scholarly journals Complexity and ultrastructure of infectious extracellular vesicles from cells infected by non-enveloped virus

2019 ◽  
Author(s):  
Jie E. Yang ◽  
Evan D. Rossignol ◽  
Deborah Chang ◽  
Joseph Zaia ◽  
Isaac Forrester ◽  
...  
Keyword(s):  
Extracellular Vesicles ◽  
Cell Lysis ◽  
Viral Transmission ◽  
Viral Rna ◽  
Host Cells ◽  
Replication Proteins ◽  
Enveloped Viruses ◽  
Enveloped Virus ◽  
Positive Sense ◽  
Negative Sense

AbstractEnteroviruses support cell-to-cell viral transmission prior to their canonical lytic spread of virus. Poliovirus (PV), a prototype for human pathogenic positive-sense RNA enteroviruses, and picornaviruses in general, transport multiple virionsen blocvia infectious extracellular vesicles secreted from host cells. Using biochemical and biophysical methods we identify multiple components in these secreted vesicles, including PV virions; positive and negative-sense viral RNA; essential viral replication proteins; ribosomal and regulatory cellular RNAs; and numerous host cell proteins, such as regulators of cellular metabolism and structural remodeling. Using cryo-electron tomography, we visualize the near-native three-dimensional architecture of secreted infectious extracellular vesicles containing both virions and a unique mat-like structure. Based on our biochemical data (western blot, RNA-Seq, and mass spectrometry), these mat-like structures are expected to be comprised of unencapsidated RNA and proteins. Our data show that, prior to cell lysis, non-enveloped viruses are secreted within infectious vesicles that also transport viral and host RNAs and proteins.ImportanceThe family of picornaviridae is comprised of small positive-sense RNA viruses, many of which are significant human pathogens. Picornaviruses exploit secreted extracellular vesicles for cell-to-cell viral transmission without cell lysis, and poliovirus serves as a model system for picornaviruses that are not protected by a surrounding membrane (non-enveloped viruses). The structure and contents of these vesicles secreted by virus-infected cells are described here. In addition to mature virions, these vesicles carry negative-sense, ‘template’ viral RNA and essential replication proteins, as well as cellular resources from the host. Their complex contents may comprise an enhanced virulence factor for propagation of infection, and understanding their structure and function is helping elucidate the mechanism by which extracellular vesicles contribute to the spread of non-enveloped virus infection.

scholarly journals Intercellular Transmission of Naked Viruses through Extracellular Vesicles: Focus on Polyomaviruses

Viruses ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 1086
Author(s):  
Francois Helle ◽  
Lynda Handala ◽  
Marine Bentz ◽  
Gilles Duverlie ◽  
Etienne Brochot
Keyword(s):  
Immune System ◽  
Extracellular Vesicles ◽  
Rna Viruses ◽  
Viral Transmission ◽  
Viral Fitness ◽  
Host Cells ◽  
Dna Viruses ◽  
Recent Advances ◽  
Viral Particles ◽  
Similar Strategy

Extracellular vesicles have recently emerged as a novel mode of viral transmission exploited by naked viruses to exit host cells through a nonlytic pathway. Extracellular vesicles can allow multiple viral particles to collectively traffic in and out of cells, thus enhancing the viral fitness and diversifying the transmission routes while evading the immune system. This has been shown for several RNA viruses that belong to the Picornaviridae, Hepeviridae, Reoviridae, and Caliciviridae families; however, recent studies also demonstrated that the BK and JC viruses, two DNA viruses that belong to the Polyomaviridae family, use a similar strategy. In this review, we provide an update on recent advances in understanding the mechanisms used by naked viruses to hijack extracellular vesicles, and we discuss the implications for the biology of polyomaviruses.

scholarly journals A non-enveloped arbovirus released in lysosome-derived extracellular vesicles induces super-infection exclusion

