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Prosper P, Rodríguez Puertas R, Guérin DMA, Branda MM. Computational method for designing vaccines applied to virus-like particles (VLPs) as epitope carriers. Vaccine 2024; 42:3916-3929. [PMID: 38782665 DOI: 10.1016/j.vaccine.2024.05.025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 04/06/2024] [Accepted: 05/04/2024] [Indexed: 05/25/2024]
Abstract
Nonenveloped virus-like particles (VLPs) are self-assembled oligomeric structures composed of one or more proteins that originate from diverse viruses. Because these VLPs have similar antigenicity to the parental virus, they are successfully used as vaccines against cognate virus infection. Furthermore, after foreign antigenic sequences are inserted in their protein components (chimVLPs), some VLPs are also amenable to producing vaccines against pathogens other than the virus it originates from (these VLPs are named platform or epitope carrier). Designing chimVLP vaccines is challenging because the immunogenic response must be oriented against a given antigen without altering stimulant properties inherent to the VLP. An important step in this process is choosing the location of the sequence modifications because this must be performed without compromising the assembly and stability of the original VLP. Currently, many immunogenic data and computational tools can help guide the design of chimVLPs, thus reducing experimental costs and work. In this study, we analyze the structure of a novel VLP that originate from an insect virus and describe the putative regions of its three structural proteins amenable to insertion. For this purpose, we employed molecular dynamics (MD) simulations to assess chimVLP stability by comparing mutated and wild-type (WT) VLP protein trajectories. We applied this procedure to design a chimVLP that can serve as a prophylactic vaccine against the SARS-CoV-2 virus. The methodology described in this work is generally applicable for VLP-based vaccine development.
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Affiliation(s)
- Pascalita Prosper
- Instituto de Física Aplicada - INFAP, Universidad Nacional de San Luis/CONICET, Argentina, Av. Ejército de los Andes 950, 5700 San Luis, San Luis, Argentina
| | - Rafael Rodríguez Puertas
- Universidad del País Vasco (UPV/EHU), Dept. Farmacología, Facultad de Medicina, B° Sarriena S/N, 48940 Leioa, Vizcaya, Spain; Neurodegenerative Diseases, BioCruces Bizkaia Health Research Institute, Barakaldo, Spain
| | - Diego M A Guérin
- Universidad del País Vasco (UPV/EHU) and Instituto Biofisika (CSIC, UPV/EHU), B° Sarriena S/N, 48940 Leioa, Vizcaya, Spain
| | - María Marta Branda
- Instituto de Física Aplicada - INFAP, Universidad Nacional de San Luis/CONICET, Argentina, Av. Ejército de los Andes 950, 5700 San Luis, San Luis, Argentina.
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Cao X, Wang Z, Pang J, Sun L, Kondo H, Andika IB. Identification of a novel dicistro-like virus associated with the roots of tomato plants. Arch Virol 2023; 168:214. [PMID: 37523067 DOI: 10.1007/s00705-023-05843-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2023] [Accepted: 06/26/2023] [Indexed: 08/01/2023]
Abstract
Viruses belonging to the family Dicistroviridae have a monopartite positive-sense single-stranded RNA genome and infect a variety of arthropods. Using high-throughput sequencing, we detected a novel dicistro-like virus, tentatively named "tomato root-associated dicistro-like virus" (TRaDLV), in the roots of tomato plants showing yellow mosaic symptoms on the leaves. The diseased tomato plants were coinfected with multiple plant viruses, and TRaDLV was present in the roots but not in the leaves. The genome of TRaDLV is 8726 nucleotides in length, excluding the poly(A) tail, and contains two open reading frames (ORFs) separated by an intergenic region (IGR). The TRaDLV genome showed characteristics similar to those of dicistroviruses, including the presence of a 3C-like protease domain, repeated amino acid sequences representing multiple copies of viral genome-linked protein (VPg)-like sequences in the ORF1 polyprotein, and a series of stem-loop structures resembling an internal ribosome entry site in the IGR. Phylogenetic analysis revealed that TRaDLV clustered with unclassified dicistro-like viruses from invertebrates or identified in samples of plant-derived material. These findings indicate the existence of a novel dicistro-like virus that may associate with plant roots or a root-inhabiting organism.
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Affiliation(s)
- Xinran Cao
- College of Plant Health and Medicine, Qingdao Agricultural University, 266109, Qingdao, China
- Shandong Agricultural University, 271018, Tai'an, China
- Shouguang International vegetable Sci-tech Fair Management Service Center, 262700, Shouguang, China
| | - Ziqi Wang
- College of Plant Health and Medicine, Qingdao Agricultural University, 266109, Qingdao, China
| | - Jianguo Pang
- University Library, Northwest A&F University, 712100, Xianyang, China
| | - Liying Sun
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, 712100, Xianyang, China
| | - Hideki Kondo
- Institute of Plant Science and Resources, Okayama University, 710-0046, Kurashiki, Japan
| | - Ida Bagus Andika
- College of Plant Health and Medicine, Qingdao Agricultural University, 266109, Qingdao, China.
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Valles SM, Zhao C, Rivers AR, Iwata RL, Oi DH, Cha DH, Collignon RM, Cox NA, Morton GJ, Calcaterra LA. RNA virus discoveries in the electric ant, Wasmannia auropunctata. Virus Genes 2023; 59:276-289. [PMID: 36729322 PMCID: PMC10025213 DOI: 10.1007/s11262-023-01969-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Accepted: 01/13/2023] [Indexed: 02/03/2023]
Abstract
Despite being one of the most destructive invasive species of ants, only two natural enemies are known currently for Wasmannia auropunctata, commonly known as the electric ant or little fire ant. Because viruses can be effective biological control agents against many insect pests, including ants, a metagenomics/next-generation sequencing approach was used to facilitate discovery of virus sequences from the transcriptomes of W. auropunctata. Five new and complete positive sense, single-stranded RNA virus genomes, and one new negative sense, single-stranded RNA virus genome were identified, sequenced, and characterized from W. auropunctata collected in Argentina by this approach, including a dicistrovirus (Electric ant dicistrovirus), two polycipiviruses (Electric ant polycipivirus 1; Electric ant polycipivirus 2), a solinvivirus (Electric ant solinvivirus), a divergent genome with similarity to an unclassified group in the Picornavirales (Electric ant virus 1), and a rhabdovirus (Electric ant rhabdovirus). An additional virus genome was detected that is likely Solenopsis invicta virus 10 (MH727527). The virus genome sequences were absent from the transcriptomes of W. auropunctata collected in the USA (Hawaii and Florida). Additional limited field surveys corroborated the absence of these viruses in regions where the electric ant is invasive (the USA and Australia). The replicative genome strand of four of the viruses (Electric ant polycipivirus 2, Electric ant solinvivirus, Electric ant virus 1, and Solenopsis invicta virus 10 (in the electric ant) was detected in Argentinean-collected W. auropunctata indicating that the ant is a host for these viruses. These are the first virus discoveries to be made from W. auropunctata.
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Affiliation(s)
- Steven M Valles
- Center for Medical, Agricultural and Veterinary Entomology, USDA-ARS, 1600 SW 23rd Drive, Gainesville, FL, USA.
| | - Chaoyang Zhao
- Center for Medical, Agricultural and Veterinary Entomology, USDA-ARS, 1600 SW 23rd Drive, Gainesville, FL, USA
| | - Adam R Rivers
- Genomics and Bioinformatics Research Unit, USDA-ARS, 1600 SW 23rd Drive, Gainesville, FL, USA
| | - Ryo L Iwata
- Genomics and Bioinformatics Research Unit, USDA-ARS, 1600 SW 23rd Drive, Gainesville, FL, USA
| | - David H Oi
- Center for Medical, Agricultural and Veterinary Entomology, USDA-ARS, 1600 SW 23rd Drive, Gainesville, FL, USA
| | - Dong H Cha
- Daniel K. Inouye U.S. Pacific Basin Agricultural Research Center, USDA-ARS, 64 Nowelo St, Hilo, HI, USA
| | - R Max Collignon
- Daniel K. Inouye U.S. Pacific Basin Agricultural Research Center, USDA-ARS, 64 Nowelo St, Hilo, HI, USA
| | - Nastassja A Cox
- National Electric Ant Eradication Program, Department of Agriculture and Fisheries, Biosecurity Queensland, 21-23 Redden Street, Cairns, QLD, 4870, Australia
| | - Gary J Morton
- National Electric Ant Eradication Program, Department of Agriculture and Fisheries, Biosecurity Queensland, 21-23 Redden Street, Cairns, QLD, 4870, Australia
| | - Luis A Calcaterra
- Fundación para el Estudio de Especies Invasivas, Bolívar 1559, B1686EFA, Hurlingham, Buenos Aires, Argentina
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Penrice-Randal R, Hartley C, Beliavskaia A, Dong X, Brandner-Garrod L, Whitten M, Bell-Sakyi L. New Cell Lines Derived from Laboratory Colony Triatoma infestans and Rhodnius prolixus, Vectors of Trypanosoma cruzi, Do Not Harbour Triatoma Virus. INSECTS 2022; 13:906. [PMID: 36292854 PMCID: PMC9603895 DOI: 10.3390/insects13100906] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Revised: 09/27/2022] [Accepted: 10/03/2022] [Indexed: 06/16/2023]
Abstract
Triatomine bugs of the genera Triatoma and Rhodnius are vectors of Chagas disease, a neglected tropical disease of humans in South America caused by Trypanosoma cruzi. Triatoma virus (TrV), a natural pathogen of Triatoma infestans, has been proposed as a possible tool for the bio-control of triatomine bugs, but research into this virus has been hampered by a lack of suitable host cells for in vitro propagation. Here we report establishment and partial characterisation of continuous cell lines from embryos of T. infestans (TIE/LULS54) and Rhodnius prolixus (RPE/LULS53 and RPE/LULS57). RNAseq screening by a sequence-independent, single primer amplification approach confirmed the absence of TrV and other RNA viruses known to infect R. prolixus, indicating that these new cell lines could be used for propagation of TrV.
