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Xue M, Sofer L, Simon V, Arvy N, Diop M, Lion R, Beucher G, Bordat A, Tilsner J, Gallois J, German‐Retana S. AtHVA22a, a plant-specific homologue of Reep/DP1/Yop1 family proteins is involved in turnip mosaic virus propagation. MOLECULAR PLANT PATHOLOGY 2024; 25:e13466. [PMID: 38767756 PMCID: PMC11104427 DOI: 10.1111/mpp.13466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Revised: 04/08/2024] [Accepted: 04/14/2024] [Indexed: 05/22/2024]
Abstract
The movement of potyviruses, the largest genus of single-stranded, positive-sense RNA viruses responsible for serious diseases in crops, is very complex. As potyviruses developed strategies to hijack the host secretory pathway and plasmodesmata (PD) for their transport, the goal of this study was to identify membrane and/or PD-proteins that interact with the 6K2 protein, a potyviral protein involved in replication and cell-to-cell movement of turnip mosaic virus (TuMV). Using split-ubiquitin membrane yeast two-hybrid assays, we screened an Arabidopsis cDNA library for interactors of TuMV6K2. We isolated AtHVA22a (Hordeum vulgare abscisic acid responsive gene 22), which belongs to a multigenic family of transmembrane proteins, homologous to Receptor expression-enhancing protein (Reep)/Deleted in polyposis (DP1)/Yop1 family proteins in animal and yeast. HVA22/DP1/Yop1 family genes are widely distributed in eukaryotes, but the role of HVA22 proteins in plants is still not well known, although proteomics analysis of PD fractions purified from Arabidopsis suspension cells showed that AtHVA22a is highly enriched in a PD proteome. We confirmed the interaction between TuMV6K2 and AtHVA22a in yeast, as well as in planta by using bimolecular fluorescence complementation and showed that TuMV6K2/AtHVA22a interaction occurs at the level of the viral replication compartment during TuMV infection. Finally, we showed that the propagation of TuMV is increased when AtHVA22a is overexpressed in planta but slowed down upon mutagenesis of AtHVA22a by CRISPR-Cas9. Altogether, our results indicate that AtHVA22a plays an agonistic effect on TuMV propagation and that the C-terminal tail of the protein is important in this process.
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Affiliation(s)
- Mingshuo Xue
- Univ. Bordeaux UMR 1332, Biologie du Fruit et Pathologie, INRAe, Equipe de VirologieVillenave d'Ornon CedexFrance
| | - Luc Sofer
- Univ. Bordeaux UMR 1332, Biologie du Fruit et Pathologie, INRAe, Equipe de VirologieVillenave d'Ornon CedexFrance
| | - Vincent Simon
- Univ. Bordeaux UMR 1332, Biologie du Fruit et Pathologie, INRAe, Equipe de VirologieVillenave d'Ornon CedexFrance
| | - Nathalie Arvy
- Univ. Bordeaux UMR 1332, Biologie du Fruit et Pathologie, INRAe, Equipe de VirologieVillenave d'Ornon CedexFrance
| | - Mamoudou Diop
- UR 1052, INRAe, GAFL Domaine St MauriceMontfavet CedexFrance
| | - Roxane Lion
- Univ. Bordeaux UMR 1332, Biologie du Fruit et Pathologie, INRAe, Equipe de VirologieVillenave d'Ornon CedexFrance
| | - Guillaume Beucher
- Univ. Bordeaux UMR 1332, Biologie du Fruit et Pathologie, INRAe, Equipe de VirologieVillenave d'Ornon CedexFrance
| | - Amandine Bordat
- Univ. Bordeaux UMR 1332, Biologie du Fruit et Pathologie, INRAe, Equipe de VirologieVillenave d'Ornon CedexFrance
| | - Jens Tilsner
- Cell and Molecular SciencesJames Hutton InstituteDundeeUK
- Biomedical Sciences Research ComplexUniversity of St AndrewsSt AndrewsUK
| | | | - Sylvie German‐Retana
- Univ. Bordeaux UMR 1332, Biologie du Fruit et Pathologie, INRAe, Equipe de VirologieVillenave d'Ornon CedexFrance
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2
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Sinclair P, Zhao L, Beggs CB, Illingworth CJR. The airborne transmission of viruses causes tight transmission bottlenecks. Nat Commun 2024; 15:3540. [PMID: 38670957 PMCID: PMC11053022 DOI: 10.1038/s41467-024-47923-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Accepted: 04/12/2024] [Indexed: 04/28/2024] Open
Abstract
The transmission bottleneck describes the number of viral particles that initiate an infection in a new host. Previous studies have used genome sequence data to suggest that transmission bottlenecks for influenza and SARS-CoV-2 involve few viral particles, but the general principles of virus transmission are not fully understood. Here we show that, across a broad range of circumstances, tight transmission bottlenecks are a simple consequence of the physical process of airborne viral transmission. We use mathematical modelling to describe the physical process of the emission and inhalation of infectious particles, deriving the result that that the great majority of transmission bottlenecks involve few viral particles. While exceptions to this rule exist, the circumstances needed to create these exceptions are likely very rare. We thus provide a physical explanation for previous inferences of bottleneck size, while predicting that tight transmission bottlenecks prevail more generally in respiratory virus transmission.
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Affiliation(s)
- Patrick Sinclair
- MRC University of Glasgow Centre for Virus Research, Glasgow, UK
| | - Lei Zhao
- Section for GeoGenetics, Globe Institute, University of Copenhagen, Copenhagen, Denmark
| | - Clive B Beggs
- Carnegie School of Sport, Leeds Beckett University, Leeds, UK
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3
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Hodoameda P, Ebel GD, Mukhopadhyay S, Clem RJ. Extreme infectious titer variability in individual Aedes aegypti mosquitoes infected with Sindbis virus is associated with both differences in virus population structure and dramatic disparities in specific infectivity. PLoS Pathog 2024; 20:e1012047. [PMID: 38412195 PMCID: PMC10923411 DOI: 10.1371/journal.ppat.1012047] [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: 07/15/2023] [Revised: 03/08/2024] [Accepted: 02/13/2024] [Indexed: 02/29/2024] Open
Abstract
Variability in how individuals respond to pathogens is a hallmark of infectious disease, yet the basis for individual variation in host response is often poorly understood. The titer of infectious virus among individual mosquitoes infected with arboviruses is frequently observed to vary by several orders of magnitude in a single experiment, even when the mosquitoes are highly inbred. To better understand the basis for this titer variation, we sequenced populations of Sindbis virus (SINV) obtained from individual infected Aedes aegypti mosquitoes that, despite being from a highly inbred laboratory colony, differed in their titers of infectious virus by approximately 10,000-fold. We observed genetic differences between these virus populations that indicated the virus present in the midguts of low titer mosquitoes was less fit than that of high titer mosquitoes, possibly due to founder effects that occurred during midgut infection. Furthermore, we found dramatic differences in the specific infectivity or SI (the ratio of infectious units/viral genome equivalents) between these virus populations, with the SI of low titer mosquitoes being up to 10,000-fold lower than that of high titer mosquitoes. Despite having similar amounts of viral genomes, low titer mosquitoes appeared to contain less viral particles, suggesting that viral genomes were packaged into virions less efficiently than in high titer mosquitoes. Finally, antibiotic treatment, which has been shown to suppress mosquito antiviral immunity, caused an increase in SI. Our results indicate that the extreme variation that is observed in SINV infectious titer between individual Ae. aegypti mosquitoes is due to both genetic differences between virus populations and to differences in the proportion of genomes that are packaged into infectious particles.
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Affiliation(s)
- Peter Hodoameda
- Division of Biology, Kansas State University, Manhattan, Kansas United States of America
| | - Gregory D. Ebel
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado United States of America
| | - Suchetana Mukhopadhyay
- Department of Biology, Indiana University, Bloomington, Indiana United States of America
| | - Rollie J. Clem
- Division of Biology, Kansas State University, Manhattan, Kansas United States of America
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Xavier CAD, Godinho MT, Mar TB, Ferro CG, Sande OFL, Silva JC, Ramos-Sobrinho R, Nascimento RN, Assunção I, Lima GSA, Lima ATM, Murilo Zerbini F. Evolutionary dynamics of bipartite begomoviruses revealed by complete genome analysis. Mol Ecol 2021; 30:3747-3767. [PMID: 34021651 DOI: 10.1111/mec.15997] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 05/07/2021] [Accepted: 05/14/2021] [Indexed: 12/17/2022]
Abstract
Several key evolutionary events marked the evolution of geminiviruses, culminating with the emergence of divided (bipartite) genomes represented by viruses classified in the genus Begomovirus. This genus represents the most abundant group of multipartite viruses, contributing significantly to the observed abundance of multipartite species in the virosphere. Although aspects related to virus-host interactions and evolutionary dynamics have been extensively studied, the bipartite nature of these viruses has been little explored in evolutionary studies. Here, we performed a parallel evolutionary analysis of the DNA-A and DNA-B segments of New World begomoviruses. A total of 239 full-length DNA-B sequences obtained in this study, combined with 292 DNA-A and 76 DNA-B sequences retrieved from GenBank, were analysed. The results indicate that the DNA-A and DNA-B respond differentially to evolutionary processes, with the DNA-B being more permissive to variation and more prone to recombination than the DNA-A. Although a clear geographic segregation was observed for both segments, differences in the genetic structure between DNA-A and DNA-B were also observed, with cognate segments belonging to distinct genetic clusters. DNA-B coding regions evolve under the same selection pressures than DNA-A coding regions. Together, our results indicate an interplay between reassortment and recombination acting at different levels across distinct subpopulations and segments.
