Journal articles: 'Virus-based particles'

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Kang, Sang-Moo, Jae-Min Song, Fu-Shi Quan, and Richard W. Compans. "Influenza vaccines based on virus-like particles." Virus Research 143, no. 2 (August 2009): 140–46. http://dx.doi.org/10.1016/j.virusres.2009.04.005.

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Wichgers Schreur, Paul J., Nadia Oreshkova, Frank Harders, Alex Bossers, Rob J. M. Moormann, and Jeroen Kortekaas. "Paramyxovirus-based production of Rift Valley fever virus replicon particles." Journal of General Virology 95, no. 12 (December 1, 2014): 2638–48. http://dx.doi.org/10.1099/vir.0.067660-0.

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Replicon-particle-based vaccines combine the efficacy of live-attenuated vaccines with the safety of inactivated or subunit vaccines. Recently, we developed Rift Valley fever virus (RVFV) replicon particles, also known as nonspreading RVFV (NSR), and demonstrated that a single vaccination with these particles can confer sterile immunity in target animals. NSR particles can be produced by transfection of replicon cells, which stably maintain replicating RVFV S and L genome segments, with an expression plasmid encoding the RVFV glycoproteins, Gn and Gc, normally encoded by the M-genome segment. Here, we explored the possibility to produce NSR with the use of a helper virus. We show that replicon cells infected with a Newcastle disease virus expressing Gn and Gc (NDV-GnGc) were able to produce high levels of NSR particles. In addition, using reverse genetics and site-directed mutagenesis, we were able to create an NDV-GnGc variant that lacks the NDV fusion protein and contains two amino acid substitutions in, respectively, Gn and HN. The resulting virus uses a unique entry pathway that facilitates the efficient production of NSR in a one-component system. The novel system provides a promising alternative for transfection-based NSR production.

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Eskelin, Katri, Minna M. Poranen, and Hanna M. Oksanen. "Asymmetrical Flow Field-Flow Fractionation on Virus and Virus-Like Particle Applications." Microorganisms 7, no. 11 (November 12, 2019): 555. http://dx.doi.org/10.3390/microorganisms7110555.

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Asymmetrical flow field-flow fractionation (AF4) separates sample components based on their sizes in the absence of a stationary phase. It is well suited for high molecular weight samples such as virus-sized particles. The AF4 experiment can potentially separate molecules within a broad size range (~103−109 Da; particle diameter from 2 nm to 0.5−1 μm). When coupled to light scattering detectors, it enables rapid assays on the size, size distribution, degradation, and aggregation of the studied particle populations. Thus, it can be used to study the quality of purified viruses and virus-like particles. In addition to being an advanced analytical characterization technique, AF4 can be used in a semi-preparative mode. Here, we summarize and provide examples on the steps that need optimization for obtaining good separation with the focus on virus-sized particles.

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Neumann, Gabriele, Tokiko Watanabe, and Yoshihiro Kawaoka. "Plasmid-Driven Formation of Influenza Virus-Like Particles." Journal of Virology 74, no. 1 (January 1, 2000): 547–51. http://dx.doi.org/10.1128/jvi.74.1.547-551.2000.

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ABSTRACT We established a plasmid-based system for generating infectious influenza virus-like particles entirely from cloned cDNAs. Human embryonic kidney cells (293T) were transfected with plasmids encoding the influenza A virus structural proteins and with a plasmid encoding an influenza virus-like viral RNA (vRNA) which contained an antisense copy of the cDNA for green fluorescence protein (GFP) flanked by an RNA polymerase I promoter and terminator. Intracellular transcription of the latter construct by RNA polymerase I generated GFP vRNA that was packaged into influenza virus-like particles. This system, which produced more than 104 infectious particles per ml of supernatant, would be useful in studies of influenza virus replication and particle formation. It might also benefit efforts in vaccine production and in the development of improved gene therapy vectors.

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Hare, David N., Susan E. Collins, Subhendu Mukherjee, Yueh-Ming Loo, Michael Gale, Luke J. Janssen, and Karen L. Mossman. "Membrane Perturbation-Associated Ca2+Signaling and Incoming Genome Sensing Are Required for the Host Response to Low-Level Enveloped Virus Particle Entry." Journal of Virology 90, no. 6 (December 30, 2015): 3018–27. http://dx.doi.org/10.1128/jvi.02642-15.

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ABSTRACTThe type I interferon (IFN) response is an important aspect of innate antiviral defense, and the transcription factor IRF3 plays an important role in its induction. Membrane perturbation during fusion, a necessary step for enveloped virus particle entry, appears sufficient to induce transcription of a subset of IFN-stimulated genes (ISGs) in an IRF3-dependent, IFN-independent fashion. IRF3 is emerging as a central node in host cell stress responses, although it remains unclear how different forms of stress activate IRF3. Here, we investigated the minimum number of Sendai virus (SeV) and human cytomegalovirus (HCMV) particles required to activate IRF3 and trigger an antiviral response. We found that Ca2+signaling associated with membrane perturbation and recognition of incoming viral genomes by cytosolic nucleic acid receptors are required to activate IRF3 in response to fewer than 13 particles of SeV and 84 particles of HCMV per cell. Moreover, it appears that Ca2+signaling is important for activation of STING and IRF3 following HCMV particle entry, suggesting that Ca2+signaling sensitizes cells to recognize genomes within incoming virus particles. To our knowledge, this is the first evidence that cytosolic nucleic acid sensors recognize genomes within incoming virus particles prior to virus replication. These studies highlight the exquisite sensitivity of the cellular response to low-level stimuli and suggest that virus particle entry is sensed as a stress signal.IMPORTANCEThe mechanism by which replicating viruses trigger IRF3 activation and type I IFN induction through the generation and accumulation of viral pathogen-associated molecular patterns has been well characterized. However, the mechanism by which enveloped virus particle entry mediates a stress response, leading to IRF3 activation and the IFN-independent response, remained elusive. Here, we find that Ca2+signaling associated with membrane perturbation appears to sensitize cells to recognize genomes within incoming virus particles. To our knowledge, this is the first study to show that cytosolic receptors recognize genomes within incoming virus particles prior to virus replication. These findings not only highlight the sensitivity of cellular responses to low-level virus particle stimulation, but provide important insights into how nonreplicating virus vectors or synthetic lipid-based carriers used as clinical delivery vehicles activate innate immune responses.

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Szakács, Zoltán, Tamás Mészáros, Marien I. de Jonge, and Róbert E. Gyurcsányi. "Selective counting and sizing of single virus particles using fluorescent aptamer-based nanoparticle tracking analysis." Nanoscale 10, no. 29 (2018): 13942–48. http://dx.doi.org/10.1039/c8nr01310a.

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Selective labelling of virus particles with fluorescent aptamers enables their identification, sizing and counting at the single particle level even in clinical samples by fluorescent nanoparticle tracking analysis.

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Sykora, Sabine, Alessandro Cumbo, Gaël Belliot, Pierre Pothier, Charlotte Arnal, Yves Dudal, Philippe F. X. Corvini, and Patrick Shahgaldian. "Virus-like particles as virus substitutes to design artificial virus-recognition nanomaterials." Chemical Communications 51, no. 12 (2015): 2256–58. http://dx.doi.org/10.1039/c4cc08843c.

