Journal articles: 'Subviral Particles'

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Kaak, Michelle, Andreas Rausch, Dennis Müller, and Thomas Schanze. "Visualization and Parametrization of the Motion Behaviour of Subviral Particles." Current Directions in Biomedical Engineering 4, no. 1 (September 1, 2018): 359–62. http://dx.doi.org/10.1515/cdbme-2018-0086.

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AbstractThe development of a drug against pathogens of hemorrhagic fever, like the Marburg virus, is a great challenge. Therefore, accurate knowledge of the properties of subviral particles in the host cell must be obtained. The base for subviral particle analysis is a special fluorescence microscopy technique. In order to automate and visualize the subviral particles’ motion patterns, previously a tracking algorithm was developed. In this article a new algorithm to parameterize and visualize the achieved particle tracks is introduced. A good potential for a fast data recognition is shown, with constantly respecting a high usability for pharmaceutical researchers. This algorithm was tested on both simulated and real data and provides reproducible results.

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Bruns, Michael, Stefan Miska, Sylvie Chassot, and Hans Will. "Enhancement of Hepatitis B Virus Infection by Noninfectious Subviral Particles." Journal of Virology 72, no. 2 (February 1, 1998): 1462–68. http://dx.doi.org/10.1128/jvi.72.2.1462-1468.1998.

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ABSTRACT The biological function of the huge excess of subviral particles over virions in hepatitis B virus infections is unknown. Using the duck hepatitis B virus as a model, we unexpectedly found that subviral particles strongly enhance intracellular viral replication and gene expression. This effect is dependent on the multiplicity of infection, the ratio of virions over subviral particles, and the time point of addition of subviral particles. Most importantly, we show that the pre-S protein of the subviral particles triggers enhancement and requires the presence of the binding regions for putative cell-encoded virus receptor proteins. These data suggest that enhancement is due either to the recently described transactivation function of the pre-S protein or to signalling pathways which become activated upon binding of subviral particles to cellular receptors. The findings are of clinical importance, since they imply that infectivity of sera containing hepadnaviruses depends not only on the amount of infectious virions but also decisively on the number of particles devoid of nucleic acids. A similarly dramatic enhancing effect of noninfectious particles in other virus infections is well conceivable.

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Rausch, Andreas, and Thomas Schanze. "Fractal Dimensions of Subviral Particle Movement." Current Directions in Biomedical Engineering 4, no. 1 (September 1, 2018): 79–82. http://dx.doi.org/10.1515/cdbme-2018-0020.

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AbstractThe development of new medicines against virus infections like the Marburg virus disease requires an accurate knowledge of the respective pathogens. Conventionally, this process is very time expensive. In cooperation with the Virology of the Philipps-University in Marburg an automatic tracking algorithm for subviral particles in fluorescence image sequences was developed and programmed. To expand the benefit for the pharmaceutical researchers, also the trackevaluations need to be widely automated. In this work, a new parameterizing-method facing the fractal dimensions of spline interpolated subviral particle tracks is presented and tested with simulated and real data. The results reveal a good potential to classify tracks and, thus, types of subviral particles in infected cells.

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Garcia, Tamako, Jisu Li, Camille Sureau, Kiyoaki Ito, Yanli Qin, Jack Wands, and Shuping Tong. "Drastic Reduction in the Production of Subviral Particles Does Not Impair Hepatitis B Virus Virion Secretion." Journal of Virology 83, no. 21 (August 12, 2009): 11152–65. http://dx.doi.org/10.1128/jvi.00905-09.

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ABSTRACT Hepatitis B virus (HBV) contains three coterminal envelope proteins on the virion surface: large (L), middle (M), and small (S). The M and S proteins are also secreted as empty “subviral particles,” which exceed virions by at least 1,000-fold. The S protein serves as the morphogenic factor for both types of particles, while the L protein is required only for virion formation. We found that cotransfecting replication constructs with a small dose of the expression construct for the missing L, M, and S proteins reconstituted efficient virion secretion but only 5 to 10% of subviral particles. The L protein inhibited secretion of subviral particles in a dose-dependent manner, whereas a too-high or too-low L/S protein ratio inhibited virion secretion. Consistent with the results of cotransfection experiments, a point mutation at the −3 position of the S gene AUG codon reduced HBsAg secretion by 60 to 70% but maintained efficient virion secretion. Surprisingly, ablating M protein expression reduced virion secretion but markedly increased the maturity of virion-associated genomes, which could be reversed by providing in trans both L and M proteins but not just M protein. M protein stability was dependent on the coexpression of S protein. Our findings suggest that efficient HBV virion secretion could be maintained despite drastic reduction in subviral particle production, which supports the recent demonstration of separate secretion pathways adopted by the two types of particles. The M protein appears to facilitate core particle envelopment, thus shortening the window of plus strand DNA elongation.

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Bamford, Jaana K. H., and Dennis H. Bamford. "Large-scale purification of membrane-containing bacteriophage PRD1 and its subviral particles and its subviral particles." Virology 181, no. 1 (March 1991): 348–52. http://dx.doi.org/10.1016/0042-6822(91)90501-2.

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Chai, Ning, Ho Eun Chang, Emmanuelle Nicolas, Ziying Han, Michal Jarnik, and John Taylor. "Properties of Subviral Particles of Hepatitis B Virus." Journal of Virology 82, no. 16 (June 4, 2008): 7812–17. http://dx.doi.org/10.1128/jvi.00561-08.

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ABSTRACT In the sera of patients infected with hepatitis B virus (HBV), in addition to infectious particles, there is an excess (typically 1,000- to 100,000-fold) of empty subviral particles (SVP) composed solely of HBV envelope proteins in the form of relatively smaller spheres and filaments of variable length. Hepatitis delta virus (HDV) assembly also uses the envelope proteins of HBV to produce an infectious particle. Rate-zonal sedimentation was used to study the particles released from liver cell lines that produced SVP only, HDV plus SVP, and HBV plus SVP. The SVP made in the absence of HBV or HDV were further examined by electron microscopy. They bound efficiently to heparin columns, consistent with an ability to bind cell surface glycosaminoglycans. However, unlike soluble forms of HBV envelope protein that were potent inhibitors, the SVP did not inhibit the ability of HBV and HDV to infect primary human hepatocytes.

