protein is still not identified. All known subtype B aMPV (aMPV/B) F proteins contain a conserved Arg-Asp-Asp (RDD) motif, suggesting that the aMPV/B F protein may mediate membrane fusion via the binding of RDD to integrin. When blocked with integrin-specific peptides, aMPV/B F protein fusogenicity and viral replication were significantly reduced. Specifically we identified integrin αv and/or β1-mediated F protein fusogenicity and viral replication using antibody blocking, small interfering RNAs (siRNAs) knockdown, and overexpression. Additionally, overexpression of integrin αv and β1 in aMPV/B non-permissive cells conferred aMPV/B F protein binding and aMPV/B infection. When RDD was altered to RAE (Arg-Ala-Glu), aMPV/B F protein binding and fusogenic activity were profoundly impaired. These results suggest that integrin αvβ1 is a functional receptor for aMPV/B F protein-mediated membrane fusion and virus infection, which will provide new insights on the fusogenic mechanism and pathogenesis of aMPV. PMID:27226547

  19. Ethical Considerations in Research Participation Virality.

    PubMed

    Ellis-Barton, Carol

    2016-07-01

    This article seeks to commence and encourage discussion around the upcoming ethical challenges of virality in network structures. When the call for participation in a research project on lupus in Ireland went from an advertisement in a newsletter to a meme (unit of transmissible information) on a closed Facebook page, the ethical considerations of virality were raised. The article analyzes the Association of Internet Researchers guidelines, Facebook policies, and the context of privacy in relation to virality. Virality creates the leverage for methodological pluralism. The nature of the inquiry can determine the method rather than the other way around. Viral ethical considerations are evolving due to the cyber world becoming the primary meme of communication, with flexibility in the researcher's protocol providing opportunities for efficient, cost-effective, and diverse recruitment. PMID:27534590

  20. Non-random patterns in viral diversity

    PubMed Central

    Anthony, Simon J.; Islam, Ariful; Johnson, Christine; Navarrete-Macias, Isamara; Liang, Eliza; Jain, Komal; Hitchens, Peta L.; Che, Xiaoyu; Soloyvov, Alexander; Hicks, Allison L.; Ojeda-Flores, Rafael; Zambrana-Torrelio, Carlos; Ulrich, Werner; Rostal, Melinda K.; Petrosov, Alexandra; Garcia, Joel; Haider, Najmul; Wolfe, Nathan; Goldstein, Tracey; Morse, Stephen S.; Rahman, Mahmudur; Epstein, Jonathan H.; Mazet, Jonna K.; Daszak, Peter; Lipkin, W. Ian

    2015-01-01

    It is currently unclear whether changes in viral communities will ever be predictable. Here we investigate whether viral communities in wildlife are inherently structured (inferring predictability) by looking at whether communities are assembled through deterministic (often predictable) or stochastic (not predictable) processes. We sample macaque faeces across nine sites in Bangladesh and use consensus PCR and sequencing to discover 184 viruses from 14 viral families. We then use network modelling and statistical null-hypothesis testing to show the presence of non-random deterministic patterns at different scales, between sites and within individuals. We show that the effects of determinism are not absolute however, as stochastic patterns are also observed. In showing that determinism is an important process in viral community assembly we conclude that it should be possible to forecast changes to some portion of a viral community, however there will always be some portion for which prediction will be unlikely. PMID:26391192

  1. Hepatitis C Viral Kinetics in Special Populations

    PubMed Central

    Dahari, Harel; Layden-Almer, Jennifer E.; Perelson, Alan S.; Layden, Thomas J.

    2008-01-01

    Mathematical models of hepatitis C viral (HCV) kinetics provide a means of estimating the antiviral effectiveness of therapy, the rate of virion clearance and the rate of loss of HCV-infected cells. They have also proved useful in evaluating the extrahepatic contribution to HCV plasma viremia and they have suggested mechanisms of action for both interferon-α and ribavirin. Viral kinetic models can explain the observed HCV RNA profiles under treatment, e.g., flat partial response, biphasic and triphasic viral decay and viral rebound. Current therapy with (pegylated) interferon-α and ribavirin has a poorer success in patients having insulin resistance, hepatic fibrosis, African American ethnicity, HCV/HIV-coinfection, HCV genotype-1 and high baseline viral load. The use of mathematical modeling and statistical analysis of experimental data have been useful in understanding some of these treatment obstacles. PMID:19148305

  2. Viral dark matter and virus–host interactions resolved from publicly available microbial genomes

    PubMed Central

    Roux, Simon; Hallam, Steven J; Woyke, Tanja; Sullivan, Matthew B

    2015-01-01

    The ecological importance of viruses is now widely recognized, yet our limited knowledge of viral sequence space and virus–host interactions precludes accurate prediction of their roles and impacts. In this study, we mined publicly available bacterial and archaeal genomic data sets to identify 12,498 high-confidence viral genomes linked to their microbial hosts. These data augment public data sets 10-fold, provide first viral sequences for 13 new bacterial phyla including ecologically abundant phyla, and help taxonomically identify 7–38% of ‘unknown’ sequence space in viromes. Genome- and network-based classification was largely consistent with accepted viral taxonomy and suggested that (i) 264 new viral genera were identified (doubling known genera) and (ii) cross-taxon genomic recombination is limited. Further analyses provided empirical data on extrachromosomal prophages and coinfection prevalences, as well as evaluation of in silico virus–host linkage predictions. Together these findings illustrate the value of mining viral signal from microbial genomes. DOI: http://dx.doi.org/10.7554/eLife.08490.001 PMID:26200428

  3. Extensive multiplex PCR diagnostics reveal new insights into the epidemiology of viral respiratory infections.

    PubMed

    Nickbakhsh, S; Thorburn, F; VON Wissmann, B; McMENAMIN, J; Gunson, R N; Murcia, P R

    2016-07-01

    Viral respiratory infections continue to pose a major global healthcare burden. At the community level, the co-circulation of respiratory viruses is common and yet studies generally focus on single aetiologies. We conducted the first comprehensive epidemiological analysis to encompass all major respiratory viruses in a single population. Using extensive multiplex PCR diagnostic data generated by the largest NHS board in Scotland, we analysed 44230 patient episodes of respiratory illness that were simultaneously tested for 11 virus groups between 2005 and 2013, spanning the 2009 influenza A pandemic. We measured viral infection prevalence, described co-infections, and identified factors independently associated with viral infection using multivariable logistic regression. Our study provides baseline measures and reveals new insights that will direct future research into the epidemiological consequences of virus co-circulation. In particular, our study shows that (i) human coronavirus infections are more common during influenza seasons and in co-infections than previously recognized, (ii) factors associated with co-infection differ from those associated with viral infection overall, (iii) virus prevalence has increased over time especially in infants aged <1 year, and (iv) viral infection risk is greater in the post-2009 pandemic era, likely reflecting a widespread change in the viral population that warrants further investigation. PMID:26931455

  4. Formation of a stable complex between the human immunodeficiency virus integrase protein and viral DNA.

    PubMed Central

    Vink, C; Lutzke, R A; Plasterk, R H

    1994-01-01

    The integrase (IN) protein of the human immunodeficiency virus (HIV) mediates two distinct reactions: (i) specific removal of two nucleotides from the 3' ends of the viral DNA and (ii) integration of the viral DNA into target DNA. Although IN discriminates between specific (viral) DNA and nonspecific DNA in physical in vitro assays, a sequence-specific DNA-binding domain could not be identified in the protein. A nonspecific DNA-binding domain, however, was found at the C terminus of the protein. We examined the DNA-binding characteristics of HIV-1 IN, and found that a stable complex of IN and viral DNA is formed in the presence of Mn2+. The IN-viral DNA complex is resistant to challenge by an excess of competitor DNA. Stable binding of IN to the viral DNA requires that the protein contains an intact N-terminal domain and active site (in the central region of the protein), in addition to the C-terminal DNA-binding domain. Images PMID:7937134

  5. Stem cell gene therapy for HIV: strategies to inhibit viral entry and replication.

    PubMed

    DiGiusto, David L

    2015-03-01

    Since the demonstration of a cure of an HIV+ patient with an allogeneic stem cell transplant using naturally HIV-resistant cells, significant interest in creating similar autologous products has fueled the development of a variety of "cell engineering" approaches to stem cell therapy for HIV. Among the more well-studied strategies is the inhibition of viral entry through disruption of expression of viral co-receptors or through competitive inhibitors of viral fusion with the cell membrane. Preclinical evaluation of these approaches often starts in vitro but ultimately is tested in animal models prior to clinical implementation. In this review, we trace the development of several key approaches (meganucleases, short hairpin RNA (shRNA), and fusion inhibitors) to modification of hematopoietic stem cells designed to impart resistance to HIV to their T-cell and monocytic progeny. The basic evolution of technologies through in vitro and in vivo testing is discussed as well as the pros and cons of each approach and how the addition of postentry inhibitors may enhance the overall antiviral efficacy of these approaches. PMID:25578054

  6. A soluble form of Epstein-Barr virus gH/gL inhibits EBV-induced membrane fusion and does not function in fusion

    SciTech Connect

    Rowe, Cynthia L.; Connolly, Sarah A.; Chen, Jia; Jardetzky, Theodore S.; Longnecker, Richard

    2013-02-05

    We investigated whether soluble EBV gH/gL (sgH/gL) functions in fusion and made a series of truncations of gH/gL domains based on the gH/gL crystal structure. We found sgH/gL failed to mediate cell-cell fusion both when co-expressed with the other entry glycoproteins and when added exogenously to fusion assays. Interestingly, sgH/gL inhibited cell-cell fusion in a dose dependent manner when co-expressed. sgH/gL from HSV was unable to inhibit EBV fusion, suggesting the inhibition was specific to EBV gH/gL. sgH/gL stably binds gp42, but not gB nor gH/gL. The domain mutants, DI/gL, DI-II/gL and DI-II-III/gL were unable to bind gp42. Instead, DI-II/gL, DI-II-III/gL and sgH/gL but not DI/gL decreased the expression of gp42, resulting in decreased overall fusion. Overall, our results suggest that domain IV may be required for proper folding and the transmembrane domain and cytoplasmic tail of EBV gH/gL are required for the most efficient fusion.