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Zhou, Jie, Jianjian Wei, Ka-Tim Choy, Sin Fun Sia, Dewi K. Rowlands, Dan Yu, Chung-Yi Wu, et al. "Defining the sizes of airborne particles that mediate influenza transmission in ferrets." Proceedings of the National Academy of Sciences 115, no. 10 (February 20, 2018): E2386—E2392. http://dx.doi.org/10.1073/pnas.1716771115.

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Epidemics and pandemics of influenza are characterized by rapid global spread mediated by non-mutually exclusive transmission modes. The relative significance between contact, droplet, and airborne transmission is yet to be defined, a knowledge gap for implementing evidence-based infection control measures. We devised a transmission chamber that separates virus-laden particles by size and determined the particle sizes mediating transmission of influenza among ferrets through the air. Ferret-to-ferret transmission was mediated by airborne particles larger than 1.5 µm, consistent with the quantity and size of virus-laden particles released by the donors. Onward transmission by donors was most efficient before fever onset and may continue for 5 days after inoculation. Multiple virus gene segments enhanced the transmissibility of a swine influenza virus among ferrets by increasing the release of virus-laden particles into the air. We provide direct experimental evidence of influenza transmission via droplets and fine droplet nuclei, albeit at different efficiency.

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Uematsu, Yasushi, Michael Vajdy, Ying Lian, Silvia Perri, Catherine E. Greer, Harold S. Legg, Grazia Galli, et al. "Lack of Interference with Immunogenicity of a Chimeric Alphavirus Replicon Particle-Based Influenza Vaccine by Preexisting Antivector Immunity." Clinical and Vaccine Immunology 19, no. 7 (May 23, 2012): 991–98. http://dx.doi.org/10.1128/cvi.00031-12.

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ABSTRACTAntivector immunity has been recognized as a potential caveat of using virus-based vaccines. In the present study, an alphavirus-based replicon particle vaccine platform, which has demonstrated robust immunogenicity in animal models, was tested for effects of antivector immunity on immunogenicity against hemagglutinin of influenza virus as a target antigen and efficacy for protection against lethal challenge with the virus. Chimeric alphavirus-based replicon particles, comprising Venezuelan equine encephalitis virus nonstructural and Sindbis virus structural components, induced efficient protective antibody responses, which were not adversely influenced after multiple immunizations with the same vector expressing various antigens.

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Devignot, Stephanie, Eric Bergeron, Stuart Nichol, Ali Mirazimi, and Friedemann Weber. "A Virus-Like Particle System Identifies the Endonuclease Domain of Crimean-Congo Hemorrhagic Fever Virus." Journal of Virology 89, no. 11 (March 25, 2015): 5957–67. http://dx.doi.org/10.1128/jvi.03691-14.

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ABSTRACTCrimean-Congo hemorrhagic fever virus(CCHFV; genusNairovirus) is an extremely pathogenic member of theBunyaviridaefamily. Since handling of the virus requires a biosafety level 4 (BSL-4) facility, little is known about pathomechanisms and host interactions. Here, we describe the establishment of a transcriptionally competent virus-like particle (tc-VLP) system for CCHFV. Recombinant polymerase (L), nucleocapsid protein (N) and a reporter minigenome expressed in human HuH-7 cells resulted in formation of transcriptionally active nucleocapsids that could be packaged by coexpressed CCHFV glycoproteins into tc-VLPs. The tc-VLPs resembled authentic virus particles in their protein composition and neutralization sensitivity to anti-CCHFV antibodies and could recapitulate all steps of the viral replication cycle. Particle attachment, entry, and primary transcription were modeled by infection of naive cells. The subsequent steps of genome replication, secondary transcription, and particle assembly and release can be obtained upon passaging the tc-VLPs on cells expressing CCHFV structural proteins. The utility of the VLP system was demonstrated by showing that the endonuclease domain of L is located around amino acid D693, as was predictedin silicoby B. Morin et al. (PLoS Pathog 6:e1001038, 2010,http://dx.doi.org/10.1371/journal.ppat.1001038). The tc-VLP system will greatly facilitate studies and diagnostics of CCHFV under non-BSL-4 conditions.IMPORTANCECrimean-Congo hemorrhagic fever virus (CCHFV) is an extremely virulent pathogen of humans. Since the virus can be handled only at the highest biosafety level, research is restricted to a few specialized laboratories. We developed a plasmid-based system to produce virus-like particles with the ability to infect cells and transcribe a reporter genome. Due to the absence of viral genes, the virus-like particles are unable to spread or cause disease, thus allowing study of aspects of CCHFV biology under relaxed biosafety conditions.

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Bundy, Bradley C., Marc J. Franciszkowicz, and James R. Swartz. "Escherichia coli-based cell-free synthesis of virus-like particles." Biotechnology and Bioengineering 100, no. 1 (2008): 28–37. http://dx.doi.org/10.1002/bit.21716.

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Reichel, Christoph, Claus Ruehland, Christian O. A. Reiser, and Juergen Hess. "Protein-Based Nanosystems: Virus-Like-Particles in Modern Vaccine Development." Journal of Biomedical Nanotechnology 2, no. 3 (October 1, 2006): 186–200. http://dx.doi.org/10.1166/jbn.2006.035.

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Jegerlehner, Andrea, Franziska Zabel, Alice Langer, Klaus Dietmeier, Gary T. Jennings, Philippe Saudan, and Martin F. Bachmann. "Bacterially Produced Recombinant Influenza Vaccines Based on Virus-Like Particles." PLoS ONE 8, no. 11 (November 18, 2013): e78947. http://dx.doi.org/10.1371/journal.pone.0078947.

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Blokhina, E. A., and N. V. Ravin. "CONSTRUCTION OF MOSAIC HBC PARTICLES PRESENTING CONSERVATIVE FRAGMENTS OF M2 PROTEIN AND HEMAGGLUTININ OF INFLUENZA A VIRUS." Problems of Virology, Russian journal 63, no. 3 (June 20, 2018): 130–35. http://dx.doi.org/10.18821/0507-4088-2018-63-3-130-135.

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Virus-like HBc particles formed as a result of the self-assembly of the nuclear antigen of the hepatitis B virus can be used as a highly immunogenic carrier for the presentation of foreign epitopes when creating recombinant vaccines. We use this vehicle to create influenza vaccines based on the conservative antigens of the influenza virus, the extracellular domain of the transmembrane protein M2 (M2e) and the fragment of the second subunit of hemagglutinin (HA2). Presentation on the surface of HBc particles should improve the immunogenicity of these peptides. Using genetic engineering techniques, we obtained a fusion protein in which the HA2 sequence is attached to the N-terminus of the HBc antigen, and the M2e peptide is included in the immunodominant loop region exposed on the surface of HBc particle. The hybrid protein expressed in Escherichia coli and purified under denaturing conditions formed virus-like HBc particles after refolding in vitro. Refolding of this protein in the presence of a previously denatured HBc antigen carrying no inserts resulted in formation of mosaic virus-like particles. The developed method will allow construction of mosaic HBc particles carrying different target epitopes of the influenza virus by combining the corresponding modified HBc proteins, which opens the possibility of creating vaccines with a wider spectrum of protection.

