Journal articles: 'Subvirale Partikel'

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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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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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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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Tan, Ming, and Xi Jiang. "Subviral particle as vaccine and vaccine platform." Current Opinion in Virology 6 (June 2014): 24–33. http://dx.doi.org/10.1016/j.coviro.2014.02.009.

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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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Zhang, Jing, Yongxiang Wang, Shuwen Fu, Quan Yuan, Qianru Wang, Ningshao Xia, Yumei Wen, Jisu Li, and Shuping Tong. "Role of Small Envelope Protein in Sustaining the Intracellular and Extracellular Levels of Hepatitis B Virus Large and Middle Envelope Proteins." Viruses 13, no. 4 (April 2, 2021): 613. http://dx.doi.org/10.3390/v13040613.

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Hepatitis B virus (HBV) expresses co-terminal large (L), middle (M), and small (S) envelope proteins. S protein drives virion and subviral particle secretion, whereas L protein inhibits subviral particle secretion but coordinates virion morphogenesis. We previously found that preventing S protein expression from a subgenomic construct eliminated M protein. The present study further examined impact of S protein on L and M proteins. Mutations were introduced to subgenomic construct of genotype A or 1.1 mer replication construct of genotype A or D, and viral proteins were analyzed from transfected Huh7 cells. Mutating S gene ATG to prevent expression of full-length S protein eliminated M protein, reduced intracellular level of L protein despite its blocked secretion, and generated a truncated S protein through translation initiation from a downstream ATG. Truncated S protein was secretion deficient and could inhibit secretion of L, M, S proteins from wild-type constructs. Providing full-length S protein in trans rescued L protein secretion and increased its intracellular level from mutants of lost S gene ATG. Lost core protein expression reduced all the three envelope proteins. In conclusion, full-length S protein could sustain intracellular and extracellular L and M proteins, while truncated S protein could block subviral particle secretion.

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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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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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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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Lawton, Jeffrey A., Mary K. Estes, and B. V. Venkataram Prasad. "Identification and Characterization of a Transcription Pause Site in Rotavirus." Journal of Virology 75, no. 4 (February 15, 2001): 1632–42. http://dx.doi.org/10.1128/jvi.75.4.1632-1642.2001.

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ABSTRACT In rotavirus, transcription of the 11 double-stranded RNA genome segments occurs within the structurally intact subviral particle, and nascent transcripts are released through channels penetrating the two capsid layers at the icosahedral vertices. To gain insight into the early molecular events in transcription, we used high-resolution polyacrylamide gel electrophoresis to investigate the length distribution of transcription products at various times following initiation. We observed that, in the subviral particle under normal conditions, transcript initiation and capping are followed by a momentary pause in elongation after the addition of 6 to 7 nucleotides. In the absence of the capping reaction cofactorS-adenosylmethionine, conditions under which the rate of nucleotide incorporation is reduced, we observe a significant decrease in the ratio of paused to full-length transcripts. We propose that this pause site may represent the point at which specific molecular events take place to facilitate processive elongation. Furthermore, our results indicate that the presence of specific ligands on the viral surface, such as VP7 in the mature virion, inhibits polymerase function. From the perspective of the viral replication cycle, this inhibition may serve to ensure that transcription occurs with greatest efficiency only after the virus has entered the cytoplasm and assumed the form of a double-layered particle.

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11

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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12

Au, Kit-Sing, Nora M. Mattion, and Mary K. Estes. "A Subviral Particle Binding Domain on the Rotavirus Nonstructural Glycoprotein NS28." Virology 194, no. 2 (June 1993): 665–73. http://dx.doi.org/10.1006/viro.1993.1306.

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13

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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Leppik, Ludmila, Karin Gunst, Matti Lehtinen, Joakim Dillner, Karin Streker, and Ethel-Michele de Villiers. "In Vivo and In Vitro Intragenomic Rearrangement of TT Viruses." Journal of Virology 81, no. 17 (June 27, 2007): 9346–56. http://dx.doi.org/10.1128/jvi.00781-07.