  7. Fusion of Pedigreed Preferential Relations as Beliefs

    NASA Astrophysics Data System (ADS)

    Suzuki, Yoshitaka; Tojo, Satoshi

    Belief fusion, instead of AGM belief revision, was first proposed to solve the problem of inconsistency, that arised from repetitive application of the operation when agents' knowledge were amalgamated. In the preceding work of Maynard-Reid II and Shoham, the fusion operator is applied to belief states, which is total preorders over possible worlds which is based on the semantics of belief revision. Moreover, they introduced the pedigreed belief state, which represented multiple sources of belief states, ordered by a credibility ranking. However in the theory, all the sources must be totally ordered and thus applicable area is quite restrictive. In this paper, we realize the fusion operator of multiple agents for partially ordered sources. When we consider such a partial ranking over sources, there is no need to restrict that each agent has total preorders over possible worlds. The preferential model, based on the semantics on nonmonotonic reasoning, allows each agent to have strict partial orders over possible worlds. Especially, such an order is called a preferential relation, that prescribes a world is more plausible than the other. Therefore, we introduce an operation which combines multiple preferential relations of agents. In addition, we show that our operation can properly include the ordinary belief fusion.

  8. Fusion/Astrophysics Teacher Research Academy

    NASA Astrophysics Data System (ADS)

    Correll, Donald

    2005-10-01

    In order to engage California high school science teachers in the area of plasma physics and fusion research, LLNL's Fusion Energy Program has partnered with the UC Davis Edward Teller Education Center, ETEC (http://etec.ucdavis.edu), the Stanford University Solar Center (http://solar-center.stanford.edu) and LLNL's Science / Technology Education Program, STEP (http://education.llnl.gov). A four-level ``Fusion & Astrophysics Research Academy'' has been designed to give teachers experience in conducting research using spectroscopy with their students. Spectroscopy, and its relationship to atomic physics and electromagnetism, provides for an ideal plasma `bridge' to the CA Science Education Standards (http://www.cde.ca.gov/be/st/ss/scphysics.asp). Teachers attend multiple-day professional development workshops to explore new research activities for use in the high school science classroom. A Level I, 3-day program consists of two days where teachers learn how plasma researchers use spectrometers followed by instructions on how to use a research grade spectrometer for their own investigations. A 3rd day includes touring LLNL's SSPX (http://www.mfescience.org/sspx/) facility to see spectrometry being used to measure plasma properties. Spectrometry classroom kits are made available for loaning to participating teachers. Level I workshop results (http://education.llnl.gov/fusion&_slash;astro/) will be presented along with plans being developed for Level II (one week advanced SKA's), Level III (pre-internship), and Level IV (summer internship) research academies.

  9. An unexpected twist in viral capsid maturation

    SciTech Connect

    Gertsman, Ilya; Gan, Lu; Guttman, Miklos; Lee, Kelly; Speir, Jeffrey A.; Duda, Robert L.; Hendrix, Roger W.; Komives, Elizabeth A.; Johnson, John E.

    2009-04-14

    Lambda-like double-stranded (ds) DNA bacteriophage undergo massive conformational changes in their capsid shell during the packaging of their viral genomes. Capsid shells are complex organizations of hundreds of protein subunits that assemble into intricate quaternary complexes that ultimately are able to withstand over 50 atm of pressure during genome packaging. The extensive integration between subunits in capsids requires the formation of an intermediate complex, termed a procapsid, from which individual subunits can undergo the necessary refolding and structural rearrangements needed to transition to the more stable capsid. Although various mature capsids have been characterized at atomic resolution, no such procapsid structure is available for a dsDNA virus or bacteriophage. Here we present a procapsid X-ray structure at 3.65 {angstrom} resolution, termed prohead II, of the lambda-like bacteriophage HK97, the mature capsid structure of which was previously solved to 3.44 {angstrom}. A comparison of the two largely different capsid forms has unveiled an unprecedented expansion mechanism that describes the transition. Crystallographic and hydrogen/deuterium exchange data presented here demonstrate that the subunit tertiary structures are significantly different between the two states, with twisting and bending motions occurring in both helical and -sheet regions. We also identified subunit interactions at each three-fold axis of the capsid that are maintained throughout maturation. The interactions sustain capsid integrity during subunit refolding and provide a fixed hinge from which subunits undergo rotational and translational motions during maturation. Previously published calorimetric data of a closely related bacteriophage, P22, showed that capsid maturation was an exothermic process that resulted in a release of 90 kJ mol{sup -1} of energy. We propose that the major tertiary changes presented in this study reveal a structural basis for an exothermic

  10. An Unexpected Twist in Viral Capsid Maturation

    PubMed Central

    Gertsman, Ilya; Gan, Lu; Guttman, Miklos; Lee, Kelly; Speir, Jeffrey A.; Duda, Robert L.; Hendrix, Roger W.; Komives, Elizabeth A.; Johnson, John E.

    2009-01-01

    Lambda-like dsDNA bacteriophage undergo massive conformational changes in their capsid shell during the packaging of their viral genomes. Capsid shells are complex organizations of hundreds of protein subunits that assemble into intricate quaternary complexes that ultimately are able to withstand over 50 atm. of pressure during genome packaging1. The extensive integration between subunits in capsids is unlikely to form in a single assembly step, therefore requiring formation of an intermediate complex, termed a procapsid, from which individual subunits can undergo the necessary refolding and structural rearrangements needed to transition to the more stable capsid. Though various mature capsids have been characterized at atomic resolution, no such procapsid structure is available for a dsDNA virus or bacteriophage that undergoes large scale conformational changes. We present a procapsid x-ray structure at 3.65Å resolution, termed Prohead II, of the lambda like bacteriophage HK97, whose mature capsid structure was previously solved to 3.44 Å2. A comparison of the two largely different capsid forms has unveiled an unprecedented expansion mechanism that describes the transition. Crystallographic and Hydrogen/Deuterium exchange data presented here demonstrates that the subunit tertiary structures are significantly different between the two states, with twisting and bending motions occurring in both helical and β-sheet regions. We have also discovered conserved subunit interactions at each 3-fold of the virus capsid, from which capsid subunits maintain their integrity during refolding, facilitating the rotational and translational motions of maturation. Calormetric data of a closely related bacteriophage, P22, showed that capsid maturation was an exothermic process that resulted in a release of 90KJ/mol of energy3. We propose the major tertiary changes presented in this study reveal a structural basis for an exothermic maturation process likely present in many ds

  11. Measles Virus Fusion Protein: Structure, Function and Inhibition

    PubMed Central

    Plattet, Philippe; Alves, Lisa; Herren, Michael; Aguilar, Hector C.