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Affiliation(s)
- Rebekah Penrice-Randal
- Department of Infection Biology and Microbiomes, Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, 146 Brownlow Hill, Liverpool L3 5RF, UK
| | - Catherine Hartley
- Department of Infection Biology and Microbiomes, Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, 146 Brownlow Hill, Liverpool L3 5RF, UK
| | - Alexandra Beliavskaia
- Department of Infection Biology and Microbiomes, Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, 146 Brownlow Hill, Liverpool L3 5RF, UK
| | - Xiaofeng Dong
- Department of Infection Biology and Microbiomes, Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, 146 Brownlow Hill, Liverpool L3 5RF, UK
| | - Luke Brandner-Garrod
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK
| | - Miranda Whitten
- Swansea University Institute of Life Science, College of Medicine, Swansea University, Singleton Park, Swansea SA2 8PP, UK
| | - Lesley Bell-Sakyi
- Department of Infection Biology and Microbiomes, Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, 146 Brownlow Hill, Liverpool L3 5RF, UK
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Moradi Z. Meta-transcriptomic analysis reveals an isolate of aphid lethal paralysis virus from Wisteria sinensis in Iran. Virus Res 2022; 315:198770. [DOI: 10.1016/j.virusres.2022.198770] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 02/28/2022] [Accepted: 04/08/2022] [Indexed: 12/21/2022]
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Cardoso MA, Brito TFD, Brito IADA, Berni MA, Coelho VL, Pane A. The Neglected Virome of Triatomine Insects. FRONTIERS IN TROPICAL DISEASES 2022. [DOI: 10.3389/fitd.2022.828712] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The Triatominae subfamily (Reduviidae) harbors some hematophagous insect species that have been firmly connected to the transmission of Trypanosoma cruzi, the causative agent of Chagas disease. Triatomines not only host and transmit trypanosomatids, but also coexist with a variety of symbiotic microorganisms that generally reside in the insect’s intestinal flora. The microbiome has profound effects on the physiology, immunity, fitness and survival of animals and plants. The interaction between triatomines and bacteria has been investigated to some extent and has revealed important bacteria symbionts. In contrast, the range of viral species that can infect triatomine insects is almost completely unknown. In some cases, genomic and metatranscriptomic approaches have uncovered sequences related to possible viral genomes, but, to date, only eight positive single-strand RNA viruses, namely Triatoma virus and Rhodnius prolixus viruses 1 - 7 have been investigated in more detail. Here, we review the literature available on triatomine viruses and the viruses-insect host relationship. The lack of broader metagenomic and metatranscriptomic studies in these medically relevant insects underscores the importance of expanding our knowledge of the triatomine virome both for surveillance purposes as well as to possibly harness their potential for insect vector population control strategies.
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7
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de Brito TF, Coelho VL, Cardoso MA, Brito IADA, Berni MA, Zenk FL, Iovino N, Pane A. Transovarial transmission of a core virome in the Chagas disease vector Rhodnius prolixus. PLoS Pathog 2021; 17:e1009780. [PMID: 34407148 PMCID: PMC8372912 DOI: 10.1371/journal.ppat.1009780] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2020] [Accepted: 07/02/2021] [Indexed: 01/09/2023] Open
Abstract
Triatomine assassin bugs comprise hematophagous insect vectors of Trypanosoma cruzi, the causative agent of Chagas disease. Although the microbiome of these species has been investigated to some extent, only one virus infecting Triatoma infestans has been identified to date. Here, we describe for the first time seven (+) single-strand RNA viruses (RpV1-7) infecting Rhodnius prolixus, a primary vector of Chagas disease in Central and South America. We show that the RpVs belong to the Iflaviridae, Permutotetraviridae and Solemoviridae and are vertically transmitted from the mothers to the progeny via transovarial transmission. Consistent with this, all the RpVs, except RpV2 that is related to the entomopathogenic Slow bee paralysis virus, established persistent infections in our R. prolixus colony. Furthermore, we show that R. prolixus ovaries express 22-nucleotide viral siRNAs (vsiRNAs), but not viral piRNAs, that originate from the processing of dsRNA intermediates during viral replication of the RpVs. Interestingly, the permutotetraviruses and sobemoviruses display shared pools of vsiRNAs that might provide the basis for a cross-immunity system. The vsiRNAs are maternally deposited in the eggs, where they likely contribute to reduce the viral load and protect the developing embryos. Our results unveil for the first time a complex core virome in R. prolixus and begin to shed light on the RNAi-based antiviral defenses in triatomines.
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Affiliation(s)
| | - Vitor Lima Coelho
- Institute of Biomedical Sciences, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Maira Arruda Cardoso
- Institute of Biomedical Sciences, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | | | - Mateus Antonio Berni
- Institute of Biomedical Sciences, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Fides Lea Zenk
- Department of Chromatin Regulation, Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany
| | - Nicola Iovino
- Department of Chromatin Regulation, Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany
| | - Attilio Pane
- Institute of Biomedical Sciences, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
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8
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Tetter S, Terasaka N, Steinauer A, Bingham RJ, Clark S, Scott AJP, Patel N, Leibundgut M, Wroblewski E, Ban N, Stockley PG, Twarock R, Hilvert D. Evolution of a virus-like architecture and packaging mechanism in a repurposed bacterial protein. Science 2021; 372:1220-1224. [PMID: 34112695 DOI: 10.1126/science.abg2822] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Accepted: 04/29/2021] [Indexed: 12/14/2022]
Abstract
Viruses are ubiquitous pathogens of global impact. Prompted by the hypothesis that their earliest progenitors recruited host proteins for virion formation, we have used stringent laboratory evolution to convert a bacterial enzyme that lacks affinity for nucleic acids into an artificial nucleocapsid that efficiently packages and protects multiple copies of its own encoding messenger RNA. Revealing remarkable convergence on the molecular hallmarks of natural viruses, the accompanying changes reorganized the protein building blocks into an interlaced 240-subunit icosahedral capsid that is impermeable to nucleases, and emergence of a robust RNA stem-loop packaging cassette ensured high encapsidation yields and specificity. In addition to evincing a plausible evolutionary pathway for primordial viruses, these findings highlight practical strategies for developing nonviral carriers for diverse vaccine and delivery applications.
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Affiliation(s)
- Stephan Tetter
- Laboratory of Organic Chemistry, ETH Zurich, 8093 Zurich, Switzerland
| | - Naohiro Terasaka
- Laboratory of Organic Chemistry, ETH Zurich, 8093 Zurich, Switzerland
| | - Angela Steinauer
- Laboratory of Organic Chemistry, ETH Zurich, 8093 Zurich, Switzerland
| | - Richard J Bingham
- Departments of Mathematics and Biology, University of York, York YO10 5DD, UK
| | - Sam Clark
- Departments of Mathematics and Biology, University of York, York YO10 5DD, UK
| | - Andrew J P Scott
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK
| | - Nikesh Patel
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK
| | - Marc Leibundgut
- Institute of Molecular Biology and Biophysics, ETH Zurich, 8093 Zurich, Switzerland
| | - Emma Wroblewski
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK
| | - Nenad Ban
- Institute of Molecular Biology and Biophysics, ETH Zurich, 8093 Zurich, Switzerland
| | - Peter G Stockley
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK
| | - Reidun Twarock
- Departments of Mathematics and Biology, University of York, York YO10 5DD, UK
| | - Donald Hilvert
- Laboratory of Organic Chemistry, ETH Zurich, 8093 Zurich, Switzerland.