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Affiliation(s)
- César A D Xavier
- Dep. de Fitopatologia/BIOAGRO, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil
| | - Márcio T Godinho
- Dep. de Fitopatologia/BIOAGRO, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil
| | - Talita B Mar
- Dep. de Fitopatologia/BIOAGRO, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil
| | - Camila G Ferro
- Dep. de Fitopatologia/BIOAGRO, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil
| | - Osvaldo F L Sande
- Dep. de Fitopatologia/BIOAGRO, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil
| | - José C Silva
- Dep. de Bioquímica e Biologia Molecular/BIOAGRO, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil
| | - Roberto Ramos-Sobrinho
- Dep. de Fitopatologia/BIOAGRO, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil
| | - Renato N Nascimento
- Centro de Ciências Agrárias/Fitossanidade, Universidade Federal de Alagoas, Rio Largo, Alagoas, Brazil
| | - Iraildes Assunção
- Centro de Ciências Agrárias/Fitossanidade, Universidade Federal de Alagoas, Rio Largo, Alagoas, Brazil
| | - Gaus S A Lima
- Centro de Ciências Agrárias/Fitossanidade, Universidade Federal de Alagoas, Rio Largo, Alagoas, Brazil
| | - Alison T M Lima
- Instituto de Ciências Agrárias, Universidade Federal de Uberlândia, Uberlândia, Minas Gerais, Brazil
| | - F Murilo Zerbini
- Dep. de Fitopatologia/BIOAGRO, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil
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Ramazzotti D, Angaroni F, Maspero D, Gambacorti-Passerini C, Antoniotti M, Graudenzi A, Piazza R. VERSO: A comprehensive framework for the inference of robust phylogenies and the quantification of intra-host genomic diversity of viral samples. PATTERNS (NEW YORK, N.Y.) 2021; 2:100212. [PMID: 33728416 PMCID: PMC7953447 DOI: 10.1016/j.patter.2021.100212] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 11/30/2020] [Accepted: 01/22/2021] [Indexed: 12/22/2022]
Abstract
We introduce VERSO, a two-step framework for the characterization of viral evolution from sequencing data of viral genomes, which is an improvement on phylogenomic approaches for consensus sequences. VERSO exploits an efficient algorithmic strategy to return robust phylogenies from clonal variant profiles, also in conditions of sampling limitations. It then leverages variant frequency patterns to characterize the intra-host genomic diversity of samples, revealing undetected infection chains and pinpointing variants likely involved in homoplasies. On simulations, VERSO outperforms state-of-the-art tools for phylogenetic inference. Notably, the application to 6,726 amplicon and RNA sequencing samples refines the estimation of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) evolution, while co-occurrence patterns of minor variants unveil undetected infection paths, which are validated with contact tracing data. Finally, the analysis of SARS-CoV-2 mutational landscape uncovers a temporal increase of overall genomic diversity and highlights variants transiting from minor to clonal state and homoplastic variants, some of which fall on the spike gene. Available at: https://github.com/BIMIB-DISCo/VERSO.
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Affiliation(s)
- Daniele Ramazzotti
- Department of Medicine and Surgery, Università degli Studi di Milano-Bicocca, Monza, Italy
| | - Fabrizio Angaroni
- Department of Informatics, Systems and Communication, Università degli Studi di Milano-Bicocca, Milan, Italy
| | - Davide Maspero
- Department of Informatics, Systems and Communication, Università degli Studi di Milano-Bicocca, Milan, Italy
- Inst. of Molecular Bioimaging and Physiology, Consiglio Nazionale delle Ricerche (IBFM-CNR), Segrate, Milan, Italy
| | | | - Marco Antoniotti
- Department of Informatics, Systems and Communication, Università degli Studi di Milano-Bicocca, Milan, Italy
- Bicocca Bioinformatics, Biostatistics and Bioimaging Centre – B4, Milan, Italy
| | - Alex Graudenzi
- Inst. of Molecular Bioimaging and Physiology, Consiglio Nazionale delle Ricerche (IBFM-CNR), Segrate, Milan, Italy
- Bicocca Bioinformatics, Biostatistics and Bioimaging Centre – B4, Milan, Italy
| | - Rocco Piazza
- Department of Medicine and Surgery, Università degli Studi di Milano-Bicocca, Monza, Italy
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McLeish MJ, Fraile A, García-Arenal F. Population Genomics of Plant Viruses: The Ecology and Evolution of Virus Emergence. PHYTOPATHOLOGY 2021; 111:32-39. [PMID: 33210987 DOI: 10.1094/phyto-08-20-0355-fi] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The genomics era has revolutionized studies of adaptive evolution by monitoring large numbers of loci throughout the genomes of many individuals. Ideally, the investigation of emergence in plant viruses requires examining the population dynamics of both virus and host, their interactions with each other, with other organisms and the abiotic environment. Genetic mechanisms that affect demographic processes are now being studied with high-throughput technologies, traditional genetics methods, and new computational tools for big-data. In this review, we discuss the utility of these approaches to monitor and detect changes in virus populations within cells and individuals, and over wider areas across species and communities of ecosystems. The advent of genomics in virology has fostered a multidisciplinary approach to tackling disease risk. The ability to make sense of the information now generated in this integrated setting is by far the most substantial obstacle to the ultimate goal of plant virology to minimize the threats to food security posed by disease. To achieve this goal, it is imperative to understand and forecast how populations respond to future changes in complex natural systems.
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Affiliation(s)
- Michael J McLeish
- Centro de Biotecnología y Genómica de Plantas (CBGP), Universidad Politécnica de Madrid (UPM) and Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA) and E.T.S.I. Agronómica, Alimentaria y de Biosistemas, Campus de Montegancedo, UPM, 28223 Pozuelo de Alarcón, Madrid, Spain
| | - Aurora Fraile
- Centro de Biotecnología y Genómica de Plantas (CBGP), Universidad Politécnica de Madrid (UPM) and Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA) and E.T.S.I. Agronómica, Alimentaria y de Biosistemas, Campus de Montegancedo, UPM, 28223 Pozuelo de Alarcón, Madrid, Spain
| | - Fernando García-Arenal
- Centro de Biotecnología y Genómica de Plantas (CBGP), Universidad Politécnica de Madrid (UPM) and Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA) and E.T.S.I. Agronómica, Alimentaria y de Biosistemas, Campus de Montegancedo, UPM, 28223 Pozuelo de Alarcón, Madrid, Spain
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7
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Inferring Transmission Bottleneck Size from Viral Sequence Data Using a Novel Haplotype Reconstruction Method. J Virol 2020; 94:JVI.00014-20. [PMID: 32295920 PMCID: PMC7307158 DOI: 10.1128/jvi.00014-20] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Accepted: 04/08/2020] [Indexed: 12/12/2022] Open
Abstract
Viral populations undergo a repeated cycle of within-host growth followed by transmission. Viral evolution is affected by each stage of this cycle. The number of viral particles transmitted from one host to another, known as the transmission bottleneck, is an important factor in determining how the evolutionary dynamics of the population play out, restricting the extent to which the evolved diversity of the population can be passed from one host to another. Previous study of viral sequence data has suggested that the transmission bottleneck size for influenza A transmission between human hosts is small. Reevaluating these data using a novel and improved method, we largely confirm this result, albeit that we infer a slightly higher bottleneck size in some cases, of between 1 and 13 virions. While a tight bottleneck operates in human influenza transmission, it is not extreme in nature; some diversity can be meaningfully retained between hosts. The transmission bottleneck is defined as the number of viral particles that transmit from one host to establish an infection in another. Genome sequence data have been used to evaluate the size of the transmission bottleneck between humans infected with the influenza virus; however, the methods used to make these estimates have some limitations. Specifically, viral allele frequencies, which form the basis of many calculations, may not fully capture a process which involves the transmission of entire viral genomes. Here, we set out a novel approach for inferring viral transmission bottlenecks; our method combines an algorithm for haplotype reconstruction with maximum likelihood methods for bottleneck inference. This approach allows for rapid calculation and performs well when applied to data from simulated transmission events; errors in the haplotype reconstruction step did not adversely affect inferences of the population bottleneck. Applied to data from a previous household transmission study of influenza A infection, we confirm the result that the majority of transmission events involve a small number of viruses, albeit with slightly looser bottlenecks being inferred, with between 1 and 13 particles transmitted in the majority of cases. While influenza A transmission involves a tight population bottleneck, the bottleneck is not so tight as to universally prevent the transmission of within-host viral diversity. IMPORTANCE Viral populations undergo a repeated cycle of within-host growth followed by transmission. Viral evolution is affected by each stage of this cycle. The number of viral particles transmitted from one host to another, known as the transmission bottleneck, is an important factor in determining how the evolutionary dynamics of the population play out, restricting the extent to which the evolved diversity of the population can be passed from one host to another. Previous study of viral sequence data has suggested that the transmission bottleneck size for influenza A transmission between human hosts is small. Reevaluating these data using a novel and improved method, we largely confirm this result, albeit that we infer a slightly higher bottleneck size in some cases, of between 1 and 13 virions. While a tight bottleneck operates in human influenza transmission, it is not extreme in nature; some diversity can be meaningfully retained between hosts.
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Garcia S, Hily JM, Komar V, Gertz C, Demangeat G, Lemaire O, Vigne E. Detection of Multiple Variants of Grapevine Fanleaf Virus in Single Xiphinema index Nematodes. Viruses 2019; 11:v11121139. [PMID: 31835488 PMCID: PMC6950412 DOI: 10.3390/v11121139] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Revised: 11/08/2019] [Accepted: 12/05/2019] [Indexed: 11/16/2022] Open
Abstract
Grapevine fanleaf virus (GFLV) is responsible for a widespread disease in vineyards worldwide. Its genome is composed of two single-stranded positive-sense RNAs, which both show a high genetic diversity. The virus is transmitted from grapevine to grapevine by the ectoparasitic nematode Xiphinema index. Grapevines in diseased vineyards are often infected by multiple genetic variants of GFLV but no information is available on the molecular composition of virus variants retained in X. index following nematodes feeding on roots. In this work, aviruliferous X. index were fed on three naturally GFLV-infected grapevines for which the virome was characterized by RNAseq. Six RNA-1 and four RNA-2 molecules were assembled segregating into four and three distinct phylogenetic clades of RNA-1 and RNA-2, respectively. After 19 months of rearing, single and pools of 30 X. index tested positive for GFLV. Additionally, either pooled or single X. index carried multiple variants of the two GFLV genomic RNAs. However, the full viral genetic diversity found in the leaves of infected grapevines was not detected in viruliferous nematodes, indicating a genetic bottleneck. Our results provide new insights into the complexity of GFLV populations and the putative role of X. index as reservoirs of virus diversity.
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Affiliation(s)
- Shahinez Garcia
- Unité Mixte de Recherche (UMR) Santé de la Vigne et Qualité du Vin, Institut National de la Recherche Agronomique (INRA)-Université de Strasbourg, BP 20507, 68021 Colmar Cedex, France; (S.G.); (V.K.); (C.G.); (G.D.); (O.L.)
| | - Jean-Michel Hily
- Unité Mixte de Recherche (UMR) Santé de la Vigne et Qualité du Vin, Institut National de la Recherche Agronomique (INRA)-Université de Strasbourg, BP 20507, 68021 Colmar Cedex, France; (S.G.); (V.K.); (C.G.); (G.D.); (O.L.)