    2016-01-01

    Measles virus (MeV), a highly contagious member of the Paramyxoviridae family, causes measles in humans. The Paramyxoviridae family of negative single-stranded enveloped viruses includes several important human and animal pathogens, with MeV causing approximately 120,000 deaths annually. MeV and canine distemper virus (CDV)-mediated diseases can be prevented by vaccination. However, sub-optimal vaccine delivery continues to foster MeV outbreaks. Post-exposure prophylaxis with antivirals has been proposed as a novel strategy to complement vaccination programs by filling herd immunity gaps. Recent research has shown that membrane fusion induced by the morbillivirus glycoproteins is the first critical step for viral entry and infection, and determines cell pathology and disease outcome. Our molecular understanding of morbillivirus-associated membrane fusion has greatly progressed towards the feasibility to control this process by treating the fusion glycoprotein with inhibitory molecules. Current approaches to develop anti-membrane fusion drugs and our knowledge on drug resistance mechanisms strongly suggest that combined therapies will be a prerequisite. Thus, discovery of additional anti-fusion and/or anti-attachment protein small-molecule compounds may eventually translate into realistic therapeutic options. PMID:27110811

  12. Measles Virus Fusion Protein: Structure, Function and Inhibition.

    PubMed

    Plattet, Philippe; Alves, Lisa; Herren, Michael; Aguilar, Hector C

    2016-04-01

    Measles virus (MeV), a highly contagious member of the Paramyxoviridae family, causes measles in humans. The Paramyxoviridae family of negative single-stranded enveloped viruses includes several important human and animal pathogens, with MeV causing approximately 120,000 deaths annually. MeV and canine distemper virus (CDV)-mediated diseases can be prevented by vaccination. However, sub-optimal vaccine delivery continues to foster MeV outbreaks. Post-exposure prophylaxis with antivirals has been proposed as a novel strategy to complement vaccination programs by filling herd immunity gaps. Recent research has shown that membrane fusion induced by the morbillivirus glycoproteins is the first critical step for viral entry and infection, and determines cell pathology and disease outcome. Our molecular understanding of morbillivirus-associated membrane fusion has greatly progressed towards the feasibility to control this process by treating the fusion glycoprotein with inhibitory molecules. Current approaches to develop anti-membrane fusion drugs and our knowledge on drug resistance mechanisms strongly suggest that combined therapies will be a prerequisite. Thus, discovery of additional anti-fusion and/or anti-attachment protein small-molecule compounds may eventually translate into realistic therapeutic options. PMID:27110811

  13. Fusion for Space Propulsion

    NASA Technical Reports Server (NTRS)

    Thio, Y. C. Francis; Schafer, Charles (Technical Monitor)

    2001-01-01

    There is little doubt that humans will attempt to explore and develop the solar system in this century. A large amount of energy will be required for accomplishing this. The need for fusion propulsion is discussed. For a propulsion system, there are three important thermodynamical attributes: (1) The absolute amount of energy available, (2) the propellant exhaust velocity, and (3) the jet power per unit mass of the propulsion system (specific power). For human exploration and development of the solar system, propellant exhaust velocity in excess of 100 km/s and specific power in excess of 10 kW/kg are required. Chemical combustion can produce exhaust velocity up to about 5 km/s. Nuclear fission processes typically result in producing energy in the form of heat that needs to be manipulated at temperatures limited by materials to about 2,800 K. Using the energy to heat a hydrogen propellant increases the exhaust velocity by only a factor of about two. Alternatively the energy can be converted into electricity which is then used to accelerate particles to high exhaust velocity. The necessary power conversion and conditioning equipment, however, increases the mass of the propulsion system for the same jet power by more than two orders of magnitude over chemical system, thus greatly limits the thrust-to-weight ratio attainable. The principal advantage of the fission process is that its development is relatively mature and is available right now. If fusion can be developed, fusion appears to have the best of all worlds in terms of propulsion - it can provide the absolute amount, the propellant exhaust velocity, and the high specific jet power. An intermediate step towards pure fusion propulsion is a bimodal system in which a fission reactor is used to provide some of the energy to drive a fusion propulsion unit. The technical issues related to fusion for space propulsion are discussed. The technical priorities for developing and applying fusion for propulsion are

  14. Ebola Viral Glycoprotein Bound to Its Endosomal Receptor Niemann-Pick C1.

    PubMed

    Wang, Han; Shi, Yi; Song, Jian; Qi, Jianxun; Lu, Guangwen; Yan, Jinghua; Gao, George F

    2016-01-14

    Filoviruses, including Ebola and Marburg, cause fatal hemorrhagic fever in humans and primates. Understanding how these viruses enter host cells could help to develop effective therapeutics. An endosomal protein, Niemann-Pick C1 (NPC1), has been identified as a necessary entry receptor for this process, and priming of the viral glycoprotein (GP) to a fusion-competent state is a prerequisite for NPC1 binding. Here, we have determined the crystal structure of the primed GP (GPcl) of Ebola virus bound to domain C of NPC1 (NPC1-C) at a resolution of 2.3 Å. NPC1-C utilizes two protruding loops to engage a hydrophobic cavity on head of GPcl. Upon enzymatic cleavage and NPC1-C binding, conformational change in the GPcl further affects the state of the internal fusion loop, triggering membrane fusion. Our data therefore provide structural insights into filovirus entry in the late endosome and the molecular basis for design of therapeutic inhibitors of viral entry. PMID:26771495

  15. Importance of SARS-CoV spike protein Trp-rich region in viral infectivity

    SciTech Connect

    Lu Yanning; Neo, T.L.; Liu, D.Xi.; Tam, James P.

    2008-07-04

    SARS-CoV entry is mediated by spike glycoprotein. During the viral and host cellular membrane fusion, HR1 and HR2 form 6-helix bundle, positioning the fusion peptide closely to the C-terminal region of ectodomain to drive apposition and subsequent membrane fusion. Connecting to the HR2 region is a Trp-rich region which is absolutely conserved in members of coronaviruses. To investigate the importance of Trp-rich region in SARS-CoV entry, we produced different mutated S proteins using Alanine scan strategy. SARS-CoV pseudotyped with mutated S protein was used to measure viral infectivity. To restore the aromaticity of Ala-mutants, we performed rescue experiments using phenylalanine substitutions. Our results show that individually substituted Ala-mutants substantially decrease infectivity by >90%, global Ala-mutants totally abrogated infectivity. In contrast, Phe-substituted mutants are able to restore 10-25% infectivity comparing to the wild-type. The results suggest that the Trp-rich region of S protein is essential for SARS-CoV infectivity.

  16. Regulation of Paramyxovirus Fusion Activation: the Hemagglutinin-Neuraminidase Protein Stabilizes the Fusion Protein in a Pretriggered State

    PubMed Central

    Salah, Zuhair W.; Gui, Long; DeVito, Ilaria; Jurgens, Eric M.; Lu, Hong; Yokoyama, Christine C.; Palermo, Laura M.; Lee, Kelly K.

    2012-01-01

    The hemagglutinin (HA)-neuraminidase protein (HN) of paramyxoviruses carries out three discrete activities, each of which affects the ability of HN to promote viral fusion and entry: receptor binding, receptor cleaving (neuraminidase), and triggering of the fusion protein. Binding of HN to its sialic acid receptor on a target cell triggers its activation of the fusion protein (F), which then inserts into the target cell and mediates the membrane fusion that initiates infection. We provide new evidence for a fourth function of HN: stabilization of the F protein in its pretriggered state before activation. Influenza virus hemagglutinin protein (uncleaved HA) was used as a nonspecific binding protein to tether F-expressing cells to target cells, and heat was used to activate F, indicating that the prefusion state of F can be triggered to initiate structural rearrangement and fusion by temperature. HN expression along with uncleaved HA and F enhances the F activation if HN is permitted to engage the receptor. However, if HN is prevented from engaging the receptor by the use of a small compound, temperature-induced F activation is curtailed. The results indicate that HN helps stabilize the prefusion state of F, and analysis of a stalk domain mutant HN reveals that the stalk domain of HN mediates the F-stabilization effect. PMID:22993149

  17. Low-pH conformational changes of rabies virus glycoprotein and their role in membrane fusion.

    PubMed Central

    Gaudin, Y; Ruigrok, R W; Knossow, M; Flamand, A

    1993-01-01

    Fusion of rabies virus with membranes occurs at acidic pH and is mediated by the viral spike glycoprotein (G). In this paper, we provide the basis for a description of structural transitions associated with exposure to low pH and of their role in membrane fusion. First, we have extended previous studies of fusion kinetics and we have shown that low-pH inhibition of fusion is detectable at 0.5 pH units higher than fusion. Second, low-pH-induced conformational changes were analyzed by using electron microscopy and monoclonal antibody binding assays. The existence of a pH-dependent equilibrium between the native and a low-pH inactive conformation was demonstrated. Third, besides these two conformations, we, using the fluorescent probe ANS (8-anilino-1-naphthalenesulfonic acid), provide evidence for the existence of a transient third state which appears to be more hydrophobic than the native state. Our results suggest that this transient state is responsible for viral aggregation at low pH and could play a role in the first steps of the fusion mechanism. Images PMID:8437221

  18. Viral kinetic modeling: state of the art

    DOE PAGESBeta

    Canini, Laetitia; Perelson, Alan S.