2020 ◽  
Author(s):  
Thomas Labadie ◽  
Polly Roy
Keyword(s):  
Extracellular Vesicles ◽  
Defense Mechanism ◽  
Degradation Process ◽  
Free Virus ◽  
Enveloped Viruses ◽  
Virus Particles ◽  
Enveloped Virus ◽  
Super Infection

AbstractRecent developments on extracellular vesicles (EVs) containing multiple virus particles challenge the rigid definition of non-enveloped viruses. However, how non-enveloped viruses hijack cell machinery to promote non-lytic release in EVs, and their functional roles, remain to be clarified. Here we used Bluetongue virus (BTV) as a model of a non-enveloped arthropod-borne virus and observed that the majority of viruses are released in EVs, both in vitro and in the blood of infected animals. Based on the cellular proteins detected in these EVs, and use of inhibitors targeting the cellular degradation process, we demonstrated that these extracellular vesicles are derived from secretory lysosomes, in which the acidic pH is neutralized upon the infection. Moreover, we report that secreted EVs are more efficient than free-viruses for initiating infections, but that they trigger super-infection exclusion that only free-viruses can overcome.Author summaryRecent discoveries of non-enveloped virus secreted in EVs opened the door to new developments in our understanding of the transmission and pathogenicity of these viruses. In particular, how these viruses hijack the host cellular secretion machinery, and the role of these EVs compared with free-virus particles remained to be explored. Here, we tackled these two aspects, by studying BTV, an emerging arthropod-borne virus causing epidemics worldwide. We showed that this virus is mainly released in EVs, in vivo and in the blood of infected animals, and that inhibition of the cell degradation machinery decreases the release of infectious EVs, but not free-virus particles. We found that BTV must neutralize the pH of lysosomes, which are important organelles of the cell degradation machinery, for efficient virus release in EVs. Our results highlight unique features for a virus released in EVs, explaining how BTV transits in lysosomes without being degraded. Interestingly, we observed that EVs are more infectious than free-virus particles, but only free-viruses are able to overcome the super-infection exclusion, which is a common cellular defense mechanism. In conclusion, our study stresses the dual role played by both forms, free and vesicular, in the virus life cycle.

scholarly journals Role of an Internal and Two 3′-Terminal RNA Elements in Assembly of Tombusvirus Replicase

2005 ◽  
Vol 79 (16) ◽  
pp. 10608-10618 ◽  
Author(s):  
Zivile Panaviene ◽  
Tadas Panavas ◽  
Peter D. Nagy
Keyword(s):  
Rna Virus ◽  
Viral Rna ◽  
Host Cells ◽  
Replication Proteins ◽  
Rna Sequences ◽  
Alternative Structures ◽  
Recognition Element ◽  
Rna Elements

ABSTRACT Plus-strand RNA virus replication requires the assembly of the viral replicase complexes on intracellular membranes in the host cells. The replicase of Cucumber necrosis virus (CNV), a tombusvirus, contains the viral p33 and p92 replication proteins and possible host factors. In addition, the assembly of CNV replicase is stimulated in the presence of plus-stranded viral RNA (Z. Panaviene et al., J. Virol. 78:8254-8263, 2004). To define cis-acting viral RNA sequences that stimulate replicase assembly, we performed a systematic deletion approach with a model tombusvirus replicon RNA in Saccharomyces cerevisiae, which also coexpressed p33 and p92 replication proteins. In vitro replicase assays performed with purified CNV replicase preparations from yeast revealed critical roles for three RNA elements in CNV replicase assembly: the internal p33 recognition element (p33RE), the replication silencer element (RSE), and the 3′-terminal minus-strand initiation promoter (gPR). Deletion or mutagenesis of these elements reduced the activity of the CNV replicase to a minimal level. In addition to the primary sequences of gPR, RSE, and p33RE, formation of two alternative structures among these elements may also play a role in replicase assembly. Altogether, the role of multiple RNA elements in tombusvirus replicase assembly could be an important factor to ensure fidelity of template selection during replication.