- Institut Français de la Vigne et du Vin (IFV), 30240 Le Grau-Du-Roi, France
| | - Véronique Komar
- Unité Mixte de Recherche (UMR) Santé de la Vigne et Qualité du Vin, Institut National de la Recherche Agronomique (INRA)-Université de Strasbourg, BP 20507, 68021 Colmar Cedex, France; (S.G.); (V.K.); (C.G.); (G.D.); (O.L.)
| | - Claude Gertz
- Unité Mixte de Recherche (UMR) Santé de la Vigne et Qualité du Vin, Institut National de la Recherche Agronomique (INRA)-Université de Strasbourg, BP 20507, 68021 Colmar Cedex, France; (S.G.); (V.K.); (C.G.); (G.D.); (O.L.)
| | - Gérard Demangeat
- Unité Mixte de Recherche (UMR) Santé de la Vigne et Qualité du Vin, Institut National de la Recherche Agronomique (INRA)-Université de Strasbourg, BP 20507, 68021 Colmar Cedex, France; (S.G.); (V.K.); (C.G.); (G.D.); (O.L.)
| | - Olivier Lemaire
- Unité Mixte de Recherche (UMR) Santé de la Vigne et Qualité du Vin, Institut National de la Recherche Agronomique (INRA)-Université de Strasbourg, BP 20507, 68021 Colmar Cedex, France; (S.G.); (V.K.); (C.G.); (G.D.); (O.L.)
| | - Emmanuelle Vigne
- Unité Mixte de Recherche (UMR) Santé de la Vigne et Qualité du Vin, Institut National de la Recherche Agronomique (INRA)-Université de Strasbourg, BP 20507, 68021 Colmar Cedex, France; (S.G.); (V.K.); (C.G.); (G.D.); (O.L.)
- Correspondence: ; Tel.: +33-389-224-955
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9
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Chisholm PJ, Busch JW, Crowder DW. Effects of life history and ecology on virus evolutionary potential. Virus Res 2019; 265:1-9. [PMID: 30831177 DOI: 10.1016/j.virusres.2019.02.018] [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: 11/19/2018] [Revised: 02/27/2019] [Accepted: 02/28/2019] [Indexed: 11/28/2022]
Abstract
The life history traits of viruses pose many consequences for viral population structure. In turn, population structure may influence the evolutionary trajectory of a virus. Here we review factors that affect the evolutionary potential of viruses, including rates of mutation and recombination, bottlenecks, selection pressure, and ecological factors such as the requirement for hosts and vectors. Mutation, while supplying a pool of raw genetic material, also results in the generation of numerous unfit mutants. The infection of multiple host species may expand a virus' ecological niche, although it may come at a cost to genetic diversity. Vector-borne viruses often experience a diminished frequency of positive selection and exhibit little diversity, and resistance against vector-borne viruses may thus be more durable than against non-vectored viruses. Evidence indicates that adaptation to a vector is more evolutionarily difficult than adaptation to a host. Overall, a better understanding of how various factors influence viral dynamics in both plant and animal pathosystems will lead to more effective anti-viral treatments and countermeasures.
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Affiliation(s)
- Paul J Chisholm
- Department of Entomology, Washington State University, 166 FSHN Building, Pullman, WA, 99164, USA.
| | - Jeremiah W Busch
- School of Biological Sciences, Washington State University, PO Box 644236, Pullman, WA, 99164, USA.
| | - David W Crowder
- Department of Entomology, Washington State University, 166 FSHN Building, Pullman, WA, 99164, USA.
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Shannon Entropy to Evaluate Substitution Rate Variation Among Viral Nucleotide Positions in Datasets of Viral siRNAs. Methods Mol Biol 2019; 1746:187-195. [PMID: 29492896 DOI: 10.1007/978-1-4939-7683-6_15] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Next-generation sequencing has opened the door to the reconstruction of viral populations and examination of the composition of mutant spectra in infected cells, tissues, and host organisms. In this chapter we present details on the use of the Shannon entropy method to estimate the site-specific nucleotide relative variability of turnip crinkle virus, a positive (+) stranded RNA plant virus, in a large dataset of short RNAs of Cicer arietinum L., a natural reservoir of the virus. We propose this method as a viral metagenomics tool to provide a more detailed description of the viral quasispecies in infected plant tissue. Viral replicative fitness relates to an optimal composition of variants that provide the molecular basis of virus behavior in the complex environment of natural infections. A complete description of viral quasispecies may have implications in determining fitness landscapes for host-virus coexistence and help to design specific diagnostic protocols and antiviral strategies.
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11
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Montarry J, Bardou-Valette S, Mabon R, Jan PL, Fournet S, Grenier E, Petit EJ. Exploring the causes of small effective population sizes in cyst nematodes using artificial Globodera pallida populations. Proc Biol Sci 2019; 286:20182359. [PMID: 30963865 PMCID: PMC6367184 DOI: 10.1098/rspb.2018.2359] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Accepted: 12/12/2018] [Indexed: 02/02/2023] Open
Abstract
The effective size of a population is the size of an ideal population which would undergo genetic drift at the same rate as the real population. The balance between selection and genetic drift depends on the effective population size ( Ne), rather than the real numbers of individuals in the population ( N). The objectives of the present study were to estimate Ne in the potato cyst nematode Globodera pallida and to explore the causes of a low Ne/ N ratio in cyst nematodes using artificial populations. Using a temporal analysis of 24 independent populations, the median Ne was 58 individuals (min Ne = 25 and max Ne = 228). Ne is commonly lower than N but in the case of cyst nematodes, the Ne/ N ratio was extremely low. Using artificial populations showed that this low ratio did not result from migration, selection and overlapping generations, but could be explain by the fact that G. pallida populations deviate in structure from the assumptions of the ideal population by having unequal sex ratios, high levels of inbreeding and a high variance in family sizes. The consequences of a low Ne, resulting in a strong intensity of genetic drift, could be important for their control because G. pallida populations will have a low capacity to adapt to changing environments.
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Affiliation(s)
- Josselin Montarry
- INRA, UMR1349 IGEPP, Institute of Genetic Environment and Plant Protection, 35653 Le Rheu, France
| | - Sylvie Bardou-Valette
- INRA, UMR1349 IGEPP, Institute of Genetic Environment and Plant Protection, 35653 Le Rheu, France
| | - Romain Mabon
- INRA, UMR1349 IGEPP, Institute of Genetic Environment and Plant Protection, 35653 Le Rheu, France
| | - Pierre-Loup Jan
- INRA, Agrocampus-Ouest, UMR985 ESE, Ecology and Ecosystem Health, 35042 Rennes, France
| | - Sylvain Fournet
- INRA, UMR1349 IGEPP, Institute of Genetic Environment and Plant Protection, 35653 Le Rheu, France
| | - Eric Grenier
- INRA, UMR1349 IGEPP, Institute of Genetic Environment and Plant Protection, 35653 Le Rheu, France
| | - Eric J. Petit
- INRA, Agrocampus-Ouest, UMR985 ESE, Ecology and Ecosystem Health, 35042 Rennes, France
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12
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Population bottlenecks in multicomponent viruses: first forays into the uncharted territory of genome-formula drift. Curr Opin Virol 2018; 33:184-190. [DOI: 10.1016/j.coviro.2018.09.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Revised: 08/28/2018] [Accepted: 09/07/2018] [Indexed: 11/23/2022]
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13
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Lumby CK, Nene NR, Illingworth CJR. A novel framework for inferring parameters of transmission from viral sequence data. PLoS Genet 2018; 14:e1007718. [PMID: 30325921 PMCID: PMC6203404 DOI: 10.1371/journal.pgen.1007718] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Revised: 10/26/2018] [Accepted: 09/26/2018] [Indexed: 11/18/2022] Open
Abstract
Transmission between hosts is a critical part of the viral lifecycle. Recent studies of viral transmission have used genome sequence data to evaluate the number of particles transmitted between hosts, and the role of selection as it operates during the transmission process. However, the interpretation of sequence data describing transmission events is a challenging task. We here present a novel and comprehensive framework for using short-read sequence data to understand viral transmission events, designed for influenza virus, but adaptable to other viral species. Our approach solves multiple shortcomings of previous methods for this purpose; for example, we consider transmission as an event involving whole viruses, rather than sets of independent alleles. We demonstrate how selection during transmission and noisy sequence data may each affect naive inferences of the population bottleneck, accounting for these in our framework so as to achieve a correct inference. We identify circumstances in which selection for increased viral transmission may or may not be identified from data. Applying our method to experimental data in which transmission occurs in the presence of strong selection, we show that our framework grants a more quantitative insight into transmission events than previous approaches, inferring the bottleneck in a manner that accounts for selection, both for within-host virulence, and for inherent viral transmissibility. Our work provides new opportunities for studying transmission processes in influenza, and by extension, in other infectious diseases.
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Affiliation(s)
- Casper K. Lumby
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Nuno R. Nene
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Christopher J. R. Illingworth
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
- Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge, United Kingdom
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14
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Abstract
The study of tobacco mosaic virus and other tobamovirus species has greatly contributed to the development of all areas of virology, including virus evolution. Research with tobamoviruses has been pioneer, or particularly significant, in all major areas of research in this field, including: the characterization of the genetic diversity of virus populations, the mechanisms and rates of generation of genetic diversity, the analysis of the genetic structure of virus populations and of the factors that shape it, the adaptation of viruses to hosts and the evolution of host range, and the evolution of virus taxa and of virus-host interactions. Many of these continue to be hot topics in evolutionary biology, or have been identified recently as such, including (i) host-range evolution, (ii) predicting the overcoming of resistance in crops, (iii) trade-offs between virus life-history traits in virus evolution, and (iv) the codivergence of viruses and hosts at different taxonomical and spatial scales. Tobamoviruses may be particularly appropriate to address these topics with plant viruses, as they provide convenient experimental systems, and as the detailed knowledge on their molecular and structural biology allows the analysis of the mechanisms behind evolutionary processes. Also, the extensive information on parameters related to infection dynamics and population structure may facilitate the development of realistic models to predict virus evolution. Certainly, tobamoviruses will continue to be favorite system for the study of virus evolution.
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Affiliation(s)
- Aurora Fraile
- Centro de Biotecnología y Genómica de Plantas UPM-INIA, and E.T.S.I., Agronómica, Alimentaria y de Biosistemas, Universidad Politécnica de Madrid, Madrid, Spain
| | - Fernando García-Arenal
- Centro de Biotecnología y Genómica de Plantas UPM-INIA, and E.T.S.I., Agronómica, Alimentaria y de Biosistemas, Universidad Politécnica de Madrid, Madrid, Spain.
