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Molecular Microbiology Jun 2022Human cytomegalovirus (HCMV) is a ubiquitous herpesvirus and the leading cause of congenital disabilities as well as a significant cause of disease in immunocompromised... (Review)
Review
Human cytomegalovirus (HCMV) is a ubiquitous herpesvirus and the leading cause of congenital disabilities as well as a significant cause of disease in immunocompromised patients. The envelopment and egress of HCMV particles is an essential step of the viral life cycle as it determines viral spread and potentially tropism. Here we review the current literature on HCMV envelopment and egress with a particular focus on the role of virus-containing multivesicular body-like vesicles for virus egress and spread. We discuss the difficulties of determining the cellular provenance of these structures in light of viral redistribution of cellular marker proteins and provide potential paths to illuminate their genesis. Finally, we discuss how divergent egress pathways could result in virions of different tropisms.
Topics: Cytomegalovirus; Humans; Proteins; Virion; Virus Assembly
PubMed: 35607767
DOI: 10.1111/mmi.14946 -
Viruses Aug 2021Hantaviruses infect a wide range of hosts including insectivores and rodents and can also cause zoonotic infections in humans, which can lead to severe disease with... (Review)
Review
Hantaviruses infect a wide range of hosts including insectivores and rodents and can also cause zoonotic infections in humans, which can lead to severe disease with possible fatal outcomes. Hantavirus outbreaks are usually linked to the population dynamics of the host animals and their habitats being in close proximity to humans, which is becoming increasingly important in a globalized world. Currently there is neither an approved vaccine nor a specific and effective antiviral treatment available for use in humans. Hantaviruses belong to the order with a tri-segmented negative-sense RNA genome. They encode only five viral proteins and replicate and transcribe their genome in the cytoplasm of infected cells. However, many details of the viral amplification cycle are still unknown. In recent years, structural biology methods such as cryo-electron tomography, cryo-electron microscopy, and crystallography have contributed essentially to our understanding of virus entry by membrane fusion as well as genome encapsidation by the nucleoprotein. In this review, we provide an update on the hantavirus replication cycle with a special focus on structural virology aspects.
Topics: Animals; Cryoelectron Microscopy; Crystallography, X-Ray; Genome, Viral; Orthohantavirus; Hantavirus Infections; Humans; Rodentia; Viral Proteins; Virus Assembly; Virus Internalization; Virus Replication
PubMed: 34452426
DOI: 10.3390/v13081561 -
Nano Letters Apr 2021Designer virus-inspired proteins drive the manufacturing of more effective, safer gene-delivery systems and simpler models to study viral assembly. However,...
Designer virus-inspired proteins drive the manufacturing of more effective, safer gene-delivery systems and simpler models to study viral assembly. However, self-assembly of engineered viromimetic proteins on specific nucleic acid templates, a distinctive viral property, has proved difficult. Inspired by viral packaging signals, we harness the programmability of CRISPR-Cas12a to direct the nucleation and growth of a self-assembling synthetic polypeptide into virus-like particles (VLP) on specific DNA molecules. Positioning up to ten nuclease-dead Cas12a (dCas12a) proteins along a 48.5 kbp DNA template triggers particle growth and full DNA encapsidation at limiting polypeptide concentrations. Particle growth rate is further increased when dCas12a is dimerized with a polymerization silk-like domain. Such improved self-assembly efficiency allows for discrimination between cognate versus noncognate DNA templates by the synthetic polypeptide. CRISPR-guided VLPs will help to develop programmable bioinspired nanomaterials with applications in biotechnology as well as viromimetic scaffolds to improve our understanding of viral self-assembly.
Topics: Clustered Regularly Interspaced Short Palindromic Repeats; DNA; Nucleocapsid; Virion; Virus Assembly
PubMed: 33729813
DOI: 10.1021/acs.nanolett.0c04640 -
Journal of Virology Sep 2021We have developed a flexible platform for delivery of proteins to target cell interiors using paramyxovirus-like particles. The key enabling feature is an appendage, 15...