scholarly journals Targeting the Fusion Process of SARS-CoV-2 Infection by Small Molecule Inhibitors

mBio ◽  
2022 ◽  
Author(s):  
Seung Bum Park ◽  
Parker Irvin ◽  
Zongyi Hu ◽  
Mohsin Khan ◽  
Xin Hu ◽  
...  
Keyword(s):  
Membrane Fusion ◽  
Small Molecule ◽  
Small Molecule Inhibitors ◽  
Host Cells ◽  
Fusion Process ◽  
Enveloped Viruses ◽  
Enveloped Virus ◽  
Fusion Inhibitors

SARS-CoV-2 is an enveloped virus that requires membrane fusion for entry into host cells. Since the fusion process is relatively conserved among enveloped viruses, we tested our HCV fusion inhibitors, dichlorcyclizine and fluoxazolevir, against SARS-CoV-2.

scholarly journals Tracking of Native Viral RNA of Enveloped Viruses in Living Host Cells

2014 ◽  
Vol 106 (2) ◽  
pp. 494a
Author(s):  
Matthias Schade ◽  
Felix Hövelmann ◽  
Hannah Sabeth Sperber ◽  
Peter Witkowski ◽  
Oliver Seitz ◽  
...  
Keyword(s):  
Viral Rna ◽  
Host Cells ◽  
Enveloped Viruses

scholarly journals Critical Assessment of Purification and Analytical Technologies for Enveloped Viral Vector and Vaccine Processing and Their Current Limitations in Resolving Co-Expressed Extracellular Vesicles

Vaccines ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 823
Author(s):  
Aline Minh ◽  
Amine A. Kamen
Keyword(s):  
Extracellular Vesicles ◽  
Viral Vectors ◽  
Viral Vector ◽  
Genetic Diseases ◽  
Genetic Material ◽  
Vaccine Safety ◽  
Downstream Processing ◽  
Enveloped Viruses ◽  
Distinctive Features ◽  
Enveloped Virus

Viral vectors and viral vaccines are invaluable tools in prevention and treatment of diseases. Many infectious diseases are controlled using vaccines designed from subunits or whole viral structures, whereas other genetic diseases and cancers are being treated by viruses used as vehicles for delivering genetic material in gene therapy or as therapeutic agents in virotherapy protocols. Viral vectors and vaccines are produced in different platforms, from traditional embryonated chicken eggs to more advanced cell cultures. All these expression systems, like most cells and cellular tissues, are known to spontaneously release extracellular vesicles (EVs). EVs share similar sizes, biophysical characteristics and even biogenesis pathways with enveloped viruses, which are currently used as key ingredients in a number of viral vectors and licensed vaccine products. Herein, we review distinctive features and similarities between EVs and enveloped viruses as we revisit the downstream processing steps and analytical technologies currently implemented to produce and document viral vector and vaccine products. Within a context of well-established viral vector and vaccine safety profiles, this review provides insights on the likely presence of EVs in the final formulation of enveloped virus products and discusses the potential to further resolve and document these components.

scholarly journals Gaussian curvature and the budding kinetics of enveloped viruses

2018 ◽  
Author(s):  
Sanjay Dharmavaram ◽  
Baochen She ◽  
Guillermo Lázaro ◽  
Michael F. Hagan ◽  
Robijn Bruinsma
Keyword(s):  
Host Cell ◽  
Lipid Bilayers ◽  
Energy Barrier ◽  
Lipid Membrane ◽  
Gauss Curvature ◽  
Host Cells ◽  
Capsid Proteins ◽  
Enveloped Viruses ◽  
Enveloped Virus ◽  
Hiv 1