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15
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Small Bottleneck Size in a Highly Multipartite Virus during a Complete Infection Cycle. J Virol 2018; 92:JVI.00139-18. [PMID: 29720515 DOI: 10.1128/jvi.00139-18] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 04/13/2018] [Indexed: 02/05/2023] Open
Abstract
Multipartite viruses package their genomic segments independently and thus incur the risk of being unable to transmit their entire genome during host-to-host transmission if they undergo severe bottlenecks. In this paper, we estimated the bottleneck size during one infection cycle of Faba bean necrotic stunt virus (FBNSV), an octopartite nanovirus whose segments have been previously shown to converge to particular and unequal relative frequencies within host plants and aphid vectors. Two methods were used to derive this estimate, one based on the probability of transmission of the virus and the other based on the temporal evolution of the relative frequency of markers for two genomic segments, one frequent and one rare (segment N and S, respectively), both in plants and vectors. Our results show that FBNSV undergoes severe bottlenecks during aphid transmission. Further, even though the bottlenecks are always narrow under our experimental conditions, they slightly widen with the number of transmitting aphids. In particular, when several aphids are used for transmission, the bottleneck size of the segments is also affected by within-plant processes and, importantly, significantly differs across segments. These results indicate that genetic drift not only must be an important process affecting the evolution of these viruses but also that these effects vary across genomic segments and, thus, across viral genes, a rather unique and intriguing situation. We further discuss the potential consequences of our findings for the transmission of multipartite viruses.IMPORTANCE Multipartite viruses package their genomic segments in independent capsids. The most obvious cost of such genomic structure is the risk of losing at least one segment during host-to-host transmission. A theoretical study has shown that for nanoviruses, composed of 6 to 8 segments, hundreds of copies of each segment need to be transmitted to ensure that at least one copy of each segment was present in the host. These estimations seem to be very high compared to the size of the bottlenecks measured with other viruses. Here, we estimated the bottleneck size during one infection cycle of FBNSV, an octopartite nanovirus. We show that these bottlenecks are always narrow (few viral particles) and slightly widen with the number of transmitting aphids. These results contrast with theoretical predictions and illustrate the fact that a new conceptual framework is probably needed to understand the transmission of highly multipartite viruses.
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16
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Weger-Lucarelli J, Garcia SM, Rückert C, Byas A, O'Connor SL, Aliota MT, Friedrich TC, O'Connor DH, Ebel GD. Using barcoded Zika virus to assess virus population structure in vitro and in Aedes aegypti mosquitoes. Virology 2018; 521:138-148. [PMID: 29935423 DOI: 10.1016/j.virol.2018.06.004] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Revised: 06/06/2018] [Accepted: 06/08/2018] [Indexed: 01/12/2023]
Abstract
Arboviruses such as Zika virus (ZIKV, Flaviviridae; Flavivirus) must replicate in both mammalian and insect hosts possessing strong immune defenses. Accordingly, transmission between and replication within hosts involves genetic bottlenecks, during which viral population size and genetic diversity may be significantly reduced. To help quantify these bottlenecks and their effects, we constructed 4 "barcoded" ZIKV populations that theoretically contain thousands of barcodes each. After identifying the most diverse barcoded virus, we passaged this virus 3 times in 2 mammalian and mosquito cell lines and characterized the population using deep sequencing of the barcoded region of the genome. C6/36 maintain higher barcode diversity, even after 3 passages, than Vero. Additionally, field-caught mosquitoes exposed to the virus to assess bottlenecks in a natural host. A progressive reduction in barcode diversity occurred throughout systemic infection of these mosquitoes. Differences in bottlenecks during systemic spread were observed between different populations of Aedes aegypti.
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Affiliation(s)
- James Weger-Lucarelli
- Arthropod-Borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO, United States.
| | - Selene M Garcia
- Arthropod-Borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO, United States
| | - Claudia Rückert
- Arthropod-Borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO, United States
| | - Alex Byas
- Arthropod-Borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO, United States
| | - Shelby L O'Connor
- Department of Pathology and Laboratory Medicine, University of Wisconsin-Madison, Madison, WI, United States
| | - Matthew T Aliota
- Department of Pathobiological Sciences, University of Wisconsin-Madison, Madison, WI, United States
| | - Thomas C Friedrich
- Department of Pathobiological Sciences, University of Wisconsin-Madison, Madison, WI, United States; Wisconsin National Primate Research Center, University of Wisconsin-Madison, Madison, WI, United States
| | - David H O'Connor
- Department of Pathology and Laboratory Medicine, University of Wisconsin-Madison, Madison, WI, United States; Wisconsin National Primate Research Center, University of Wisconsin-Madison, Madison, WI, United States
| | - Gregory D Ebel
- Arthropod-Borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO, United States.
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17
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Mauck KE, Chesnais Q, Shapiro LR. Evolutionary Determinants of Host and Vector Manipulation by Plant Viruses. Adv Virus Res 2018; 101:189-250. [PMID: 29908590 DOI: 10.1016/bs.aivir.2018.02.007] [Citation(s) in RCA: 85] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Plant viruses possess adaptations for facilitating acquisition, retention, and inoculation by vectors. Until recently, it was hypothesized that these adaptations are limited to virus proteins that enable virions to bind to vector mouthparts or invade their internal tissues. However, increasing evidence suggests that viruses can also manipulate host plant phenotypes and vector behaviors in ways that enhance their own transmission. Manipulation of vector-host interactions occurs through virus effects on host cues that mediate vector orientation, feeding, and dispersal behaviors, and thereby, the probability of virus transmission. Effects on host phenotypes vary by pathosystem but show a remarkable degree of convergence among unrelated viruses whose transmission is favored by the same vector behaviors. Convergence based on transmission mechanism, rather than phylogeny, supports the hypothesis that virus effects are adaptive and not just by-products of infection. Based on this, it has been proposed that viruses manipulate hosts through multifunctional proteins that facilitate exploitation of host resources and elicitation of specific changes in host phenotypes. But this proposition is rarely discussed in the context of the numerous constraints on virus evolution imposed by molecular and environmental factors, which figure prominently in research on virus-host interactions not dealing with host manipulation. To explore the implications of this oversight, we synthesized available literature to identify patterns in virus effects among pathogens with shared transmission mechanisms and discussed the results of this synthesis in the context of molecular and environmental constraints on virus evolution, limitations of existing studies, and prospects for future research.
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Affiliation(s)
- Kerry E Mauck
- Department of Entomology, University of California, Riverside, Riverside, CA, United States.
| | - Quentin Chesnais
- Department of Entomology, University of California, Riverside, Riverside, CA, United States
| | - Lori R Shapiro
- Department of Applied Ecology, North Carolina State University, Raleigh, NC, United States
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18
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Evolutionary dynamics of dengue virus populations within the mosquito vector. Curr Opin Virol 2016; 21:47-53. [DOI: 10.1016/j.coviro.2016.07.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2016] [Revised: 07/23/2016] [Accepted: 07/27/2016] [Indexed: 02/05/2023]
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19
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Zwart MP, Elena SF. Matters of Size: Genetic Bottlenecks in Virus Infection and Their Potential Impact on Evolution. Annu Rev Virol 2016; 2:161-79. [PMID: 26958911 DOI: 10.1146/annurev-virology-100114-055135] [Citation(s) in RCA: 104] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
For virus infections of multicellular hosts, narrow genetic bottlenecks during transmission and within-host spread appear to be widespread. These bottlenecks will affect the maintenance of genetic variation in a virus population and the prevalence of mixed-strain infections, thereby ultimately determining the strength with which different random forces act during evolution. Here we consider different approaches for estimating bottleneck sizes and weigh their merits. We then review quantitative estimates of bottleneck size during cellular infection, within-host spread, horizontal transmission, and finally vertical transmission. In most cases we find that bottlenecks do regularly occur, although in many cases they appear to be virion-concentration dependent. Finally, we consider the evolutionary implications of genetic bottlenecks during virus infection. Although on average strong bottlenecks will lead to declines in fitness, we consider a number of scenarios in which bottlenecks could also be advantageous for viruses.
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Affiliation(s)
- Mark P Zwart
- Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-Universidad Politècnica de València, 46022 València, Spain; .,Institute of Theoretical Physics, University of Cologne, 50937 Cologne, Germany;
| | - Santiago F Elena
- Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-Universidad Politècnica de València, 46022 València, Spain; .,The Santa Fe Institute, Santa Fe, New Mexico 87501
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20
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Grubaugh ND, Rückert C, Armstrong PM, Bransfield A, Anderson JF, Ebel GD, Brackney DE. Transmission bottlenecks and RNAi collectively influence tick-borne flavivirus evolution. Virus Evol 2016; 2:vew033. [PMID: 28058113 PMCID: PMC5210029 DOI: 10.1093/ve/vew033] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Arthropod-borne RNA viruses exist within hosts as heterogeneous populations of viral variants and, as a result, possess great genetic plasticity. Understanding the micro-evolutionary forces shaping these viruses can provide insights into how they emerge, adapt, and persist in new and changing ecological niches. While considerable attention has been directed toward studying the population dynamics of mosquito-borne viruses, little is known about tick-borne virus populations. Therefore, using a mouse and Ixodes scapularis tick transmission model, we examined Powassan virus (POWV; Flaviviridae, Flavivirus) populations in and between both the vertebrate host and arthropod vector. We found that genetic bottlenecks, RNAi-mediated diversification, and selective constraints collectively influence POWV evolution. Together, our data provide a mechanistic explanation for the slow, long-term evolutionary trends of POWV, and suggest that all arthropod-borne viruses encounter similar selective pressures at the molecular level (i.e. RNAi), yet evolve much differently due to their unique rates and modes of transmission.