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ABSTRACT The in vitro replication of the Torque teno virus (TT virus) tth8 full-length genome and particle formation in a Hodgkin's lymphoma-derived cell line after transfection with cloned viral DNA were demonstrated. Analyses of the transcription patterns of tth8 and tth7 TT virus isolates in a number of lymphoma and T-cell leukemia cell lines indicated differential additional splicing events and intragenomic rearrangement generating open reading frames which could not be deducted from the genomic sequence. We also demonstrated the presence of rearranged TT virus genomes in vivo in sera taken from pregnant mothers whose children later developed childhood leukemia, as well as sera from control mothers. Control experiments using religated cloned genomic tth8 DNA mixed with cellular DNA did not result in such subviral molecules. These subviral isolates ranged from 172 bp to full-length TT virus genomes. Possible in vivo selection for specific rearranged molecules was indicated by the presence of one isolate (561 bp) in 11 serum samples. It remains to be clarified whether selected rearranged subviral components resulting from specific TT virus types may contribute to the initiation of disease. These data demonstrate new features of TT viruses suggesting possible similarities to plant viruses of the family Geminiviridae, as well as raise questions about the documented plurality and diversity of anelloviruses.

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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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Ferlenghi, Ilaria, Mairi Clarke, Twan Ruttan, Steven L. Allison, Juliane Schalich, Franz X. Heinz, Stephen C. Harrison, Felix A. Rey, and Stephen D. Fuller. "Molecular Organization of a Recombinant Subviral Particle from Tick-Borne Encephalitis Virus." Molecular Cell 7, no. 3 (March 2001): 593–602. http://dx.doi.org/10.1016/s1097-2765(01)00206-4.

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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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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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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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Fuschiotti, P., P. Fender, G. Schoehn, and J. F. Conway. "Development of the dodecahedral penton particle from adenovirus 3 for therapeutic application." Journal of General Virology 87, no. 10 (October 1, 2006): 2901–5. http://dx.doi.org/10.1099/vir.0.82025-0.

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The subviral dodecahedral particle of adenovirus 3, which assembles spontaneously in insect cells expressing the viral penton base protein, shows promise as a vector for drug delivery. Its ability to gain cell entry has been demonstrated and recent structural analysis has outlined details of the interfaces between penton bases and the importance of proteolysis of the penton base N terminus for assembly, providing a basis for understanding particle assembly and stability. Here, work in manipulating the assembly status of the dodecahedron by changing buffer conditions and subsequent success in passively encapsidating a marker molecule is described. This represents an important stage towards development of the dodecahedral particle for use as a delivery vehicle capable of targeting therapeutic molecules to specific cell types.

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David, Guillaume, Marie-Laure Fogeron, Maarten Schledorn, Roland Montserret, Uta Haselmann, Susanne Penzel, Aurélie Badillo, et al. "Strukturelle Untersuchung subviraler Partikel durch die Kombination von zellfreier Proteinherstellung mit 110 kHz MAS-NMR-Spektroskopie." Angewandte Chemie 130, no. 17 (March 25, 2018): 4877–82. http://dx.doi.org/10.1002/ange.201712091.

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Harutyunyan, S., H. Kowalski, and D. Blaas. "The Rhinovirus Subviral A-Particle Exposes 3'-Terminal Sequences of Its Genomic RNA." Journal of Virology 88, no. 11 (March 26, 2014): 6307–17. http://dx.doi.org/10.1128/jvi.00539-14.

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Tan, Ming, and Xi Jiang. "The P Domain of Norovirus Capsid Protein Forms a Subviral Particle That Binds to Histo-Blood Group Antigen Receptors." Journal of Virology 79, no. 22 (November 15, 2005): 14017–30. http://dx.doi.org/10.1128/jvi.79.22.14017-14030.2005.

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ABSTRACT Norovirus is the most important cause of nonbacterial acute gastroenteritis. We have shown previously that the isolated P domain containing the hinge forms a dimer and binds to histo-blood group antigen (HBGA) receptors with a low affinity (M. Tan, R. S. Hegde, and X. Jiang, J. Virol. 78:6233-6242, 2004). Here, we reported that the P domain of VA387 without the hinge forms a small particle with a significantly increased receptor binding affinity. An end-linked oligopeptide containing one or more cysteines promoted P-particle formation by forming intermolecular disulfide bridges. The binding sensitivity of the P particle to HBGAs was enhanced >700-fold compared to the P dimer, which was comparable to that of virus-like particles. The binding specificity of the P particle was further confirmed by strong binding to the Caco-2 cells, a human colon carcinoma cell line. This binding enhancement was observed in the P particles of both norovirus GI and GII strains. The P particle is estimated to contain 12 P dimers, in which the P2 subdomain builds up the outer layer, while the P1 subdomain forms the internal core. Taken together, our data indicate that the P domain is involved not only in dimerization but also in polymerization of the protein during the capsid assembling. The enhanced receptor binding of the P particle reflects the intrinsic feature of the viral capsid. The easy production of the P particle and its strong binding to HBGAs suggest that the P particle is useful in studying pathogenesis and morphogenesis of norovirus and candidates for antiviral or vaccine development.