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Steinmann, Eike, Christiane Brohm, Stephanie Kallis, Ralf Bartenschlager, and Thomas Pietschmann. "Efficient trans-Encapsidation of Hepatitis C Virus RNAs into Infectious Virus-Like Particles." Journal of Virology 82, no. 14 (May 14, 2008): 7034–46. http://dx.doi.org/10.1128/jvi.00118-08.

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ABSTRACT Recently, complete replication of hepatitis C virus (HCV) in tissue culture was established using the JFH1 isolate. To analyze determinants of HCV genome packaging and virion assembly, we developed a system that supports particle production based on trans-packaging of subgenomic viral RNAs. Using JFH1 helper viruses, we show that subgenomic JFH1 replicons lacking the entire core to NS2 coding region are efficiently encapsidated into infectious virus-like particles. Similarly, chimeric helper viruses with heterologous structural proteins trans-package subgenomic JFH1 replicons. Like authentic cell culture-produced HCV (HCVcc) particles, these trans-complemented HCV particles (HCVTCP) penetrate target cells in a CD81 receptor-dependent fashion. Since HCVTCP production was limited by competition between the helper and subgenomic RNA and to avoid contamination of HCVTCP stocks with helper viruses, we created HCV packaging cells. These cells encapsidate various HCV replicons with high efficiency, reaching infectivity titers up to 106 tissue culture infectious doses 50 per milliliter. The produced particles display a buoyant density comparable to HCVcc particles and can be propagated in the packaging cell line but support only a single-round infection in naïve cells. Together, this work demonstrates that subgenomic HCV replicons are assembly competent, thus excluding cis-acting RNA elements in the core-to-NS2 genomic region essential for RNA packaging. The experimental system described here should be helpful to decipher the mechanisms of HCV assembly and to identify RNA elements and viral proteins involved in particle formation. Similar to other vector systems of plus-strand RNA viruses, HCVTCP may prove valuable for gene delivery or vaccination approaches.

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Lagos-Sandoval, José Arturo, Jorge Eduardo Salazar-Zuñiga, and Edwing Oswaldo Berdugo-Romero. "Design and simulation of microfluidic device for the detection of HIV." Visión electrónica 1, no. 2 (August 13, 2018): 192–97. http://dx.doi.org/10.14483/22484728.18376.

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This article presents a diagnostic device model, which by using chemical reagents and microfluidics that makes a sort of particle separation and was developed to diagnose an acquired viral immunodeficiency. The device allows to isolate leukocytes and apply a reagent that measures the presence or absence of this virus. The design on the other hand uses tools such as SolidWorks and Autodesk Simulation, which, with the rupture of the membranes and the separation of their components, allows the chemical reaction in the particles and the detection of the virus. Based on the choice of particle analysis and validating the performance of the fluid maintained in the filter stage, which is represented by 5 flow lines, it shows the movement of 5 particles with the same diameter. Additionally, three tests were performed that varied the diameter of the particles to 5 μm, 10 μm and a larger diameter particle (15 μm). The results show that, with a diameter of 5 μm, the particles move smoothly and the filter can reach the next stage. The particles of 10 μm in diameter presented a normal blood flow, however, an obstruction in the particles of 15 μm in diameter can be observed.

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Turkki, Vesa, Elisa Alppila, Seppo Ylä-Herttuala, and Hanna P. Lesch. "Experimental Evaluation of an Interferometric Light Microscopy Particle Counter for Titering and Characterization of Virus Preparations." Viruses 13, no. 5 (May 19, 2021): 939. http://dx.doi.org/10.3390/v13050939.

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Virus particle concentration is a critical piece of information for virology, viral vaccines and gene therapy research. We tested a novel nanoparticle counting device, “Videodrop”, for its efficacy in titering and characterization of virus particles. The Videodrop nanoparticle counter is based on interferometric light microscopy (ILM). The method allows the detection of particles under the diffraction limit capabilities of conventional light microscopy. We analyzed lenti-, adeno-, and baculovirus samples in different concentrations and compared the readings against traditional titering and characterization methods. The tested Videodrop particle counter is especially useful when measuring high-concentration purified virus preparations. Certain non-purified sample types or small viruses may be impossible to characterize or may require the use of standard curve or background subtraction methods, which increases the duration of the analysis. Together, our testing shows that Videodrop is a reasonable option for virus particle counting in situations where a moderate number of samples need to be analyzed quickly.

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Sherer, Nathan M., Jing Jin, and Walther Mothes. "Directional Spread of Surface-Associated Retroviruses Regulated by Differential Virus-Cell Interactions." Journal of Virology 84, no. 7 (January 20, 2010): 3248–58. http://dx.doi.org/10.1128/jvi.02155-09.

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ABSTRACT The spread of viral infections involves the directional progression of virus particles from infected cells to uninfected target cells. Prior to entry, the binding of virus particles to specific cell surface receptors can trigger virus surfing, an actin-dependent lateral transport of viruses toward the cell body (M. J. Lehmann et al., J. Cell Biol. 170:317-325, 2005; M. Schelhaas, et al., PLoS Pathog. 4:e1000148, 2008; J. L. Smith, D. S. Lidke, and M. A. Ozbun, Virology 381:16-21, 2008). Here, we have used live-cell imaging to demonstrate that for cells chronically infected with the gammaretrovirus murine leukemia virus in which receptor has been downregulated, a significant portion of completely assembled virus particles are not immediately released into the supernatant but retain long-term association with the cell surface. Retention can be attributed, at least in part, to nonspecific particle attachment to cell surface glycosylaminoglycans. In contrast to virus surfing, viruses retained at the surface of infected cells undergo a lateral motility that is random and actin independent. This diffusive motility can be abruptly halted and converted into inward surfing after treatment with Polybrene, a soluble cation that increases virus-cell adsorption. In the absence of Polybrene, particle diffusion allows for an outward flow of viruses to the infected cell periphery. Peripheral particles are readily captured by and transmitted to neighboring uninfected target cells in a directional fashion. These data demonstrate a surface-based mechanism for the directional spread of viruses regulated by differential virus-cell interactions.

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Makra, István, Péter Terejánszky, and Róbert E. Gyurcsányi. "A method based on light scattering to estimate the concentration of virus particles without the need for virus particle standards." MethodsX 2 (2015): 91–99. http://dx.doi.org/10.1016/j.mex.2015.02.003.

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Wang, Xiaohong, Martin Sapp, Neil D. Christensen, and Joakim Dillner. "Heparin-based ELISA reduces background reactivity in virus-like particle-based papillomavirus serology." Journal of General Virology 86, no. 1 (January 1, 2005): 65–73. http://dx.doi.org/10.1099/vir.0.80472-0.