    2014-06-25

    Viral kinetic modeling has led to increased understanding of the within host dynamics of viral infections and the effects of therapy. Here we review recent developments in the modeling of viral infection kinetics with emphasis on two infectious diseases: hepatitis C and influenza. We review how viral kinetic modeling has evolved from simple models of viral infections treated with a drug or drug cocktail with an assumed constant effectiveness to models that incorporate drug pharmacokinetics and pharmacodynamics, as well as phenomenological models that simply assume drugs have time varying-effectiveness. We also discuss multiscale models that include intracellular events in viralmore » replication, models of drug-resistance, models that include innate and adaptive immune responses and models that incorporate cell-to-cell spread of infection. Overall, viral kinetic modeling has provided new insights into the understanding of the disease progression and the modes of action of several drugs. In conclusion, we expect that viral kinetic modeling will be increasingly used in the coming years to optimize drug regimens in order to improve therapeutic outcomes and treatment tolerability for infectious diseases.« less

  19. Viral infections of the folds (intertriginous areas).

    PubMed

    Adışen, Esra; Önder, Meltem

    2015-01-01

    Viruses are considered intracellular obligates with a nucleic acid, either RNA or DNA. They have the ability to encode proteins involved in viral replication and production of the protective coat within the host cells but require host cell ribosomes and mitochondria for translation. The members of the families Herpesviridae, Poxviridae, Papovaviridae, and Picornaviridae are the most commonly known agents for the cutaneous viral diseases, but other virus families, such as Adenoviridae, Togaviridae, Parvoviridae, Paramyxoviridae, Flaviviridae, and Hepadnaviridae, can also infect the skin. Though the cutaneous manifestations of viral infections are closely related to the type and the transmission route of the virus, viral skin diseases may occur in almost any part of the body. In addition to friction caused by skin-to-skin touch, skin folds are warm and moist areas of the skin that have limited air circulation. These features provide a fertile breeding ground for many kinds of microorganisms, including bacteria and fungi. In contrast to specific bacterial and fungal agents that have an affinity for the skin folds, except for viral diseases of the anogenital area, which have well-known presentations, viral skin infections that have a special affinity to the skin folds are not known. Many viral exanthems may affect the skin folds during the course of the infection, but here we focus only on the ones that usually affect the fold areas and also on the less well-known conditions or recently described associations. PMID:26051057

  20. Assembly of viral genomes from metagenomes

    PubMed Central

    Smits, Saskia L.; Bodewes, Rogier; Ruiz-Gonzalez, Aritz; Baumgärtner, Wolfgang; Koopmans, Marion P.; Osterhaus, Albert D. M. E.; Schürch, Anita C.

    2014-01-01

    Viral infections remain a serious global health issue. Metagenomic approaches are increasingly used in the detection of novel viral pathogens but also to generate complete genomes of uncultivated viruses. In silico identification of complete viral genomes from sequence data would allow rapid phylogenetic characterization of these new viruses. Often, however, complete viral genomes are not recovered, but rather several distinct contigs derived from a single entity are, some of which have no sequence homology to any known proteins. De novo assembly of single viruses from a metagenome is challenging, not only because of the lack of a reference genome, but also because of intrapopulation variation and uneven or insufficient coverage. Here we explored different assembly algorithms, remote homology searches, genome-specific sequence motifs, k-mer frequency ranking, and coverage profile binning to detect and obtain viral target genomes from metagenomes. All methods were tested on 454-generated sequencing datasets containing three recently described RNA viruses with a relatively large genome which were divergent to previously known viruses from the viral families Rhabdoviridae and Coronaviridae. Depending on specific characteristics of the target virus and the metagenomic community, different assembly and in silico gap closure strategies were successful in obtaining near complete viral genomes. PMID:25566226

  1. Losartan and enalapril decrease viral absorption and interleukin 1 beta production by macrophages in an experimental dengue virus infection.

    PubMed

    Hernández-Fonseca, Juan Pablo; Durán, Anyelo; Valero, Nereida; Mosquera, Jesús

    2015-11-01

    The role of angiotensin II (Ang II) in dengue virus infection remains unknown. The aim of this study was to determine the effect of losartan, an antagonist of the angiotensin II type 1 receptor (AT1 receptor), and enalapril, an inhibitor of angiotensin I-converting enzyme (ACE), on viral antigen expression and IL-1β production in peritoneal macrophages infected with dengue virus type 2. Mice treated with losartan or enalapril and untreated controls were infected intraperitoneally with the virus, and macrophages were analyzed. Infection resulted in increased IL-1β production and a high percentage of cells expressing viral antigen, and this was decreased by treatment with anti-Ang II drugs, suggesting a role for Ang II in dengue virus infection. PMID:26321474

  2. Surface Exposure of the HIV-1 Env Cytoplasmic Tail LLP2 Domain during the Membrane Fusion Process

    PubMed Central

    Lu, Lu; Zhu, Yun; Huang, Jinghe; Chen, Xi; Yang, Hengwen; Jiang, Shibo; Chen, Ying-Hua

    2008-01-01

    HIV-1 gp41 cytoplasmic tail (CT) is highly conserved among HIV-1 isolates, particularly the region designated lentivirus lytic peptide (LLP1–2), which includes two α-helical domains LLP1 and LLP2. Although the gp41 CT is recognized as a modulator of viral fusogenicity, little is known about the regulatory mechanism of this region in the viral fusion process. Here we report that anti-LLP1–2 and anti-LLP2 antibodies (IgG) inhibited HIV-1 Env-mediated cell fusion and bound to the interface between effector and target cells at a suboptimal temperature (31.5 °C), which slows down the fusion process and prolongs the fusion intermediate state. This suggests that LLP1–2, especially the LLP2 region located inside the viral membrane, is transiently exposed on the membrane surface during the fusion process. Synthetic LLP2 peptide could bind to the gp41 six-helix bundle core with high binding affinity. These results suggest that the gp41 CT may interact with the gp41 core, via the surface-exposed LLP2 domain, to regulate Env-mediated membrane fusion. PMID:18408000

  3. Lateral Lumbar Interbody Fusion

    PubMed Central

    Hughes, Alexander; Girardi, Federico; Sama, Andrew; Lebl, Darren; Cammisa, Frank

    2015-01-01

    The lateral lumbar interbody fusion (LLIF) is a relatively new technique that allows the surgeon to access the intervertebral space from a direct lateral approach either anterior to or through the psoas muscle. This approach provides an alternative to anterior lumbar interbody fusion with instrumentation, posterior lumbar interbody fusion, and transforaminal lumbar interbody fusion for anterior column support. LLIF is minimally invasive, safe, better structural support from the apophyseal ring, potential for coronal plane deformity correction, and indirect decompression, which have has made this technique popular. LLIF is currently being utilized for a variety of pathologies including but not limited to adult de novo lumbar scoliosis, central and foraminal stenosis, spondylolisthesis, and adjacent segment degeneration. Although early clinical outcomes have been good, the potential for significant neurological and vascular vertebral endplate complications exists. Nevertheless, LLIF is a promising technique with the potential to more effectively treat complex adult de novo scoliosis and achieve predictable fusion while avoiding the complications of traditional anterior surgery and posterior interbody techniques. PMID:26713134

  4. Lateral Lumbar Interbody Fusion.

    PubMed

    Pawar, Abhijit; Hughes, Alexander; Girardi, Federico; Sama, Andrew; Lebl, Darren; Cammisa, Frank

    2015-12-01

    The lateral lumbar interbody fusion (LLIF) is a relatively new technique that allows the surgeon to access the intervertebral space from a direct lateral approach either anterior to or through the psoas muscle. This approach provides an alternative to anterior lumbar interbody fusion with instrumentation, posterior lumbar interbody fusion, and transforaminal lumbar interbody fusion for anterior column support. LLIF is minimally invasive, safe, better structural support from the apophyseal ring, potential for coronal plane deformity correction, and indirect decompression, which have has made this technique popular. LLIF is currently being utilized for a variety of pathologies including but not limited to adult de novo lumbar scoliosis, central and foraminal stenosis, spondylolisthesis, and adjacent segment degeneration. Although early clinical outcomes have been good, the potential for significant neurological and vascular vertebral endplate complications exists. Nevertheless, LLIF is a promising technique with the potential to more effectively treat complex adult de novo scoliosis and achieve predictable fusion while avoiding the complications of traditional anterior surgery and posterior interbody techniques. PMID:26713134

  5. Fusion, magnetic confinement

    SciTech Connect

    Berk, H.L.

    1992-08-06

    An overview is presented of the principles of magnetic confinement of plasmas for the purpose of achieving controlled fusion conditions. Sec. 1 discusses the different nuclear fusion reactions which can be exploited in prospective fusion reactors and explains why special technologies need to be developed for the supply of tritium or {sup 3}He, the probable fuels. In Sec. 2 the Lawson condition, a criterion that is a measure of the quality of confinement relative to achieving fusion conditions, is explained. In Sec. 3 fluid equations are used to describe plasma confinement. Specific confinement configurations are considered. In Sec. 4 the orbits of particle sin magneti and electric fields are discussed. In Sec. 5 stability considerations are discussed. It is noted that confinement systems usually need to satisfy stability constraints imposed by ideal magnetohydrodynamic (MHD) theory. The paper culminates with a summary of experimental progress in magnetic confinement. Present experiments in tokamaks have reached the point that the conditions necessary to achieve fusion are being satisfied.

  6. Myoblast fusion in Drosophila

    SciTech Connect

    Haralalka, Shruti; Abmayr, Susan M.