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Virion structure and in vitro genome release mechanism of dicistrovirus Kashmir bee virus. J Virol 2021; 95:JVI.01950-20. [PMID: 33658338 PMCID: PMC8139710 DOI: 10.1128/jvi.01950-20] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Infections of Kashmir bee virus (KBV) are lethal for honeybees and have been associated with colony collapse disorder. KBV and closely related viruses contribute to the ongoing decline in the number of honeybee colonies in North America, Europe, Australia, and other parts of the world. Despite the economic and ecological impact of KBV, its structure and infection process remain unknown. Here we present the structure of the virion of KBV determined to a resolution of 2.8 Å. We show that the exposure of KBV to acidic pH induces a reduction in inter-pentamer contacts within capsids and the reorganization of its RNA genome from a uniform distribution to regions of high and low density. Capsids of KBV crack into pieces at acidic pH, resulting in the formation of open particles lacking pentamers of capsid proteins. The large openings of capsids enable the rapid release of genomes and thus limit the probability of their degradation by RNases. The opening of capsids may be a shared mechanism for the genome release of viruses from the family Dicistroviridae ImportanceThe western honeybee (Apis mellifera) is indispensable for maintaining agricultural productivity as well as the abundance and diversity of wild flowering plants. However, bees suffer from environmental pollution, parasites, and pathogens, including viruses. Outbreaks of virus infections cause the deaths of individual honeybees as well as collapses of whole colonies. Kashmir bee virus has been associated with colony collapse disorder in the US, and no cure of the disease is currently available. Here we report the structure of an infectious particle of Kashmir bee virus and show how its protein capsid opens to release the genome. Our structural characterization of the infection process determined that therapeutic compounds stabilizing contacts between pentamers of capsid proteins could prevent the genome release of the virus.
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Naitow H, Hamaguchi T, Maki-Yonekura S, Isogai M, Yoshikawa N, Yonekura K. Apple latent spherical virus structure with stable capsid frame supports quasi-stable protrusions expediting genome release. Commun Biol 2020; 3:488. [PMID: 32887929 PMCID: PMC7474077 DOI: 10.1038/s42003-020-01217-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2020] [Accepted: 08/11/2020] [Indexed: 01/30/2023] Open
Abstract
Picorna-like plant viruses are non-enveloped RNA spherical viruses of ~30 nm. Part of the survival of these viruses depends on their capsid being stable enough to harbour the viral genome and yet malleable enough to allow its release. However, molecular mechanisms remain obscure. Here, we report a structure of a picorna-like plant virus, apple latent spherical virus, at 2.87 Å resolution by single-particle cryo-electron microscopy (cryo-EM) with a cold-field emission beam. The cryo-EM map reveals a unique structure composed of three capsid proteins Vp25, Vp20, and Vp24. Strikingly Vp25 has a long N-terminal extension, which substantially stabilises the capsid frame of Vp25 and Vp20 subunits. Cryo-EM images also resolve RNA genome leaking from a pentameric protrusion of Vp24 subunits. The structures and observations suggest that genome release occurs through occasional opening of the Vp24 subunits, possibly suppressed to a low frequency by the rigid frame of the other subunits.
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Affiliation(s)
- Hisashi Naitow
- Biostructural Mechanism Laboratory, RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo, Hyogo, 679-5148, Japan
| | - Tasuku Hamaguchi
- Biostructural Mechanism Laboratory, RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo, Hyogo, 679-5148, Japan
| | - Saori Maki-Yonekura
- Biostructural Mechanism Laboratory, RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo, Hyogo, 679-5148, Japan
| | - Masamichi Isogai
- Plant Pathology Laboratory, Faculty of Agriculture, Iwate University, Ueda 3-chome 18-8, Morioka, Iwate, 020-8550, Japan
| | - Nobuyuki Yoshikawa
- Agri-Innovation Center, Iwate University, Ueda 3-chome 18-8, Morioka, Iwate, 020-8550, Japan
| | - Koji Yonekura
- Biostructural Mechanism Laboratory, RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo, Hyogo, 679-5148, Japan. .,Advanced Electron Microscope Development Unit, RIKEN-JEOL Collaboration Center, RIKEN Baton Zone Program, 1-1-1 Kouto, Sayo, Hyogo, 679-5148, Japan.
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11
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Virion structures and genome delivery of honeybee viruses. Curr Opin Virol 2020; 45:17-24. [PMID: 32679289 DOI: 10.1016/j.coviro.2020.06.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 06/10/2020] [Accepted: 06/18/2020] [Indexed: 10/23/2022]
Abstract
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.
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12
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Capsid Structure of a Marine Algal Virus of the Order Picornavirales. J Virol 2020; 94:JVI.01855-19. [PMID: 32024776 DOI: 10.1128/jvi.01855-19] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Accepted: 01/29/2020] [Indexed: 12/17/2022] Open
Abstract
The order Picornavirales includes viruses that infect different kinds of eukaryotes and that share similar properties. The capsid proteins (CPs) of viruses in the order that infect unicellular organisms, such as algae, presumably possess certain characteristics that have changed little over the course of evolution, and thus these viruses may resemble the Picornavirales ancestor in some respects. Herein, we present the capsid structure of Chaetoceros tenuissimus RNA virus type II (CtenRNAV-II) determined using cryo-electron microscopy at a resolution of 3.1 Å, the first alga virus belonging to the family Marnaviridae of the order Picornavirales A structural comparison to related invertebrate and vertebrate viruses revealed a unique surface loop of the major CP VP1 that had not been observed previously, and further, revealed that another VP1 loop obscures the so-called canyon, which is a host-receptor binding site for many of the mammalian Picornavirales viruses. VP2 has an N-terminal tail, which has previously been reported as a primordial feature of Picornavirales viruses. The above-mentioned and other critical structural features provide new insights on three long-standing theories about Picornavirales: (i) the canyon hypothesis, (ii) the primordial VP2 domain swap, and (iii) the hypothesis that alga Picornavirales viruses could share characteristics with the Picornavirales ancestor.IMPORTANCE Identifying the acquired structural traits in virus capsids is important for elucidating what functions are essential among viruses that infect different hosts. The Picornavirales viruses infect a broad spectrum of hosts, ranging from unicellular algae to insects and mammals and include many human pathogens. Those viruses that infect unicellular protists, such as algae, are likely to have undergone fewer structural changes during the course of evolution compared to those viruses that infect multicellular eukaryotes and thus still share some characteristics with the Picornavirales ancestor. This article describes the first atomic capsid structure of an alga Marnavirus, CtenRNAV-II. A comparison to capsid structures of the related invertebrate and vertebrate viruses identified a number of structural traits that have been functionally acquired or lost during the course of evolution. These observations provide new insights on past theories on the viability and evolution of Picornavirales viruses.
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Stuart DI, Ren J, Wang X, Rao Z, Fry EE. Hepatitis A Virus Capsid Structure. Cold Spring Harb Perspect Med 2019; 9:cshperspect.a031807. [PMID: 30037986 DOI: 10.1101/cshperspect.a031807] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Hepatitis A virus (HAV) has been enigmatic, evading detailed structural analysis for many years. Its recently determined high-resolution structure revealed an angular surface without the indentations often characteristic of receptor-binding sites. The viral protein 1 (VP1) β-barrel shows no sign of a pocket factor and the amino terminus of VP2 displays a "domain swap" across the pentamer interface, as in a subset of mammalian picornaviruses and insect picorna-like viruses. Structure-based phylogeny confirms this placement. These differences suggest an uncoating mechanism distinct from that of enteroviruses. An empty capsid structure reveals internal differences in VP0 and the VP1 amino terminus connected with particle maturation. An HAV/Fab complex structure, in which the antigen-binding fragment (Fab) appears to act as a receptor-mimic, clarifies some historical epitope mapping data, but some remain difficult to reconcile. We still have little idea of the structural features of enveloped HAV particles.
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Affiliation(s)
- David I Stuart
- Division of Structural Biology, The Henry Wellcome Building for Genomic Medicine, The Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK.,Diamond Light Source Ltd, Diamond House, Harwell Science and Innovation Campus, Didcot OX11 0DE, UK
| | - Jingshan Ren
- Division of Structural Biology, The Henry Wellcome Building for Genomic Medicine, The Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Xiangxi Wang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Science, Beijing 100101, China
| | - Zihe Rao
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Science, Beijing 100101, China.,Laboratory of Structural Biology, School of Medicine, Tsinghua University, Beijing 100084, China
| | - Elizabeth E Fry
- Division of Structural Biology, The Henry Wellcome Building for Genomic Medicine, The Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
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Cryo-electron Microscopy Structures of Novel Viruses from Mud Crab Scylla paramamosain with Multiple Infections. J Virol 2019; 93:JVI.02255-18. [PMID: 30651355 DOI: 10.1128/jvi.02255-18] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Accepted: 12/19/2018] [Indexed: 12/18/2022] Open
Abstract
Viruses associated with sleeping disease (SD) in crabs cause great economic losses to aquaculture, and no effective measures are available for their prevention. In this study, to help develop novel antiviral strategies, single-particle cryo-electron microscopy was applied to investigate viruses associated with SD. The results not only revealed the structure of mud crab dicistrovirus (MCDV) but also identified a novel mud crab tombus-like virus (MCTV) not previously detected using molecular biology methods. The structure of MCDV at a 3.5-Å resolution reveals three major capsid proteins (VP1 to VP3) organized into a pseudo-T=3 icosahedral capsid, and affirms the existence of VP4. Unusually, MCDV VP3 contains a long C-terminal region and forms a novel protrusion that has not been observed in other dicistrovirus. Our results also reveal that MCDV can release its genome via conformation changes of the protrusions when viral mixtures are heated. The structure of MCTV at a 3.3-Å resolution reveals a T= 3 icosahedral capsid with common features of both tombusviruses and nodaviruses. Furthermore, MCTV has a novel hydrophobic tunnel beneath the 5-fold vertex and 30 dimeric protrusions composed of the P-domains of the capsid protein at the 2-fold axes that are exposed on the virion surface. The structural features of MCTV are consistent with a novel type of virus.IMPORTANCE Pathogen identification is vital for unknown infectious outbreaks, especially for dual or multiple infections. Sleeping disease (SD) in crabs causes great economic losses to aquaculture worldwide. Here we report the discovery and identification of a novel virus in mud crabs with multiple infections that was not previously detected by molecular, immune, or traditional electron microscopy (EM) methods. High-resolution structures of pathogenic viruses are essential for a molecular understanding and developing new disease prevention methods. The three-dimensional (3D) structure of the mud crab tombus-like virus (MCTV) and mud crab dicistrovirus (MCDV) determined in this study could assist the development of antiviral inhibitors. The identification of a novel virus in multiple infections previously missed using other methods demonstrates the usefulness of this strategy for investigating multiple infectious outbreaks, even in humans and other animals.