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The interaction between human papillomavirus (HPV) particles and cell surface heparan sulfate requires intact conformation of the HPV particles. Type-specific HPV serology is currently based on virus-like particles (VLPs) with intact conformation. Presence of incorrectly folded VLPs in VLP preparations is recognized as an important cause of cross-reactivity in HPV serology. Heparin-coated microtitre plates were evaluated for capturing conformationally correct VLPs and improving the type specificity of HPV serology. Hybrid VLPs between HPV16 and HPV11, which had been found to have significant reactivity with children's sera and a batch of HPV18 VLPs that had failed the quality control because of significant reactivity with sera from virginal women, were tested in parallel with heparin ELISA, ordinary ELISA and type-specific mAb capture ELISA. Control sera from children that had detectable reactivity with HPV16/11 hybrid VLPs in ordinary ELISA did not react in heparin-based ELISA, but some hybrid VLPs also had background reactivity in capture ELISAs. Control sera from virginal women that had some reactivity with a poor quality HPV18 VLP preparation in ordinary ELISA had no reactivity in heparin or capture ELISA, suggesting that certain VLP preparations expose cross-reactive epitopes that are not exposed on VLPs with heparin-binding ability. As the sensitivity was similar or only marginally affected by the use of heparin plates, use of heparin-coated plates may improve the type specificity of VLP-based ELISAs and reduce interassay variability attributable to variable quality of different VLP batches.

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Miller, M. F., G. D. Gagne, R. Lesniewski, and D. A. Peterson. "Quantitative recovery of virus from blood plasma using a polycarbonate filter purification procedure." Proceedings, annual meeting, Electron Microscopy Society of America 46 (1988): 76–77. http://dx.doi.org/10.1017/s0424820100102468.

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Polycarbonate filters (Nuclepore Corporation, Pleasanton, CA) have beep used for sizing particulates such as virus particles and liposomes. Unlike nitrocellulose, polyester and other types of filters which are comprised of a relatively thick meshwork of interwoven fibers, polycarbonate filters are thin and contain precisely sized, straight-bore holes (Fig. 1). These features suggest that loss of particles due to nonspecific adsorption or entrapment in the filter matrix might be less for polycarbonate filters. In the present study, we have devised a purification technique based on the sequential filtration of blood plasma through a series of polycarbonate filters. The technique was evaluated by seeding chimpanzee blood plasma with human rotavirus (65-70 nm dia.) and determining recovery of purified virus using a sensitive electron microscope virus particle counting technique.Whole normal blood plasma (10 ml) was seeded with highly purified rotavirus to a final concentration of about 1010 particles per ml.

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Roose, Kenny, Sarah De Baets, Bert Schepens, and Xavier Saelens. "Hepatitis B core–based virus–like particles to present heterologous epitopes." Expert Review of Vaccines 12, no. 2 (February 2013): 183–98. http://dx.doi.org/10.1586/erv.12.150.

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Fu, Yu, and Jinming Li. "A novel delivery platform based on Bacteriophage MS2 virus-like particles." Virus Research 211 (January 2016): 9–16. http://dx.doi.org/10.1016/j.virusres.2015.08.022.

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Kim, Hye-Jin, Ho Sun Son, Sang Won Lee, Youngsil Yoon, Ji-Yeon Hyeon, Gyung Tae Chung, June-Woo Lee, and Jung Sik Yoo. "Efficient expression of enterovirus 71 based on virus-like particles vaccine." PLOS ONE 14, no. 3 (March 7, 2019): e0210477. http://dx.doi.org/10.1371/journal.pone.0210477.

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Beaumont, Elodie, and Philippe Roingeard. "Prospects for prophylactic hepatitis C vaccines based on virus-like particles." Human Vaccines & Immunotherapeutics 9, no. 5 (May 14, 2013): 1112–18. http://dx.doi.org/10.4161/hv.23900.

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Bragard, C., G. H. Duncan, S. V. Wesley, R. A. Naidu, and M. A. Mayo. "Virus-like particles assemble in plants and bacteria expressing the coat protein gene of Indian peanut clump virus." Microbiology 81, no. 1 (January 1, 2000): 267–72. http://dx.doi.org/10.1099/0022-1317-81-1-267.

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cDNA copies of the coat protein (CP) gene of Indian peanut clump virus (IPCV)-H were introduced into cells of Nicotiana benthamiana or Escherichia coli by transformation with vectors based on pROKII or pET respectively. In both plant and bacterial cells, IPCV CP was expressed and assembled to form virus-like particles (VLP). In plant extracts, the smallest preponderant particle length was about 50 nm. Other abundant lengths were about 85 and about 120 nm. The commonest VLP length in bacterial extracts was about 30 nm. Many of the longer VLP appeared to comprise aggregates of shorter particles. The lengths of the supposed ‘monomer’ VLP corresponded approximately to those expected for encapsidated CP gene transcript RNA. Immunocapture RT–PCR, using primers designed to amplify the CP gene, confirmed that the VLP contained RNA encoding IPCV-H CP. The results show that encapsidation does not require the presence of the 5′-terminal untranslated sequence of the virus RNA and suggest that if there is an ‘origin of assembly’ motif or sequence, it lies within the CP gene. When transgenic plants expressing IPCV-H CP were inoculated with IPCV-L, a strain that is serologically distinct from IPCV-H, the virus particles that accumulated contained both types of CP.

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Pushko, Peter, Joan Geisbert, Michael Parker, Peter Jahrling, and Jonathan Smith. "Individual and Bivalent Vaccines Based on Alphavirus Replicons Protect Guinea Pigs against Infection with Lassa and Ebola Viruses." Journal of Virology 75, no. 23 (December 1, 2001): 11677–85. http://dx.doi.org/10.1128/jvi.75.23.11677-11685.2001.

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ABSTRACT Lassa and Ebola viruses cause acute, often fatal, hemorrhagic fever diseases, for which no effective vaccines are currently available. Although lethal human disease outbreaks have been confined so far to sub-Saharan Africa, they also pose significant epidemiological concern worldwide as demonstrated by several instances of accidental importation of the viruses into North America and Europe. In the present study, we developed experimental individual vaccines for Lassa virus and bivalent vaccines for Lassa and Ebola viruses that are based on an RNA replicon vector derived from an attenuated strain of Venezuelan equine encephalitis virus. The Lassa and Ebola virus genes were expressed from recombinant replicon RNAs that also encoded the replicase function and were capable of efficient intracellular self-amplification. For vaccinations, the recombinant replicons were incorporated into virus-like replicon particles. Guinea pigs vaccinated with particles expressing Lassa virus nucleoprotein or glycoprotein genes were protected from lethal challenge with Lassa virus. Vaccination with particles expressing Ebola virus glycoprotein gene also protected the animals from lethal challenge with Ebola virus. In order to evaluate a single vaccine protecting against both Lassa and Ebola viruses, we developed dual-expression particles that expressed glycoprotein genes of both Ebola and Lassa viruses. Vaccination of guinea pigs with either dual-expression particles or with a mixture of particles expressing Ebola and Lassa virus glycoprotein genes protected the animals against challenges with Ebola and Lassa viruses. The results showed that immune responses can be induced against multiple vaccine antigens coexpressed from an alphavirus replicon and suggested the possibility of engineering multivalent vaccines based upon alphavirus vectors for arenaviruses, filoviruses, and possibly other emerging pathogens.