    2010-11-01

    The body wall musculature of a Drosophila larva is composed of an intricate pattern of 30 segmentally repeated muscle fibers in each abdominal hemisegment. Each muscle fiber has unique spatial and behavioral characteristics that include its location, orientation, epidermal attachment, size and pattern of innervation. Many, if not all, of these properties are dictated by founder cells, which determine the muscle pattern and seed the fusion process. Myofibers are then derived from fusion between a specific founder cell and several fusion competent myoblasts (FCMs) fusing with as few as 3-5 FCMs in the small muscles on the most ventral side of the embryo and as many as 30 FCMs in the larger muscles on the dorsal side of the embryo. The focus of the present review is the formation of the larval muscles in the developing embryo, summarizing the major issues and players in this process. We have attempted to emphasize experimentally-validated details of the mechanism of myoblast fusion and distinguish these from the theoretically possible details that have not yet been confirmed experimentally. We also direct the interested reader to other recent reviews that discuss myoblast fusion in Drosophila, each with their own perspective on the process . With apologies, we use gene nomenclature as specified by Flybase (http://flybase.org) but provide Table 1 with alternative names and references.

  7. BEATRIX-II program: First annual progress report, January 1988--December 1988: Annex-III to IEA implementing agreement for a programme of research and development on radiation damage in fusion materials

    SciTech Connect

    Hollenberg, G.W.

    1989-03-01

    The objective of the BEATRIX-II experiment is to design, conduct, and evaluate a Collaborative, in-situ tritium-recovery experiment in the Fast Flux Test Facility (FFTF). Continuous monitoring of candidate solid breeder material's performance with respect to thermal conductivity, temperature stability, and tritium release is to be accomplished up to extended lithium burnup levels under simulated blanket environments. 6 refs., 21 figs., 10 tabs.

  8. Ebola viral disease and pregnancy

    PubMed Central

    Caluwaerts, Séverine; Achar, Jay

    2015-01-01

    Ebola viral disease’s interaction with pregnancy is poorly understood and remains a particular challenge for medical and para-medical personnel responding to an outbreak. This review article is written with the benefit of hindsight and experience from the largest recorded Ebola outbreak in history. We have provided a broad overview of the issues that arise for pregnant women and for the professionals treating them during an Ebola outbreak. The discussion focuses on the specifics of Ebola infection in pregnancy and possible management strategies, including the delivery of an infected woman. We have also discussed the wider challenges posed to pregnant women and their carers during an epidemic, including the identification of suspected Ebola-infected pregnant women and the impact of the disease on pre-existing health services. This paper outlines current practices in the field, as well as highlighting the gaps in our knowledge and the paramount need to protect the health-care workers directly involved in the management of pregnant women. PMID:26457118

  9. Viral population estimation using pyrosequencing.

    PubMed

    Eriksson, Nicholas; Pachter, Lior; Mitsuya, Yumi; Rhee, Soo-Yon; Wang, Chunlin; Gharizadeh, Baback; Ronaghi, Mostafa; Shafer, Robert W; Beerenwinkel, Niko

    2008-04-01

    The diversity of virus populations within single infected hosts presents a major difficulty for the natural immune response as well as for vaccine design and antiviral drug therapy. Recently developed pyrophosphate-based sequencing technologies (pyrosequencing) can be used for quantifying this diversity by ultra-deep sequencing of virus samples. We present computational methods for the analysis of such sequence data and apply these techniques to pyrosequencing data obtained from HIV populations within patients harboring drug-resistant virus strains. Our main result is the estimation of the population structure of the sample from the pyrosequencing reads. This inference is based on a statistical approach to error correction, followed by a combinatorial algorithm for constructing a minimal set of haplotypes that explain the data. Using this set of explaining haplotypes, we apply a statistical model to infer the frequencies of the haplotypes in the population via an expectation-maximization (EM) algorithm. We demonstrate that pyrosequencing reads allow for effective population reconstruction by extensive simulations and by comparison to 165 sequences obtained directly from clonal sequencing of four independent, diverse HIV populations. Thus, pyrosequencing can be used for cost-effective estimation of the structure of virus populations, promising new insights into viral evolutionary dynamics and disease control strategies. PMID:18437230

  10. Thrombosis Associated with Viral Hepatitis

    PubMed Central

    Galli, Luca; Gerdes, Victor E.A.; Guasti, Luigina; Squizzato, Alessandro

    2014-01-01

    Viral hepatitis may promote the development of venous thromboembolism (VTE) and, more specifically, portal vein thrombosis (PVT). In this narrative review, we summarize the clinical data and discuss the possible pathogenetic roles of cytomegalovirus (CMV), Epstein-Barr virus (EBV), and hepatitis A, B, and C viruses (HAV, HBV, HCV) in the occurrence of VTE. CMV is the first qualified candidate to enter the list of VTE minor risk factors, and in the rare case of fulminant infection, both EBV and CMV, like any severe infection or inflammatory disease, increase risk for thrombosis. In chronic hepatitis B and C, it remains controversial whether antiphospholipid antibodies are important for thrombotic complications or merely an epiphenomenon. Retinal vein occlusion described in chronic hepatitis C is usually attributed to the treatment with interferon. Eltrombopag, used for HCV-related thrombocytopenia, has been associated with increased thrombotic risk. The imbalance between procoagulant and anticoagulant factors associated with chronic liver disease may have clinical implications. This may help to explain why these patients are not protected from clinical events such as VTE, PVT, and the progression of liver fibrosis. PMID:26357629

  11. Viral vectors for cancer immunotherapy.

    PubMed

    Harrop, Richard; Carroll, Miles W

    2006-01-01

    Over the last decade, immunotherapy approaches for the treatment of cancer have been investigated with renewed vigour, perhaps catalyzed by the clinical successes seen with monoclonal antibody and cytokine based therapies. The identification of tumor-associated antigens (TAAs) in multiple cancer types has enabled the development of targeted immunotherapies and allayed some of the safety concerns associated with the induction of deleterious autoimmune reactions. In addition to the TAA or therapeutic gene, the antigen delivery system is equally as important for the development of a successful cancer vaccine. One approach to induce a potent and targeted antitumor response is to use viruses to deliver the TAA to cells of the immune system. A diverse array of oncolytic viruses and recombinant viral vectors encoding numerous therapeutic genes or TAAs have been tested in pre-clinical studies and produced results which, in some cases, justify their clinical development as potential cancer immunotherapies. Within the last 5-10 years, many such recombinant vectors have made the transition from pre-clinical research to clinical development and it is these, which are given most weight in this review. PMID:16146772

  12. Inflammasome control of viral infection

    PubMed Central

    Lupfer, Christopher; Malik, Ankit; Kanneganti, Thirumala-Devi

    2015-01-01

    The inflammasome is a caspase-1 containing complex that activates the proinflammatory cytokines IL-1β and IL-18 and results in the proinflammatory cell death known as pyroptosis. Numerous recent publications have highlighted the importance of inflammasome activation in the control of virus infection. Inflammasome activation during viral infection is dependent on a variety of upstream receptors including the NOD-Like receptor, RIG-I-Like receptor and AIM2-Like receptor families. Various receptors also function in inflammasome activation in different cellular compartments, including the cytoplasm and the nucleus. The effectiveness of inflammasomes at suppressing virus replication is highlighted by the prevalence and diversity of virus encoded inflammasome inhibitors. Also, the host has a myriad of regulatory mechanisms in place to prevent unwanted inflammasome activation and overt inflammation. Finally, recent reports begin to suggest that inflammasome activation and inflammasome modulation may have important clinical applications. Herein, we highlight recent advances and discuss potential future directions toward understanding the role of inflammasomes during virus infection. PMID:25771504

  13. Neutron irradiation experiments for fusion reactor materials through JUPITER program

    NASA Astrophysics Data System (ADS)

    Abe, K.; Kohyama, A.; Namba, C.; Wiffen, F. W.; Jones, R. H.

    1998-10-01

    A Japan-USA Program of irradiation experiments for fusion research, "JUPITER", has been established as a 6 year program from 1995 to 2000. The goal is to study "the dynamic behavior of fusion reactor materials and their response to variable and complex irradiation environment". This is phase-three of the collaborative program, which follows RTNS-II Program (Phase-1: 1982-1986) and FFTF/MOTA Program (Phase-2: 1987-1994). This program is to provide a scientific basis for application of materials performance data, generated by fission reactor experiments, to anticipated fusion environments. Following the systematic study on cumulative irradiation effects, done through FFTF/MOTA Program, JUPITER is emphasizing the importance of dynamic irradiation effects on materials performance in fusion systems. The irradiation experiments in this program include low activation structural materials, functional ceramics and other innovative materials. The experimental data are analyzed by theoretical modeling and computer simulation to integrate the above effects.