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Affiliation(s)
- Nathan D Grubaugh
- Department of Microbiology Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Fort Collins, CO, USA
| | - Claudia Rückert
- Department of Microbiology Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Fort Collins, CO, USA
| | - Philip M Armstrong
- The Connecticut Agricultural Experiment Station, Center for Vector Biology and Zoonotic Diseases, New Haven, CT, USA
| | - Angela Bransfield
- The Connecticut Agricultural Experiment Station, Center for Vector Biology and Zoonotic Diseases, New Haven, CT, USA
| | - John F Anderson
- The Connecticut Agricultural Experiment Station, Center for Vector Biology and Zoonotic Diseases, New Haven, CT, USA
| | - Gregory D Ebel
- Department of Microbiology Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Fort Collins, CO, USA
| | - Doug E Brackney
- The Connecticut Agricultural Experiment Station, Center for Vector Biology and Zoonotic Diseases, New Haven, CT, USA
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21
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Lequime S, Fontaine A, Ar Gouilh M, Moltini-Conclois I, Lambrechts L. Genetic Drift, Purifying Selection and Vector Genotype Shape Dengue Virus Intra-host Genetic Diversity in Mosquitoes. PLoS Genet 2016; 12:e1006111. [PMID: 27304978 PMCID: PMC4909269 DOI: 10.1371/journal.pgen.1006111] [Citation(s) in RCA: 97] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Accepted: 05/17/2016] [Indexed: 01/15/2023] Open
Abstract
Due to their error-prone replication, RNA viruses typically exist as a diverse population of closely related genomes, which is considered critical for their fitness and adaptive potential. Intra-host demographic fluctuations that stochastically reduce the effective size of viral populations are a challenge to maintaining genetic diversity during systemic host infection. Arthropod-borne viruses (arboviruses) traverse several anatomical barriers during infection of their arthropod vectors that are believed to impose population bottlenecks. These anatomical barriers have been associated with both maintenance of arboviral genetic diversity and alteration of the variant repertoire. Whether these patterns result from stochastic sampling (genetic drift) rather than natural selection, and/or from the influence of vector genetic heterogeneity has not been elucidated. Here, we used deep sequencing of full-length viral genomes to monitor the intra-host evolution of a wild-type dengue virus isolate during infection of several mosquito genetic backgrounds. We estimated a bottleneck size ranging from 5 to 42 founding viral genomes at initial midgut infection, irrespective of mosquito genotype, resulting in stochastic reshuffling of the variant repertoire. The observed level of genetic diversity increased following initial midgut infection but significantly differed between mosquito genetic backgrounds despite a similar initial bottleneck size. Natural selection was predominantly negative (purifying) during viral population expansion. Taken together, our results indicate that dengue virus intra-host genetic diversity in the mosquito vector is shaped by genetic drift and purifying selection, and point to a novel role for vector genetic factors in the genetic breadth of virus populations during infection. Identifying the evolutionary forces acting on arboviral populations within their arthropod vector provides novel insights into arbovirus evolution. During infection of their arthropod vectors, arthropod-borne viruses (arboviruses) such as dengue viruses traverse several anatomical barriers that are believed to cause dramatic reductions in population size. Such population bottlenecks challenge the maintenance of viral genetic diversity, which is considered critical for fitness and adaptability of arboviruses. Anatomical barriers in the vector were previously associated with both maintenance of arboviral genetic diversity and alteration of the variant repertoire. However, the relative role of random processes and natural selection, and the influence of vector genetic heterogeneity have not been elucidated. In this study, we used high-throughput sequencing to monitor dengue virus genetic diversity during infection of several genetic backgrounds of their mosquito vector. Our results show that initial infection of the vector is randomly founded by only a few tens of individual virus genomes. The overall level of viral genetic diversity generated during infection was predominantly under purifying selection but differed significantly between mosquito genetic backgrounds. Thus, in addition to random evolutionary forces and the purging of deleterious mutations that shape dengue virus genetic diversity during vector infection, our results also point to a novel role for vector genetic factors in the genetic breadth of virus populations.
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Affiliation(s)
- Sebastian Lequime
- Insect-Virus Interactions Group, Department of Genomes and Genetics, Institut Pasteur, Paris, France
- Centre National de la Recherche Scientifique, Unité de Recherche Associée 3012, Paris, France
- Université Pierre et Marie Curie, Cellule Pasteur UPMC, Paris, France
- * E-mail: (SL); (LL)
| | - Albin Fontaine
- Insect-Virus Interactions Group, Department of Genomes and Genetics, Institut Pasteur, Paris, France
- Centre National de la Recherche Scientifique, Unité de Recherche Associée 3012, Paris, France
- Equipe Résidente de Recherche d’Infectiologie Tropicale, Division Expertise, Institut de Recherche Biomédicale des Armées, Brétigny-sur-Orge, France
| | - Meriadeg Ar Gouilh
- Unité Environnement et Risques Infectieux, Cellule d’Intervention Biologique d’Urgence, Department of Infection and Epidemiology, Institut Pasteur, Paris, France
- EA4655, Unité Risques Microbiens U2RM, Université de Caen Normandie, Caen, France
| | - Isabelle Moltini-Conclois
- Insect-Virus Interactions Group, Department of Genomes and Genetics, Institut Pasteur, Paris, France
- Centre National de la Recherche Scientifique, Unité de Recherche Associée 3012, Paris, France
| | - Louis Lambrechts
- Insect-Virus Interactions Group, Department of Genomes and Genetics, Institut Pasteur, Paris, France
- Centre National de la Recherche Scientifique, Unité de Recherche Associée 3012, Paris, France
- * E-mail: (SL); (LL)
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22
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Thébaud G, Michalakis Y. Comment on "Large Bottleneck Size in Cauliflower Mosaic Virus Populations during Host Plant Colonization" by Monsion et al. (2008). PLoS Pathog 2016; 12:e1005512. [PMID: 27078639 PMCID: PMC4831687 DOI: 10.1371/journal.ppat.1005512] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Accepted: 02/29/2016] [Indexed: 11/18/2022] Open
Affiliation(s)
- Gaël Thébaud
- INRA, UMR 385 BGPI, Montpellier, France
- * E-mail:
| | - Yannis Michalakis
- MIVEGEC, UMR 5290 CNRS IRD Université de Montpellier, Montpellier, France
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23
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Grubaugh ND, Weger-Lucarelli J, Murrieta RA, Fauver JR, Garcia-Luna SM, Prasad AN, Black WC, Ebel GD. Genetic Drift during Systemic Arbovirus Infection of Mosquito Vectors Leads to Decreased Relative Fitness during Host Switching. Cell Host Microbe 2016; 19:481-92. [PMID: 27049584 DOI: 10.1016/j.chom.2016.03.002] [Citation(s) in RCA: 106] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Revised: 02/19/2016] [Accepted: 03/07/2016] [Indexed: 11/30/2022]
Abstract
The emergence of mosquito-borne RNA viruses, such as West Nile virus (WNV), is facilitated by genetically complex virus populations within hosts. Here, we determine whether WNV enzootic (Culex tarsalis, Cx. quinquefasciatus, and Cx. pipiens) and bridge vectors (Aedes aegypti) have differential impacts on viral mutational diversity and fitness. During systemic mosquito infection, WNV faced stochastic reductions in genetic diversity that rapidly was recovered during intra-tissue population expansions. Interestingly, this intrahost selection and diversification was mosquito species dependent with Cx. tarsalis and Cx. quinquefasciatus exhibiting greater WNV divergence. However, recovered viral populations contained a preponderance of potentially deleterious mutations (i.e., high mutational load) and had lower relative fitness in avian cells compared to input virus. These findings demonstrate that the adaptive potential associated with mosquito transmission varies depending on the mosquito species and carries a significant fitness cost in vertebrates.
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Affiliation(s)
- Nathan D Grubaugh
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - James Weger-Lucarelli
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - Reyes A Murrieta
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - Joseph R Fauver
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - Selene M Garcia-Luna
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - Abhishek N Prasad
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - William C Black
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - Gregory D Ebel
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA.
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24
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Random Plant Viral Variants Attain Temporal Advantages During Systemic Infections and in Turn Resist other Variants of the Same Virus. Sci Rep 2015; 5:15346. [PMID: 26481091 PMCID: PMC4612314 DOI: 10.1038/srep15346] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Accepted: 09/22/2015] [Indexed: 01/19/2023] Open
Abstract
Infection of plants with viruses containing multiple variants frequently leads to dominance by a few random variants in the systemically infected leaves (SLs), for which a plausible explanation is lacking. We show here that SL dominance by a given viral variant is adequately explained by its fortuitous lead in systemic spread, coupled with its resistance to superinfection by other variants. We analyzed the fate of a multi-variant turnip crinkle virus (TCV) population in Arabidopsis and N. benthamiana plants. Both wild-type and RNA silencing-defective plants displayed a similar pattern of random dominance by a few variant genotypes, thus discounting a prominent role for RNA silencing. When introduced to plants sequentially as two subpopulations, a twelve-hour head-start was sufficient for the first set to dominate. Finally, SLs of TCV-infected plants became highly resistant to secondary invasions of another TCV variant. We propose that random distribution of variant foci on inoculated leaves allows different variants to lead systemic movement in different plants. The leading variants then colonize large areas of SLs, and resist the superinfection of lagging variants in the same areas. In conclusion, superinfection resistance is the primary driver of random enrichment of viral variants in systemically infected plants.
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Abel S, Abel zur Wiesch P, Davis BM, Waldor MK. Analysis of Bottlenecks in Experimental Models of Infection. PLoS Pathog 2015; 11:e1004823. [PMID: 26066486 PMCID: PMC4465827 DOI: 10.1371/journal.ppat.1004823] [Citation(s) in RCA: 89] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Affiliation(s)
- Sören Abel
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts, United States of America
- Division of Infectious Diseases, Brigham & Women’s Hospital, Boston, Massachusetts, United States of America
- Department of Pharmacy, University of Tromsø (UiT), The Arctic University of Norway, Tromsø, Norway
- * E-mail: (SA); (MKW)
| | - Pia Abel zur Wiesch
- Department of Pharmacy, University of Tromsø (UiT), The Arctic University of Norway, Tromsø, Norway
- Division of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, Connecticut, United States of America
| | - Brigid M. Davis
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts, United States of America
- Division of Infectious Diseases, Brigham & Women’s Hospital, Boston, Massachusetts, United States of America
| | - Matthew K. Waldor
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts, United States of America
- Division of Infectious Diseases, Brigham & Women’s Hospital, Boston, Massachusetts, United States of America
- Howard Hughes Medical Institute, Boston, Massachusetts, United States of America
- * E-mail: (SA); (MKW)
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Demographics of natural oral infection of mosquitos by Venezuelan equine encephalitis virus. J Virol 2015; 89:4020-2. [PMID: 25589654 DOI: 10.1128/jvi.03265-14] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The within-host diversity of virus populations can be drastically limited during between-host transmission, with primary infection of hosts representing a major constraint to diversity maintenance. However, there is an extreme paucity of quantitative data on the demographic changes experienced by virus populations during primary infection. Here, the multiplicity of cellular infection (MOI) and population bottlenecks were quantified during primary mosquito infection by Venezuelan equine encephalitis virus, an arbovirus causing neurological disease in humans and equids.