AbstractThe formation of a membrane-enveloped virus such as HIV-1 starts with the assembly of a curved layer of capsid proteins lining the interior of the plasma membrane (PM) of the host cell. This layer grows into a spherical shell enveloped by a lipid membrane that is connected to the PM via a curved neck (“budding”). For many enveloped viruses the scission of this neck is not spontaneous. Instead, the elaborate “ESCRT” cell machinery needs to be recruited to carry out that task. It is not clear why this is necessary since scission is spontaneous for much simpler systems, such as vesiculation driven by phase-separation inside lipid bilayers. Recently, Brownian dynamics simulations of enveloped virus budding reproduced protracted pausing and stalling after formation of the neck [1], which suggest that the origin of pausing/stalling is to be found in the physics of the budding process. Here, we show that the pausing/stalling observed in the simulations can be understood as a purely kinetic phenomenon associated with a “geometrical” energy barrier that must be overcome by capsid proteins diffusing along the membrane prior to incorporation into the viral capsid. This geometrical energy barrier is generated by the conflict between the positive Gauss curvature of the capsid and the large negative Gauss curvature of the neck region. The theory is compared with the Brownian simulations of the budding of enveloped viruses.Author summaryDespite intense study, the life-cycle of the HIV-1 virus continues to pose mysteries. One of these concerns the assembly of the HIV-1 virus inside infected host cells: it is interrupted at the very last moment. During the subsequent pause, HIV-1 recruits a complex cell machinery, the so-called “ESCRT pathway”. The ESCRT proteins pinch-off the “viral bud” from the host cell. In this paper, we propose that the reason for the stalling emerges from the fundamental physics of the lipid membrane that surrounds the virus. The membrane mostly follows the spherical geometry of the virus, but in the pinch-off region the geometry is radically different: it resembles a neck. By combining numerical and analytical methods, we demonstrate that a neck geometry creates a barrier to protein entry, thus blocking proteins required to complete viral assembly. This “geometrical barrier” mechanism is general: such a barrier should form during assembly of all membrane-enveloped viruses – including the Ebola and Herpes viruses. Indeed many families of enveloped viruses also recruit the ESCRT machinery for pinch-off. A fundamental understanding of the budding process could enable a new strategy to combat enveloped viruses, based on selective stabilization of membrane neck geometries.

scholarly journals Helicobacter pylori Outer Membrane Vesicles and Extracellular Vesicles from Helicobacter pylori-Infected Cells in Gastric Disease Development

2021 ◽  
Vol 22 (9) ◽  
pp. 4823
Author(s):  
María Fernanda González ◽  
Paula Díaz ◽  
Alejandra Sandoval-Bórquez ◽  
Daniela Herrera ◽  
Andrew F. G. Quest
Keyword(s):  
Gastric Cancer ◽  
Helicobacter Pylori ◽  
Outer Membrane ◽  
Extracellular Vesicles ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Host Cells ◽  
Gastric Epithelium ◽  
Infected Cells ◽  
H Pylori

Extracellular vesicles (EVs) are cell-derived vesicles important in intercellular communication that play an essential role in host-pathogen interactions, spreading pathogen-derived as well as host-derived molecules during infection. Pathogens can induce changes in the composition of EVs derived from the infected cells and use them to manipulate their microenvironment and, for instance, modulate innate and adaptive inflammatory immune responses, both in a stimulatory or suppressive manner. Gastric cancer is one of the leading causes of cancer-related deaths worldwide and infection with Helicobacter pylori (H. pylori) is considered the main risk factor for developing this disease, which is characterized by a strong inflammatory component. EVs released by host cells infected with H. pylori contribute significantly to inflammation, and in doing so promote the development of disease. Additionally, H. pylori liberates vesicles, called outer membrane vesicles (H. pylori-OMVs), which contribute to atrophia and cell transformation in the gastric epithelium. In this review, the participation of both EVs from cells infected with H. pylori and H. pylori-OMVs associated with the development of gastric cancer will be discussed. By deciphering which functions of these external vesicles during H. pylori infection benefit the host or the pathogen, novel treatment strategies may become available to prevent disease.

scholarly journals Lipoproteins Are Responsible for the Pro-Inflammatory Property of Staphylococcus aureus Extracellular Vesicles