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Patient, Romuald, Christophe Hourioux, Pierre-Yves Sizaret, Sylvie Trassard, Camille Sureau, and Philippe Roingeard. "Hepatitis B Virus Subviral Envelope Particle Morphogenesis and Intracellular Trafficking." Journal of Virology 81, no. 8 (January 31, 2007): 3842–51. http://dx.doi.org/10.1128/jvi.02741-06.

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ABSTRACT Hepatitis B virus (HBV) is unusual in that its surface proteins (small [S], medium, and large [L]) are not only incorporated into the virion envelope but they also bud into empty subviral particles in great excess over virions. The morphogenesis of these subviral envelope particles remains unclear, but the S protein is essential and sufficient for budding. We show here that, in contrast to the presumed model, the HBV subviral particle formed by the S protein self-assembles into branched filaments in the lumen of the endoplasmic reticulum (ER). These long filaments are then folded and bridged for packing into crystal-like structures, which are then transported by ER-derived vesicles to the ER-Golgi intermediate compartment (ERGIC). Within the ERGIC, they are unpacked and relaxed, and their size and shape probably limits further progression through the secretory pathway. Such progression requires their conversion into spherical particles, which occurred spontaneously during the purification of these filaments by affinity chromatography. Small branched filaments are also formed by the L protein in the ER lumen, but these filaments are not packed into transport vesicles. They are transported less efficiently to the ERGIC, potentially accounting for the retention of the L protein within cells. These findings shed light on an important step in the HBV infectious cycle, as the intracellular accumulation of HBV subviral filaments may be directly linked to viral pathogenesis.

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Nugent, C. I., and K. Kirkegaard. "RNA binding properties of poliovirus subviral particles." Journal of virology 69, no. 1 (1995): 13–22. http://dx.doi.org/10.1128/jvi.69.1.13-22.1995.

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Chiang, Ying-Wei, Jaw-Chin Wu, Kuei-Chun Wang, Szu-Ting Chou, and Yu-Chen Hu. "Varied Properties of Hepatitis-Delta Virus-like Particles Produced by Baculovirus-Transduced Mammalian Cells." Open Biotechnology Journal 1, no. 1 (August 28, 2007): 34–40. http://dx.doi.org/10.2174/1874070700701010034.

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Hepatitis delta virus (HDV) is a defective virus that requires the supply of hepatitis B virus surface antigen (HBsAg) for replication and transmission. We have previously demonstrated that co-transduction of BHK cells with Bac- GD, a recombinant baculovirus expressing large hepatitis delta antigen (L-HDAg), and Bac-GS2, another recombinant baculovirus expressing HBsAg, gives rise to the assembly and secretion of 22 nm HBsAg subviral particles and 35-37 nm HDV-like particles (HDV VLP). In this study we uncovered oversize particles (>50 nm in diameter) comprised of HBsAg and L-HDAg and the particle properties varied with the relative dosages of Bac-GD and Bac-GS2, as demonstrated by Western blot, transmission electron microscopy and immunogold labeling. At a given Bac-GS2 dosage, decreasing the Bac-GD dosage resulted in the expression of more HBsAg, elevated secretion of HBsAg subviral particles, incorporation of more HBsAg into the HDV VLP, narrower particle size distribution and lower particle density. These data collectively demonstrated that the composition, and hence the properties, of HDV VLPs could be manipulated by altering the relative expression levels of structure proteins.

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Op De Beeck, Anne, Richard Molenkamp, Mélanie Caron, Amena Ben Younes, Peter Bredenbeek, and Jean Dubuisson. "Role of the Transmembrane Domains of prM and E Proteins in the Formation of Yellow Fever Virus Envelope." Journal of Virology 77, no. 2 (January 15, 2003): 813–20. http://dx.doi.org/10.1128/jvi.77.2.813-820.2003.

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ABSTRACT Flavivirus envelope proteins have been shown to play a major role in virus assembly. These proteins are anchored into cellular and viral membranes by their C-terminal domain. These domains are composed of two hydrophobic stretches separated by a short hydrophilic segment containing at least one charged residue. We investigated the role of the transmembrane domains of prM and E in the envelope formation of the flavivirus yellow fever virus (YFV). Alanine scanning insertion mutagenesis has been used to examine the role of the transmembrane domains of prM and E in YFV subviral particle formation. Most of the insertions had a dramatic effect on the release of YFV subviral particles. Some of these mutations were introduced into the viral genome. The ability of these mutant viruses to produce infectious particles was severely reduced. The alanine insertions did not affect prM-E heterodimerization. In addition, replacement of the charged residues present in the middle of the transmembrane domains had no effect on subviral particle release. Taken together, these data indicate that the transmembrane domains of prM and E play a crucial role in the biogenesis of YFV envelope. In addition, these data indicate some differences between the transmembrane domains of the hepaciviruses and the flaviviruses.

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Müller, Dennis, Andreas Rausch, Olga Dolnik, and Thomas Schanze. "Comparing human and algorithmic tracking of subviral particles in fluorescence microscopic image sequences." Current Directions in Biomedical Engineering 3, no. 2 (September 7, 2017): 543–47. http://dx.doi.org/10.1515/cdbme-2017-0114.

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AbstractTracking of subviral particles with automated methods enables the analysis of intracellular processes exhibited by viruses. A linear assignment problem solver and a Kalman-filter have been added to an existing particle tracking algorithm. First results produced with simulated image sequences showed that the improved algorithm is able to improve tracking results by closing gaps in the particle’s trajectories. Here we report on the evaluation of the LAP-Kalman algorithm using real fluorescence-microscopic images. The results from the original and improved algorithm have been compared to the results of manual tracking. Evaluation results indicate that the improved algorithm is capable to reconstruct missing parts of particle tracks in difficult conditions. However, the evaluation of the algorithms and the manual tracking is a complex task because of the low image contrast and high object density with intersecting tracks in the live-cell images.

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Jiang, Bingfu, Kiyoshi Himmelsbach, Huimei Ren, Klaus Boller, and Eberhard Hildt. "Subviral Hepatitis B Virus Filaments, like Infectious Viral Particles, Are Released via Multivesicular Bodies." Journal of Virology 90, no. 7 (December 30, 2015): 3330–41. http://dx.doi.org/10.1128/jvi.03109-15.