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Human cytomegalovirus intrahost evolution-a new avenue for understanding and controlling herpesvirus infections. Curr Opin Virol 2014; 8:109-15. [PMID: 25154343 DOI: 10.1016/j.coviro.2014.08.001] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Revised: 07/31/2014] [Accepted: 08/02/2014] [Indexed: 01/31/2023]
Abstract
Human cytomegalovirus (HCMV) is exquisitely adapted to the human host, and much research has focused on its evolution over long timescales spanning millennia. Here, we review recent data exploring the evolution of the virus on much shorter timescales, on the order of days or months. We describe the intrahost genetic diversity of the virus isolated from humans, and how this diversity contributes to HCMV spatiotemporal evolution. We propose mechanisms to explain the high levels of intrahost diversity and discuss how this new information may shed light on HCMV infection and pathogenesis.
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Abstract
Viruses are common agents of plant infectious diseases. During last decades, worldwide agriculture production has been compromised by a series of epidemics caused by new viruses that spilled over from reservoir species or by new variants of classic viruses that show new pathogenic and epidemiological properties. Virus emergence has been generally associated with ecological change or with intensive agronomical practices. However, the complete picture is much more complex since the viral populations constantly evolve and adapt to their new hosts and vectors. This chapter puts emergence of plant viruses into the framework of evolutionary ecology, genetics, and epidemiology. We will stress that viral emergence begins with the stochastic transmission of preexisting genetic variants from the reservoir to the new host, whose fate depends on their fitness on each hosts, followed by adaptation to new hosts or vectors, and finalizes with an efficient epidemiological spread.
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Affiliation(s)
- Santiago F Elena
- Instituto de Biología Molecular y Celular de Plantas, CSIC-UPV, Campus UPV, València, Spain; The Santa Fe Institute, Santa Fe, New Mexico, USA
| | - Aurora Fraile
- Centro de Biotecnología y Genómica de Plantas, UPM-INIA, and ETSI Agrónomos, UPM, Campus de Montegancedo, Madrid, Spain
| | - Fernando García-Arenal
- Centro de Biotecnología y Genómica de Plantas, UPM-INIA, and ETSI Agrónomos, UPM, Campus de Montegancedo, Madrid, Spain.
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Tromas N, Zwart MP, Lafforgue G, Elena SF. Within-host spatiotemporal dynamics of plant virus infection at the cellular level. PLoS Genet 2014; 10:e1004186. [PMID: 24586207 PMCID: PMC3937225 DOI: 10.1371/journal.pgen.1004186] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2013] [Accepted: 01/06/2014] [Indexed: 11/27/2022] Open
Abstract
A multicellular organism is not a monolayer of cells in a flask; it is a complex, spatially structured environment, offering both challenges and opportunities for viruses to thrive. Whereas virus infection dynamics at the host and within-cell levels have been documented, the intermediate between-cell level remains poorly understood. Here, we used flow cytometry to measure the infection status of thousands of individual cells in virus-infected plants. This approach allowed us to determine accurately the number of cells infected by two virus variants in the same host, over space and time as the virus colonizes the host. We found a low overall frequency of cellular infection (<0.3), and few cells were coinfected by both virus variants (<0.1). We then estimated the cellular contagion rate (R), the number of secondary infections per infected cell per day. R ranged from 2.43 to values not significantly different from zero, and generally decreased over time. Estimates of the cellular multiplicity of infection (MOI), the number of virions infecting a cell, were low (<1.5). Variance of virus-genotype frequencies increased strongly from leaf to cell levels, in agreement with a low MOI. Finally, there were leaf-dependent differences in the ease with which a leaf could be colonized, and the number of virions effectively colonizing a leaf. The modeling of infection patterns suggests that the aggregation of virus-infected cells plays a key role in limiting spread; matching the observation that cell-to-cell movement of plant viruses can result in patches of infection. Our results show that virus expansion at the between-cell level is restricted, probably due to the host environment and virus infection itself.
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Affiliation(s)
- Nicolas Tromas
- Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-UPV, València, Spain
| | - Mark P. Zwart
- Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-UPV, València, Spain
| | - Guillaume Lafforgue
- Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-UPV, València, Spain
| | - Santiago F. Elena
- Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-UPV, València, Spain
- The Santa Fe Institute, Santa Fe, New Mexico, United States of America
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The temporal evolution and global spread of Cauliflower mosaic virus, a plant pararetrovirus. PLoS One 2014; 9:e85641. [PMID: 24465629 PMCID: PMC3897471 DOI: 10.1371/journal.pone.0085641] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Accepted: 12/02/2013] [Indexed: 11/29/2022] Open
Abstract
Cauliflower mosaic virus (CaMV) is a plant pararetrovirus with a double-stranded DNA genome. It is the type member of the genus Caulimovirus in the family Caulimoviridae. CaMV is transmitted by sap inoculation and in nature by aphids in a semi-persistent manner. To investigate the patterns and timescale of CaMV migration and evolution, we sequenced and analyzed the genomes of 67 isolates of CaMV collected mostly in Greece, Iran, Turkey, and Japan together with nine published sequences. We identified the open-reading frames (ORFs) in the genomes and inferred their phylogeny. After removing recombinant sequences, we estimated the substitution rates, divergence times, and phylogeographic patterns of the virus populations. We found that recombination has been a common feature of CaMV evolution, and that ORFs I–V have a different evolutionary history from ORF VI. The ORFs have evolved at rates between 1.71 and 5.81×10−4 substitutions/site/year, similar to those of viruses with RNA or ssDNA genomes. We found four geographically confined lineages. CaMV probably spread from a single population to other parts of the world around 400–500 years ago, and is now widely distributed among Eurasian countries. Our results revealed evidence of frequent gene flow between populations in Turkey and those of its neighboring countries, with similar patterns observed for Japan and the USA. Our study represents the first report on the spatial and temporal spread of a plant pararetrovirus.
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Epstein-Barr virus latent membrane protein 1 genetic variability in peripheral blood B cells and oropharyngeal fluids. J Virol 2014; 88:3744-55. [PMID: 24429365 DOI: 10.1128/jvi.03378-13] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
UNLABELLED We report the diversity of latent membrane protein 1 (LMP1) gene founder sequences and the level of Epstein-Barr virus (EBV) genome variability over time and across anatomic compartments by using virus genomes amplified directly from oropharyngeal wash specimens and peripheral blood B cells during acute infection and convalescence. The intrahost nucleotide variability of the founder virus was 0.02% across the region sequences, and diversity increased significantly over time in the oropharyngeal compartment (P = 0.004). The LMP1 region showing the greatest level of variability in both compartments, and over time, was concentrated within the functional carboxyl-terminal activating regions 2 and 3 (CTAR2 and CTAR3). Interestingly, a deletion in a proline-rich repeat region (amino acids 274 to 289) of EBV commonly reported in EBV sequenced from cancer specimens was not observed in acute infectious mononucleosis (AIM) patients. Taken together, these data highlight the diversity in circulating EBV genomes and its potential importance in disease pathogenesis and vaccine design. IMPORTANCE This study is among the first to leverage an improved high-throughput deep-sequencing methodology to investigate directly from patient samples the degree of diversity in Epstein-Barr virus (EBV) populations and the extent to which viral genome diversity develops over time in the infected host. Significant variability of circulating EBV latent membrane protein 1 (LMP1) gene sequences was observed between cellular and oral wash samples, and this variability increased over time in oral wash samples. The significance of EBV genetic diversity in transmission and disease pathogenesis are discussed.
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Fabre F, Moury B, Johansen EI, Simon V, Jacquemond M, Senoussi R. Narrow bottlenecks affect Pea seedborne mosaic virus populations during vertical seed transmission but not during leaf colonization. PLoS Pathog 2014; 10:e1003833. [PMID: 24415934 PMCID: PMC3887104 DOI: 10.1371/journal.ppat.1003833] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Accepted: 10/29/2013] [Indexed: 11/19/2022] Open
Abstract
The effective size of populations (Ne) determines whether selection or genetic drift is the predominant force shaping their genetic structure and evolution. Populations having high Ne adapt faster, as selection acts more intensely, than populations having low Ne, where random effects of genetic drift dominate. Estimating Ne for various steps of plant virus life cycle has been the focus of several studies in the last decade, but no estimates are available for the vertical transmission of plant viruses, although virus seed transmission is economically significant in at least 18% of plant viruses in at least one plant species. Here we study the co-dynamics of two variants of Pea seedborne mosaic virus (PSbMV) colonizing leaves of pea plants (Pisum sativum L.) during the whole flowering period, and their subsequent transmission to plant progeny through seeds. Whereas classical estimators of Ne could be used for leaf infection at the systemic level, as virus variants were equally competitive, dedicated stochastic models were needed to estimate Ne during vertical transmission. Very little genetic drift was observed during the infection of apical leaves, with Ne values ranging from 59 to 216. In contrast, a very drastic genetic drift was observed during vertical transmission, with an average number of infectious virus particles contributing to the infection of a seedling from an infected mother plant close to one. A simple model of vertical transmission, assuming a cumulative action of virus infectious particles and a virus density threshold required for vertical transmission to occur fitted the experimental data very satisfactorily. This study reveals that vertically-transmitted viruses endure bottlenecks as narrow as those imposed by horizontal transmission. These bottlenecks are likely to slow down virus adaptation and could decrease virus fitness and virulence.