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Mergener, Klaus, Michael Fäcke, Reinhold Welker, Volker Brinkmann, Hans R. Gelderblom, and Hans-Georg Krüsslich. "Analysis of HIV particle formation using transient expression of subviral constructs in mammalian cells." Virology 186, no. 1 (January 1992): 25–39. http://dx.doi.org/10.1016/0042-6822(92)90058-w.

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Boyce, Mark, Josa Wehrfritz, Rob Noad, and Polly Roy. "Purified Recombinant Bluetongue Virus VP1 Exhibits RNA Replicase Activity." Journal of Virology 78, no. 8 (April 15, 2004): 3994–4002. http://dx.doi.org/10.1128/jvi.78.8.3994-4002.2004.

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ABSTRACT The polymerase protein of all known double-stranded RNA (dsRNA) viruses is located within a complex subviral core particle that is responsible for transcription of the viral genome. For members of the family Reoviridae, this particle allows messenger sense RNA synthesis while sequestering the viral genome away from cellular dsRNA surveillance systems during infection of eukaryotic cells. The core particle of bluetongue virus (BTV) consists of the major structural proteins VP3 and VP7 and the minor enzymatic proteins VP1 (polymerase), VP4 (capping enzyme), and VP6 (helicase). In this report we have characterized fully processive dsRNA synthesis by VP1 from a viral plus-strand RNA template in the absence of the other proteins of the BTV core. This replicase activity consists of de novo initiation of synthesis, followed by elongation of the minus strand. Purified VP1 exhibits little sequence specificity for BTV plus-strand template, suggesting that the choice of viral over nonviral RNA template comes from its association with other proteins within the viral core.

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Yoshimura, Masato, Nai-Chi Chen, Hong-Hsiang Guan, Phimonphan Chuankhayan, Chien-Chih Lin, Atsushi Nakagawa, and Chun-Jung Chen. "Noncrystallographic symmetry-constrained map obtained by direct density optimization." Acta Crystallographica Section D Structural Biology 76, no. 2 (January 31, 2020): 147–54. http://dx.doi.org/10.1107/s2059798319017297.

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Noncrystallographic symmetry (NCS) averaging following molecular-replacement phasing is generally the major technique used to solve a structure with several molecules in one asymmetric unit, such as a spherical icosahedral viral particle. As an alternative method to NCS averaging, a new approach to optimize or to refine the electron density directly under NCS constraints is proposed. This method has the same effect as the conventional NCS-averaging method but does not include the process of Fourier synthesis to generate the electron density from amplitudes and the corresponding phases. It has great merit for the solution of structures with limited data that are either twinned or incomplete at low resolution. This method was applied to the case of the T = 1 shell-domain subviral particle of Penaeus vannamei nodavirus with data affected by twinning using the REFMAC5 refinement software.

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Tan, Ming, and Xi Jiang. "Norovirus P particle: a subviral nanoparticle for vaccine development against norovirus, rotavirus and influenza virus." Nanomedicine 7, no. 6 (June 2012): 889–97. http://dx.doi.org/10.2217/nnm.12.62.

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Lazar, Catalin, Alina Macovei, Stefana Petrescu, and Norica Branza-Nichita. "Activation of ERAD Pathway by Human Hepatitis B Virus Modulates Viral and Subviral Particle Production." PLoS ONE 7, no. 3 (March 26, 2012): e34169. http://dx.doi.org/10.1371/journal.pone.0034169.

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Siegler, Vera D., and Volker Bruss. "Role of Transmembrane Domains of Hepatitis B Virus Small Surface Proteins in Subviral-Particle Biogenesis." Journal of Virology 87, no. 3 (November 14, 2012): 1491–96. http://dx.doi.org/10.1128/jvi.02500-12.

