Members of the family Secoviridae are non-enveloped plant viruses with mono- or bipartite linear positive-sense ssRNA genomes with a combined genome of 9 to 13.7 kb and icosahedral particles 25-30 nm in diameter. They are related to picornaviruses and are members of the order Picornavirales. Genera in the family are distinguished by the host range, vector, genomic features and phylogeny of the member viruses. Most members infect dicotyledonous plants, and many cause serious disease epidemics. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) report on the family Secoviridae, which is available at ictv.global/report/secoviridae.
Viral nanoparticles represent potential natural versatile platforms for targeted gene and drug delivery. Improving the efficiency of gene transfer mediated by viral vectors could not only enhance their therapeutic potential, but also contribute to understanding the limitations in interactions of nanoparticles with cells and the development of new therapeutic approaches. In this study, four cell-penetrating peptides (CPPs), cationic octaarginine (R8), histidine-rich peptides (LAH4 and KH27K) and fusogenic peptide (FUSO), are investigated for their effect on infection by mouse polyomavirus (MPyV) or on transduction of reporter genes delivered by MPyV or related viral vectors. Peptides noncovalently associated with viral particles enhance gene transfer (with the exception of FUSO). Removal of cellular heparan sulfates by the heparinase does not significantly change the enhancing potential of CPPs. Instead, CPPs influences the physical state of viral particles: R8 slightly destabilizes the intact virus, KH27K induces its aggregation and LAH4 promotes disassembly and aggregation of the particles that massively and rapidly associate with cells. The findings indicate that peptides acting as transduction-enhancing agents of polyomavirus-based nanoparticles modulate their physical state, which can be an important prerequisite for sensitization of cells and determination of the further fate of viral particles inside cells.
- MeSH
- genetické vektory * MeSH
- HEK293 buňky MeSH
- kapsida metabolismus ultrastruktura MeSH
- lidé MeSH
- myši MeSH
- oligopeptidy chemie metabolismus MeSH
- penetrační peptidy chemie metabolismus MeSH
- Polyomavirus genetika metabolismus ultrastruktura MeSH
- transdukce genetická * MeSH
- virion genetika metabolismus ultrastruktura MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- srovnávací studie MeSH
The western honeybee is the primary pollinator of numerous food crops. Furthermore, honeybees are essential for ecosystem stability by sustaining the diversity and abundance of wild flowering plants. However, the worldwide population of honeybees is under pressure from environmental stress and pathogens. Viruses from the families Iflaviridae and Dicistroviridae, together with their vector, the parasitic mite Varroa destructor, are the major threat to the world's honeybees. Dicistroviruses and iflaviruses have capsids with icosahedral symmetries. Acidic pH triggers the genome release of both dicistroviruses and iflaviruses. The capsids of iflaviruses expand, whereas those of dicistroviruses remain compact until the genome release. Furthermore, dicistroviruses use inner capsid proteins, whereas iflaviruses employ protruding domains or minor capsid proteins from the virion surface to penetrate membranes and deliver their genomes into the cell cytoplasm. The structural characterization of the infection process opens up possibilities for the development of antiviral compounds.
- MeSH
- genom virový * MeSH
- kapsida chemie metabolismus MeSH
- koncentrace vodíkových iontů MeSH
- konformace proteinů MeSH
- krystalografie rentgenová MeSH
- kyseliny MeSH
- molekulární modely MeSH
- RNA-viry metabolismus MeSH
- včely virologie MeSH
- virion chemie genetika MeSH
- virové nemoci veterinární MeSH
- virové plášťové proteiny chemie MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
Phages infecting Staphylococcus aureus can be used as therapeutics against antibiotic-resistant bacterial infections. However, there is limited information about the mechanism of genome delivery of phages that infect Gram-positive bacteria. Here, we present the structures of native S. aureus phage P68, genome ejection intermediate, and empty particle. The P68 head contains 72 subunits of inner core protein, 15 of which bind to and alter the structure of adjacent major capsid proteins and thus specify attachment sites for head fibers. Unlike in the previously studied phages, the head fibers of P68 enable its virion to position itself at the cell surface for genome delivery. The unique interaction of one end of P68 DNA with one of the 12 portal protein subunits is disrupted before the genome ejection. The inner core proteins are released together with the DNA and enable the translocation of phage genome across the bacterial membrane into the cytoplasm.