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ABSTRACTIn addition to infectious viral particles, hepatitis B virus-replicating cells secrete large amounts of subviral particles assembled by the surface proteins, but lacking any capsid and genome. Subviral particles form spheres (22-nm particles) and filaments. Filaments contain a much larger amount of the large surface protein (LHBs) compared to spheres. Spheres are released via the constitutive secretory pathway, while viral particles are ESCRT-dependently released via multivesicular bodies (MVBs). The interaction of virions with the ESCRT machinery is mediated by α-taxilin that connects the viral surface protein LHBs with the ESCRT component tsg101. Since filaments in contrast to spheres contain a significant amount of LHBs, it is unclear whether filaments are released like spheres or like virions. To study the release of subviral particles in the absence of virion formation, a core-deficient HBV mutant was generated. Confocal microscopy, immune electron microscopy of ultrathin sections and isolation of MVBs revealed that filaments enter MVBs. Inhibition of MVB biogenesis by the small-molecule inhibitor U18666A or inhibition of ESCRT functionality by coexpression of transdominant negative mutants (Vps4A, Vps4B, and CHMP3) abolishes the release of filaments while the secretion of spheres is not affected. These data indicate that in contrast to spheres which are secreted via the secretory pathway, filaments are released via ESCRT/MVB pathway like infectious viral particles.IMPORTANCEThis study revises the current model describing the release of subviral particles by showing that in contrast to spheres, which are secreted via the secretory pathway, filaments are released via the ESCRT/MVB pathway like infectious viral particles. These data significantly contribute to a better understanding of the viral morphogenesis and might be helpful for the design of novel antiviral strategies.

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Wang, Guoji, Kelly A. Dryden, Kevin M. Coombsf, Deirdre B. Furlongt, and Baker S. Timothy. "CRYO-Electron Microscopy of Reovirus Intermediate Subviral Particles." Proceedings, annual meeting, Electron Microscopy Society of America 48, no. 1 (August 12, 1990): 276–77. http://dx.doi.org/10.1017/s0424820100180136.

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Reovirus, the type member of the Reoviridae family, contains a segmented dsRNA genome, a multi-shell protein capsid structure, and transcriptase activity. The virus has been extensively characterized biochemically and genetically, although details of the structural organization of the RNA and protein components are not completely established. Reovirus contains eight structural proteins, three in the outer capsid (σ1, σ3, μ1C) and five associated with the core capsid (σ2, λl, λ2, λ3, μ2) . A number of morphogenetically related viral products including mature virions, cores and intermediate subviral particles (ISVP) exist naturally in the host cell. ISVPs are similar to virions, but lack σ3, and the cell recognition protein, σl extends radially outward from the viral surface by ∽40 nm. We have initialized a study of the structure of unstained, frozen-hydrated ISVPs using cryo-electron microscopy and three-dimensional image reconstruction techniques.ISVP samples were generated by digesting purified reovirus with α-chymotrypsin for 20 minutes.Aliquots of 4μl were applied to freshly-prepared, perforated carbon films, blotted with filter paper and rapidly plunged into liquid ethane. The sample was maintained at∽-170°C and images were recorded in a Philips EM420 microscope at ∽1 μm underfocus and at a nominal magnification of 30,000 × with an electron dose <1000e-/nm2.

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Pepperl-Klindworth, S., N. Frankenberg, S. Riegler, and B. Plachter. "Protein delivery by subviral particles of human cytomegalovirus." Gene Therapy 10, no. 3 (January 23, 2003): 278–84. http://dx.doi.org/10.1038/sj.gt.3301879.

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Jore, J. P. M., G. Veldhuisen, P. H. Pouwels, R. Vrijsen, B. Rombaut, and A. Boeye. "Synthesis of poliomyelitis subviral particles in S. cerevisiae." Vaccine 10, no. 4 (January 1992): 266. http://dx.doi.org/10.1016/0264-410x(92)90183-k.

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Hewat, Elizabeth A., and Dieter Blaas. "Nonneutralizing Human Rhinovirus Serotype 2-Specific Monoclonal Antibody 2G2 Attaches to the Region That Undergoes the Most Dramatic Changes upon Release of the Viral RNA." Journal of Virology 80, no. 24 (September 27, 2006): 12398–401. http://dx.doi.org/10.1128/jvi.01399-06.

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ABSTRACT The monoclonal antibody 2G2 has been used extensively for detection and quantification of structural changes of human rhinovirus serotype 2 during infection. It recognizes exclusively A and B subviral particles, not native virus. We have elucidated the basis of this selectivity by determining the footprint of 2G2. Since viral escape mutants obviously cannot be obtained, the structures of complexes between Fab fragments of 2G2 and 80S subviral B particles were determined by cryoelectron microscopy. The footprint of the antibody corresponds to the capsid region that we predicted would undergo the most dramatic changes upon RNA release.

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Kaak, Michelle, Andreas Rausch, and Thomas Schanze. "Automatic Classification of the Movements of Directed and Undirected Subviral Particles." Current Directions in Biomedical Engineering 6, no. 3 (September 1, 2020): 147–50. http://dx.doi.org/10.1515/cdbme-2020-3038.

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AbstractThe development of drugs against pathogens that cause hemorrhagic fever, such as Marburg and Ebola virus, requires researchers to gather much information about the virus. The accelerating of the research process is of great interest; therefore a new algorithm was developed to analyze intracellular processes. The algorithm will classify the motion characteristics of subviral particles in fluorescence microscopic image sequences of Ebola or Marburg virusinfected cells. The classification is based on the calculation of mean squared displacement. The results look promising to distinguish different particle tracks in active and passive transport. The paper ends with a discussion.

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Jore, J. P. M., G. Veldhuisen, M. Kottenhagen, P. H. Pouwels, A. Foriers, B. Rombaut, and A. Boeyé. "Formation of poliomyelitis subviral particles in the yeastSaccharomyces cerevisiae." Yeast 10, no. 7 (July 1994): 907–22. http://dx.doi.org/10.1002/yea.320100706.

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Halewyck, Hadewych, Iuliana Oita, Bert Thys, Bieke Dejaegher, Yvan Vander Heyden, and Bart Rombaut. "Identification of poliovirions and subviral particles by capillary electrophoresis." ELECTROPHORESIS 31, no. 19 (September 29, 2010): 3281–87. http://dx.doi.org/10.1002/elps.201000274.

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Kremser, Leopold, Gerhard Bilek, Dieter Blaas, and Ernst Kenndler. "Capillary electrophoresis of viruses, subviral particles and virus complexes." Journal of Separation Science 30, no. 11 (July 2007): 1704–13. http://dx.doi.org/10.1002/jssc.200700105.