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ABSTRACTThe hepatitis B virus (HBV) surface proteins not only are incorporated into the virion envelope but in addition form subviral particles (SVP) consisting solely of surface proteins and lipids. Heterologous expression of the small HBV envelope protein S produces secreted spherical SVP 20 nm in diameter, with approximately 100 S molecules per particle. The pathway leading from the initial S translation product as a multispanning transmembrane protein to the final SVP is largely unknown. To investigate the role of the four transmembrane domains (TM) of S in this process, we introduced mutations in these regions and characterized their effects on SVP formation in transfected Huh7 cells. We found that the insertion of one amino acid in the center of the α-helix of TM1 or the exchange of TM1 with a heterologous TM blocked SVP release and SVP formation by coexpressed wild-type S chains in a transdominant negative fashion. Surprisingly, this effect was partially neutralized when the mutations were expressed in the background of the HBV surface protein M, suggesting that mutations in TM1 could partially be complemented by the pre-S2 domain. The exchange of TM2 with heterologous TMs that form α-helices of the same lengths was also incompatible with SVP formation. However, these mutants no longer blocked SVP formation by coexpressed wild-type S. We conclude that TM2 is essential for the stable assembly of S chains by establishing intramembrane interactions.

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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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Lin, Xinwen, Trix Twelkmeyer, Danming Zhu, Li Zhang, Yang Zhao, Chao Zhang, Yoichiro Iwakura, et al. "Homeostatic regulation of T follicular helper and antibody response to particle antigens by IL-1Ra of medullary sinus macrophage origin." Proceedings of the National Academy of Sciences 118, no. 17 (April 19, 2021): e2019798118. http://dx.doi.org/10.1073/pnas.2019798118.

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Hepatitis B virus (HBV) vaccines are composed of surface antigen HBsAg that spontaneously assembles into subviral particles. Factors that impede its humoral immunity in 5% to 10% of vaccinees remain elusive. Here, we showed that the low-level interleukin-1 receptor antagonist (IL-1Ra) can predict antibody protection both in mice and humans. Mechanistically, murine IL-1Ra–inhibited T follicular helper (Tfh) cell expansion and subsequent germinal center (GC)-dependent humoral immunity, resulting in significantly weakened protection against the HBV challenge. Compared to soluble antigens, HBsAg particle antigen displayed a unique capture/uptake and innate immune activation, including IL-1Ra expression, preferably of medullary sinus macrophages. In humans, a unique polymorphism in the RelA/p65 binding site of IL-1Ra enhancer associated IL-1Ra levels with ethnicity-dependent vaccination outcome. Therefore, the differential IL-1Ra response to particle antigens probably creates a suppressive milieu for Tfh/GC development, and neutralization of IL-1Ra would resurrect antibody response in HBV vaccine nonresponders.

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Ko, Tzu-Ping, Cheng-Chung Lee, Chia-Cheng Chou, Masato Yoshimura, Min-Ying Wang, and Andrew H. J. Wang. "1P195 Crystal structure of infectious bursal disease virus VP2 subviral particle : Implications in virion assembly and immunogenicity(6. Macromolecular assembly,Poster Session,Abstract,Meeting Program of EABS & BSJ 2006)." Seibutsu Butsuri 46, supplement2 (2006): S195. http://dx.doi.org/10.2142/biophys.46.s195_3.

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Corrias, M. V., O. Flore, E. Broi, M. E. Marongiu, A. Pani, S. Torelli, and P. La Colla. "Characterization and role in morphogenesis of a new subviral particle (55S) isolated from poliovirus-infected cells." Journal of Virology 61, no. 2 (1987): 561–69. http://dx.doi.org/10.1128/jvi.61.2.561-569.1987.

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Kumar, M., and D. Blaas. "Human Rhinovirus Subviral A Particle Binds to Lipid Membranes over a Twofold Axis of Icosahedral Symmetry." Journal of Virology 87, no. 20 (August 14, 2013): 11309–12. http://dx.doi.org/10.1128/jvi.02055-13.

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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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Chai, Keli, Zhaohuan Wang, Yali Xu, Junshi Zhang, Juan Tan, and Wentao Qiao. "Palmitoylation of the Bovine Foamy Virus Envelope Glycoprotein Is Required for Viral Replication." Viruses 13, no. 1 (December 27, 2020): 31. http://dx.doi.org/10.3390/v13010031.