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Affiliation(s)
- Frédéric Fabre
- INRA, UR407 Pathologie Végétale, Domaine Saint Maurice, Montfavet, France
| | - Benoît Moury
- INRA, UR407 Pathologie Végétale, Domaine Saint Maurice, Montfavet, France
| | - Elisabeth Ida Johansen
- University of Copenhagen, Department of Plant and Environmental Sciences, Frederiksberg C, Denmark
| | - Vincent Simon
- INRA, UR407 Pathologie Végétale, Domaine Saint Maurice, Montfavet, France
| | | | - Rachid Senoussi
- INRA, UR546 Biostatistique et Processus Spatiaux, Domaine Saint-Paul, Site Agroparc, Avignon, France
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A phylogeographical study of the cauliflower mosaic virus population in mid-Eurasia Iran using complete genome analysis. Arch Virol 2013; 159:1329-40. [PMID: 24343265 DOI: 10.1007/s00705-013-1910-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Accepted: 10/26/2013] [Indexed: 10/25/2022]
Abstract
The full-length sequences of 34 Iranian cauliflower mosaic virus (CaMV) isolates were compared with others from public nucleotide sequence databases to provide a comprehensive overview of the genetic variability and patterns of genetic exchange in CaMV isolates from Iran. Based on the severity of symptoms and their ability to infect Brassica oleracea var. capitata, Iranian CaMV isolates were grouped into two distinct biotypes: latent/mild mottle (LI/MMo) and severe (S) infection. Recombination breakpoints were detected between the large intergenic region (LIR) and open reading frame (ORF) V (event 2); between ORF VII and ORF II (event 3), between ORF I and ORF III (event 4), and within ORF VI (event 1). Phylogenetic analysis indicated that Iranian CaMV isolates clustered into two subgroups belonging to group I (GI) that were distinct from North American and European isolates from group II (GII). Northeast Iranian isolates (subgroup B) and CaMV isolates from subgroup A closely corresponded to the S and LI/MMo biological groups, respectively. Genome-wide pairwise identity analysis of the CaMV isolates revealed three regions of pairwise identity representation: 92-94 % for GII and 94-96 % and 98-100 % for subgroups A and B. The within-population diversity was lower than the between-population diversity, suggesting the contribution of a founder effect on diversification of CaMV isolates. Amino acid sequences were conserved, with ω values ranging from 0.074 to 0.717 in different proteins. Thirteen amino acids in the deduced proteins of ORFs I, II, III, VI and VII were under positive selection (ω > 1), whereas purifying selection applied to the proteins encoded by ORFs IV and V. This study suggests that variation in the CaMV population can be explained by host-range differentiation and selection pressure. Moreover, recombination analysis revealed that a genomic exchange is responsible for the emergence of CaMV strains, providing valuable new information for understanding the diversity and evolution of caulimoviruses.
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34
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Majer E, Daròs JA, Zwart MP. Stability and fitness impact of the visually discernible Rosea1 marker in the Tobacco etch virus genome. Viruses 2013; 5:2153-68. [PMID: 24022073 PMCID: PMC3798895 DOI: 10.3390/v5092153] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Revised: 08/26/2013] [Accepted: 08/29/2013] [Indexed: 11/24/2022] Open
Abstract
Antirrhinum majus Rosea1 (Ros1) is an MYB-related transcription factor that induces anthocyanin biosynthesis in plant tissues, and has been shown to be suitable for visual tracking of virus infection in plants. However, activation of anthocyanin biosynthesis has far reaching effects on plant physiology and could consequently have negative effects on viral replication. Therefore, viruses carrying the Ros1 marker might have a low fitness and consequently rapidly lose the marker. To compare the stability of the Ros1 marker, we generated Tobacco etch virus (TEV) based constructs containing either Ros1 or the enhanced green fluorescent protein (eGFP) between the NIb and CP cistrons (TEV-Ros1 and TEV-eGFP, respectively). We measured the within-host competitive fitness of both viruses by direct competitions with a common competitor during infection of Nicotiana tabacum. The fitness of TEV-Ros1 was significantly lower than that of TEV-eGFP, and both recombinant viruses had a significantly lower fitness than the wild-type virus. Nevertheless, after seven weeks of infection in N. tabacum, similar levels of marker gene instability where found for both viruses. Despite lower fitness of the marked virus, Ros1 is therefore a viable alternative marker for tracking viral infection in plants.
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Affiliation(s)
| | | | - Mark P. Zwart
- Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-Universidad Politécnica de Valencia, Ingeniero Fausto Elio s/n, 46022 València, Spain; E-Mails: (E.M.); (J.-A.D.)
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35
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Urbino C, Gutiérrez S, Antolik A, Bouazza N, Doumayrou J, Granier M, Martin DP, Peterschmitt M. Within-host dynamics of the emergence of Tomato yellow leaf curl virus recombinants. PLoS One 2013; 8:e58375. [PMID: 23472190 PMCID: PMC3589402 DOI: 10.1371/journal.pone.0058375] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2012] [Accepted: 02/04/2013] [Indexed: 11/18/2022] Open
Abstract
Tomato yellow leaf curl virus (TYLCV) is a highly damaging begomovirus native to the Middle East. TYLCV has recently spread worldwide, recombining with other begomoviruses. Recent analysis of mixed infections between TYLCV and Tomato leaf curl Comoros begomovirus (ToLCKMV) has shown that, although natural selection preserves certain co-evolved intra-genomic interactions, numerous and diverse recombinants are produced at 120 days post-inoculation (dpi), and recombinant populations from different tomato plants are very divergent. Here, we investigate the population dynamics that lead to such patterns in tomato plants co-infected with TYLCV and ToLCKMV either by agro-inoculation or using the natural whitefly vector Bemisia tabaci. We monitored the frequency of parental and recombinant genotypes independently in 35 plants between 18 and 330 dpi and identified 177 recombinants isolated at different times. Recombinants were detected from 18 dpi and their frequency increased over time to reach about 50% at 150 dpi regardless of the inoculation method. The distribution of breakpoints detected on 96 fully sequenced recombinants was consistent with a continuous generation of new recombinants as well as random and deterministic effects in their maintenance. A severe population bottleneck of around 10 genomes was estimated during early systemic infection–a phenomenon that could account partially for the heterogeneity in recombinant patterns observed among plants. The detection of the same recombinant genome in six of the thirteen plants analysed beyond 30 dpi supported the influence of selection on observed recombination patterns. Moreover, a highly virulent recombinant genotype dominating virus populations within one plant has, apparently, the potential to be maintained in the natural population according to its infectivity, within-host accumulation, and transmission efficiency - all of which were similar or intermediate to those of the parent genotypes. Our results anticipate the outcomes of natural encounters between TYLCV and ToLCKMV.
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36
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Lafforgue G, Tromas N, Elena SF, Zwart MP. Dynamics of the establishment of systemic Potyvirus infection: independent yet cumulative action of primary infection sites. J Virol 2012; 86:12912-22. [PMID: 22993154 PMCID: PMC3497618 DOI: 10.1128/jvi.02207-12] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2012] [Accepted: 09/11/2012] [Indexed: 11/20/2022] Open
Abstract
In the clinic, farm, or field, for many viruses there is a high prevalence of mixed-genotype infections, indicating that multiple virions have initiated infection and that there can be multiple sites of primary infection within the same host. The dynamic process by which multiple primary infection sites interact with each other and the host is poorly understood, undoubtedly due to its high complexity. In this study, we attempted to unravel the basic interactions underlying this process using a plant RNA virus, as removing the inoculated leaf can instantly and rigorously eliminate all primary infection sites. Effective population size in the inoculated leaf and time of removal of the inoculated leaf were varied in experiments, and it was found that both factors positively influenced if the plant became systemically infected and what proportion of cells in the systemic tissue were infected, as measured by flow cytometry. Fitting of probabilistic models of infection to our data demonstrated that a null model in which the action of each focus is independent of the presence of other foci was better supported than a dependent-action model. The cumulative effect of independently acting foci therefore determined when plants became infected and how many individual cells were infected. There was no evidence for interference between primary infection sites, which is surprising given the planar structure of leaves. By showing that a simple null model is supported, we experimentally confirmed--to our knowledge for the first time--the minimal components that dictate interactions of a conspecific virus population establishing systemic infection.
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Affiliation(s)
- Guillaume Lafforgue
- Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-UPV, València, Spain
| | - Nicolas Tromas
- Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-UPV, València, Spain
| | - Santiago F. Elena
- Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-UPV, València, Spain
- The Santa Fe Institute, Santa Fe, New Mexico, USA
| | - Mark P. Zwart
- Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-UPV, València, Spain
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Circulating virus load determines the size of bottlenecks in viral populations progressing within a host. PLoS Pathog 2012; 8:e1003009. [PMID: 23133389 PMCID: PMC3486874 DOI: 10.1371/journal.ppat.1003009] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2012] [Accepted: 09/19/2012] [Indexed: 01/07/2023] Open
Abstract
For any organism, population size, and fluctuations thereof, are of primary importance in determining the forces driving its evolution. This is particularly true for viruses--rapidly evolving entities that form populations with transient and explosive expansions alternating with phases of migration, resulting in strong population bottlenecks and associated founder effects that increase genetic drift. A typical illustration of this pattern is the progression of viral disease within a eukaryotic host, where such demographic fluctuations are a key factor in the emergence of new variants with altered virulence. Viruses initiate replication in one or only a few infection foci, then move through the vasculature to seed secondary infection sites and so invade distant organs and tissues. Founder effects during this within-host colonization might depend on the concentration of infectious units accumulating and circulating in the vasculature, as this represents the infection dose reaching new organs or "territories". Surprisingly, whether or not the easily measurable circulating (plasma) virus load directly drives the size of population bottlenecks during host colonization has not been documented in animal viruses, while in plants the virus load within the sap has never been estimated. Here, we address this important question by monitoring both the virus concentration flowing in host plant sap, and the number of viral genomes founding the population in each successive new leaf. Our results clearly indicate that the concentration of circulating viruses directly determines the size of bottlenecks, which hence controls founder effects and effective population size during disease progression within a host.
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38
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Gutiérrez S, Michalakis Y, Blanc S. Virus population bottlenecks during within-host progression and host-to-host transmission. Curr Opin Virol 2012; 2:546-55. [DOI: 10.1016/j.coviro.2012.08.001] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2012] [Accepted: 08/01/2012] [Indexed: 12/11/2022]
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Forrester NL, Guerbois M, Seymour RL, Spratt H, Weaver SC. Vector-borne transmission imposes a severe bottleneck on an RNA virus population. PLoS Pathog 2012; 8:e1002897. [PMID: 23028310 PMCID: PMC3441635 DOI: 10.1371/journal.ppat.1002897] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2011] [Accepted: 07/25/2012] [Indexed: 11/28/2022] Open
Abstract
RNA viruses typically occur in genetically diverse populations due to their error-prone genome replication. Genetic diversity is thought to be important in allowing RNA viruses to explore sequence space, facilitating adaptation to changing environments and hosts. Some arboviruses that infect both a mosquito vector and a mammalian host are known to experience population bottlenecks in their vectors, which may constrain their genetic diversity and could potentially lead to extinction events via Muller's ratchet. To examine this potential challenge of bottlenecks for arbovirus perpetuation, we studied Venezuelan equine encephalitis virus (VEEV) enzootic subtype IE and its natural vector Culex (Melanoconion) taeniopus, as an example of a virus-vector interaction with a long evolutionary history. Using a mixture of marked VEEV clones to infect C. taeniopus and real-time RT-PCR to track these clones during mosquito infection and dissemination, we observed severe bottleneck events that resulted in a significant drop in the number of clones present. At higher initial doses, the midgut was readily infected and there was a severe bottleneck at the midgut escape. Following a lower initial dose, the major bottleneck occurred at initial midgut infection. A second, less severe bottleneck was identified at the salivary gland infection stage following intrathoracic inoculation. Our results suggest that VEEV consistently encounters bottlenecks during infection, dissemination and transmission by its natural enzootic vector. The potential impacts of these bottlenecks on viral fitness and transmission, and the viral mechanisms that prevent genetic drift leading to extinction, deserve further study. The ability of arboviruses to perpetuate in nature given that they must infect two disparate hosts (the mosquito vector and the vertebrate host) remains a mystery. We studied how viral genetic diversity is impacted by the dual host transmission cycle. Our studies of an enzootic cycle using Venezuelan equine encephalitis virus (VEEV) and its natural mosquito, Culex taeniopus, revealed the stages of infection that result in a viral population bottleneck. Using a set of marked VEEV clones and repeated sampling at various time points following C. taeniopus infection, we determined the number of clones in various mosquito tissues culminating in transmission. Bottlenecks were identified but the stage of occurrence was dependent on the dose that initiated infection. Understanding the points at which mosquito-borne viruses are constrained will shed light on the ways in which virus diversity varies, leading to selection of mutants that may result in host range changes or alterations in virulence.