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Allison, Steven L., Yizhi J. Tao, Gabriel O'Riordain, Christian W. Mandl, Stephen C. Harrison, and Franz X. Heinz. "Two Distinct Size Classes of Immature and Mature Subviral Particles from Tick-Borne Encephalitis Virus." Journal of Virology 77, no. 21 (November 1, 2003): 11357–66. http://dx.doi.org/10.1128/jvi.77.21.11357-11366.2003.

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ABSTRACT Flaviviruses assemble in the endoplasmic reticulum by a mechanism that appears to be driven by lateral interactions between heterodimers of the envelope glycoproteins E and prM. Immature intracellular virus particles are then transported through the secretory pathway and converted to their mature form by cleavage of the prM protein by the cellular protease furin. Earlier studies showed that when the prM and E proteins of tick-borne encephalitis virus are expressed together in mammalian cells, they assemble into membrane-containing, icosahedrally symmetrical recombinant subviral particles (RSPs), which are smaller than whole virions but retain functional properties and undergo cleavage maturation, yielding a mature form in which the E proteins are arranged in a regular T = 1 icosahedral lattice. In this study, we generated immature subviral particles by mutation of the furin recognition site in prM. The mutation resulted in the secretion of two distinct size classes of particles that could be separated by sucrose gradient centrifugation. Electron microscopy showed that the smaller particles were approximately the same size as the previously described mature RSPs, whereas the larger particles were approximately the same size as the virus. Particles of the larger size class were also detected with a wild-type construct that allowed prM cleavage, although in this case the smaller size class was far more prevalent. Subtle differences in endoglycosidase sensitivity patterns suggested that, in contrast to the small particles, the E glycoproteins in the large subviral particles and whole virions might be in nonequivalent structural environments during intracellular transport, with a portion of them inaccessible to cellular glycan processing enzymes. These proteins thus appear to have the intrinsic ability to form alternative assembly products that could provide important clues about the role of lateral envelope protein interactions in flavivirus assembly.

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Konopleva, M. V., M. V. Sokolova, N. V. Shevlyagina, A. I. Bazhenov, A. A. Fel’Dsherova, M. A. Krymskij, V. N. Borisova, T. A. Semenenko, V. G. Nesterenko, and A. P. Suslov. "MORPHOLOGICAL ANALYSIS OF HEPATITIS B VIRUS WITH ESCAPE MUTATIONS IN S-gene G145R AND S143L." Problems of Virology, Russian journal 62, no. 3 (June 20, 2017): 119–28. http://dx.doi.org/10.18821/0507-4088-2017-62-3-119-128.

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Background. In terms of serological properties and immunization, the wild type of HBsAg HBV and its G145R mutant behave as different antigens. This testifies to serious structural changes, which presumably could have a significant impact on the morphogenesis of virions and subviral particles. Nevertheless, morphological and ultrastructural investigations of HBV with G145R mutation have not been carried yet. Objectives. Research of structural and morphological organization of HBV in the presence of the G145R escape mutation. Methods. Studies of sera, purified viruses and recombinant HBsAg were carried out by transmission electron microscopy by the method of negative staining and indirect reaction of immunelabeling using monoclonal antibodies of different specificity. Specimens of wild type HBV and HBV with S143L mutation obtained in an identical manner were used as the control. Results. The presence of typical virus particles of HBV was shown in the specimens of wild strain and HBV with S143L mutation. Specimens of HBV with G145R mutation were characterized by expressed morphological heterogeneity. In the initial serum and in the specimen of purified virus containing G145R mutant, large oval particles 60-70 nm and up to 200 nm in size, respectively, were found. The presence of antigen structures of HBV in all heterogeneous forms was confirmed. It was shown that forming of subviral particles in the process of expression of the recombinant HBsAg with G145R mutation depends on conditions of expression and purification of the protein. They can vary from well-formed circular and oval particles to practically unstructured fine-grained masses. Conclusion. Direct data on the impact of G145R escape-mutation in S-gene, in contrast to S143L mutation, on the morphogenesis of virions and subviral particles of HBV were obtained.

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Rausch, Andreas, Dennis Müller, and Thomas Schanze. "Improvement of a subviral particle tracker by the use of a LAP-Kalman-algorithm." Current Directions in Biomedical Engineering 2, no. 1 (September 1, 2016): 415–18. http://dx.doi.org/10.1515/cdbme-2016-0092.

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AbstractAutomated detection and tracking of subviral particles is a promising method to obtain insights in complicated virus-cell interactions. This paper describes the implementation of a linear assignment problem solver and a Kalman-filter in an existing particle tracking algorithm. Two different simulated image sequences are used for the evaluation of the algorithms. Tracking and detection results of the new implemented solver are compared to the results of the original algorithm. The improved algorithm is able to improve the results by closing gaps in the particle tracks.

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W. Kron, Matthias, and Florian Kreppel. "Adenovirus Vectors and Subviral Particles for Protein and Peptide Delivery." Current Gene Therapy 12, no. 5 (September 1, 2012): 362–73. http://dx.doi.org/10.2174/156652312802762563.

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Leith, I. R., R. T. Hay, and W. C. Russell. "Adenovirus Subviral Particles and Cores Can Support Limited DNA Replication." Journal of General Virology 70, no. 12 (December 1, 1989): 3235–48. http://dx.doi.org/10.1099/0022-1317-70-12-3235.

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Kronenberger, P., R. Vrijsen, and A. Boeye. "Compartmentalization of subviral particles during poliovirus eclipse in HeLa cells." Journal of General Virology 73, no. 7 (July 1, 1992): 1739–44. http://dx.doi.org/10.1099/0022-1317-73-7-1739.

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Rombaut, B., and J. P. Jore. "Immunogenic, non-infectious polio subviral particles synthesized in Saccharomyces cerevisiae." Journal of General Virology 78, no. 8 (August 1, 1997): 1829–32. http://dx.doi.org/10.1099/0022-1317-78-8-1829.

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Patient, Romuald, Christophe Hourioux, and Philippe Roingeard. "Morphogenesis of hepatitis B virus and its subviral envelope particles." Cellular Microbiology 11, no. 11 (November 2009): 1561–70. http://dx.doi.org/10.1111/j.1462-5822.2009.01363.x.