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Membrane proteins of enveloped viruses have been reported to undergo palmitoylation, a post-translational modification often having a critical role in the function of these viral proteins and hence viral replication. In this study, we report that the foamy virus (FV) envelope (Env) glycoprotein is palmitoylated. Specifically, we found that bovine foamy virus (BFV) Env (BEnv) is palmitoylated at amino acid positions C58 and C59 by BDHHC3 and BDHHC20 in a DHHC motif-dependent manner. In addition, mutations C58S and C58/59S significantly decrease cell surface expression of BEnv, subviral particle (SVP) egress, and its membrane fusion activity, thus ultimately inhibiting BFV replication. The C59S mutation exerts a minor effect in this regard. Taken together, these data demonstrate that the function of BEnv in the context of BFV replication is under the regulation of palmitoylation.

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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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Garriga, Damià, Jordi Querol-Audí, Fernando Abaitua, Irene Saugar, Joan Pous, Núria Verdaguer, José R. Castón, and José F. Rodriguez. "The 2.6-Angstrom Structure of Infectious Bursal Disease Virus-Derived T=1 Particles Reveals New Stabilizing Elements of the Virus Capsid." Journal of Virology 80, no. 14 (July 15, 2006): 6895–905. http://dx.doi.org/10.1128/jvi.00368-06.

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ABSTRACT Infectious bursal disease virus (IBDV), a member of the Birnaviridae family, is a double-stranded RNA virus that causes a highly contagious disease in young chickens leading to significant economic losses in the poultry industry. The VP2 protein, the only structural component of the IBDV icosahedral capsid, spontaneously assembles into T=1 subviral particles (SVP) when individually expressed as a chimeric gene. We have determined the crystal structure of the T=1 SVP to 2.60 Å resolution. Our results show that the 20 trimeric VP2 clusters forming the T=1 shell are further stabilized by calcium ions located at the threefold icosahedral axes. The structure also reveals a new unexpected domain swapping that mediates interactions between adjacent trimers: a short helical segment located close to the end of the long C-terminal arm of VP2 is projected toward the threefold axis of a neighboring VP2 trimer, leading to a complex network of interactions that increases the stability of the T=1 particles. Analysis of crystal packing shows that the exposed capsid residues, His253 and Thr284, determinants of IBDV virulence and the adaptation of the virus to grow in cell culture, are involved in particle-particle interactions.

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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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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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Lee, Cheng-Chung, Tzu-Ping Ko, Chia-Cheng Chou, Masato Yoshimura, Shyue-Ru Doong, Min-Ying Wang, and Andrew H. J. Wang. "Crystal structure of infectious bursal disease virus VP2 subviral particle at 2.6Å resolution: Implications in virion assembly and immunogenicity." Journal of Structural Biology 155, no. 1 (July 2006): 74–86. http://dx.doi.org/10.1016/j.jsb.2006.02.014.

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Shaw, Kit L., Dirk Lindemann, Mark J. Mulligan, and Paul A. Goepfert. "Foamy Virus Envelope Glycoprotein Is Sufficient for Particle Budding and Release." Journal of Virology 77, no. 4 (February 15, 2003): 2338–48. http://dx.doi.org/10.1128/jvi.77.4.2338-2348.2003.

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ABSTRACT Foamy viruses (FVs) are classified in the family Retroviridae, but recent data have shown that they are not conventional retroviruses. Notably, several characteristics of their particle replication strategies are more similar to those of hepatitis B virus (HBV) than those of typical retroviruses. Compared to conventional retroviruses, which require only Gag proteins for budding and release of virus-like particles (VLPs), both FV and HBV require Env proteins. In the case of HBV, Env (S protein) alone is sufficient to form subviral particles (SVPs). Because FVs also depend on Env for budding, we tested whether FV Env alone could produce SVPs. The Env proteins of FV and murine leukemia virus (MuLV) were both released into cell culture supernatants and migrated into isopycnic gradients; however, unlike MuLV Env, FV Env displayed characteristics of SVPs. FV Env particles were of greater density than those of MuLV (1.11 versus 1.07 g/ml, respectively), which strongly suggested that the released proteins of FV Env were particulate. When we examined FV SVPs by immunoelectron microscopy, we found particles that were consistent in morphology, size, and staining with gold beads, similar to FV VLPs and unlike the particle-like structures of MuLV Env, which were more consistent with vesicles produced from nonspecific membrane “blebbing.” Taken together, our results demonstrated that FV Env alone is sufficient for particle budding. This finding is unique among retroviruses and further demonstrated the similarities between FV and HBV.