2021 ◽  
Vol 22 (13) ◽  
pp. 7099
Author(s):  
Pradeep Kumar Kopparapu ◽  
Meghshree Deshmukh ◽  
Zhicheng Hu ◽  
Majd Mohammad ◽  
Marco Maugeri ◽  
...  
Keyword(s):  
Extracellular Vesicles ◽  
Inflammatory Responses ◽  
Surface Proteins ◽  
Host Cells ◽  
Immune Stimulation ◽  
Domains Of Life ◽  
Major Surface ◽  
Staphylococcal Aureus

Staphylococcal aureus (S. aureus), a Gram-positive bacteria, is known to cause various infections. Extracellular vesicles (EVs) are a heterogeneous array of membranous structures secreted by cells from all three domains of life, i.e., eukaryotes, bacteria, and archaea. Bacterial EVs are implied to be involved in both bacteria–bacteria and bacteria–host interactions during infections. It is still unclear how S. aureus EVs interact with host cells and induce inflammatory responses. In this study, EVs were isolated from S. aureus and mutant strains deficient in either prelipoprotein lipidation (Δlgt) or major surface proteins (ΔsrtAB). Their immunostimulatory capacities were assessed both in vitro and in vivo. We found that S. aureus EVs induced pro-inflammatory responses both in vitro and in vivo. However, this activity was dependent on lipidated lipoproteins (Lpp), since EVs isolated from the Δlgt showed no stimulation. On the other hand, EVs isolated from the ΔsrtAB mutant showed full immune stimulation, indicating the cell wall anchoring of surface proteins did not play a role in immune stimulation. The immune stimulation of S. aureus EVs was mediated mainly by monocytes/macrophages and was TLR2 dependent. In this study, we demonstrated that not only free Lpp but also EV-imbedded Lpp had high pro-inflammatory activity.

scholarly journals Effects of Gag Mutation and Processing on Retroviral Dimeric RNA Maturation

2006 ◽  
Vol 80 (3) ◽  
pp. 1242-1249 ◽  
Author(s):  
William Fu ◽  
Que Dang ◽  
Kunio Nagashima ◽  
Eric O. Freed ◽  
Vinay K. Pathak ◽  
...  
Keyword(s):  
Viral Protein ◽  
Leukemia Virus ◽  
Viral Rna ◽  
Host Cells ◽  
Protein Cleavage ◽  
Rna Packaging ◽  
Virus Rna ◽  
Rna Dimer ◽  
Rna Maturation ◽  
Hiv 1

ABSTRACT After their release from host cells, most retroviral particles undergo a maturation process, which includes viral protein cleavage, core condensation, and increased stability of the viral RNA dimer. Inactivating the viral protease prevents protein cleavage; the resulting virions lack condensed cores and contain fragile RNA dimers. Therefore, protein cleavage is linked to virion morphological change and increased stability of the RNA dimer. However, it is unclear whether protein cleavage is sufficient for mediating virus RNA maturation. We have observed a novel phenotype in a murine leukemia virus capsid mutant, which has normal virion production, viral protein cleavage, and RNA packaging. However, this mutant also has immature virion morphology and contains a fragile RNA dimer, which is reminiscent of protease-deficient mutants. To our knowledge, this mutant provides the first evidence that Gag cleavage alone is not sufficient to promote RNA dimer maturation. To extend our study further, we examined a well-defined human immunodeficiency virus type 1 (HIV-1) Gag mutant that lacks a functional PTAP motif and produces immature virions without major defects in viral protein cleavage. We found that the viral RNA dimer in the PTAP mutant is more fragile and unstable compared with those from wild-type HIV-1. Based on the results of experiments using two different Gag mutants from two distinct retroviruses, we conclude that Gag cleavage is not sufficient for promoting RNA dimer maturation, and we propose that there is a link between the maturation of virion morphology and the viral RNA dimer.

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