We have developed a flexible platform for delivery of proteins to target cell interiors using paramyxovirus-like particles. The key enabling feature is an appendage, 15 to 30 amino acid residues in length, that is added to cargo proteins and that induces them to bind to the viral matrix (M) protein during virus-like particle (VLP) assembly. The cargo is then incorporated within the VLPs as they bud, using the same interactions that normally direct viral genome packaging. The appendage can also serve as an epitope tag for cargo detection using a nucleocapsid (NP) protein-specific monoclonal antibody. Using this approach, we generated luciferase-loaded VLPs, green fluorescent protein-loaded VLPs, superoxide dismutase-loaded VLPs, and Cre recombinase-loaded VLPs. In each case, the VLPs could efficiently deliver their functional cargos to target cells and, in the case of Cre recombinase, to target cell nuclei. The strategy was employed using two different VLP production platforms, one based on parainfluenza virus 5 (PIV5) and the other based on Nipah virus, and in both cases efficient cargo packaging and delivery could be achieved. These findings provide a foundation for development of paramyxovirus-like particles as tools for safe and efficient delivery of therapeutic proteins to cells and tissues. Therapeutic proteins including transcription factors and genome editors have enormous clinical potential but are currently limited in part due to the challenges of safely and efficiently delivering these proteins to the interiors of target cells. Here, we have developed a new strategy for protein delivery based on manipulation of paramyxovirus genome packaging interactions.
Topics: Drug Delivery Systems; Genetic Engineering; Humans; Luciferases, Renilla; Nucleocapsid; Paramyxoviridae; Viral Matrix Proteins; Virion; Virus Assembly
PubMed: 34379508
DOI: 10.1128/JVI.01030-21 -
Wiley Interdisciplinary Reviews.... Jul 2020Viruses are highly ordered supramolecular complexes that have evolved to propagate by hijacking the host cell's machinery. Although viruses are very diverse, spreading... (Review)
Review
Viruses are highly ordered supramolecular complexes that have evolved to propagate by hijacking the host cell's machinery. Although viruses are very diverse, spreading through cells of all kingdoms of life, they share common functions and properties. Next to the general interest in virology, fundamental viral mechanisms are of growing importance in other disciplines such as biomedicine and (bio)nanotechnology. However, in order to optimally make use of viruses and virus-like particles, for instance as vehicle for targeted drug delivery or as building blocks in electronics, it is essential to understand their basic chemical and physical properties and characteristics. In this context, the number of studies addressing the mechanisms governing viral properties and processes has recently grown drastically. This review summarizes a specific part of these scientific achievements, particularly addressing physical virology approaches aimed to understand the self-assembly of viruses and the mechanical properties of viral particles. Using a physicochemical perspective, we have focused on fundamental studies providing an overview of the molecular basis governing these key aspects of viral systems. This article is categorized under: Biology-Inspired Nanomaterials > Protein and Virus-Based Structures Nanotechnology Approaches to Biology > Nanoscale Systems in Biology.
Topics: Biomechanical Phenomena; Genome, Viral; Humans; Virion; Virus Assembly; Viruses
PubMed: 31960585
DOI: 10.1002/wnan.1613 -
Cell Host & Microbe Nov 2019Dengue virus assembly requires cleavage of viral C-prM-E polyprotein into three structural proteins (capsid, premembrane, and envelope), packaging of viral RNA with C...
Dengue virus assembly requires cleavage of viral C-prM-E polyprotein into three structural proteins (capsid, premembrane, and envelope), packaging of viral RNA with C protein into nucleocapsid, and budding of prM and E proteins into virions. The molecular mechanisms underlying these assembly events are unclear. Here, we show that dengue nonstructural protein 2A (NS2A protein) recruits viral RNA, structural proteins, and protease to the site of virion assembly and coordinates nucleocapsid and virus formation. The last 285 nucleotides of viral 3' UTR serve as a "recruiting signal for packaging" that binds to a cytosolic loop of NS2A. This interaction allows NS2A to recruit nascent RNA from the replication complex to the virion assembly site. NS2A also recruits the C-prM-E polyprotein and NS2B-NS3 protease to the virion assembly site by interacting with prM, E, and NS3, leading to coordinated C-prM-E cleavage. Mature C protein assembles onto genomic RNA to form nucleocapsid, followed by prM and E envelopment and virion formation.
Topics: Aedes; Animals; Cell Line; Chlorocebus aethiops; Cricetinae; Dengue Virus; HEK293 Cells; Humans; Nucleocapsid; RNA Helicases; RNA, Viral; Serine Endopeptidases; Vero Cells; Viral Envelope Proteins; Viral Nonstructural Proteins; Viral Proteins; Virus Assembly
PubMed: 31631053
DOI: 10.1016/j.chom.2019.09.015 -
Microbiology and Immunology Oct 2019The family Flaviviridae comprises four genera, namely, Flavivirus, Pestivirus, Pegivirus, and Hepacivirus. These viruses have similar genome structures, but the genomes... (Review)
Review
The family Flaviviridae comprises four genera, namely, Flavivirus, Pestivirus, Pegivirus, and Hepacivirus. These viruses have similar genome structures, but the genomes of Pestivirus and Flavivirus encode the secretory glycoproteins E and NS1, respectively. E plays an important role in virus particle formation and cell entry, whereas NS1 participates in the formation of replication complexes and virus particles. Conversely, apolipoproteins are known to participate in the formation of infectious particles of hepatitis C virus (HCV) and various secretory glycoproteins play a similar role in HCV particles formation, suggesting that there is no strong specificity for the function of secretory glycoproteins in infectious-particle formation. In addition, recent studies have shown that host-derived apolipoproteins and virus-derived E and NS1 play comparable roles in infectious-particle formation of both HCV and pestiviruses. In this review, we summarize the roles of secretory glycoproteins in the formation of Flaviviridae virus particles.