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Branda MM, Guérin DMA. Alkalinization of Icosahedral Non-enveloped Viral Capsid Interior Through Proton Channeling. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1215:181-199. [DOI: 10.1007/978-3-030-14741-9_9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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16
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Abstract
Honey bee pollination is required to sustain the biodiversity of wild flora and for agricultural production; however, honey bee populations in Europe and North America are declining due to virus infections. Sacbrood virus (SBV) infection is lethal to honey bee larvae and decreases the fitness of honey bee colonies. Here we present the structure of the SBV particle and show that it contains 60 copies of a minor capsid protein attached to its surface. No similar minor capsid proteins have been previously observed in any of the related viruses. We also present a structural analysis of the genome release of SBV. The possibility of blocking virus genome delivery may provide a tool to prevent the spread of this honey bee pathogen. Infection by sacbrood virus (SBV) from the family Iflaviridae is lethal to honey bee larvae but only rarely causes the collapse of honey bee colonies. Despite the negative effect of SBV on honey bees, the structure of its particles and mechanism of its genome delivery are unknown. Here we present the crystal structure of SBV virion and show that it contains 60 copies of a minor capsid protein (MiCP) attached to the virion surface. No similar MiCPs have been previously reported in any of the related viruses from the order Picornavirales. The location of the MiCP coding sequence within the SBV genome indicates that the MiCP evolved from a C-terminal extension of a major capsid protein by the introduction of a cleavage site for a virus protease. The exposure of SBV to acidic pH, which the virus likely encounters during cell entry, induces the formation of pores at threefold and fivefold axes of the capsid that are 7 Å and 12 Å in diameter, respectively. This is in contrast to vertebrate picornaviruses, in which the pores along twofold icosahedral symmetry axes are currently considered the most likely sites for genome release. SBV virions lack VP4 subunits that facilitate the genome delivery of many related dicistroviruses and picornaviruses. MiCP subunits induce liposome disruption in vitro, indicating that they are functional analogs of VP4 subunits and enable the virus genome to escape across the endosome membrane into the cell cytoplasm.
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Viso JF, Belelli P, Machado M, González H, Pantano S, Amundarain MJ, Zamarreño F, Branda MM, Guérin DMA, Costabel MD. Multiscale modelization in a small virus: Mechanism of proton channeling and its role in triggering capsid disassembly. PLoS Comput Biol 2018; 14:e1006082. [PMID: 29659564 PMCID: PMC5919690 DOI: 10.1371/journal.pcbi.1006082] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 04/26/2018] [Accepted: 03/09/2018] [Indexed: 12/04/2022] Open
Abstract
In this work, we assess a previously advanced hypothesis that predicts the existence of ion channels in the capsid of small and non-enveloped icosahedral viruses. With this purpose we examine Triatoma Virus (TrV) as a case study. This virus has a stable capsid under highly acidic conditions but disassembles and releases the genome in alkaline environments. Our calculations range from a subtle sub-atomic proton interchange to the dismantling of a large-scale system representing several million of atoms. Our results provide structure-based explanations for the three roles played by the capsid to enable genome release. First, we observe, for the first time, the formation of a hydrophobic gate in the cavity along the five-fold axis of the wild-type virus capsid, which can be disrupted by an ion located in the pore. Second, the channel enables protons to permeate the capsid through a unidirectional Grotthuss-like mechanism, which is the most likely process through which the capsid senses pH. Finally, assuming that the proton leak promotes a charge imbalance in the interior of the capsid, we model an internal pressure that forces shell cracking using coarse-grained simulations. Although qualitatively, this last step could represent the mechanism of capsid opening that allows RNA release. All of our calculations are in agreement with current experimental data obtained using TrV and describe a cascade of events that could explain the destabilization and disassembly of similar icosahedral viruses. Plant and animal small non-enveloped viruses are composed of a capsid shell that encloses the genome. One of the multiple functions played by the capsid is to protect the genome against host defenses and to withstand environmental aggressions, such as dehydration. This highly specialized capsule selectively recognizes and binds to the target tissue infected by the virus. In the viral cycle, the ultimate function of the capsid is to release the genome. Observations of many viruses demonstrate that the pH of the medium can trigger genome release. Nevertheless, the mechanism underlying this process at the atomic level is poorly understood. In this work, we computationally modeled the mechanism by which the capsid senses environmental pH and the destabilization process that permits genome release. Our calculations predict that a cavity that traverses the capsid functions as a hydrophobic gate, a feature already observed in membrane ion channels. Moreover, our results predict that this cavity behaves as a proton diode because the proton transit can only occur from the capsid interior to the exterior. In turn, our calculations describe a cascade of events that could explain the destabilization and dismantling of an insect virus, but this description could also apply to many vertebrate viruses.
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Affiliation(s)
- Juan Francisco Viso
- Departamento de Física (DF), Universidad Nacional del Sur (UNS), Bahía Blanca, Argentina
- DF-UNS, Grupo de Biofísica, Instituto de Física del Sur (IFISUR, UNS/CONICET), Bahía Blanca, Argentina
| | - Patricia Belelli
- DF-UNS, Grupo de Materiales y Sistemas Catalíticos (GRUMASICA), IFISUR, Bahía Blanca, Argentina
| | - Matías Machado
- Grupo de Simulaciones Biomoleculares, Institut Pasteur de Montevideo, Montevideo, Uruguay
| | - Humberto González
- Grupo de Simulaciones Biomoleculares, Institut Pasteur de Montevideo, Montevideo, Uruguay
| | - Sergio Pantano
- Grupo de Simulaciones Biomoleculares, Institut Pasteur de Montevideo, Montevideo, Uruguay
| | - María Julia Amundarain
- Departamento de Física (DF), Universidad Nacional del Sur (UNS), Bahía Blanca, Argentina
- DF-UNS, Grupo de Biofísica, Instituto de Física del Sur (IFISUR, UNS/CONICET), Bahía Blanca, Argentina
| | - Fernando Zamarreño
- Departamento de Física (DF), Universidad Nacional del Sur (UNS), Bahía Blanca, Argentina
- DF-UNS, Grupo de Biofísica, Instituto de Física del Sur (IFISUR, UNS/CONICET), Bahía Blanca, Argentina
| | - Maria Marta Branda
- Departamento de Física (DF), Universidad Nacional del Sur (UNS), Bahía Blanca, Argentina
- DF-UNS, Grupo de Materiales y Sistemas Catalíticos (GRUMASICA), IFISUR, Bahía Blanca, Argentina
| | - Diego M. A. Guérin
- Instituto Biofisika (UPV/EHU, CSIC), Department of Biochemistry and Molecular Biology, University of the Basque Country (EHU), Barrio Sarriena S/N, Leioa, Vizcaya, Spain
- * E-mail: (MDC); (DMAG)
| | - Marcelo D. Costabel
- Departamento de Física (DF), Universidad Nacional del Sur (UNS), Bahía Blanca, Argentina
- DF-UNS, Grupo de Biofísica, Instituto de Física del Sur (IFISUR, UNS/CONICET), Bahía Blanca, Argentina
- * E-mail: (MDC); (DMAG)
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Martín-González N, Guérin Darvas SM, Durana A, Marti GA, Guérin DMA, de Pablo PJ. Exploring the role of genome and structural ions in preventing viral capsid collapse during dehydration. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:104001. [PMID: 29350623 PMCID: PMC7104708 DOI: 10.1088/1361-648x/aaa944] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Revised: 01/12/2018] [Accepted: 01/19/2018] [Indexed: 06/07/2023]
Abstract
Even though viruses evolve mainly in liquid milieu, their horizontal transmission routes often include episodes of dry environment. Along their life cycle, some insect viruses, such as viruses from the Dicistroviridae family, withstand dehydrated conditions with presently unknown consequences to their structural stability. Here, we use atomic force microscopy to monitor the structural changes of viral particles of Triatoma virus (TrV) after desiccation. Our results demonstrate that TrV capsids preserve their genome inside, conserving their height after exposure to dehydrating conditions, which is in stark contrast with other viruses that expel their genome when desiccated. Moreover, empty capsids (without genome) resulted in collapsed particles after desiccation. We also explored the role of structural ions in the dehydration process of the virions (capsid containing genome) by chelating the accessible cations from the external solvent milieu. We observed that ion suppression helps to keep the virus height upon desiccation. Our results show that under drying conditions, the genome of TrV prevents the capsid from collapsing during dehydration, while the structural ions are responsible for promoting solvent exchange through the virion wall.