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Stanke, Nicole, Annett Stange, Daniel Lüftenegger, Hanswalter Zentgraf, and Dirk Lindemann. "Ubiquitination of the Prototype Foamy Virus Envelope Glycoprotein Leader Peptide Regulates Subviral Particle Release." Journal of Virology 79, no. 24 (December 15, 2005): 15074–83. http://dx.doi.org/10.1128/jvi.79.24.15074-15083.2005.

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ABSTRACT Foamy virus (FV) particle egress is unique among retroviruses because of its essential requirement for Gag and Env coexpression for budding and particle release. The FV glycoprotein undergoes a highly unusual biosynthesis resulting in the generation of three particle-associated, mature subunits, leader peptide (LP), surface (SU), and transmembrane (TM), derived from a precursor protein by posttranslational proteolysis mediated by furin or furinlike proteases. Previously at least three LP products of different molecular weights were detected in purified FV particles. Here we demonstrate that the higher-molecular-weight forms gp28LP and gp38LP are ubiquitinated variants of the major gp18LP cleavage product, which has a type II membrane topology. Furthermore, we show that all five lysine residues located within the N-terminal 60-amino-acid cytoplasmic domain of gp18LP can potentially be ubiquitinated, however, there seems to be a preference for using the first three. Inactivation of ubiquitination sites individually resulted in no obvious phenotype. However, simultaneous inactivation of the first three or all five ubiquitination sites in gp18LP led to a massive increase in subviral particles released by these mutant glycoproteins that were readily detectable by electron microscopy analysis upon expression of the ubiquitination-deficient glycoprotein by itself or in a proviral context. Surprisingly, only the quintuple ubiquitination mutant showed a two- to threefold increase in single-cycle infectivity assays, whereas all other mutants displayed infectivities similar to that of the wild type. Taken together, these data suggest that the balance between viral and subviral particle release of FVs is regulated by ubiquitination of the glycoprotein LP.

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Kofler, Regina M., Franz X. Heinz, and Christian W. Mandl. "Capsid Protein C of Tick-Borne Encephalitis Virus Tolerates Large Internal Deletions and Is a Favorable Target for Attenuation of Virulence." Journal of Virology 76, no. 7 (April 1, 2002): 3534–43. http://dx.doi.org/10.1128/jvi.76.7.3534-3543.2002.

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ABSTRACT Deletions ranging in size from 4 to 21 amino acid residues were introduced into the capsid protein of the flavivirus tick-borne encephalitis (TBE) virus. These deletions incrementally affected a hydrophobic domain which is present at the center of all flavivirus capsid protein sequences and part of which may form an amphipathic alpha-helix. In the context of the full-length TBE genome, the deletions did not measurably affect protein expression and up to a deletion length of 16 amino acid residues, corresponding to almost 17% of mature protein C, viable virus was recovered. This virus was strongly attenuated but highly immunogenic in adult mice, revealing capsid protein C as a new and attractive target for the directed attenuation of flaviviruses. Apparently, the larger deletions interfered with the correct assembly of infectious virus particles, and this disturbance of virion assembly is likely to be the molecular basis of attenuation. However, all of the mutants carrying large deletions produced substantial amounts of subviral particles, which as judged from density gradient analyses were identical to recombinant subviral particles as obtained by the expression of the surface proteins prM and E alone. The structural and functional flexibility of protein C revealed in this study and its predicted largely alpha-helical conformation are reminiscent of capsid proteins of other enveloped viruses, such as alphaviruses (N-terminal domain of the capsid protein), retroviruses, and hepadnaviruses and suggest that all of these may belong to a common structural class, which is fundamentally distinct from the classical β-barrel structures of many icosahedral viral capsids. The possibility of attenuating flaviviruses by disturbing virus assembly and favoring the production of noninfectious but highly immunogenic subviral particles opens up a promising new avenue for the development of live flavivirus vaccines.

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Schmidt, Dennis, Andreas Rausch, and Thomas Schanze. "Deep learning-based recognition of cell structures in fluorescence microscopy sequences with respect to their morphology on cells infected with Marburg virus." Current Directions in Biomedical Engineering 6, no. 3 (September 1, 2020): 501–4. http://dx.doi.org/10.1515/cdbme-2020-3129.

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AbstractThe Institute of Virology at the Philipps-Universität Marburg is currently researching possible drugs to combat the Marburg virus. This involves classifying cell structures based on fluoroscopic microscopic image sequences. Conventionally, membranes of cells must be marked for better analysis, which is time consuming. In this work, an approach is presented to identify cell structures in images that are marked for subviral particles. It could be shown that there is a correlation between the distribution of subviral particles in an infected cell and the position of the cell’s structures. The segmentation is performed with a "Mask-R-CNN" algorithm, presented in this work. The model (a region-based convolutional neural network) is applied to enable a robust and fast recognition of cell structures. Furthermore, the network architecture is described. The proposed method is tested on data evaluated by experts. The results show a high potential and demonstrate that the method is suitable.

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Rausch, Andreas, and Thomas Schanze. "Improving subviral particle tracks in fluoroscopic image sequences by global motion compensation." Current Directions in Biomedical Engineering 3, no. 2 (September 7, 2017): 211–15. http://dx.doi.org/10.1515/cdbme-2017-0044.

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AbstractAutomatic detection and tracking of subviral particles in image sequences is an indispensable supportive method for modern medicine research programs. This paper describes the development of a highly adaptable camera-to-world system motion invariant tracking algorithm. A translation compensation is obtained by cross correlations. Particles are detected by an implemented existing algorithm. The detected particles are linked by solving a Linear Assignment Problem. For highly stable results the tracks are improved by Kalman filtering. The algorithm is tested on simulated sequences. The results show a great ability for stable tracking.

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Anderson, D. A., and B. C. Ross. "Morphogenesis of hepatitis A virus: isolation and characterization of subviral particles." Journal of Virology 64, no. 11 (1990): 5284–89. http://dx.doi.org/10.1128/jvi.64.11.5284-5289.1990.

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Pfister, T., D. Egger, and K. Bienz. "Poliovirus subviral particles associated with progeny RNA in the replication complex." Journal of General Virology 76, no. 1 (January 1, 1995): 63–71. http://dx.doi.org/10.1099/0022-1317-76-1-63.

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Fedotina, V. L., A. V. Krylov, and J. G. Atabekov. "Subviral rhabdovirus particles in millet infected with winter wheat mosaic virus." Archives Of Phytopathology And Plant Protection 21, no. 2 (January 1985): 111–20. http://dx.doi.org/10.1080/03235408509435919.