- MeSH
- bakteriofágy genetika MeSH
- buněčná membrána genetika MeSH
- cytoplazma genetika MeSH
- DNA virů genetika MeSH
- genom virový genetika MeSH
- Staphylococcus aureus genetika MeSH
- virion genetika MeSH
- virové plášťové proteiny genetika MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The mechanism of action of various viruses has been the primary focus of many studies. Yet, the data on RNA modifications in any type of virus are scarce. Methods for the sensitive analysis of RNA modifications have been developed only recently and they have not been applied to viruses. In particular, the RNA composition of HIV-1 virions has never been determined with sufficiently exact methods. Here, we reveal that the RNA of HIV-1 virions contains surprisingly high amount of the 1-methyladenosine. We are the first to use a liquid chromatography-mass spectrometry analysis (LC/MS) of virion RNA, which we combined with m1A profiling and deep sequencing. We found that m1A was present in the tRNA, but not in the genomic HIV-1 RNA and the abundant 7SL RNA. We were able to calculate that an HIV-1 virion contains per 2 copies of genomic RNA and 14 copies of 7SL RNA also 770 copies of tRNA, which is approximately 10 times more than thus far expected. These new insights into the composition of the HIV-1 virion can help in future studies to identify the role of nonprimer tRNAs in retroviruses. Moreover, we present a promising new tool for studying the compositions of virions.
- MeSH
- adenosin analogy a deriváty metabolismus MeSH
- chromatografie kapalinová metody MeSH
- genom virový genetika MeSH
- HIV-1 genetika fyziologie MeSH
- hmotnostní spektrometrie metody MeSH
- lidé MeSH
- nádorové buněčné linie MeSH
- RNA malá cytoplazmatická genetika MeSH
- RNA transferová genetika metabolismus MeSH
- RNA virová genetika metabolismus MeSH
- sekvence nukleotidů MeSH
- sestavení viru genetika MeSH
- signál-rozpoznávající částice genetika MeSH
- virion genetika metabolismus MeSH
- vysoce účinné nukleotidové sekvenování metody MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Viruses from the genus Enterovirus are important human pathogens. Receptor binding or exposure to acidic pH in endosomes converts enterovirus particles to an activated state that is required for genome release. However, the mechanism of enterovirus uncoating is not well understood. Here, we use cryo-electron microscopy to visualize virions of human echovirus 18 in the process of genome release. We discover that the exit of the RNA from the particle of echovirus 18 results in a loss of one, two, or three adjacent capsid-protein pentamers. The opening in the capsid, which is more than 120 Å in diameter, enables the release of the genome without the need to unwind its putative double-stranded RNA segments. We also detect capsids lacking pentamers during genome release from echovirus 30. Thus, our findings uncover a mechanism of enterovirus genome release that could become target for antiviral drugs.
- MeSH
- Cercopithecus aethiops MeSH
- dvouvláknová RNA chemie genetika MeSH
- elektronová kryomikroskopie MeSH
- enterovirus B lidský genetika ultrastruktura MeSH
- epitelové buňky ultrastruktura virologie MeSH
- genom virový * MeSH
- kapsida chemie ultrastruktura MeSH
- koncentrace vodíkových iontů MeSH
- lidé MeSH
- RNA virová chemie genetika MeSH
- simulace molekulární dynamiky MeSH
- svlékání virového obalu genetika MeSH
- virion genetika ultrastruktura MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Retroviruses assemble and bud from infected cells in an immature form and require proteolytic maturation for infectivity. The CA (capsid) domains of the Gag polyproteins assemble a protein lattice as a truncated sphere in the immature virion. Proteolytic cleavage of Gag induces dramatic structural rearrangements; a subset of cleaved CA subsequently assembles into the mature core, whose architecture varies among retroviruses. Murine leukemia virus (MLV) is the prototypical γ-retrovirus and serves as the basis of retroviral vectors, but the structure of the MLV CA layer is unknown. Here we have combined X-ray crystallography with cryoelectron tomography to determine the structures of immature and mature MLV CA layers within authentic viral particles. This reveals the structural changes associated with maturation, and, by comparison with HIV-1, uncovers conserved and variable features. In contrast to HIV-1, most MLV CA is used for assembly of the mature core, which adopts variable, multilayered morphologies and does not form a closed structure. Unlike in HIV-1, there is similarity between protein-protein interfaces in the immature MLV CA layer and those in the mature CA layer, and structural maturation of MLV could be achieved through domain rotations that largely maintain hexameric interactions. Nevertheless, the dramatic architectural change on maturation indicates that extensive disassembly and reassembly are required for mature core growth. The core morphology suggests that wrapping of the genome in CA sheets may be sufficient to protect the MLV ribonucleoprotein during cell entry.