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Affiliation(s)
- Natalia Martín-González
- Departamento de Física de la Materia Condensada C-III and Instituto de Física de la Materia Condensada (IFIMAC), Universidad Autónoma de Madrid, Cantoblanco 28049 Madrid, Spain
| | - Sofía M Guérin Darvas
- Department of Biochemistry and Molecular Biology, University of the Basque Country (UPV/EHU), Barrio Sarriena S/N, 48940, Leioa, Vizcaya, Spain
| | - Aritz Durana
- Instituto Biofisika (IBF, UPV/EHU, CSIC), Parque Científico de la UPV/EHU, Barrio Sarriena S/N, 48940, Leioa, Vizcaya, Spain
- Fundación Biofísica Bizkaia, Edificio Biblioteca Central UPV/EHU, Bº Sarriena S/N, 48940, Leioa, Vizcaya, Spain
| | - Gerardo A Marti
- Centro de Estudios Parasitológicos y de Vectores (CEPAVE-CCT-La Plata-CONICET-UNLP), Boulevard 120 e/61 y 62, 1900 La Plata, Argentina
| | - Diego M A Guérin
- Department of Biochemistry and Molecular Biology, University of the Basque Country (UPV/EHU), Barrio Sarriena S/N, 48940, Leioa, Vizcaya, Spain
- Instituto Biofisika (IBF, UPV/EHU, CSIC), Parque Científico de la UPV/EHU, Barrio Sarriena S/N, 48940, Leioa, Vizcaya, Spain
| | - Pedro J de Pablo
- Departamento de Física de la Materia Condensada C-III and Instituto de Física de la Materia Condensada (IFIMAC), Universidad Autónoma de Madrid, Cantoblanco 28049 Madrid, Spain
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19
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Machado MR, González HC, Pantano S. MD Simulations of Viruslike Particles with Supra CG Solvation Affordable to Desktop Computers. J Chem Theory Comput 2017; 13:5106-5116. [DOI: 10.1021/acs.jctc.7b00659] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Matı́as R. Machado
- Biomolecular Simulations
Group, Institut Pasteur de Montevideo, Mataojo 2020, Montevideo CP 11400, Uruguay
| | - Humberto C. González
- Biomolecular Simulations
Group, Institut Pasteur de Montevideo, Mataojo 2020, Montevideo CP 11400, Uruguay
| | - Sergio Pantano
- Biomolecular Simulations
Group, Institut Pasteur de Montevideo, Mataojo 2020, Montevideo CP 11400, Uruguay
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20
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Structure of deformed wing virus, a major honey bee pathogen. Proc Natl Acad Sci U S A 2017; 114:3210-3215. [PMID: 28270616 DOI: 10.1073/pnas.1615695114] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The worldwide population of western honey bees (Apis mellifera) is under pressure from habitat loss, environmental stress, and pathogens, particularly viruses that cause lethal epidemics. Deformed wing virus (DWV) from the family Iflaviridae, together with its vector, the mite Varroa destructor, is likely the major threat to the world's honey bees. However, lack of knowledge of the atomic structures of iflaviruses has hindered the development of effective treatments against them. Here, we present the virion structures of DWV determined to a resolution of 3.1 Å using cryo-electron microscopy and 3.8 Å by X-ray crystallography. The C-terminal extension of capsid protein VP3 folds into a globular protruding (P) domain, exposed on the virion surface. The P domain contains an Asp-His-Ser catalytic triad that is, together with five residues that are spatially close, conserved among iflaviruses. These residues may participate in receptor binding or provide the protease, lipase, or esterase activity required for entry of the virus into a host cell. Furthermore, nucleotides of the DWV RNA genome interact with VP3 subunits. The capsid protein residues involved in the RNA binding are conserved among honey bee iflaviruses, suggesting a putative role of the genome in stabilizing the virion or facilitating capsid assembly. Identifying the RNA-binding and putative catalytic sites within the DWV virion structure enables future analyses of how DWV and other iflaviruses infect insect cells and also opens up possibilities for the development of antiviral treatments.
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21
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Virion Structure of Black Queen Cell Virus, a Common Honeybee Pathogen. J Virol 2017; 91:JVI.02100-16. [PMID: 28077635 PMCID: PMC5331821 DOI: 10.1128/jvi.02100-16] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Accepted: 12/21/2016] [Indexed: 01/06/2023] Open
Abstract
Viral diseases are a major threat to honeybee (Apis mellifera) populations worldwide and therefore an important factor in reliable crop pollination and food security. Black queen cell virus (BQCV) is the etiological agent of a fatal disease of honeybee queen larvae and pupae. The virus belongs to the genus Triatovirus from the family Dicistroviridae, which is part of the order Picornavirales. Here we present a crystal structure of BQCV determined to a resolution of 3.4 Å. The virion is formed by 60 copies of each of the major capsid proteins VP1, VP2, and VP3; however, there is no density corresponding to a 75-residue-long minor capsid protein VP4 encoded by the BQCV genome. We show that the VP4 subunits are present in the crystallized virions that are infectious. This aspect of the BQCV virion is similar to that of the previously characterized triatoma virus and supports the recent establishment of the separate genus Triatovirus within the family Dicistroviridae. The C terminus of VP1 and CD loops of capsid proteins VP1 and VP3 of BQCV form 34-Å-tall finger-like protrusions at the virion surface. The protrusions are larger than those of related dicistroviruses. IMPORTANCE The western honeybee is the most important pollinator of all, and it is required to sustain the agricultural production and biodiversity of wild flowering plants. However, honeybee populations worldwide are suffering from virus infections that cause colony losses. One of the most common, and least known, honeybee pathogens is black queen cell virus (BQCV), which at high titers causes queen larvae and pupae to turn black and die. Here we present the three-dimensional virion structure of BQCV, determined by X-ray crystallography. The structure of BQCV reveals large protrusions on the virion surface. Capsid protein VP1 of BQCV does not contain a hydrophobic pocket. Therefore, the BQCV virion structure provides evidence that capsid-binding antiviral compounds that can prevent the replication of vertebrate picornaviruses may be ineffective against honeybee virus infections.
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Cryo-electron Microscopy Study of the Genome Release of the Dicistrovirus Israeli Acute Bee Paralysis Virus. J Virol 2017; 91:JVI.02060-16. [PMID: 27928006 PMCID: PMC5286892 DOI: 10.1128/jvi.02060-16] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Accepted: 11/21/2016] [Indexed: 01/09/2023] Open
Abstract
Viruses of the family Dicistroviridae can cause substantial economic damage by infecting agriculturally important insects. Israeli acute bee paralysis virus (IAPV) causes honeybee colony collapse disorder in the United States. High-resolution molecular details of the genome delivery mechanism of dicistroviruses are unknown. Here we present a cryo-electron microscopy analysis of IAPV virions induced to release their genomes in vitro. We determined structures of full IAPV virions primed to release their genomes to a resolution of 3.3 Å and of empty capsids to a resolution of 3.9 Å. We show that IAPV does not form expanded A particles before genome release as in the case of related enteroviruses of the family Picornaviridae. The structural changes observed in the empty IAPV particles include detachment of the VP4 minor capsid proteins from the inner face of the capsid and partial loss of the structure of the N-terminal arms of the VP2 capsid proteins. Unlike the case for many picornaviruses, the empty particles of IAPV are not expanded relative to the native virions and do not contain pores in their capsids that might serve as channels for genome release. Therefore, rearrangement of a unique region of the capsid is probably required for IAPV genome release.
IMPORTANCE Honeybee populations in Europe and North America are declining due to pressure from pathogens, including viruses. Israeli acute bee paralysis virus (IAPV), a member of the family Dicistroviridae, causes honeybee colony collapse disorder in the United States. The delivery of virus genomes into host cells is necessary for the initiation of infection. Here we present a structural cryo-electron microscopy analysis of IAPV particles induced to release their genomes. We show that genome release is not preceded by an expansion of IAPV virions as in the case of related picornaviruses that infect vertebrates. Furthermore, minor capsid proteins detach from the capsid upon genome release. The genome leaves behind empty particles that have compact protein shells.
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Cryo-EM study of slow bee paralysis virus at low pH reveals iflavirus genome release mechanism. Proc Natl Acad Sci U S A 2017; 114:598-603. [PMID: 28053231 DOI: 10.1073/pnas.1616562114] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Viruses from the family Iflaviridae are insect pathogens. Many of them, including slow bee paralysis virus (SBPV), cause lethal diseases in honeybees and bumblebees, resulting in agricultural losses. Iflaviruses have nonenveloped icosahedral virions containing single-stranded RNA genomes. However, their genome release mechanism is unknown. Here, we show that low pH promotes SBPV genome release, indicating that the virus may use endosomes to enter host cells. We used cryo-EM to study a heterogeneous population of SBPV virions at pH 5.5. We determined the structures of SBPV particles before and after genome release to resolutions of 3.3 and 3.4 Å, respectively. The capsids of SBPV virions in low pH are not expanded. Thus, SBPV does not appear to form "altered" particles with pores in their capsids before genome release, as is the case in many related picornaviruses. The egress of the genome from SBPV virions is associated with a loss of interpentamer contacts mediated by N-terminal arms of VP2 capsid proteins, which result in the expansion of the capsid. Pores that are 7 Å in diameter form around icosahedral threefold symmetry axes. We speculate that they serve as channels for the genome release. Our findings provide an atomic-level characterization of the genome release mechanism of iflaviruses.