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Taghavian, Omid, Manoj K. Mandal, Nicole F. Steinmetz, Stefan Rasche, Holger Spiegel, Rainer Fischer, and Stefan Schillberg. "A potential nanobiotechnology platform based on infectious bursal disease subviral particles." RSC Advances 2, no. 5 (2012): 1970. http://dx.doi.org/10.1039/c2ra00857b.

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Helmberger-Jones, Mary, and John T. Patton. "Characterization of subviral particles in cells infected with simian rotavirus SA11." Virology 155, no. 2 (December 1986): 655–65. http://dx.doi.org/10.1016/0042-6822(86)90225-4.

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Stange, Annett, Daniel Lüftenegger, Juliane Reh, Winfried Weissenhorn, and Dirk Lindemann. "Subviral Particle Release Determinants of Prototype Foamy Virus." Journal of Virology 82, no. 20 (August 6, 2008): 9858–69. http://dx.doi.org/10.1128/jvi.00949-08.

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ABSTRACT Glycoproteins of several viruses have the capacity to induce release of noninfectious, capsidless particulate structures containing only the viral glycoprotein. Such structures are often called subviral particles (SVP). Foamy viruses (FVs), a special type of retroviruses with a replication strategy combining features of both orthoretroviruses and hepadnaviruses, express a glycoprotein (Env) which has the ability to induce SVP release. However, unlike human hepatitis B virus, prototype FV (PFV) naturally secretes only small amounts of SVPs, because ubiquitination of the Env protein seems to suppress the intrinsic capacity for induction of SVP release. In this study, we characterized the structural determinants influencing PFV SVP release, examined the role of specific Env ubiquitination sites in the regulation of this process, and analyzed the requirement of the cellular vacuolar protein sorting (VPS) machinery for SVP egress. We observed that the cytoplasmic and membrane-spanning domains of both the leader peptide (LP) and the transmembrane (TM) subunit harbor essential as well as inhibitory domains. Furthermore, only ubiquitination at the most N-terminal lysine residues (K14 and K15) in LP reduced cell surface expression and suppressed SVP release to wild-type levels. This suggests that interaction of Env with cellular components required for SVP release suppression is effective only when Env is ubiquitinated at these lysine residues but not at others. Finally, SVP release was sensitive to dominant-negative mutants of late components, but not early components, of the cellular VPS machinery. PFV therefore differs from hepatitis B virus in using the same cellular pathway for egress of both virions and SVPs.

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Grgacic, E. V. L., and H. Schaller. "A Metastable Form of the Large Envelope Protein of Duck Hepatitis B Virus: Low-pH Release Results in a Transition to a Hydrophobic, Potentially Fusogenic Conformation." Journal of Virology 74, no. 11 (June 1, 2000): 5116–22. http://dx.doi.org/10.1128/jvi.74.11.5116-5122.2000.

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ABSTRACT We have examined the structure and fusion potential of the duck hepatitis B virus (DHBV) envelope proteins by treating subviral particles with deforming agents known to release envelope proteins of viruses from a metastable to a fusion-active state. Exposure of DHBV particles to low pH triggered a major structural change in the large envelope protein (L), resulting in exposure of trypsin sites within its S domain but without affecting the same region in the small surface protein (S) subunits. This conformational change was associated with increased hydrophobicity of the particle surface, most likely arising from surface exposure of the hydrophobic first transmembrane domain (TM1). In the hydrophobic conformation, DHBV particles were able to bind to liposomes and intact cells, while in their absence these particles aggregated, resulting in viral inactivation. These results suggests that some L molecules are in a spring-loaded metastable state which, when released, exposes a previously hidden hydrophobic domain, a transition potentially representing the fusion-active state of the envelope.

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Wilk, Thomas, Brent Gowen, and Stephen D. Fuller. "Actin Associates with the Nucleocapsid Domain of the Human Immunodeficiency Virus Gag Polyprotein." Journal of Virology 73, no. 3 (March 1, 1999): 1931–40. http://dx.doi.org/10.1128/jvi.73.3.1931-1940.1999.

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ABSTRACT Recently, it was shown that actin molecules are present in human immunodeficiency virus type 1 (HIV-1) particles. We have examined the basis for incorporation and the location of actin molecules within HIV-1 and murine retrovirus particles. Our results show that the retroviral Gag polyprotein is sufficient for actin uptake. Immunolabeling studies demonstrate that actin molecules localize to a specific radial position within the immature particle, clearly displaced from the matrix domain underneath the viral membrane but in proximity to the nucleocapsid (NC) domain of the Gag polyprotein. When virus or subviral Gag particles were disrupted with nonionic detergent, actin molecules remained associated with the disrupted particles. Actin molecules remained in a stable complex with the NC cleavage product (or an NC-RNA complex) after treatment of the disrupted HIV-1 particles with recombinant HIV-1 protease. In contrast, matrix and capsid molecules were released. The same result was obtained when mature HIV-1 particles were disrupted with detergent. Taken together, these results indicate that actin molecules are associated with the NC domain of the viral polyprotein.

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Kotov, Alexander, Jing Zhou, Paula Flicker, and Christopher Aiken. "Association of Nef with the Human Immunodeficiency Virus Type 1 Core." Journal of Virology 73, no. 10 (October 1, 1999): 8824–30. http://dx.doi.org/10.1128/jvi.73.10.8824-8830.1999.

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ABSTRACT Highly conserved among primate lentiviruses, the human immunodeficiency virus type 1 (HIV-1) Nef protein enhances viral infectivity by an unknown mechanism. Nef-defective virions are blocked at a stage of the HIV-1 life cycle between entry and reverse transcription, possibly virus uncoating. Nef is present in purified HIV-1 particles; however, it has not been determined whether Nef is specifically recruited into HIV-1 particles or whether virion-associated Nef plays a functional role in HIV-1 replication. To address the specificity and potential functionality of virion-associated Nef, we determined the subviral localization of Nef. HIV-1 cores were isolated by detergent treatment of concentrated virions followed by equilibrium density gradient sedimentation. Relative to HIV-1 virions, HIV-1 cores contained equivalent amounts of reverse transcriptase and integrase, decreased amounts of the viral matrix protein, and trace quantities of the viral transmembrane glycoprotein gp41. Examination of the particles by electron microscopy revealed cone-shaped structures characteristic of lentiviral cores. Similar quantities of proteolytically processed Nef protein were detected in gradient fractions of HIV-1 cores and intact virions. In addition, detergent-resistant subviral complexes isolated from immature HIV-1 particles contained similar quantities of Nef as untreated virions. These results demonstrate that Nef stably associates with the HIV-1 core and suggest that virion-associated Nef plays a functional role in accelerating HIV-1 replication.