- MeSH
- elektronová kryomikroskopie MeSH
- genové produkty gag chemie genetika ultrastruktura MeSH
- HEK293 buňky MeSH
- HIV-1 chemie genetika ultrastruktura MeSH
- kapsida chemie ultrastruktura MeSH
- krystalografie rentgenová MeSH
- kvarterní struktura proteinů MeSH
- lidé MeSH
- molekulární modely MeSH
- myši MeSH
- proteinové domény MeSH
- sekvence aminokyselin MeSH
- sekvenční homologie aminokyselin MeSH
- tomografie elektronová MeSH
- virion chemie genetika ultrastruktura MeSH
- virové plášťové proteiny chemie genetika ultrastruktura MeSH
- virus myší leukemie chemie genetika ultrastruktura MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Research Support, N.I.H., Intramural MeSH
- srovnávací studie MeSH
Nucleocytoplasmic large DNA viruses (NCLDVs) blur the line between viruses and cells. Melbournevirus (MelV, family Marseilleviridae) belongs to a new family of NCLDVs. Here we present an electron cryo-microscopy structure of the MelV particle, with the large triangulation number T = 309 constructed by 3080 pseudo-hexagonal capsomers. The most distinct feature of the particle is a large and dense body (LDB) consistently found inside all particles. Electron cryo-tomography of 147 particles shows that the LDB is preferentially located in proximity to the probable lipid bilayer. The LDB is 30 nm in size and its density matches that of a genome/protein complex. The observed LDB reinforces the structural complexity of MelV, setting it apart from other NCLDVs.
- MeSH
- DNA viry genetika fyziologie ultrastruktura MeSH
- elektronová kryomikroskopie MeSH
- genom virový MeSH
- kapsida metabolismus ultrastruktura MeSH
- sestavení viru MeSH
- virion genetika fyziologie ultrastruktura MeSH
- virové proteiny genetika metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Tick-borne encephalitis virus (TBEV) causes 13,000 cases of human meningitis and encephalitis annually. However, the structure of the TBEV virion and its interactions with antibodies are unknown. Here, we present cryo-EM structures of the native TBEV virion and its complex with Fab fragments of neutralizing antibody 19/1786. Flavivirus genome delivery depends on membrane fusion that is triggered at low pH. The virion structure indicates that the repulsive interactions of histidine side chains, which become protonated at low pH, may contribute to the disruption of heterotetramers of the TBEV envelope and membrane proteins and induce detachment of the envelope protein ectodomains from the virus membrane. The Fab fragments bind to 120 out of the 180 envelope glycoproteins of the TBEV virion. Unlike most of the previously studied flavivirus-neutralizing antibodies, the Fab fragments do not lock the E-proteins in the native-like arrangement, but interfere with the process of virus-induced membrane fusion.
- MeSH
- elektronová kryomikroskopie MeSH
- exprese genu MeSH
- fúze membrán genetika MeSH
- imunoglobuliny - Fab fragmenty biosyntéza chemie MeSH
- internalizace viru MeSH
- koncentrace vodíkových iontů MeSH
- lidé MeSH
- multimerizace proteinu MeSH
- nádorové buněčné linie MeSH
- neurony patologie virologie MeSH
- neutralizující protilátky biosyntéza chemie MeSH
- proteinové domény MeSH
- protilátky virové biosyntéza chemie MeSH
- virion genetika metabolismus ultrastruktura MeSH
- virové proteiny chemie genetika metabolismus MeSH
- viry klíšťové encefalitidy genetika metabolismus ultrastruktura MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
MS2 phage-like particles (MS2 PLP) are artificially constructed pseudo-viral particles derived from bacteriophage MS2. They are able to carry a specific single stranded RNA (ssRNA) sequence of choice inside their capsid, thus protecting it against the effects of ubiquitous nucleases. Such particles are able to mimic ssRNA viruses and, thus, may serve as the process control for molecular detection and quantification of such agents in several kinds of matrices, vaccines and vaccine candidates, drug delivery systems, and systems for the display of immunologically active peptides or nanomachines. Currently, there are several different in vivo plasmid-driven packaging systems for production of MS2 PLP. In order to combine all the advantages of the available systems and to upgrade and simplify the production and purification of MS2 PLP, a one-plasmid double-expression His-tag system was designed. The described system utilizes a unique fusion insertional mutation enabling purification of particles using His-tag affinity. Using this new production system, highly pure MS2 PLP can be quickly produced and purified by a fast performance liquid chromatography (FPLC) approach. The system can be easily adapted to produce other MS2 PLP with different properties.
- MeSH
- Levivirus * chemie genetika metabolismus MeSH
- plazmidy * genetika metabolismus MeSH
- rekombinantní fúzní proteiny * biosyntéza chemie genetika izolace a purifikace MeSH
- virion * chemie genetika izolace a purifikace metabolismus MeSH
- virové plášťové proteiny * biosyntéza chemie genetika izolace a purifikace MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