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Sánchez-Eugenia R, Durana A, López-Marijuan I, Marti GA, Guérin DMA. X-ray structure of Triatoma virus empty capsid: insights into the mechanism of uncoating and RNA release in dicistroviruses. J Gen Virol 2016; 97:2769-2779. [DOI: 10.1099/jgv.0.000580] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Rubén Sánchez-Eugenia
- Instituto Biofisika (CSIC, UPV/EHU), Barrio Sarriena S/N, 48940 Leioa, Bizkaia, Spain
| | - Aritz Durana
- Instituto Biofisika (CSIC, UPV/EHU), Barrio Sarriena S/N, 48940 Leioa, Bizkaia, Spain
- Fundación Biofísica Bizkaia, Barrio Sarriena S/N, 48940 Leioa, Bizkaia, Spain
| | - Ibai López-Marijuan
- Instituto Biofisika (CSIC, UPV/EHU), Barrio Sarriena S/N, 48940 Leioa, Bizkaia, Spain
- Fundación Biofísica Bizkaia, Barrio Sarriena S/N, 48940 Leioa, Bizkaia, Spain
| | - Gerardo A. Marti
- Centro de Estudios Parasitológicos y de Vectores (CEPAVE-CCT-La Plata-CONICET-UNLP), Boulevard 120 e/61 y 62, 1900 La Plata, Argentina
| | - Diego M. A. Guérin
- Instituto Biofisika (CSIC, UPV/EHU), Barrio Sarriena S/N, 48940 Leioa, Bizkaia, Spain
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencia y Tecnología, Universidad del País Vasco (UPV/EHU), Barrio Sarriena S/N, 48940 Leioa, Bizkaia, Spain
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Virion Structure of Israeli Acute Bee Paralysis Virus. J Virol 2016; 90:8150-9. [PMID: 27384649 PMCID: PMC5008081 DOI: 10.1128/jvi.00854-16] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Accepted: 06/24/2016] [Indexed: 01/10/2023] Open
Abstract
The pollination services provided by the western honeybee (Apis mellifera) are critical for agricultural production and the diversity of wild flowering plants. However, honeybees suffer from environmental pollution, habitat loss, and pathogens, including viruses that can cause fatal diseases. Israeli acute bee paralysis virus (IAPV), from the family Dicistroviridae, has been shown to cause colony collapse disorder in the United States. Here, we present the IAPV virion structure determined to a resolution of 4.0 Å and the structure of a pentamer of capsid protein protomers at a resolution of 2.7 Å. IAPV has major capsid proteins VP1 and VP3 with noncanonical jellyroll β-barrel folds composed of only seven instead of eight β-strands, as is the rule for proteins of other viruses with the same fold. The maturation of dicistroviruses is connected to the cleavage of precursor capsid protein VP0 into subunits VP3 and VP4. We show that a putative catalytic site formed by the residues Asp-Asp-Phe of VP1 is optimally positioned to perform the cleavage. Furthermore, unlike many picornaviruses, IAPV does not contain a hydrophobic pocket in capsid protein VP1 that could be targeted by capsid-binding antiviral compounds. IMPORTANCE Honeybee pollination is required for agricultural production and to sustain the biodiversity of wild flora. However, honeybee populations in Europe and North America are under pressure from pathogens, including viruses that cause colony losses. Viruses from the family Dicistroviridae can cause honeybee infections that are lethal, not only to individual honeybees, but to whole colonies. Here, we present the virion structure of an Aparavirus, Israeli acute bee paralysis virus (IAPV), a member of a complex of closely related viruses that are distributed worldwide. IAPV exhibits unique structural features not observed in other picorna-like viruses. Capsid protein VP1 of IAPV does not contain a hydrophobic pocket, implying that capsid-binding antiviral compounds that can prevent the replication of vertebrate picornaviruses may be ineffective against honeybee virus infections.
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Virion Structure of Iflavirus Slow Bee Paralysis Virus at 2.6-Angstrom Resolution. J Virol 2016; 90:7444-7455. [PMID: 27279610 PMCID: PMC4984619 DOI: 10.1128/jvi.00680-16] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2016] [Accepted: 05/27/2016] [Indexed: 12/29/2022] Open
Abstract
The western honeybee (Apis mellifera) is the most important commercial insect pollinator. However, bees are under pressure from habitat loss, environmental stress, and pathogens, including viruses that can cause lethal epidemics. Slow bee paralysis virus (SBPV) belongs to the Iflaviridae family of nonenveloped single-stranded RNA viruses. Here we present the structure of the SBPV virion determined from two crystal forms to resolutions of 3.4 Å and 2.6 Å. The overall structure of the virion resembles that of picornaviruses, with the three major capsid proteins VP1 to 3 organized into a pseudo-T3 icosahedral capsid. However, the SBPV capsid protein VP3 contains a C-terminal globular domain that has not been observed in other viruses from the order Picornavirales. The protruding (P) domains form “crowns” on the virion surface around each 5-fold axis in one of the crystal forms. However, the P domains are shifted 36 Å toward the 3-fold axis in the other crystal form. Furthermore, the P domain contains the Ser-His-Asp triad within a surface patch of eight conserved residues that constitutes a putative catalytic or receptor-binding site. The movements of the domain might be required for efficient substrate cleavage or receptor binding during virus cell entry. In addition, capsid protein VP2 contains an RGD sequence that is exposed on the virion surface, indicating that integrins might be cellular receptors of SBPV.
IMPORTANCE Pollination by honeybees is needed to sustain agricultural productivity as well as the biodiversity of wild flora. However, honeybee populations in Europe and North America have been declining since the 1950s. Honeybee viruses from the Iflaviridae family are among the major causes of honeybee colony mortality. We determined the virion structure of an Iflavirus, slow bee paralysis virus (SBPV). SBPV exhibits unique structural features not observed in other picorna-like viruses. The SBPV capsid protein VP3 has a large C-terminal domain, five of which form highly prominent protruding “crowns” on the virion surface. However, the domains can change their positions depending on the conditions of the environment. The domain includes a putative catalytic or receptor binding site that might be important for SBPV cell entry.
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Structure of Ljungan virus provides insight into genome packaging of this picornavirus. Nat Commun 2015; 6:8316. [PMID: 26446437 PMCID: PMC4633645 DOI: 10.1038/ncomms9316] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Accepted: 08/07/2015] [Indexed: 11/11/2022] Open
Abstract
Picornaviruses are responsible for a range of human and animal diseases, but how their RNA genome is packaged remains poorly understood. A particularly poorly studied group within this family are those that lack the internal coat protein, VP4. Here we report the atomic structure of one such virus, Ljungan virus, the type member of the genus Parechovirus B, which has been linked to diabetes and myocarditis in humans. The 3.78-Å resolution cryo-electron microscopy structure shows remarkable features, including an extended VP1 C terminus, forming a major protuberance on the outer surface of the virus, and a basic motif at the N terminus of VP3, binding to which orders some 12% of the viral genome. This apparently charge-driven RNA attachment suggests that this branch of the picornaviruses uses a different mechanism of genome encapsidation, perhaps explored early in the evolution of picornaviruses. The Ljungan virus is a picornavirus that lacks the internal coat protein VP4, and the packaging of its RNA genome is poorly understood. Here, the authors use cryo-electron microscopy to visualize this virus and suggest that it uses a different mechanism to other viruses for encapsidation of its genome.
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Structural Basis of Human Parechovirus Neutralization by Human Monoclonal Antibodies. J Virol 2015; 89:9571-80. [PMID: 26157123 DOI: 10.1128/jvi.01429-15] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Accepted: 07/02/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Since it was first recognized in 2004 that human parechoviruses (HPeV) are a significant cause of central nervous system and neonatal sepsis, their clinical importance, primarily in children, has started to emerge. Intravenous immunoglobulin treatment is the only treatment available in such life-threatening cases and has given moderate success. Direct inhibition of parechovirus infection using monoclonal antibodies is a potential treatment. We have developed two neutralizing monoclonal antibodies against HPeV1 and HPeV2, namely, AM18 and AM28, which also cross-neutralize other viruses. Here, we present the mapping of their epitopes using peptide scanning, surface plasmon resonance, fluorescence-based thermal shift assays, electron cryomicroscopy, and image reconstruction. We determined by peptide scanning and surface plasmon resonance that AM18 recognizes a linear epitope motif including the arginine-glycine-aspartic acid on the C terminus of capsid protein VP1. This epitope is normally used by the virus to attach to host cell surface integrins during entry and is found in 3 other viruses that AM18 neutralizes. Therefore, AM18 is likely to cause virus neutralization by aggregation and by blocking integrin binding to the capsid. Further, we show by electron cryomicroscopy, three-dimensional reconstruction, and pseudoatomic model fitting that ordered RNA interacts with HPeV1 VP1 and VP3. AM28 recognizes quaternary epitopes on the capsid composed of VP0 and VP3 loops from neighboring pentamers, thereby increasing the RNA accessibility temperature for the virus-AM28 complex compared to the virus alone. Thus, inhibition of RNA uncoating probably contributes to neutralization by AM28. IMPORTANCE Human parechoviruses can cause mild infections to severe diseases in young children, such as neonatal sepsis, encephalitis, and cardiomyopathy. Intravenous immunoglobulin treatment is the only treatment available in such life-threatening cases. In order to develop more targeted treatment, we have searched for human monoclonal antibodies that would neutralize human parechoviruses 1 and 2, associated with mild infections such as gastroenteritis and severe infections of the central nervous system, and thus allow safe treatment. In the current study, we show how two such promising antibodies interact with the virus, modeling the atomic interactions between the virus and the antibody to propose how neutralization occurs. Both antibodies can cause aggregation; in addition, one antibody interferes with the virus recognizing its target cell, while the other, recognizing only the whole virus, inhibits the genome uncoating and replication in the cell.