  14. Genetic basis of cell-cell fusion mechanisms

    PubMed Central

    Aguilar, Pablo S.; Baylies, Mary K.; Fleissner, Andre; Helming, Laura; Inoue, Naokazu; Podbilewicz, Benjamin; Wang, Hongmei; Wong, Melissa

    2013-01-01

    Cell-cell fusion in sexually reproducing organisms is a mechanism to merge gamete genomes, and in multicellular organisms, it is a strategy to sculpt organs such as muscles, bones, and placenta. Moreover, this mechanism has been implicated in pathological conditions such as infection and cancer. Study of genetic model organisms has uncovered a unifying principle: cell fusion is a genetically programmed process. This process can be divided in three stages: (i) competence: cell induction and differentiation, (ii) commitment: cell determination, migration and adhesion, and (iii) cell fusion: membrane merging and cytoplasmic mixing. Recent work has led to the discovery of fusogens, cell fusion proteins that are necessary and sufficient to fuse cell membranes. Two unrelated families of fusogens have been discovered, one in mouse placenta and one in Caenorhabditis elegans (Syncytins and F proteins, respectively). Current research aims to identify new fusogens and determine the mechanisms by which fusogens merge membranes. PMID:23453622

  15. Interaction of the influenza hemagglutinin fusion peptide with lipid bilayers: area expansion and permeation.

    PubMed Central

    Longo, M L; Waring, A J; Hammer, D A

    1997-01-01

    Fusion is a crucial event in the infection of animal cells by enveloped viruses (e.g., HIV or influenza). Viral fusion is mediated by glycoproteins, spanning the viral envelope, which attach to a membrane surface and induce fusion of the viral envelope to the cellular membrane. Influenza fusion protein (hemagglutinin) contains an amino-terminal segment critical to fusion, referred to as the fusion peptide. We show here that the native fusion peptide (wt-20) of hemagglutinin destabilizes membranes formed of 99% 1 -stearoyl-2-oleoylphosphatidylcholine (SOPC). The first step in destabilization is rapid insertion of the peptide into the membrane, in which membrane area increases by as much as 11% in just seconds. We visualized and quantified the area expansion by using optical video microscopy combined with micropipette aspiration. This rapid membrane area expansion is followed by the formation of membrane defects in the size range of 0.5 nm, and results in membrane rupture. Both the rate of area increase and maximum area increase are significantly higher at a pH near 5.0 compared to pH 7.0. These results suggest that enhanced membrane insertion of wt-20 and accompanying area expansion at pH 5.0 are responsible for the relatively greater lytic activity at this pH. We show that a deletion of the N-terminal glycine of wt-20 results in a lack of area expansion or membrane perturbation at pH 5.0. Images FIGURE 1 FIGURE 2 PMID:9284310

  16. Characterization of the fusion core in zebrafish endogenous retroviral envelope protein

    SciTech Connect

    Shi, Jian; Zhang, Huaidong; Gong, Rui; Xiao, Gengfu

    2015-05-08

    Zebrafish endogenous retrovirus (ZFERV) is the unique endogenous retrovirus in zebrafish, as yet, containing intact open reading frames of its envelope protein gene in zebrafish genome. Similarly, several envelope proteins of endogenous retroviruses in human and other mammalian animal genomes (such as syncytin-1 and 2 in human, syncytin-A and B in mouse) were identified and shown to be functional in induction of cell–cell fusion involved in placental development. ZFERV envelope protein (Env) gene appears to be also functional in vivo because it is expressible. After sequence alignment, we found ZFERV Env shares similar structural profiles with syncytin and other type I viral envelopes, especially in the regions of N- and C-terminal heptad repeats (NHR and CHR) which were crucial for membrane fusion. We expressed the regions of N + C protein in the ZFERV Env (residues 459–567, including predicted NHR and CHR) to characterize the fusion core structure. We found N + C protein could form a stable coiled-coil trimer that consists of three helical NHR regions forming a central trimeric core, and three helical CHR regions packing into the grooves on the surface of the central core. The structural characterization of the fusion core revealed the possible mechanism of fusion mediated by ZFERV Env. These results gave comprehensive explanation of how the ancient virus infects the zebrafish and integrates into the genome million years ago, and showed a rational clue for discovery of physiological significance (e.g., medicate cell–cell fusion). - Highlights: • ZFERV Env shares similar structural profiles with syncytin and other type I viral envelopes. • The fusion core of ZFERV Env forms stable coiled-coil trimer including three NHRs and three CHRs. • The structural mechanism of viral entry mediated by ZFERV Env is disclosed. • The results are helpful for further discovery of physiological function of ZFERV Env in zebrafish.

  17. Direct Visualization of Ebola Virus Fusion Triggering in the Endocytic Pathway

    PubMed Central

    Spence, Jennifer S.; Krause, Tyler B.; Mittler, Eva; Jangra, Rohit K.

    2016-01-01

    ABSTRACT Ebola virus (EBOV) makes extensive and intricate use of host factors in the cellular endosomal/lysosomal pathway to release its genome into the cytoplasm and initiate infection. Following viral internalization into endosomes, host cysteine proteases cleave the EBOV fusion glycoprotein (GP) to unmask the binding site for its intracellular receptor, the cholesterol transporter Niemann-Pick C1 (NPC1). GP-NPC1 interaction is required for viral entry. Despite these and other recent discoveries, late events in EBOV entry following GP-NPC1 binding and culminating in GP-catalyzed fusion between viral and cellular lipid bilayers remain enigmatic. A mechanistic understanding of EBOV membrane fusion has been hampered by the failure of previous efforts to reconstitute fusion in vitro or at the cell surface. This report describes an assay to monitor initial steps directly in EBOV membrane fusion—triggering of GP and virus-cell lipid mixing—by single virions in live cells. Fusogenic triggering of GP occurs predominantly in Rab7-positive (Rab7+) endosomes, absolutely requires interaction between proteolytically primed GP and NPC1, and is blocked by key GP-specific neutralizing antibodies with therapeutic potential. Unexpectedly, cysteine protease inhibitors do not inhibit lipid mixing by virions bearing precleaved GP, even though they completely block cytoplasmic entry by these viruses, as shown previously. These results point to distinct cellular requirements for different steps in EBOV membrane fusion and suggest a model in which host cysteine proteases are dispensable for GP fusion triggering after NPC1 binding but are required for the formation of fusion pores that permit genome delivery. PMID:26861015

  18. Desensitized Optimal Filtering and Sensor Fusion Toolkit

    NASA Technical Reports Server (NTRS)

    Karlgaard, Christopher D.

    2015-01-01

    Analytical Mechanics Associates, Inc., has developed a software toolkit that filters and processes navigational data from multiple sensor sources. A key component of the toolkit is a trajectory optimization technique that reduces the sensitivity of Kalman filters with respect to model parameter uncertainties. The sensor fusion toolkit also integrates recent advances in adaptive Kalman and sigma-point filters for non-Gaussian problems with error statistics. This Phase II effort provides new filtering and sensor fusion techniques in a convenient package that can be used as a stand-alone application for ground support and/or onboard use. Its modular architecture enables ready integration with existing tools. A suite of sensor models and noise distribution as well as Monte Carlo analysis capability are included to enable statistical performance evaluations.

  19. Comparing viral metagenomics methods using a highly multiplexed human viral pathogens reagent

    PubMed Central

    Li, Linlin; Deng, Xutao; Mee, Edward T.; Collot-Teixeira, Sophie; Anderson, Rob; Schepelmann, Silke; Minor, Philip D.; Delwart, Eric

    2014-01-01

    Unbiased metagenomic sequencing holds significant potential as a diagnostic tool for the simultaneous detection of any previously genetically described viral nucleic acids in clinical samples. Viral genome sequences can also inform on likely phenotypes including drug susceptibility or neutralization serotypes. In this study, different variables of the laboratory methods often used to generate viral metagenomics libraries on the efficiency of viral detection and virus genome coverage were compared. A biological reagent consisting of 25 different human RNA and DNA viral pathogens was used to estimate the effect of filtration and nuclease digestion, DNA/RNA extraction methods, pre-amplification and the use of different library preparation kits on the detection of viral nucleic acids. Filtration and nuclease treatment led to slight decreases in the percentage of viral sequence reads and number of viruses detected. For nucleic acid extractions silica spin columns improved viral sequence recovery relative to magnetic beads and Trizol extraction. Pre-amplification using random RT-PCR while generating more viral sequence reads resulted in detection of fewer viruses, more overlapping sequences, and lower genome coverage. The ScriptSeq library preparation method retrieved more viruses and a greater fraction of their genomes than the TruSeq and Nextera methods. Viral metagenomics sequencing was able to simultaneously detect up to 22 different viruses in the biological reagent analyzed including all those detected by qPCR. Further optimization will be required for the detection of viruses in biologically more complex samples such as tissues, blood, or feces. PMID:25497414

  20. The Viral E8^E2C Repressor Limits Productive Replication of Human Papillomavirus 16

    PubMed Central

    Straub, Elke; Dreer, Marcel; Fertey, Jasmin; Iftner, Thomas

    2014-01-01

    Productive replication of human papillomavirus type 16 (HPV16) occurs only in differentiated keratinocyte cells. In addition to the viral E2 activator protein, HPV16 and related HPV types express transcripts coding for an E8^E2C fusion protein, which limits genome replication in undifferentiated keratinocytes. To address E8^E2C's role in productive replication of HPV16, stable keratinocyte cell lines containing wild-type (wt), E8^E2C knockout (E8−), or E8 KWK mutant (mt) genomes, in which conserved E8 residues were inactivated, were established. Copy numbers of E8− and E8 KWK mt genomes and amounts of early and late viral transcripts were greatly increased compared to those for the wt in undifferentiated keratinocytes, suggesting that HPV16 E8^E2C activities are highly dependent upon the E8 part. Upon differentiation in organotypic cultures, E8 mt genomes displayed higher early viral transcript levels, but no changes in cellular differentiation or virus-induced cellular DNA replication in suprabasal cells were observed. E8 mt genomes were amplified to higher copy numbers and showed increased L1 transcripts compared to wt genomes. Furthermore, the number of cells expressing the viral late protein E4 or L1 or amplifying viral genomes was greatly increased in E8 mt cell lines. In wild-type cells, E8^E2C transcript levels did not decrease by differentiation. Our data indicate that the E8^E2C repressor limits viral transcription and replication throughout the complete life cycle of HPV16. PMID:24198405