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Loureiro, Silvia, Claudine Porta, Hemanta K. Maity, Eva Perez, Flavia F. Bagno, Abhay Kotecha, Elizabeth Fry, et al. "Universal detection of foot and mouth disease virus based on the conserved VP0 protein." Wellcome Open Research 3 (July 25, 2018): 88. http://dx.doi.org/10.12688/wellcomeopenres.14655.1.

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Background: Foot and mouth disease virus (FMDV), a member of the picornaviridae that causes vesicular disease in ungulates, has seven serotypes and a large number of strains, making universal detection challenging. The mature virion is made up of 4 structural proteins, virus protein (VP) 1 – VP4, VP1-VP3 of which form the outer surface of the particle and VP4 largely contained within. Prior to mature virion formation VP2 and VP4 occur together as VP0, a structural component of the pre-capsid which, as a result of containing the internal VP4 sequence, is relatively conserved among all strains and serotypes. Detection of VP0 might therefore represent a universal virus marker. Methods: FMDV virus protein 0 (VP0) was expressed in bacteria as a SUMO fusion protein and the SUMO carrier removed by site specific proteolysis. Rabbit polyvalent sera were generated to the isolated VP0 protein and their reactivity characterised by a number of immunoassays and by epitope mapping on peptide arrays. Results: The specific VP0 serum recognised a variety of FMDV serotypes, as virus and as virus-like-particles, by a variety of assay formats. Epitope mapping showed the predominant epitopes to occur within the unstructured but highly conserved region of the sequence shared among many serotypes. When immunogold stained VLPs were assessed by TEM analysis they revealed exposure of epitopes on the surface of some particles, consistent with particle breathing hitherto reported for some other picornaviruses but not for FMDV. Conclusion: A polyvalent serum based on the VP0 protein of FMDV represents a broadly reactive reagent capable of detection of many if not all FMDV isolates. The suggestion of particle breathing obtained with this serum suggests a reconsideration of the FMDV entry mechanism.

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Cohen, J., M. Zeidan, A. Rosner, and A. Gera. "Biological and Molecular Characterization of a New Carlavirus Isolated from an Aconitum sp." Phytopathology® 90, no. 4 (April 2000): 340–44. http://dx.doi.org/10.1094/phyto.2000.90.4.340.

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A new virus was isolated from symptomless Aconitum napellus plants. The virus, for which the name Aconitum latent virus (AcLV) is proposed, has flexuous particles 640 nm in length. The experimental host range was limited to Nicotiana clevelandii. Electron microscopy studies of ultrathin sections of infected A. napellus tissues revealed the presence of elongated virus particles. No inclusion bodies characteristic of potyvirus infection were observed. AcLV was purified from naturally infected A. napellus by cesium chloride step gradient centrifugation. In sodium dodecyl sulfate-polyacrylamide gel electrophoresis of dissociated purified virus preparations, a major protein component with a molecular mass of 35 kDa was observed. Diagnostic antibodies that could specifically bind to virus particles were produced. The 5′ terminus (620 nucleotides) of the viral RNA was cloned and sequenced. It comprised 71 nucleotides from the untranslated 5′ terminus and 549 nucleotides of an open reading frame encoding 183 amino acids. Comparison of the predicted amino acid sequence with those of other plant viruses revealed 40 to 60% identity with several carlaviruses. Based on particle morphology, absence of inclusion bodies in ultrathin sections, the relative molecular weight of the coat protein, the nucleotide sequence, and predicted amino acid homology, it is suggested that this virus belongs to the carlavirus group.

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Proença, M. C., J. F. Moura Nunes, and A. P. Alves de Matos. "Automatic detection of polyomavirus particles with local texture indicators." Microscopy and Microanalysis 19, S4 (August 2013): 67–68. http://dx.doi.org/10.1017/s1431927613000950.

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A fully automatic approach to locate polyomavirus particles in images of transmission electronic microscopy is presented, that can localize intact particles, many damaged capsids and an acceptable percentage of superposed ones; the performance is quantified in 25 electron micrographs containing nearly 390 particles, compared to the interpretation of two independent electron microscopy experts. As these particles often does not have a well-defined edge, in highly textured backgrounds (Figure 1) the initial guess of candidate points from local entropy proportion measures retains a large set of points, in order to avoid false negatives.Based in human criteria - focused on the pattern generated by the capsomeres typical of polyomavirus surface, this approach uses indicators calculated from the local co-occurrence matrix of grey levels to assess the textured pattern and prune the initial set of candidates; in some more complicated backgrounds about 2-10% of the elements will survive. A restricted set of the points accepted (Figure 2) is used to evaluate typical average and variance and reduce the set of survivors accordingly. These intermediate points are locally evaluated using i) a statistical index concerning the radiometric distribution of a circular neighborhood around the centroid of each candidate, and ii) a structural index resuming the expected morphological characteristics of eight radial intensity profiles encompassing the area of the possible particle. All the parameterization is based on the particle expected dimensions.This hierarchical approach attains 95% efficiency in the detection of intact virus particles, tolerating a certain lack of differentiation in the borders and a certain amount of shape alterations. Only 5 to 7% (according to the reference used) of the intact particles are missed by the algorithm – cases of particles with abnormal radial structures, particles with different degrees of agglutination or particles showing empty (or with different degrees of permeation) capsids. Superposed particles are detected with a success rate of 71% to 77%. In the case of distorted and/or doubtful particles, a correct detection of 72% is attained; these particles are the main source of differences between experts (a difference of 48% between both interpretations).This kind of algorithm is "tailored" for one virus family particle, in this case, the polyomavirus; it can be parameterized for different working magnifications, but cannot be applied to different virus, that has different texture, structure and typical radiometry characteristics. We believe that similar results can be obtained in other virus families with the necessary adaptations.

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Kikkert, Marjolein, Jan Van Lent, Marc Storms, Pentcho Bodegom, Richard Kormelink, and Rob Goldbach. "Tomato Spotted Wilt Virus Particle Morphogenesis in Plant Cells." Journal of Virology 73, no. 3 (March 1, 1999): 2288–97. http://dx.doi.org/10.1128/jvi.73.3.2288-2297.1999.

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ABSTRACT A model for the maturation of tomato spotted wilt virus (TSWV) particles is proposed, mainly based on results with a protoplast infection system, in which the chronology of different maturation events could be determined. By using specific monoclonal and polyclonal antisera in immunofluorescence and electron microscopy, the site of TSWV particle morphogenesis was determined to be the Golgi system. The viral glycoproteins G1 and G2 accumulate in the Golgi prior to a process of wrapping, by which the viral nucleocapsids obtain a double membrane. In a later stage of the maturation, these doubly enveloped particles fuse to each other and to the endoplasmic reticulum to form singly enveloped particles clustered in membranes. Similarities and differences between the maturation of animal-infecting (bunya)viruses and plant-infecting tospoviruses are discussed.