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Ceccarelli S, Balsalobre A, Susevich ML, Echeverria MG, Gorla DE, Marti GA. Modelling the potential geographic distribution of triatomines infected by Triatoma virus in the southern cone of South America. Parasit Vectors 2015; 8:153. [PMID: 25881183 PMCID: PMC4367828 DOI: 10.1186/s13071-015-0761-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Accepted: 02/20/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Triatoma virus (TrV) is the only entomopathogenous virus identified in triatomines. We estimated the potential geographic distribution of triatomine species naturally infected by TrV, using remotely sensed and meteorological environmental variables, to predict new potential areas where triatomines infected with TrV may be found. METHODS Detection of TrV infection in samples was performed with RT-PCR. Ecological niche models (ENM) were constructed using the MaxEnt software. We used 42 environmental variables derived from remotely sensed imagery (AVHRR) and 19 bioclimatic variables (Bioclim). The MaxEnt Jackknife procedure was used to minimize the number of environmental variables that showed an influence on final models. The goodness of fit of the model predictions was evaluated by the mean area under the curve (AUC). RESULTS We obtained 37 samples of 7 species of triatomines naturally infected with TrV. Of the TrV positive samples, 32% were from sylvatic habitat, 46% came from peridomicile habitats and 22% from domicile habitats. Five of the seven infected species were found only in the sylvatic habitat, one species only in the domicile and only Triatoma infestans was found in the three habitats. The MaxEnt model estimated with the Bioclim dataset identified five environmental variables as best predictors: temperature annual range, mean diurnal range, mean temperature of coldest quarter, temperature seasonality and annual mean temperature. The model using the AVHRR dataset identified six environmental variables: minimum Land Surface Temperature (LST), minimum Middle Infrared Radiation (MIR), LST annual amplitude, MIR annual amplitude annual, LST variance and MIR variance. The potential geographic distribution of triatomine species infected by TrV coincides with the Chaco and the Monte ecoregions either modelled by AVHRR or Bioclim environmental datasets. CONCLUSIONS Our results show that the conditions of the Dry Chaco ecoregion in Argentina are favourable for the infection of triatomine species with TrV, and open the possibility of its use as a potential agent for the biological control of peridomestic and/or sylvatic triatomine species. Results identify areas of potential occurrence that should be verified in the field.
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Affiliation(s)
- Soledad Ceccarelli
- Centro de Estudios Parasitológicos y de Vectores (CEPAVE-CCT-La Plata-CONICET - UNLP), Boulevard 120 e/61 y 62, 1900, La Plata, Argentina.
| | - Agustín Balsalobre
- Centro de Estudios Parasitológicos y de Vectores (CEPAVE-CCT-La Plata-CONICET - UNLP), Boulevard 120 e/61 y 62, 1900, La Plata, Argentina.
| | - María Laura Susevich
- Centro de Estudios Parasitológicos y de Vectores (CEPAVE-CCT-La Plata-CONICET - UNLP), Boulevard 120 e/61 y 62, 1900, La Plata, Argentina.
| | - María Gabriela Echeverria
- Cátedra de Virología, Facultad de Ciencias Veterinarias, Universidad Nacional de La Plata, (CONICET), La Plata, Buenos Aires, Argentina.
| | - David Eladio Gorla
- Centro Regional de Investigaciones Científicas y Transferencia Tecnológica (CRILAR - CONICET), La Rioja, Argentina.
| | - Gerardo Aníbal Marti
- Centro de Estudios Parasitológicos y de Vectores (CEPAVE-CCT-La Plata-CONICET - UNLP), Boulevard 120 e/61 y 62, 1900, La Plata, Argentina.
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Triatoma virus recombinant VP4 protein induces membrane permeability through dynamic pores. J Virol 2015; 89:4645-54. [PMID: 25673713 DOI: 10.1128/jvi.00011-15] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
UNLABELLED In naked viruses, membrane breaching is a key step that must be performed for genome transfer into the target cells. Despite its importance, the mechanisms behind this process remain poorly understood. The small protein VP4, encoded by the genomes of most viruses of the order Picornavirales, has been shown to be involved in membrane alterations. Here we analyzed the permeabilization activity of the natively nonmyristoylated VP4 protein from triatoma virus (TrV), a virus belonging to the Dicistroviridae family within the Picornavirales order. The VP4 protein was produced as a C-terminal maltose binding protein (MBP) fusion to achieve its successful expression. This recombinant VP4 protein is able to produce membrane permeabilization in model membranes in a membrane composition-dependent manner. The induced permeability was also influenced by the pH, being greater at higher pH values. We demonstrate that the permeabilization activity elicited by the protein occurs through discrete pores that are inserted on the membrane. Sizing experiments using fluorescent dextrans, cryo-electron microscopy imaging, and other, additional techniques showed that recombinant VP4 forms heterogeneous proteolipidic pores rather than common proteinaceous channels. These results suggest that the VP4 protein may be involved in the membrane alterations required for genome transfer or cell entry steps during dicistrovirus infection. IMPORTANCE During viral infection, viruses need to overcome the membrane barrier in order to enter the cell and replicate their genome. In nonenveloped viruses membrane fusion is not possible, and hence, other mechanisms are implemented. Among other proteins, like the capsid-forming proteins and the proteins required for viral replication, several viruses of the order Picornaviridae contain a small protein called VP4 that has been shown to be involved in membrane alterations. Here we show that the triatoma virus VP4 protein is able to produce membrane permeabilization in model membranes by the formation of heterogeneous dynamic pores. These pores formed by VP4 may be involved in the genome transfer or cell entry steps during viral infection.
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Wang X, Ren J, Gao Q, Hu Z, Sun Y, Li X, Rowlands DJ, Yin W, Wang J, Stuart DI, Rao Z, Fry EE. Hepatitis A virus and the origins of picornaviruses. Nature 2015; 517:85-88. [PMID: 25327248 PMCID: PMC4773894 DOI: 10.1038/nature13806] [Citation(s) in RCA: 132] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Accepted: 08/28/2014] [Indexed: 01/29/2023]
Abstract
Hepatitis A virus (HAV) remains enigmatic, despite 1.4 million cases worldwide annually. It differs radically from other picornaviruses, existing in an enveloped form and being unusually stable, both genetically and physically, but has proved difficult to study. Here we report high-resolution X-ray structures for the mature virus and the empty particle. The structures of the two particles are indistinguishable, apart from some disorder on the inside of the empty particle. The full virus contains the small viral protein VP4, whereas the empty particle harbours only the uncleaved precursor, VP0. The smooth particle surface is devoid of depressions that might correspond to receptor-binding sites. Peptide scanning data extend the previously reported VP3 antigenic site, while structure-based predictions suggest further epitopes. HAV contains no pocket factor and can withstand remarkably high temperature and low pH, and empty particles are even more robust than full particles. The virus probably uncoats via a novel mechanism, being assembled differently to other picornaviruses. It utilizes a VP2 'domain swap' characteristic of insect picorna-like viruses, and structure-based phylogenetic analysis places HAV between typical picornaviruses and the insect viruses. The enigmatic properties of HAV may reflect its position as a link between 'modern' picornaviruses and the more 'primitive' precursor insect viruses; for instance, HAV retains the ability to move from cell-to-cell by transcytosis.