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Zeyen, Lisa, Tatjana Döring, and Reinhild Prange. "Hepatitis B Virus Exploits ERGIC-53 in Conjunction with COPII to Exit Cells." Cells 9, no. 8 (August 12, 2020): 1889. http://dx.doi.org/10.3390/cells9081889.

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Several decades after its discovery, the hepatitis B virus (HBV) still displays one of the most successful pathogens in human populations worldwide. The identification and characterization of interactions between cellular and pathogenic components are essential for the development of antiviral treatments. Due to its small-sized genome, HBV highly depends on cellular functions to produce and export progeny particles. Deploying biochemical-silencing methods and molecular interaction studies in HBV-expressing liver cells, we herein identified the cellular ERGIC-53, a high-mannose-specific lectin, and distinct components of the endoplasmic reticulum (ER) export machinery COPII as crucial factors of viral trafficking and egress. Whereas the COPII subunits Sec24A, Sec23B and Sar1 are needed for both viral and subviral HBV particle exit, ERGIC-53 appears as an exclusive element of viral particle propagation, therefore interacting with the N146-glycan of the HBV envelope in a productive manner. Cell-imaging studies pointed to ER-derived, subcellular compartments where HBV assembly initiates. Moreover, our findings provide evidence that HBV exploits the functions of ERGIC-53 and Sec24A after the envelopment of nucleocapsids at these compartments in conjunction with endosomal sorting complexes required for transport (ESCRT) components. These data reveal novel insights into HBV assembly and trafficking, illustrating therapeutic prospects for intervening with the viral life cycle.

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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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Werr, Margaret, and Reinhild Prange. "Role for Calnexin and N-Linked Glycosylation in the Assembly and Secretion of Hepatitis B Virus Middle Envelope Protein Particles." Journal of Virology 72, no. 1 (January 1, 1998): 778–82. http://dx.doi.org/10.1128/jvi.72.1.778-782.1998.

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ABSTRACT Unlike those of the S and the L envelope proteins, the functional role of the related M protein in the life cycle of the hepatitis B virus (HBV) is less understood. We now demonstrate that a single N glycan, specific for M, is required for efficient secretion of M empty envelope particles. Moreover, this glycan mediates specific association of M with the chaperone calnexin. Conversely, the N glycan, common to all three envelope proteins, is involved neither in calnexin binding nor in subviral particle release. As proper folding and trafficking of M need the assistance of the chaperone, the glycan-dependent association of M with calnexin may thus play a crucial role in the assembly of HBV. Beyond being modified by N glycosylation, M is modified by O glycosylation occurring within its amino acid sequence at positions 27 to 47. The O glycans, however, were found to be dispensable for secretion of M but may rather support viral infectivity. Surprisingly, nonglycosylated M localizes exclusively to the cytosol, either for degradation or for a yet-unknown function.

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Pezeshkian, Nairi, Nicholas S. Groves, and Schuyler B. van Engelenburg. "Single-molecule imaging of HIV-1 envelope glycoprotein dynamics and Gag lattice association exposes determinants responsible for virus incorporation." Proceedings of the National Academy of Sciences 116, no. 50 (November 22, 2019): 25269–77. http://dx.doi.org/10.1073/pnas.1910008116.

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The HIV-1 envelope glycoprotein (Env) is sparsely incorporated onto assembling virus particles on the host cell plasma membrane in order for the virus to balance infectivity and evade the immune response. Env becomes trapped in a nascent particle on encounter with the polymeric viral protein Gag, which forms a dense protein lattice on the inner leaflet of the plasma membrane. While Env incorporation efficiency is readily measured biochemically from released particles, very little is known about the spatiotemporal dynamics of Env trapping events. Herein, we demonstrate, via high-resolution single-molecule tracking, that retention of Env trimers within single virus assembly sites requires the Env cytoplasmic tail (CT) and the L12 residue in the matrix (MA) domain of Gag but does not require curvature of the viral lattice. We further demonstrate that Env trimers are confined to subviral regions of a budding Gag lattice, supporting a model where direct interactions and/or steric corralling between the Env-CT and a lattice of MA trimers promote Env trapping and infectious HIV-1 assembly.