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Harnish, Delbert A., Brian K. Heimbuch, Michael Husband, April E. Lumley, Kimberly Kinney, Ronald E. Shaffer, and Joseph D. Wander. "Challenge of N95 Filtering Facepiece Respirators with Viable H1N1 Influenza Aerosols." Infection Control & Hospital Epidemiology 34, no. 5 (May 2013): 494–99. http://dx.doi.org/10.1086/670225.

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Objective.Specification of appropriate personal protective equipment for respiratory protection against influenza is somewhat controversial. In a clinical environment, N95 filtering facepiece respirators (FFRs) are often recommended for respiratory protection against infectious aerosols. This study evaluates the ability of N95 FFRs to capture viable H1N1 influenza aerosols.Methods.Five N95 FFR models were challenged with aerosolized viable H1N1 influenza and inert polystyrene latex particles at continuous flow rates of 85 and 170 liters per minute. Virus was assayed using Madin-Darby canine kidney cells to determine the median tissue culture infective dose (TCID50). Aerosols were generated using a Collison nebulizer containing H1N1 influenza virus at 1 × 108 TCID50/mL. To determine filtration efficiency, viable sampling was performed upstream and downstream of the FFR.Results.N95 FFRs filtered 0.8-μm particles of both H1N1 influenza and inert origins with more than 95% efficiency. With the exception of 1 model, no statistically significant difference in filtration performance was observed between influenza and inert particles of similar size. Although statistically significant differences were observed for 2 models when comparing the 2 flow rates, the differences have no significance to protection.Conclusions.This study empirically demonstrates that a National Institute for Occupational Safety and Health-approved N95 FFR captures viable H1N1 influenza aerosols as well as or better than its N95 rating, suggesting that a properly fitted FFR reduces inhalation exposure to airborne influenza virus. This study also provides evidence that filtration efficiency is based primarily on particle size rather than the nature of the particle's origin.

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Överby, Anna K., Vsevolod Popov, Etienne P. A. Neve, and Ralf F. Pettersson. "Generation and Analysis of Infectious Virus-Like Particles of Uukuniemi Virus (Bunyaviridae): a Useful System for Studying Bunyaviral Packaging and Budding." Journal of Virology 80, no. 21 (August 23, 2006): 10428–35. http://dx.doi.org/10.1128/jvi.01362-06.

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ABSTRACT In the present report we describe an infectious virus-like particle (VLP) system for the Uukuniemi (UUK) virus, a member of the Bunyaviridae family. It utilizes our recently developed reverse genetic system based on the RNA polymerase I minigenome system for UUK virus used to study replication, encapsidation, and transcription by monitoring reporter gene expression. Here, we have added the glycoprotein precursor expression plasmid together with the minigenome, nucleoprotein, and polymerase to generate VLPs, which incorporate the minigenome and are released into the supernatant. The particles are able to infect new cells, and reporter gene expression can be monitored if the trans-acting viral proteins (RNA polymerase and nucleoprotein) are also expressed in these cells. No minigenome transfer occurred in the absence of glycoproteins, demonstrating that the glycoproteins are absolutely required for the generation of infectious particles. Moreover, expression of glycoproteins alone was sufficient to produce and release VLPs. We show that the ribonucleoproteins (RNPs) are incorporated into VLPs but are not required for the generation of particles. Morphological analysis of the particles by electron microscopy revealed that VLPs, either with or without minigenomes, display a surface morphology indistinguishable from that of the authentic UUK virus and that they bud into Golgi vesicles in the same way as UUK virus does. This infectious VLP system will be very useful for studying the bunyaviral structural components required for budding and packaging of RNPs and receptor binding and may also be useful for the development of new vaccines for the human pathogens from this family.

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González-Domínguez, Irene, Eduard Puente-Massaguer, Laura Cervera, and Francesc Gòdia. "Quality Assessment of Virus-Like Particles at Single Particle Level: A Comparative Study." Viruses 12, no. 2 (February 17, 2020): 223. http://dx.doi.org/10.3390/v12020223.

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Virus-like particles (VLPs) have emerged as a powerful scaffold for antigen presentation and delivery strategies. Compared to single protein-based therapeutics, quality assessment requires a higher degree of refinement due to the structure of VLPs and their similar properties to extracellular vesicles (EVs). Advances in the field of nanotechnology with single particle and high-resolution analysis techniques provide appealing approaches to VLP characterization. In this study, six different biophysical methods have been assessed for the characterization of HIV-1-based VLPs produced in mammalian and insect cell platforms. Sample preparation and equipment set-up were optimized for the six strategies evaluated. Electron Microscopy (EM) disclosed the presence of several types of EVs within VLP preparations and cryogenic transmission electron microscopy (cryo-TEM) resulted in the best technique to resolve the VLP ultrastructure. The use of super-resolution fluorescence microscopy (SRFM), nanoparticle tracking analysis (NTA) and flow virometry enabled the high throughput quantification of VLPs. Interestingly, differences in the determination of nanoparticle concentration were observed between techniques. Moreover, NTA and flow virometry allowed the quantification of both EVs and VLPs within the same experiment while analyzing particle size distribution (PSD), simultaneously. These results provide new insights into the use of different analytical tools to monitor the production of nanoparticle-based biologicals and their associated contaminants.

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Meshcheriakova, Yulia, Alex Durrant, Emma L. Hesketh, Neil A. Ranson, and George P. Lomonossoff. "Combining high-resolution cryo-electron microscopy and mutagenesis to develop cowpea mosaic virus for bionanotechnology." Biochemical Society Transactions 45, no. 6 (November 3, 2017): 1263–69. http://dx.doi.org/10.1042/bst20160312.

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Particles of cowpea mosaic virus (CPMV) have enjoyed considerable success as nanoparticles. The development of a system for producing empty virus-like particles (eVLPs) of the virus, which are non-infectious and have the potential to be loaded with heterologous material, has increased the number of possible applications for CPMV-based particles. However, for this potential to be realised, it was essential to demonstrate that eVLPs were accurate surrogates for natural virus particles, and this information was provided by high-resolution cryo-EM studies of eVLPs. This demonstration has enabled the approaches developed for the production of modified particles developed with natural CPMV particles to be applied to eVLPs. Furthermore, a combination of cryo-EM and mutagenic studies allowed the development of particles which are permeable but which could still assemble efficiently. These particles were shown to be loadable with cobalt, indicating that they can, indeed, be used as nano-containers.

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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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Pacios, Luis F., and Fernando García-Arenal. "Comparison of properties of particles of Cucumber mosaic virus and Tomato aspermy virus based on the analysis of molecular surfaces of capsids." Journal of General Virology 87, no. 7 (July 1, 2006): 2073–83. http://dx.doi.org/10.1099/vir.0.81621-0.