  1. Viral Evasion of Natural Killer Cell Activation

    PubMed Central

    Ma, Yi; Li, Xiaojuan; Kuang, Ersheng

    2016-01-01

    Natural killer (NK) cells play a key role in antiviral innate defenses because of their abilities to kill infected cells and secrete regulatory cytokines. Additionally, NK cells exhibit adaptive memory-like antigen-specific responses, which represent a novel antiviral NK cell defense mechanism. Viruses have evolved various strategies to evade the recognition and destruction by NK cells through the downregulation of the NK cell activating receptors. Here, we review the recent findings on viral evasion of NK cells via the impairment of NK cell-activating receptors and ligands, which provide new insights on the relationship between NK cells and viral actions during persistent viral infections. PMID:27077876

  2. Some vexations that challenge viral immunology

    PubMed Central

    Rouse, Barry T.; Mueller, Scott N.

    2016-01-01

    The field of viral immunology seeks to understand mechanisms of virus-host interaction with a view of applying this knowledge to the design of effective vaccines and immunomodulators that control viral infections. This brief review discusses several areas of the field that hold substantial promise for translation, but where further work is critically required to find solutions. We emphasize that our fundamental understanding of virus-host relationships is moving in leaps and bounds, but we lag behind in applying this knowledge to the successful control of many viral infections. PMID:27303640

  3. Endosomal vesicles as vehicles for viral genomes

    PubMed Central

    Nour, Adel M.; Modis, Yorgo

    2014-01-01

    The endocytic pathway is the principal cell entry pathway for large cargo and pathogens. Among the wide variety of specialized lipid structures within endosomes, the intraluminal vesicles formed in early endosomes and transferred to late endosomal compartments are emerging as critical effectors of viral infection and immune recognition. Various viruses deliver their genomes into these intraluminal vesicles, which serve as vehicles to transport the genome to the nuclear periphery for replication. When secreted as exosomes, intraluminal vesicles containing viral genomes can infect permissive cells, or activate immune responses in myeloid cells. We therefore propose that endosomal intraluminal vesicles and exosomes are key effectors of viral pathogenesis. PMID:24746011

  4. Dynamical implications of Viral Tiling Theory.

    PubMed

    ElSawy, K M; Taormina, A; Twarock, R; Vaughan, L

    2008-05-21

    The Caspar-Klug classification of viruses whose protein shell, called viral capsid, exhibits icosahedral symmetry, has recently been extended to incorporate viruses whose capsid proteins are exclusively organised in pentamers. The approach, named 'Viral Tiling Theory', is inspired by the theory of quasicrystals, where aperiodic Penrose tilings enjoy 5-fold and 10-fold local symmetries. This paper analyses the extent to which this classification approach informs dynamical properties of the viral capsids, in particular the pattern of Raman active modes of vibrations, which can be observed experimentally. PMID:18353372

  5. Epigenetics and Genetics of Viral Latency.

    PubMed

    Lieberman, Paul M

    2016-05-11

    Viral latency can be considered a metastable, nonproductive infection state that is capable of subsequent reactivation to repeat the infection cycle. Viral latent infections have numerous associated pathologies, including cancer, birth defects, neuropathy, cardiovascular disease, chronic inflammation, and immunological dysfunctions. The mechanisms controlling the establishment, maintenance, and reactivation from latency are complex and diversified among virus families, species, and strains. Yet, as examined in this review, common properties of latent viral infections can be defined. Eradicating latent virus has become an important but elusive challenge and will require a more complete understanding of the mechanisms controlling these processes. PMID:27173930

  6. Ocular manifestations of feline viral diseases.

    PubMed

    Stiles, Jean

    2014-08-01

    Feline viral diseases are common and cats can be presented with a variety of clinical manifestations. Ocular disease associated with viral pathogens is not unusual, particularly with viruses causing upper respiratory tract disease in cats, such as feline herpesvirus type 1 and feline calicivirus. These agents mainly cause ocular surface disease. Other viruses, such as feline immunodeficiency virus and feline coronavirus, can cause uveitis, while feline leukemia virus can induce ocular lymphosarcoma. This review covers the most common viral pathogens of cats that cause ocular manifestations, the specific features of the ocular diseases caused by these viruses and therapeutic recommendations. PMID:24461645

  7. Peaceful Uses of Fusion

    DOE R&D Accomplishments Database

    Teller, E.

    1958-07-03

    Applications of thermonuclear energy for peaceful and constructive purposes are surveyed. Developments and problems in the release and control of fusion energy are reviewed. It is pointed out that the future of thermonuclear power reactors will depend upon the construction of a machine that produces more electric energy than it consumes. The fuel for thermonuclear reactors is cheap and practically inexhaustible. Thermonuclear reactors produce less dangerous radioactive materials than fission reactors and, when once brought under control, are not as likely to be subject to dangerous excursions. The interaction of the hot plasma with magnetic fields opens the way for the direct production of electricity. It is possible that explosive fusion energy released underground may be harnessed for the production of electricity before the same feat is accomplished in controlled fusion processes. Applications of underground detonations of fission devices in mining and for the enhancement of oil flow in large low-specific-yield formations are also suggested.

  8. Simulation of Fusion Plasmas

    ScienceCinema

    Holland, Chris [UC San Diego, San Diego, California, United States

    2010-01-08

    The upcoming ITER experiment (www.iter.org) represents the next major milestone in realizing the promise of using nuclear fusion as a commercial energy source, by moving into the ?burning plasma? regime where the dominant heat source is the internal fusion reactions. As part of its support for the ITER mission, the US fusion community is actively developing validated predictive models of the behavior of magnetically confined plasmas. In this talk, I will describe how the plasma community is using the latest high performance computing facilities to develop and refine our models of the nonlinear, multiscale plasma dynamics, and how recent advances in experimental diagnostics are allowing us to directly test and validate these models at an unprecedented level.

  9. Ceramics for fusion applications

    SciTech Connect

    Clinard, F.W. Jr.

    1986-01-01

    Ceramics are required for a variety of uses in both near-term fusion devices and in commercial powerplants. These materials must retain adequate structural and electrical properties under conditions of neutron, particle, and ionizing irradiation; thermal and applied stresses; and physical and chemical sputtering. Ceramics such as Al/sub 2/O/sub 3/, MgAl/sub 2/O/sub 4/, BeO, Si/sub 3/N/sub 4/ and SiC are currently under study for fusion applications, and results to date show widely-varying response to the fusion environment. Materials can be identified today which will meet initial operating requirements, but improvements in physical properties are needed to achieve satisfactory lifetimes for critical applications.

  10. Colliding Beam Fusion Reactors

    NASA Astrophysics Data System (ADS)

    Rostoker, Norman; Qerushi, Artan; Binderbauer, Michl

    2003-06-01

    The recirculating power for virtually all types of fusion reactors has previously been calculated [1] with the Fokker-Planck equation. The reactors involve non-Maxwellian plasmas. The calculations are generic in that they do not relate to specific confinement devices. In all cases except for a Tokamak with D-T fuel the recirculating power was found to exceed the fusion power by a large factor. In this paper we criticize the generality claimed for this calculation. The ratio of circulating power to fusion power is calculated for the Colliding Beam Reactor with fuels D-T, D-He3 and p-B11. The results are respectively, 0.070, 0.141 and 0.493.

  11. Spherical torus fusion reactor

    DOEpatents

    Peng, Yueng-Kay M.

    1989-04-04

    A fusion reactor is provided having a near spherical-shaped plasma with a modest central opening through which straight segments of toroidal field coils extend that carry electrical current for generating a toroidal magnet plasma confinement fields. By retaining only the indispensable components inboard of the plasma torus, principally the cooled toroidal field conductors and in some cases a vacuum containment vessel wall, the fusion reactor features an exceptionally small aspect ratio (typically about 1.5), a naturally elongated plasma cross section without extensive field shaping, requires low strength magnetic containment fields, small size and high beta. These features combine to produce a spherical torus plasma in a unique physics regime which permits compact fusion at low field and modest cost.

  12. Spherical torus fusion reactor

    DOEpatents

    Peng, Yueng-Kay M.