Topics: Apolipoproteins; Flaviviridae; Flaviviridae Infections; Glycoproteins; Host Microbial Interactions; Humans; Virion; Virus Assembly
PubMed: 31342548
DOI: 10.1111/1348-0421.12733 -
Journal of Virology Oct 2023The influenza A virus genome consists of eight distinct viral RNAs (vRNAs) that are typically packaged into a single virion as an octameric complex. How this genome...
The influenza A virus genome consists of eight distinct viral RNAs (vRNAs) that are typically packaged into a single virion as an octameric complex. How this genome complex is assembled and incorporated into the virion is poorly understood, but previous research suggests a coordinative role for packaging signals present in all vRNAs. Here, we show that disruption of two packaging signals in a model H7N7 influenza A virus results in a mixture of virions with unusual vRNA content, including empty virions, virions with one to four vRNAs, and virions with octameric complexes composed of vRNA duplicates. Our results suggest that (i) the assembly of error-free octameric complexes proceeds through a series of defined vRNA sub-complexes and (ii) virions can bud without incorporating complete octameric complexes.
Topics: Genome, Viral; Influenza A virus; Influenza A Virus, H7N7 Subtype; RNA, Viral; Viral Genome Packaging; Virion; Virus Assembly
PubMed: 37811996
DOI: 10.1128/jvi.01076-23 -
Cold Spring Harbor Perspectives in... Jan 2021Hepatitis C virus (HCV) proliferates by hijacking the host lipid machinery. In vitro replication systems revealed many aspects of the virus life cycle; in particular,... (Review)
Review
Hepatitis C virus (HCV) proliferates by hijacking the host lipid machinery. In vitro replication systems revealed many aspects of the virus life cycle; in particular, viral utilization of host lipid metabolism during HCV proliferation. HCV interacts with lipid droplets (LDs) before starting the process of virus capsid formation at the lipid-rich endoplasmic reticulum (ER) membrane compartment. HCV buds into the ER via lipoprotein assembly and secretion. Exchangeable apolipoproteins, represented by apolipoprotein E (apoE), play pivotal roles in enhancing HCV-specific infectivity. HCV virions are likely to interact with other lipoproteins circulating in blood vessels and incorporate apolipoproteins as well as lipids. This review focuses on virus assembly and egress by briefly describing the recent advances in this area.
Topics: Apolipoproteins; Hepacivirus; Hepatitis C; Humans; Lipid Metabolism; Lipoproteins; Virion; Virus Assembly
PubMed: 32122916
DOI: 10.1101/cshperspect.a036814 -
ACS Nano Sep 2022Hepatitis B virus (HBV) is an endemic, chronic virus that leads to 800000 deaths per year. Central to the HBV lifecycle, the viral core has a protein capsid assembled...
Hepatitis B virus (HBV) is an endemic, chronic virus that leads to 800000 deaths per year. Central to the HBV lifecycle, the viral core has a protein capsid assembled from many copies of a single protein. The capsid protein adopts different (quasi-equivalent) conformations to form icosahedral capsids containing 180 or 240 proteins: = 3 or = 4, respectively, in Caspar-Klug nomenclature. HBV capsid assembly has become an important target for recently developed antivirals; nonetheless, the assembly pathways and mechanisms that control HBV dimorphism remain unclear. We describe computer simulations of the HBV assembly, using a coarse-grained model that has parameters learned from all-atom molecular dynamics simulations of a complete HBV capsid and yet is computationally tractable. Dynamical simulations with the resulting model reproduce experimental observations of HBV assembly pathways and products. By constructing Markov state models and employing transition path theory, we identify pathways leading to = 3, = 4, and other experimentally observed capsid morphologies. The analysis shows that capsid polymorphism is promoted by the low HBV capsid bending modulus, where the key factors controlling polymorphism are the conformational energy landscape and protein-protein binding affinities.
Topics: Antiviral Agents; Capsid; Capsid Proteins; Hepatitis B virus; Sex Characteristics; Virus Assembly
PubMed: 36054910
DOI: 10.1021/acsnano.2c02119