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Jenna, Sarah, and Camille Sureau. "Mutations in the Carboxyl-Terminal Domain of the Small Hepatitis B Virus Envelope Protein Impair the Assembly of Hepatitis Delta Virus Particles." Journal of Virology 73, no. 4 (April 1, 1999): 3351–58. http://dx.doi.org/10.1128/jvi.73.4.3351-3358.1999.

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ABSTRACT The carboxyl-terminal domain of the small (S) envelope protein of hepatitis B virus was subjected to mutagenesis to identify sequences important for the envelopment of the nucleocapsid during morphogenesis of hepatitis delta virus (HDV) virions. The mutations consisted of carboxyl-terminal truncations of 4 to 64 amino acid residues and small combined deletions and insertions spanning the entire hydrophobic domain between residues 163 and 224. Truncation of as few as 14 residues partially inhibited glycosylation and secretion of S and prevented assembly or stability of HDV virions. Short internal combined deletions and insertions were tolerated for secretion of subviral particles with the exceptions of those affecting residues 164 to 173 and 219 to 223. However, mutants competent for subviral particle secretion had a reduced capacity for HDV assembly compared to that of the wild type. One exception was a mutant carrying a deletion of residues 214 to 218, which exhibited a twofold increase in HDV assembly (or stability), whereas deletions of residues 179 to 183, 194 to 198, and 199 to 203 were the most inhibitory. Substitutions of single amino acids between residues 194 and 198 demonstrated that HDV assembly deficiency could be assigned to the replacement of the tryptophan residue at position 196. We concluded that assembly of stable HDV particles requires a specific function of the carboxyl terminus of S which is mediated at least in part by Trp-196.

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Ho, Joan Kha-Tu, Beena Jeevan-Raj, and Hans-Jürgen Netter. "Hepatitis B Virus (HBV) Subviral Particles as Protective Vaccines and Vaccine Platforms." Viruses 12, no. 2 (January 21, 2020): 126. http://dx.doi.org/10.3390/v12020126.

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Hepatitis B remains one of the major global health problems more than 40 years after the identification of human hepatitis B virus (HBV) as the causative agent. A critical turning point in combating this virus was the development of a preventative vaccine composed of the HBV surface (envelope) protein (HBsAg) to reduce the risk of new infections. The isolation of HBsAg sub-viral particles (SVPs) from the blood of asymptomatic HBV carriers as antigens for the first-generation vaccines, followed by the development of recombinant HBsAg SVPs produced in yeast as the antigenic components of the second-generation vaccines, represent landmark advancements in biotechnology and medicine. The ability of the HBsAg SVPs to accept and present foreign antigenic sequences provides the basis of a chimeric particulate delivery platform, and resulted in the development of a vaccine against malaria (RTS,S/AS01, MosquirixTM), and various preclinical vaccine candidates to overcome infectious diseases for which there are no effective vaccines. Biomedical modifications of the HBsAg subunits allowed the identification of strategies to enhance the HBsAg SVP immunogenicity to build potent vaccines for preventative and possibly therapeutic applications. The review provides an overview of the formation and assembly of the HBsAg SVPs and highlights the utilization of the particles in key effective vaccines.

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Allnutt, F. C. Thomas, Robert M. Bowers, Christopher G. Rowe, Vikram N. Vakharia, Scott E. LaPatra, and Arun K. Dhar. "Antigenicity of infectious pancreatic necrosis virus VP2 subviral particles expressed in yeast." Vaccine 25, no. 26 (June 2007): 4880–88. http://dx.doi.org/10.1016/j.vaccine.2007.04.068.

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Cao, Jianhao, Junchang Zhang, Yanmeng Lu, Shuhong Luo, Jingqiang Zhang, and Ping Zhu. "Cryo-EM structure of native spherical subviral particles isolated from HBV carriers." Virus Research 259 (January 2019): 90–96. http://dx.doi.org/10.1016/j.virusres.2018.10.015.

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Jore, J. P. M., G. Veldhuisen, P. H. Pouwels, A. Boeye, R. Vrijsen, and B. Rombaut. "Formation of subviral particles by in vitro translation of subgenomic poliovirus RNAs." Journal of General Virology 72, no. 11 (November 1, 1991): 2721–26. http://dx.doi.org/10.1099/0022-1317-72-11-2721.

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Aillot, Ludovic, Marc Bonnin, Malika Ait-Goughoulte, Nathalie Bendriss-Vermare, Sarah Maadadi, Laura Dimier, Miroslava Subic, et al. "Interaction between Toll-Like Receptor 9-CpG Oligodeoxynucleotides and Hepatitis B Virus Virions Leads to Entry Inhibition in Hepatocytes and Reduction of Alpha Interferon Production by Plasmacytoid Dendritic Cells." Antimicrobial Agents and Chemotherapy 62, no. 4 (February 12, 2018): e01741-17. http://dx.doi.org/10.1128/aac.01741-17.

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ABSTRACTWe previously reported that Toll-like receptor 9 (TLR9)-CpG oligonucleotides could inhibit the establishment of hepatitis B virus (HBV) infections in hepatocytes. Our aim was to uncover the underlying mechanisms of this inhibition. HepaRG cells, RPMI-B lymphoblastoma cells, and primary plasmacytoid dendritic cells (pDCs) exposed to HBV and TLR9 ligands/agonists in various configurations were used. We observed an inhibition of HBV infection upon TLR9 stimulations only when agonist was applied during inoculation. This inhibition was independent of interleukin-6 (IL-6)/interferon-inducible protein 10 (IP-10) production as well as of TLR9 expression in hepatocytes. We further demonstrated an entry inhibition mechanism by showing a noncovalent binding of TLR9 agonist to HBV particles. Besides inhibiting HBV entry into hepatocytes, this biophysical interaction between HBV virions and TLR9 agonist was responsible for a reduction of alpha interferon (IFN-α) expression by pDCs. Interestingly, subviral particles composed of only HBsAg were able to genuinely inhibit the TLR9 pathway, without titrating TLR9 ligands. To conclude, our data suggest that synthetic TLR9-CpG oligonucleotides can strongly inhibit HBV entry by “coating” HBV virions and thereby preventing their interaction with cellular receptor. This titration effect of TLR9 agonist is also artifactually responsible for the inhibition of TLR9 engagement in pDCs, whereas a genuine inhibition of this innate pathway was confirmed with HBsAg subviral particles.