    1989-01-01

    A fusion reactor is provided having a near spherical-shaped plasma with a modest central opening through which straight segments of toroidal field coils extend that carry electrical current for generating a toroidal magnet plasma confinement fields. By retaining only the indispensable components inboard of the plasma torus, principally the cooled toroidal field conductors and in some cases a vacuum containment vessel wall, the fusion reactor features an exceptionally small aspect ratio (typically about 1.5), a naturally elongated plasma cross section without extensive field shaping, requires low strength magnetic containment fields, small size and high beta. These features combine to produce a spherical torus plasma in a unique physics regime which permits compact fusion at low field and modest cost.

  13. Intense fusion neutron sources

    NASA Astrophysics Data System (ADS)

    Kuteev, B. V.; Goncharov, P. R.; Sergeev, V. Yu.; Khripunov, V. I.

    2010-04-01

    The review describes physical principles underlying efficient production of free neutrons, up-to-date possibilities and prospects of creating fission and fusion neutron sources with intensities of 1015-1021 neutrons/s, and schemes of production and application of neutrons in fusion-fission hybrid systems. The physical processes and parameters of high-temperature plasmas are considered at which optimal conditions for producing the largest number of fusion neutrons in systems with magnetic and inertial plasma confinement are achieved. The proposed plasma methods for neutron production are compared with other methods based on fusion reactions in nonplasma media, fission reactions, spallation, and muon catalysis. At present, intense neutron fluxes are mainly used in nanotechnology, biotechnology, material science, and military and fundamental research. In the near future (10-20 years), it will be possible to apply high-power neutron sources in fusion-fission hybrid systems for producing hydrogen, electric power, and technological heat, as well as for manufacturing synthetic nuclear fuel and closing the nuclear fuel cycle. Neutron sources with intensities approaching 1020 neutrons/s may radically change the structure of power industry and considerably influence the fundamental and applied science and innovation technologies. Along with utilizing the energy produced in fusion reactions, the achievement of such high neutron intensities may stimulate wide application of subcritical fast nuclear reactors controlled by neutron sources. Superpower neutron sources will allow one to solve many problems of neutron diagnostics, monitor nano-and biological objects, and carry out radiation testing and modification of volumetric properties of materials at the industrial level. Such sources will considerably (up to 100 times) improve the accuracy of neutron physics experiments and will provide a better understanding of the structure of matter, including that of the neutron itself.

  14. Crystal structure of the conserved herpes virus fusion regulator complex gH-gL

    SciTech Connect

    Chowdary, Tirumala K; Cairns, Tina M; Atanasiu, Doina; Cohen, Gary H; Eisenberg, Roselyn J; Heldwein, Ekaterina E

    2010-09-13

    Herpesviruses, which cause many incurable diseases, infect cells by fusing viral and cellular membranes. Whereas most other enveloped viruses use a single viral catalyst called a fusogen, herpesviruses, inexplicably, require two conserved fusion-machinery components, gB and the heterodimer gH-gL, plus other nonconserved components. gB is a class III viral fusogen, but unlike other members of its class, it does not function alone. We determined the crystal structure of the gH ectodomain bound to gL from herpes simplex virus 2. gH-gL is an unusually tight complex with a unique architecture that, unexpectedly, does not resemble any known viral fusogen. Instead, we propose that gH-gL activates gB for fusion, possibly through direct binding. Formation of a gB-gH-gL complex is critical for fusion and is inhibited by a neutralizing antibody, making the gB-gH-gL interface a promising antiviral target.

  15. Crystal Structure of the Conserved Herpes Virus Fusion Regulator Complex gH–gL

    SciTech Connect

    Chowdary, T.; Cairns, T; Atanasiu, D; Cohen, G; Eisenberg, R; Heldwein, E

    2010-01-01

    Herpesviruses, which cause many incurable diseases, infect cells by fusing viral and cellular membranes. Whereas most other enveloped viruses use a single viral catalyst called a fusogen, herpesviruses, inexplicably, require two conserved fusion-machinery components, gB and the heterodimer gH-gL, plus other nonconserved components. gB is a class III viral fusogen, but unlike other members of its class, it does not function alone. We determined the crystal structure of the gH ectodomain bound to gL from herpes simplex virus 2. gH-gL is an unusually tight complex with a unique architecture that, unexpectedly, does not resemble any known viral fusogen. Instead, we propose that gH-gL activates gB for fusion, possibly through direct binding. Formation of a gB-gH-gL complex is critical for fusion and is inhibited by a neutralizing antibody, making the gB-gH-gL interface a promising antiviral target.

  16. Crystal structure of the conserved herpesvirus fusion regulator complex gH—gL

    SciTech Connect

    Chowdary, Tirumala K.; Cairns, Tina M.; Atanasiu, Doina; Cohen, Gary H.; Eisenberg, Roselyn J.; Heldwein, Ekaterina E.

    2015-02-09

    Herpesviruses, which cause many incurable diseases, infect cells by fusing viral and cellular membranes. Whereas most other enveloped viruses use a single viral catalyst called a fusogen, herpesviruses, inexplicably, require two conserved fusion-machinery components, gB and the heterodimer gH–gL, plus other nonconserved components. gB is a class III viral fusogen, but unlike other members of its class, it does not function alone. We determined the crystal structure of the gH ectodomain bound to gL from herpes simplex virus 2. gH–gL is an unusually tight complex with a unique architecture that, unexpectedly, does not resemble any known viral fusogen. Instead, we propose that gH–gL activates gB for fusion, possibly through direct binding. Formation of a gB–gH–gL complex is critical for fusion and is inhibited by a neutralizing antibody, making the gB–gH–gL interface a promising antiviral target.

  17. Cleavage of spike protein of SARS coronavirus by protease factor Xa is associated with viral infectivity

    SciTech Connect

    Du, Lanying; Kao, Richard Y.; Zhou, Yusen; He, Yuxian; Zhao, Guangyu; Wong, Charlotte; Jiang, Shibo; Yuen, Kwok-Yung; Jin, Dong-Yan; Zheng, Bo-Jian . E-mail: bzheng@hkucc.hku.hk

    2007-07-20

    The spike (S) protein of SARS coronavirus (SARS-CoV) has been known to recognize and bind to host receptors, whose conformational changes then facilitate fusion between the viral envelope and host cell membrane, leading to viral entry into target cells. However, other functions of SARS-CoV S protein such as proteolytic cleavage and its implications to viral infection are incompletely understood. In this study, we demonstrated that the infection of SARS-CoV and a pseudovirus bearing the S protein of SARS-CoV was inhibited by a protease inhibitor Ben-HCl. Also, the protease Factor Xa, a target of Ben-HCl abundantly expressed in infected cells, was able to cleave the recombinant and pseudoviral S protein into S1 and S2 subunits, and the cleavage was inhibited by Ben-HCl. Furthermore, this cleavage correlated with the infectivity of the pseudovirus. Taken together, our study suggests a plausible mechanism by which SARS-CoV cleaves its S protein to facilitate viral infection.

  18. Functional constraints on HIV-1 capsid: their impacts on the viral immune escape potency.

    PubMed

    Takemura, Taichiro; Murakami, Tsutomu

    2012-01-01

    In mature HIV-1 particles, viral capsid (CA) proteins form the conical core structure that encapsidates two copies of the viral RNA genome. After fusion of the viral envelope and cellular membranes, the CA core enters into the cytoplasm of the target cells. CA proteins then interact with a variety of viral other protein as well as host factors, which may either support or inhibit replication of the virus. Recent studies have revealed that CA proteins are important not only for the uncoating step but also for the later nuclear import step. Identification of proteins that interact with CA to fulfill these functions is, therefore, important for understanding the unknown HIV-1 replication machinery. CA proteins can also be targets of the host immune response. Notably, some HLA-restricted cytotoxic T-lymphocyte (CTL) responses that recognize CA functional regions can greatly contribute to delay in AIDS progression. The multi-functionality of the CA protein may limit the flexible virus evolution and reduce the possibility of an escape mutant arising. The presence of many functional regions in CA protein may make it a potential target for effective therapies. PMID:23087682

  19. DD fusion in crystals

    SciTech Connect

    Tsyganov, E. N.

    2010-12-15

    The article discusses the mechanism of DD {sup {yields} 4}He fusion and so-called nonradiative thermalization of the reaction in crystals. The dynamics of this process is considered. The assumption that the decay time of the compound nucleus depends on its excitation energy makes experiments in crystals compatible with the acceleration data.We consider the processes in the crystals that increase the intensity ofDD fusion in comparison to the amorphous media, and the yield of the reaction is estimated.

  20. Fusion welding process

    DOEpatents

    Thomas, Kenneth C.; Jones, Eric D.; McBride, Marvin A.

    1983-01-01

    A process for the fusion welding of nickel alloy steel members wherein a ferrite containing pellet is inserted into a cavity in one member and melted by a welding torch. The resulting weld nugget, a fusion of the nickel containing alloy from the members to be welded and the pellet, has a composition which is sufficiently low in nickel content such that ferrite phases occur within the weld nugget, resulting in improved weld properties. The steel alloys encompassed also include alloys containing carbon and manganese, considered nickel equivalents.