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Affiliation(s)
- Xiangxi Wang
- National Laboratory of Macromolecules, Institute of Biophysics, Chinese Academy of Science, Beijing, 100101, China
| | - Jingshan Ren
- Division of Structural Biology, University of Oxford, The Henry Wellcome Building for Genomic Medicine, Headington, Oxford, UK
| | - Qiang Gao
- National Laboratory of Macromolecules, Institute of Biophysics, Chinese Academy of Science, Beijing, 100101, China
- Sinovac Biotech Co., Ltd., Beijing, 100085, China
| | - Zhongyu Hu
- National Institutes for Food and Drug Control, No. 2, TiantanXili, Beijing 100050, China
| | - Yao Sun
- National Laboratory of Macromolecules, Institute of Biophysics, Chinese Academy of Science, Beijing, 100101, China
| | - Xuemei Li
- National Laboratory of Macromolecules, Institute of Biophysics, Chinese Academy of Science, Beijing, 100101, China
| | - David J. Rowlands
- Institute of Molecular and Cellular Biology and Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Weidong Yin
- Sinovac Biotech Co., Ltd., Beijing, 100085, China
| | - Junzhi Wang
- National Institutes for Food and Drug Control, No. 2, TiantanXili, Beijing 100050, China
| | - David I. Stuart
- Division of Structural Biology, University of Oxford, The Henry Wellcome Building for Genomic Medicine, Headington, Oxford, UK
- Diamond Light Sources, Harwell Science and Innovation Campus, Didcot, OX11 0DE, UK
| | - Zihe Rao
- National Laboratory of Macromolecules, Institute of Biophysics, Chinese Academy of Science, Beijing, 100101, China
- Laboratory of Structural Biology, School of Medicine, Tsinghua University, Beijing, 100084, China
| | - Elizabeth E. Fry
- Division of Structural Biology, University of Oxford, The Henry Wellcome Building for Genomic Medicine, Headington, Oxford, UK
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Sánchez-Eugenia R, Méndez F, Querido JFB, Silva MS, Guérin DMA, Rodríguez JF. Triatoma virus structural polyprotein expression, processing and assembly into virus-like particles. J Gen Virol 2014; 96:64-73. [PMID: 25304655 DOI: 10.1099/vir.0.071639-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In contrast to the current wealth of structural information concerning dicistrovirus particle structure, very little is known about their morphogenetic pathways. Here, we describe the expression of the two ORFs encoded by the Triatoma virus (TrV) genome. TrV, a member of the Cripavirus genus of the Dicistroviridae family, infects blood-sucking insects belonging to the Triatominae subfamily that act as vectors for the transmission of Trypanosoma cruzi, the aetiological agent of the Chagas disease. We have established a baculovirus-based model for the expression of the NS (non-structural) and P1 (structural) polyproteins. A preliminary characterization of the proteolytic processing of both polyprotein precursors has been performed using this system. We show that the proteolytic processing of the P1 polyprotein is strictly dependent upon the coexpression of the NS polyprotein, and that NS/P1 coexpression leads to the assembly of virus-like particles (VLPs) exhibiting a morphology and a protein composition akin to natural TrV empty capsids. Remarkably, the unprocessed P1 polypeptide assembles into quasi-spherical structures conspicuously larger than VLPs produced in NS/P1-coexpressing cells, likely representing a previously undescribed morphogenetic intermediate. This intermediate has not been found in members of the related Picornaviridae family currently used as a model for dicistrovirus studies, thus suggesting the existence of major differences in the assembly pathways of these two virus groups.
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Affiliation(s)
- Rubén Sánchez-Eugenia
- Unidad de Biofísica (CSIC, UPV/EHU), Barrio Sarriena S/N, 48940 Leioa, Bizkaia, Spain
| | - Fernando Méndez
- Departamento de Biología Molecular y Celular, Centro Nacional de Biotecnología-CSIC, Darwin 3, 28049 Madrid, Spain
| | - Jailson F B Querido
- Centro de Malária e Outras Doenças Tropicais, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, Rua da Junqueira, 100, 1349-008 Lisboa, Portugal.,Fundación Biofísica Bizkaia, Barrio Sarriena S/N, 48940 Leioa, Bizkaia, Spain.,Unidad de Biofísica (CSIC, UPV/EHU), Barrio Sarriena S/N, 48940 Leioa, Bizkaia, Spain
| | - Marcelo Sousa Silva
- Departamento de Bioquímica, Universidade Federal do Rio Grande do Norte, Natal, Brazil.,Centro de Malária e Outras Doenças Tropicais, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, Rua da Junqueira, 100, 1349-008 Lisboa, Portugal
| | - Diego M A Guérin
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencia y Tecnología, Universidad del País Vasco (EHU), Barrio Sarriena S/N, 48940 Leioa, Bizkaia, Spain.,Unidad de Biofísica (CSIC, UPV/EHU), Barrio Sarriena S/N, 48940 Leioa, Bizkaia, Spain
| | - José F Rodríguez
- Departamento de Biología Molecular y Celular, Centro Nacional de Biotecnología-CSIC, Darwin 3, 28049 Madrid, Spain
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Ren J, Cone A, Willmot R, Jones IM. Assembly of recombinant Israeli Acute Paralysis Virus capsids. PLoS One 2014; 9:e105943. [PMID: 25153716 PMCID: PMC4143317 DOI: 10.1371/journal.pone.0105943] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2012] [Accepted: 07/31/2014] [Indexed: 01/30/2023] Open
Abstract
The dicistrovirus Israeli Acute Paralysis Virus (IAPV) has been implicated in the worldwide decline of honey bees. Studies of IAPV and many other bee viruses in pure culture are restricted by available isolates and permissive cell culture. Here we show that coupling the IAPV major structural precursor protein ORF2 to its cognate 3C-like processing enzyme results in processing of the precursor to the individual structural proteins in a number of insect cell lines following expression by a recombinant baculovirus. The efficiency of expression is influenced by the level of IAPV 3C protein and moderation of its activity is required for optimal expression. The mature IAPV structural proteins assembled into empty capsids that migrated as particles on sucrose velocity gradients and showed typical dicistrovirus like morphology when examined by electron microscopy. Monoclonal antibodies raised to recombinant capsids were configured into a diagnostic test specific for the presence of IAPV. Recombinant capsids for each of the many bee viruses within the picornavirus family may provide virus specific reagents for the on-going investigation of the causes of honeybee loss.
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Affiliation(s)
- Junyuan Ren
- School of Biological Sciences, University of Reading, Reading, United Kingdom
| | - Abigail Cone
- School of Biological Sciences, University of Reading, Reading, United Kingdom
| | - Rebecca Willmot
- School of Biological Sciences, University of Reading, Reading, United Kingdom
| | - Ian M. Jones
- School of Biological Sciences, University of Reading, Reading, United Kingdom
- * E-mail:
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Abstract
Orsay, the first virus discovered to naturally infect Caenorhabditis elegans or any nematode, has a bipartite, positive-sense RNA genome. Sequence analyses show that Orsay is related to nodaviruses, but molecular characterizations of Orsay reveal several unique features, such as the expression of a capsid-δ fusion protein and the use of an ATG-independent mechanism for translation initiation. Here we report the crystal structure of an Orsay virus-like particle assembled from recombinant capsid protein (CP). Orsay capsid has a T = 3 icosahedral symmetry with 60 trimeric surface spikes. Each CP can be divided into three regions: an N-terminal arm that forms an extended protein interaction network at the capsid interior, an S domain with a jelly-roll, β-barrel fold forming the continuous capsid, and a P domain that forms surface spike projections. The structure of the Orsay S domain is best aligned to T = 3 plant RNA viruses but exhibits substantial differences compared with the insect-infecting alphanodaviruses, which also lack the P domain in their CPs. The Orsay P domain is remotely related to the P1 domain in calicivirus and hepatitis E virus, suggesting a possible evolutionary relationship. Removing the N-terminal arm produced a slightly expanded capsid with fewer nucleic acids packaged, suggesting that the arm is important for capsid stability and genome packaging. Because C. elegans-Orsay serves as a highly tractable model for studying viral pathogenesis, our results should provide a valuable structural framework for further studies of Orsay replication and infection.
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Querido JFB, Agirre J, Marti GA, Guérin DMA, Silva MS. Inoculation of Triatoma virus (Dicistroviridae: Cripavirus) elicits a non-infective immune response in mice. Parasit Vectors 2013; 6:66. [PMID: 23497610 PMCID: PMC3605389 DOI: 10.1186/1756-3305-6-66] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2013] [Accepted: 03/13/2013] [Indexed: 12/03/2022] Open
Abstract
Background Dicistroviridae is a new family of small, non-enveloped, +ssRNA viruses pathogenic to both beneficial arthropods and insect pests. Little is known about the dicistrovirus replication mechanism or gene function, and any knowledge on these subjects comes mainly from comparisons with mammalian viruses from the Picornaviridae family. Due to its peculiar genome organization and characteristics of the per os viral transmission route, dicistroviruses make good candidates for use as biopesticides. Triatoma virus (TrV) is a pathogen of Triatoma infestans (Hemiptera: Reduviidae), one of the main vectors of the human trypanosomiasis disease called Chagas disease. TrV was postulated as a potential control agent against Chagas’ vectors. Although there is no evidence that TrV nor other dicistroviruses replicate in species outside the Insecta class, the innocuousness of these viruses in humans and animals needs to be ascertained. Methods In this study, RT-PCR and ELISA were used to detect the infectivity of this virus in Mus musculus BALB/c mice. Results In this study we have observed that there is no significant difference in the ratio IgG2a/IgG1 in sera from animals inoculated with TrV when compared with non-inoculated animals or mice inoculated only with non-infective TrV protein capsids. Conclusions We conclude that, under our experimental conditions, TrV is unable to replicate in mice. This study constitutes the first test to evaluate the infectivity of a dicistrovirus in a vertebrate animal model.
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Affiliation(s)
- Jailson F B Querido
- Centre for Malaria and Tropical Diseases, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, Lisboa, Portugal
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