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The plant RNA viruses Cucumber mosaic virus (CMV) and Tomato aspermy virus (TAV) (genus Cucumovirus) have similar icosahedral particles, the crystal structures of which have been reported recently. Similarity in particle structure agrees with reports of stable capsids assembled from their capsid proteins and of viable recombinant viruses with chimeric capsid proteins derived from CMV and TAV. However, differences between the cucumoviruses have been reported for physicochemical properties. Here, structural and electrostatic features of the molecular surfaces are studied to investigate their relationship with these observations. Two coat-protein recombinants with structures modelled by taking CMV and TAV as templates were also included in the analysis. Results show that there exists an external region of negative electrostatic potential that has arisen from strictly conserved charged residues situated near the external HI loop of the subunits in the capsomers. This negative domain surrounds the fivefold and quasi-sixfold axes and locates above regions of positive potential that extend to cover, nearly homogeneously, the inner surface of capsids, where interaction with encapsidated RNA occurs. Differences between the outer electrostatic distributions in CMV and TAV explain the distinct response of both viruses to variations in physicochemical conditions required for particle stability and are essential to rationalize the biological activity of the coat-protein recombinants, in spite of their seemingly distinct electrostatic characteristics.

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Ngunjiri, John M., Margaret J. Sekellick, and Philip I. Marcus. "Clonogenic Assay of Type A Influenza Viruses Reveals Noninfectious Cell-Killing (Apoptosis-Inducing) Particles." Journal of Virology 82, no. 6 (January 9, 2008): 2673–80. http://dx.doi.org/10.1128/jvi.02221-07.

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ABSTRACT Clonogenic (single-cell plating) assays were used to define and quantify subpopulations of two genetically closely related variants of influenza virus A/TK/OR/71 that differed primarily in the size of the NS1 gene product; they expressed a full-size (amino acids [aa] 1 to 230) or truncated (aa 1 to 124) NS1 protein. Monolayers of Vero cells were infected with different amounts of virus, monodispersed, and plated. Cell survival curves were generated from the fraction of cells that produced visible colonies as a function of virus multiplicity. The exponential loss of colony-forming capacity at low multiplicities demonstrated that a single virus particle sufficed to kill a cell. The ratios of cell-killing particles (CKP) to plaque-forming particles (PFP) were 1:1 and 7:1 in populations of variants NS11-124 and NS11-230, respectively. This study revealed a new class of particles in influenza virus populations—noninfectious CKP. Both infectious and noninfectious CKP were 6.3 times more resistant to UV radiation than PFP activity. Based on UV target theory, a functional polymerase subunit was implicated in a rate-limiting step in cell killing. Since influenza viruses kill cells by apoptosis (programmed cell death), CKP are functionally apoptosis-inducing particles. Noninfectious CKP are present in excess of PFP in virus populations with full-size NS1 and induce apoptosis that is temporally delayed and morphologically different than that initiated by infectious CKP present in the virus population expressing truncated NS1. The identification and quantification of both infectious and noninfectious CKP defines new phenotypes in influenza virus populations and presents a challenge to determine their role in regulating infectivity, pathogenesis, and vaccine efficacy.

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Ramirez, Alejandro, Stephen Morris, Sophie Maucourant, Isabella D'Ascanio, Vincenzo Crescente, I.-Na Lu, Sophie Farinelle, Claude P. Muller, Michael Whelan, and William Rosenberg. "A virus-like particle vaccine candidate for influenza A virus based on multiple conserved antigens presented on hepatitis B tandem core particles." Vaccine 36, no. 6 (February 2018): 873–80. http://dx.doi.org/10.1016/j.vaccine.2017.12.053.

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Yun, Sang-Im, Byung-Hak Song, Yongbum Koo, Iksoo Jeon, Sung June Byun, Jong-Hyeon Park, Yi-Seok Joo, Seok-Yong Kim, and Young-Min Lee. "Japanese encephalitis virus-based replicon RNAs/particles as an expression system for HIV-1 Pr55Gag that is capable of producing virus-like particles." Virus Research 144, no. 1-2 (September 2009): 298–305. http://dx.doi.org/10.1016/j.virusres.2009.04.014.

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Schneider-Ohrum, Kirsten, Corinne Cayatte, Yi Liu, Zhaoti Wang, Alivelu Irrinki, Floro Cataniag, Nga Nguyen, et al. "Production of Cytomegalovirus Dense Bodies by Scalable Bioprocess Methods Maintains Immunogenicity and Improves Neutralizing Antibody Titers." Journal of Virology 90, no. 22 (August 31, 2016): 10133–44. http://dx.doi.org/10.1128/jvi.00463-16.

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ABSTRACTWith the goal of developing a virus-like particle-based vaccine based on dense bodies (DB) produced by human cytomegalovirus (HCMV) infections, we evaluated scalable culture, isolation, and inactivation methods and applied technically advanced assays to determine the relative purity, composition, and immunogenicity of DB particles. Our results increase our understanding of the benefits and disadvantages of methods to recover immunogenic DB and inactivate contaminating viral particles. Our results indicate that (i) HCMV strain Towne replicates in MRC-5 fibroblasts grown on microcarriers, (ii) DB particles recovered from 2-bromo-5,6-dichloro-1-beta-d-ribofuranosyl benzimidazole riboside (BDCRB)-treated cultures and purified by tangential flow filtration (TFF-DB) or glycerol tartrate gradient sedimentation (GT-DB) constitute 92% or 98%, respectively, of all particles in the final product, (iii) epithelial cell-tropic DB particles are recovered from a single round of coinfection by AD169 and Towne strain viruses, consistent with complementation between the UL130 and UL131A expressed by these strains and restoration of gH/gL/UL128-UL131A (gH pentamer), (iv) equivalent neutralizing antibody titers are induced in mice following immunization with epithelial cell-tropic DB or gH pentamer-deficient DB preparations, (v) UV-inactivated residual virus in GT-DB or TFF-DB preparations retained immunogenicity and induced neutralizing antibody, preventing viral entry into epithelial cells, and (vi) GT-DB and TFF-DB induced cellular immune responses to multiple HCMV peptides. Collectively, this work provides a foundation for future development of DB as an HCMV-based particle vaccine.IMPORTANCEDevelopment of a vaccine to prevent congenital HCMV infection remains a high priority. Vaccination with human cytomegalovirus-derived noninfectious particles, or dense bodies, may constitute a safe vaccination strategy that mimics natural infection. The standard approach for purification of virus particles has been to use a multiple-step, complex gradient that presents a potential barrier to production scale-up and commercialization. In the study described here, we employed an approach that combines treatment with an antiviral terminase inhibitor and purification by a simplified process to produce a vaccine candidate providing broad antiviral humoral and cellular immunity as a foundation for future development.

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Singh, B. R., Javed Musarrat, and Aminuddin . "Production of polyclonal antibodies against the BYMV isolate infecting gladiolus crop naturally and development of polyclonal antibodies based serological diagnostic system." International Journal of Agricultural Invention 2, no. 01 (June 30, 2017): 5–9. http://dx.doi.org/10.46492/ijai/2017.2.1.2.

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In this study a bean yellow mosaic virus isolate infecting gladiolus crop with leaf mosaic and color breaking symptoms on flower was characterized based on mechanical transmission, symptomatology on hosts, and viron particle structure and capsid protein molecular weight determination. The virus isolate was successfully purified from the propagating host and purified viron particles were used for the production of polyclonal antibodies for the development of a cost effective and sensitive serological diagnostic system. The produced polyclonal antibodies would be useful for the assessment of BYMV infection in gladiolus crop and seed materials.