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Trask, Shane D., Irene S. Kim, Stephen C. Harrison, and Philip R. Dormitzer. "A Rotavirus Spike Protein Conformational Intermediate Binds Lipid Bilayers." Journal of Virology 84, no. 4 (December 9, 2009): 1764–70. http://dx.doi.org/10.1128/jvi.01682-09.

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ABSTRACT During rotavirus entry, a virion penetrates a host cell membrane, sheds its outer capsid proteins, and releases a transcriptionally active subviral particle into the cytoplasm. VP5*, the rotavirus protein believed to interact with the membrane bilayer, is a tryptic cleavage product of the outer capsid spike protein, VP4. When a rotavirus particle uncoats, VP5* folds back, in a rearrangement that resembles the fusogenic conformational changes in enveloped-virus fusion proteins. We present direct experimental evidence that this rearrangement leads to membrane binding. VP5* does not associate with liposomes when mounted as part of the trypsin-primed spikes on intact virions, nor does it do so after it has folded back into a stably trimeric, low-energy state. But it does bind liposomes when they are added to virions before uncoating, and VP5* rearrangement is then triggered by addition of EDTA. The presence of liposomes during the rearrangement enhances the otherwise inefficient VP5* conformational change. A VP5* fragment, VP5CT, produced from monomeric recombinant VP4 by successive treatments with chymotrypsin and trypsin, also binds liposomes only when the proteolysis proceeds in their presence. A monoclonal antibody that neutralizes infectivity by blocking a postattachment entry event also blocks VP5* liposome association. We propose that VP5* binds lipid bilayers in an intermediate conformational state, analogous to the extended intermediate conformation of enveloped-virus fusion proteins.

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Coulibaly, Fasséli, Christophe Chevalier, Bernard Delmas, and Félix A. Rey. "Crystal Structure of an Aquabirnavirus Particle: Insights into Antigenic Diversity and Virulence Determinism." Journal of Virology 84, no. 4 (December 9, 2009): 1792–99. http://dx.doi.org/10.1128/jvi.01536-09.

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ABSTRACT Infectious pancreatic necrosis virus (IPNV), a pathogen of salmon and trout, imposes a severe toll on the aquaculture and sea farming industries. IPNV belongs to the Aquabirnavirus genus in the Birnaviridae family of bisegmented double-stranded RNA viruses. The virions are nonenveloped with a T=13l icosahedral capsid made by the coat protein VP2, the three-dimensional (3D) organization of which is known in detail for the family prototype, the infectious bursal disease virus (IBDV) of poultry. A salient feature of the birnavirus architecture is the presence of 260 trimeric spikes formed by VP2, projecting radially from the capsid. The spikes carry the principal antigenic sites as well as virulence and cell adaptation determinants. We report here the 3.4-Å resolution crystal structure of a subviral particle (SVP) of IPNV, containing 20 VP2 trimers organized with icosahedral symmetry. We show that, as expected, the SVPs have a very similar organization to the IBDV counterparts, with VP2 exhibiting the same overall 3D fold. However, the spikes are significantly different, displaying a more compact organization with tighter packing about the molecular 3-fold axis. Amino acids controlling virulence and cell culture adaptation cluster differently at the top of the spike, i.e., in a central bowl in IBDV and at the periphery in IPNV. In contrast, the spike base features an exposed groove, conserved across birnavirus genera, which contains an integrin-binding motif. Thus, in addition to revealing the viral antigenic determinants, the structure suggests that birnaviruses interact with different receptors for attachment and for cell internalization during entry.

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Doong, Shyue-Ru, Yi-Huei Chen, Su-Yuan Lai, Cheng-Chung Lee, Yu-Chiang Lin, and Min-Ying Wang. "Strong and Heterogeneous Adsorption of Infectious Bursal Disease VP2 Subviral Particle with Immobilized Metal Ions Dependent on Two Surface Histidine Residues." Analytical Chemistry 79, no. 20 (October 2007): 7654–61. http://dx.doi.org/10.1021/ac070745o.

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Dhar, Arun K., Robert M. Bowers, Christopher G. Rowe, and F. C. Thomas Allnutt. "Expression of a foreign epitope on infectious pancreatic necrosis virus VP2 capsid protein subviral particle (SVP) and immunogenicity in rainbow trout." Antiviral Research 85, no. 3 (March 2010): 525–31. http://dx.doi.org/10.1016/j.antiviral.2009.12.009.

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Journal articles on the topic 'Subvirale Partikel'

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