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Blazevic, Janja, Harald Rouha, Victoria Bradt, Franz X. Heinz, and Karin Stiasny. "Membrane Anchors of the Structural Flavivirus Proteins and Their Role in Virus Assembly." Journal of Virology 90, no. 14 (May 4, 2016): 6365–78. http://dx.doi.org/10.1128/jvi.00447-16.

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ABSTRACTThe structural proteins of flaviviruses carry a unique set of transmembrane domains (TMDs) at their C termini that are derived from the mode of viral polyprotein processing. They function as internal signal and stop-transfer sequences during protein translation, but possible additional roles in protein interactions required during assembly and maturation of viral particles are ill defined. To shed light on the role of TMDs in these processes, we engineered a set of tick-borne encephalitis virus mutants in which these structural elements were replaced in different combinations by the homologous sequences of a distantly related flavivirus (Japanese encephalitis virus). The effects of these modifications were analyzed with respect to protein synthesis, viral particle secretion, specific infectivity, and acidic-pH-induced maturation processes. We provide evidence that interactions involving the double-membrane anchor of the envelope protein E (a unique feature compared to other viral fusion proteins) contribute substantially to particle assembly, stability, and maturation. Disturbances of the inter- and intra-TMD interactions of E resulted in the secretion of a larger proportion of capsidless subviral particles at the expense of whole virions, suggesting a possible role in the still incompletely understood mechanism of capsid integration during virus budding. In contrast, the TMD initially anchoring the C protein to the endoplasmic reticulum membrane does not appear to take part in envelope protein interactions. We also show that E TMDs are involved in the envelope protein rearrangements that are triggered by acidic pH in thetrans-Golgi network and represent a hallmark of virus maturation.IMPORTANCEThe assembly of flaviviruses occurs in the endoplasmic reticulum and leads to the formation of immature, noninfectious particles composed of an RNA-containing capsid surrounded by a lipid membrane, with the two integrated envelope proteins, prM and E, arranged in an icosahedral lattice. The mechanism by which the capsid is formed and integrated into the budding viral envelope is currently unknown. We provide evidence that the transmembrane domains (TMDs) of E are essential for the formation of capsid-containing particles and that disturbances of these interactions lead to the preferential formation of capsidless subviral particles at the expense of whole virions. E TMD interactions also appear to be essential for the envelope protein rearrangements required for virus maturation and for the generation of infectious virions. Our data thus provide new insights into the biological functions of E TMDs and extend their role during viral polyprotein processing to additional functions in particle assembly and maturation.

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Konishi, Eiji, Atsuko Fujii, and Peter W. Mason. "Generation and Characterization of a Mammalian Cell Line Continuously Expressing Japanese Encephalitis Virus Subviral Particles." Journal of Virology 75, no. 5 (March 1, 2001): 2204–12. http://dx.doi.org/10.1128/jvi.75.5.2204-2212.2001.

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ABSTRACT We have generated a cell line (F cells) producing a secreted form of Japanese encephalitis virus (JEV) subviral particle (extracellular particles [EPs]) that contains the JEV envelope glycoprotein (E) and a precursor (prM) of the virion membrane protein (M). The F cells were engineered to synthesize these JEV products from a cDNA encoding a mutated (furin proteinase resistant) form of prM, since stable cell lines expressing E and the authentic form of prM could not be obtained, due (in part) to the cell-fusing ability of EPs containing E and M. Our biochemical alteration of the prM protein was critical for the successful production of EP-producing cell lines. EPs produced by F cells share the biochemical properties of empty viral particles produced by JEV-infected cells, except that the F-cell EPs lack hemagglutinating activity and M. F-cell EPs were recognized by a panel of monoclonal antibodies to E, and EPs were shown to be useful as vaccine candidates in mice and as diagnostic reagents in evaluating human immune responses to JE vaccination. The amounts of E antigen released into the culture fluid of F cells were similar to those found in virion fractions of JEV-infected cell culture fluids or JEV-infected weanling mouse brains (the current source of antigen used to produce human vaccines for JE). Thus, the F-cell line would appear to be a useful source of antigen for JE vaccines and diagnostics.

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Junjhon, Jiraphan, Matthawee Lausumpao, Sunpetchuda Supasa, Sansanee Noisakran, Adisak Songjaeng, Prakaimuk Saraithong, Kridsada Chaichoun, et al. "Differential Modulation of prM Cleavage, Extracellular Particle Distribution, and Virus Infectivity by Conserved Residues at Nonfurin Consensus Positions of the Dengue Virus pr-M Junction." Journal of Virology 82, no. 21 (August 20, 2008): 10776–91. http://dx.doi.org/10.1128/jvi.01180-08.

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ABSTRACT In the generation of flavivirus particles, an internal cleavage of the envelope glycoprotein prM by furin is required for the acquisition of infectivity. Unlike cleavage of the prM of other flaviviruses, cleavage of dengue virus prM is incomplete in many cell lines; the partial cleavage reflects the influence of residues at furin nonconsensus positions of the pr-M junction, as flaviviruses share basic residues at positions P1, P2, and P4, recognized by furin. In this study, viruses harboring the alanine-scanning and other multiple-point mutations of the pr-M junction were generated, employing a dengue virus background that exhibited 60 to 70% prM cleavage and a preponderance of virion-sized extracellular particles. Analysis of prM and its cleavage products in viable mutants revealed a cleavage-suppressive effect at the conserved P3 Glu residue, as well as the cleavage-augmenting effects at the P5 Arg and P6 His residues, indicating an interplay between opposing modulatory influences mediated by these residues on the cleavage of the pr-M junction. Changes in the prM cleavage level were associated with altered proportions of extracellular virions and subviral particles; mutants with reduced cleavage were enriched with subviral particles and prM-containing virions, whereas the mutant with enhanced cleavage was deprived of these particles. Alterations of virus multiplication were detected in mutants with reduced prM cleavage and were correlated with their low specific infectivities. These findings define the functional roles of charged residues located adjacent to the furin consensus sequence in the cleavage of dengue virus prM and provide plausible mechanisms by which the reduction in the pr-M junction cleavability may affect virus replication.

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Journal articles on the topic 'Subviral Particles'

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