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Speir, Jeffrey A., Brian Bothner, Chunxu Qu, Deborah A. Willits, Mark J. Young, and John E. Johnson. "Enhanced Local Symmetry Interactions Globally Stabilize a Mutant Virus Capsid That Maintains Infectivity and Capsid Dynamics." Journal of Virology 80, no. 7 (April 1, 2006): 3582–91. http://dx.doi.org/10.1128/jvi.80.7.3582-3591.2006.

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ABSTRACT Structural transitions in viral capsids play a critical role in the virus life cycle, including assembly, disassembly, and release of the packaged nucleic acid. Cowpea chlorotic mottle virus (CCMV) undergoes a well-studied reversible structural expansion in vitro in which the capsid expands by 10%. The swollen form of the particle can be completely disassembled by increasing the salt concentration to 1 M. Remarkably, a single-residue mutant of the CCMV N-terminal arm, K42R, is not susceptible to dissociation in high salt (salt-stable CCMV [SS-CCMV]) and retains 70% of wild-type infectivity. We present the combined structural and biophysical basis for the chemical stability and viability of the SS-CCMV particles. A 2.7-Å resolution crystal structure of the SS-CCMV capsid shows an addition of 660 new intersubunit interactions per particle at the center of the 20 hexameric capsomeres, which are a direct result of the K42R mutation. Protease-based mapping experiments of intact particles demonstrate that both the swollen and closed forms of the wild-type and SS-CCMV particles have highly dynamic N-terminal regions, yet the SS-CCMV particles are more resistant to degradation. Thus, the increase in SS-CCMV particle stability is a result of concentrated tethering of subunits at a local symmetry interface (i.e., quasi-sixfold axes) that does not interfere with the function of other key symmetry interfaces (i.e., fivefold, twofold, quasi-threefold axes). The result is a particle that is still dynamic but insensitive to high salt due to a new series of bonds that are resistant to high ionic strength and preserve the overall particle structure.

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Wang, Min, Jenny Jokinen, Irina Tretyakova, Peter Pushko, and Igor S. Lukashevich. "Alphavirus vector-based replicon particles expressing multivalent cross-protective Lassa virus glycoproteins." Vaccine 36, no. 5 (January 2018): 683–90. http://dx.doi.org/10.1016/j.vaccine.2017.12.046.

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Kessans, Sarah A., Mark D. Linhart, Lydia R. Meador, Jacquelyn Kilbourne, Brenda G. Hogue, Petra Fromme, Nobuyuki Matoba, and Tsafrir S. Mor. "Immunological Characterization of Plant-Based HIV-1 Gag/Dgp41 Virus-Like Particles." PLOS ONE 11, no. 3 (March 17, 2016): e0151842. http://dx.doi.org/10.1371/journal.pone.0151842.

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Carvalho, Sofia B., Ricardo J. S. Silva, Mafalda G. Moleirinho, Bárbara Cunha, Ana S. Moreira, Alex Xenopoulos, Paula M. Alves, Manuel J. T. Carrondo, and Cristina Peixoto. "Membrane‐Based Approach for the Downstream Processing of Influenza Virus‐Like Particles." Biotechnology Journal 14, no. 8 (July 3, 2019): 1800570. http://dx.doi.org/10.1002/biot.201800570.

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Lee, Chaeyeon, Aran Hwang, Leeja Jose, Ji Hyun Park, Sunah Jang, Jae Kwang Song, Yeonji Kim, et al. "RAFT/PISA based Ni-NTA polymeric particles for virus-mimetic influenza vaccines." Journal of Industrial and Engineering Chemistry 86 (June 2020): 35–38. http://dx.doi.org/10.1016/j.jiec.2020.03.004.

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Yu, Hojeong, Kyujung Kim, Kyungjae Ma, Wonju Lee, Joung-Woo Choi, Chae-Ok Yun, and Donghyun Kim. "Enhanced detection of virus particles by nanoisland-based localized surface plasmon resonance." Biosensors and Bioelectronics 41 (March 2013): 249–55. http://dx.doi.org/10.1016/j.bios.2012.08.031.

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Colant, Noelle, Beatrice Melinek, Stefanie Frank, William Rosenberg, and Daniel G. Bracewell. "Escherichia coli-Based Cell-Free Protein Synthesis for Iterative Design of Tandem-Core Virus-Like Particles." Vaccines 9, no. 3 (February 25, 2021): 193. http://dx.doi.org/10.3390/vaccines9030193.

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Tandem-core hepatitis B core antigen (HBcAg) virus-like particles (VLPs), in which two HBcAg monomers are joined together by a peptide linker, can be used to display two different antigens on the VLP surface. We produced universal influenza vaccine candidates that use this scaffold in an Escherichia coli-based cell-free protein synthesis (CFPS) platform. We then used the CFPS system to rapidly test modifications to the arginine-rich region typically found in wild-type HBcAg, the peptide linkers around the influenza antigen inserts, and the plasmid vector backbone to improve titer and quality. Using a minimal plasmid vector backbone designed for CFPS improved titers by at least 1.4-fold over the original constructs. When the linker lengths for the influenza inserts were more consistent in length and a greater variety of codons for glycine and serine were utilized, titers were further increased to over 70 μg/mL (4.0-fold greater than the original construct) and the presence of lower molecular weight product-related impurities was significantly reduced, although improvements in particle assembly were not seen. Furthermore, any constructs with the C-terminal arginine-rich region removed resulted in asymmetric particles of poor quality. This demonstrates the potential for CFPS as a screening platform for VLPs.

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Brumfield, Susan K., Alice C. Ortmann, Vincent Ruigrok, Peter Suci, Trevor Douglas, and Mark J. Young. "Particle Assembly and Ultrastructural Features Associated with Replication of the Lytic Archaeal Virus Sulfolobus Turreted Icosahedral Virus." Journal of Virology 83, no. 12 (April 8, 2009): 5964–70. http://dx.doi.org/10.1128/jvi.02668-08.

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ABSTRACT Little is known about the replication cycle of archaeal viruses. We have investigated the ultrastructural changes of Sulfolobus solfataricus P2 associated with infection by Sulfolobus turreted icosahedral virus (STIV). A time course of a near synchronous STIV infection was analyzed using both scanning and transmission electron microscopy. Assembly of STIV particles, including particles lacking DNA, was observed within cells, and fully assembled STIV particles were visible by 30 h postinfection (hpi). STIV was determined to be a lytic virus, causing cell disruption beginning at 30 hpi. Prior to cell lysis, virus infection resulted in the formation of pyramid-like projections from the cell surface. These projections, which have not been documented in any other host-virus system, appeared to be caused by the protrusion of the cell membrane beyond the bordering S-layer. These structures are thought to be sites at which progeny virus particles are released from infected cells. Based on these observations of lysis, a plaque assay was developed for STIV. From these studies we propose an overall assembly model for STIV.

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Journal articles on the topic 'Virus-based particles'

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