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Affiliation(s)
- Naomi L. Forrester
- Institute for Human Infections and Immunity, Center for Biodefense and Emerging Infectious Diseases and Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Mathilde Guerbois
- Institute for Human Infections and Immunity, Center for Biodefense and Emerging Infectious Diseases and Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Robert L. Seymour
- Institute for Human Infections and Immunity, Center for Biodefense and Emerging Infectious Diseases and Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Heidi Spratt
- Sealy Center for Preventative Medicine and Preventative Medicine and Community Health, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Scott C. Weaver
- Institute for Human Infections and Immunity, Center for Biodefense and Emerging Infectious Diseases and Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
- * E-mail:
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40
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Fabre F, Montarry J, Coville J, Senoussi R, Simon V, Moury B. Modelling the evolutionary dynamics of viruses within their hosts: a case study using high-throughput sequencing. PLoS Pathog 2012; 8:e1002654. [PMID: 22532800 PMCID: PMC3330117 DOI: 10.1371/journal.ppat.1002654] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Accepted: 03/07/2012] [Indexed: 02/04/2023] Open
Abstract
Uncovering how natural selection and genetic drift shape the evolutionary dynamics of virus populations within their hosts can pave the way to a better understanding of virus emergence. Mathematical models already play a leading role in these studies and are intended to predict future emergences. Here, using high-throughput sequencing, we analyzed the within-host population dynamics of four Potato virus Y (PVY) variants differing at most by two substitutions involved in pathogenicity properties. Model selection procedures were used to compare experimental results to six hypotheses regarding competitiveness and intensity of genetic drift experienced by viruses during host plant colonization. Results indicated that the frequencies of variants were well described using Lotka-Volterra models where the competition coefficients β(ij) exerted by variant j on variant i are equal to their fitness ratio, r(j)/r(i). Statistical inference allowed the estimation of the effect of each mutation on fitness, revealing slight (s = -0.45%) and high (s = -13.2%) fitness costs and a negative epistasis between them. Results also indicated that only 1 to 4 infectious units initiated the population of one apical leaf. The between-host variances of the variant frequencies were described using Dirichlet-multinomial distributions whose scale parameters, closely related to the fixation index F(ST), were shown to vary with time. The genetic differentiation of virus populations among plants increased from 0 to 10 days post-inoculation and then decreased until 35 days. Overall, this study showed that mathematical models can accurately describe both selection and genetic drift processes shaping the evolutionary dynamics of viruses within their hosts.
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Abstract
Comparing to natural ecosystems, the evolution of plant pathogens in agricultural ecosystems is generally faster due to high-density monocultures, large-scale application of agrochemicals, and international trade in agricultural products. Knowledge of the population genetics and evolutionary biology of plant pathogens is necessary to understand disease epidemiology, effectively breed and use resistant cultivars, and control plant diseases. In this article, we outlined the aims of population genetic studies in plant pathogens, discuss contributions of five evolutionary forces (i.e., mutation, gene flow, recombination, random genetic drift, and natural selection) to origin, maintenance, and distribution of genetic variation in time and space, and gave an overview of current research status in this field.
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Affiliation(s)
- Wen Zhu
- Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, China.
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42
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Syller J. Facilitative and antagonistic interactions between plant viruses in mixed infections. MOLECULAR PLANT PATHOLOGY 2012; 13:204-216. [PMID: 21726401 DOI: 10.1111/j.1346-3703.2011.00734.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Mixed infections of plant viruses are common in nature, and a number of important virus diseases of plants are the outcomes of interactions between causative agents. Multiple infections lead to a variety of intrahost virus-virus interactions, many of which may result in the generation of variants showing novel genetic features, and thus change the genetic structure of the viral population. Hence, virus-virus interactions in plants may be of crucial significance for the understanding of viral pathogenesis and evolution, and consequently for the development of efficient and stable control strategies. The interactions between plant viruses in mixed infections are generally categorized as synergistic or antagonistic. Moreover, mixtures of synergistic and antagonistic interactions, creating usually unpredictable biological and epidemiological consequences, are likely to occur in plants. The mechanisms of some of these are still unknown. This review aims to bring together the current knowledge on the most commonly occurring facilitative and antagonistic interactions between related or unrelated viruses infecting the same host plant. The best characterized implications of these interactions for virus-vector-host relationships are included. The terms 'synergism' and 'helper dependence' for facilitative virus-virus interactions, and 'cross-protection' and 'mutual exclusion' for antagonistic interactions, are applied in this article.
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Affiliation(s)
- Jerzy Syller
- Plant Breeding and Acclimatization Institute-National Research Institute, Centre Młochów, 05-831 Młochów, Poland.
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43
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Syller J. Facilitative and antagonistic interactions between plant viruses in mixed infections. MOLECULAR PLANT PATHOLOGY 2012; 13:204-16. [PMID: 21726401 PMCID: PMC6638836 DOI: 10.1111/j.1364-3703.2011.00734.x] [Citation(s) in RCA: 207] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Mixed infections of plant viruses are common in nature, and a number of important virus diseases of plants are the outcomes of interactions between causative agents. Multiple infections lead to a variety of intrahost virus-virus interactions, many of which may result in the generation of variants showing novel genetic features, and thus change the genetic structure of the viral population. Hence, virus-virus interactions in plants may be of crucial significance for the understanding of viral pathogenesis and evolution, and consequently for the development of efficient and stable control strategies. The interactions between plant viruses in mixed infections are generally categorized as synergistic or antagonistic. Moreover, mixtures of synergistic and antagonistic interactions, creating usually unpredictable biological and epidemiological consequences, are likely to occur in plants. The mechanisms of some of these are still unknown. This review aims to bring together the current knowledge on the most commonly occurring facilitative and antagonistic interactions between related or unrelated viruses infecting the same host plant. The best characterized implications of these interactions for virus-vector-host relationships are included. The terms 'synergism' and 'helper dependence' for facilitative virus-virus interactions, and 'cross-protection' and 'mutual exclusion' for antagonistic interactions, are applied in this article.
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Affiliation(s)
- Jerzy Syller
- Plant Breeding and Acclimatization Institute-National Research Institute, Centre Młochów, 05-831 Młochów, Poland.
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44
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Sardanyés J, Elena SF. Quasispecies spatial models for RNA viruses with different replication modes and infection strategies. PLoS One 2011; 6:e24884. [PMID: 21949777 PMCID: PMC3176287 DOI: 10.1371/journal.pone.0024884] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2010] [Accepted: 08/23/2011] [Indexed: 02/04/2023] Open
Abstract
Empirical observations and theoretical studies suggest that viruses may use different replication strategies to amplify their genomes, which impact the dynamics of mutation accumulation in viral populations and therefore, their fitness and virulence. Similarly, during natural infections, viruses replicate and infect cells that are rarely in suspension but spatially organized. Surprisingly, most quasispecies models of virus replication have ignored these two phenomena. In order to study these two viral characteristics, we have developed stochastic cellular automata models that simulate two different modes of replication (geometric vs stamping machine) for quasispecies replicating and spreading on a two-dimensional space. Furthermore, we explored these two replication models considering epistatic fitness landscapes (antagonistic vs synergistic) and different scenarios for cell-to-cell spread, one with free superinfection and another with superinfection inhibition. We found that the master sequences for populations replicating geometrically and with antagonistic fitness effects vanished at low critical mutation rates. By contrast, the highest critical mutation rate was observed for populations replicating geometrically but with a synergistic fitness landscape. Our simulations also showed that for stamping machine replication and antagonistic epistasis, a combination that appears to be common among plant viruses, populations further increased their robustness by inhibiting superinfection. We have also shown that the mode of replication strongly influenced the linkage between viral loci, which rapidly reached linkage equilibrium at increasing mutations for geometric replication. We also found that the strategy that minimized the time required to spread over the whole space was the stamping machine with antagonistic epistasis among mutations. Finally, our simulations revealed that the multiplicity of infection fluctuated but generically increased along time.
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Affiliation(s)
- Josep Sardanyés
- Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas, València, Spain.
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45
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Brackney DE, Pesko KN, Brown IK, Deardorff ER, Kawatachi J, Ebel GD. West Nile virus genetic diversity is maintained during transmission by Culex pipiens quinquefasciatus mosquitoes. PLoS One 2011; 6:e24466. [PMID: 21935412 PMCID: PMC3171416 DOI: 10.1371/journal.pone.0024466] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2011] [Accepted: 08/10/2011] [Indexed: 11/18/2022] Open
Abstract
Due to error-prone replication, RNA viruses exist within hosts as a heterogeneous population of non-identical, but related viral variants. These populations may undergo bottlenecks during transmission that stochastically reduce variability leading to fitness declines. Such bottlenecks have been documented for several single-host RNA viruses, but their role in the population biology of obligate two-host viruses such as arthropod-borne viruses (arboviruses) in vivo is unclear, but of central importance in understanding arbovirus persistence and emergence. Therefore, we tracked the composition of West Nile virus (WNV; Flaviviridae, Flavivirus) populations during infection of the vector mosquito, Culex pipiens quinquefasciatus to determine whether WNV populations undergo bottlenecks during transmission by this host. Quantitative, qualitative and phylogenetic analyses of WNV sequences in mosquito midguts, hemolymph and saliva failed to document reductions in genetic diversity during mosquito infection. Further, migration analysis of individual viral variants revealed that while there was some evidence of compartmentalization, anatomical barriers do not impose genetic bottlenecks on WNV populations. Together, these data suggest that the complexity of WNV populations are not significantly diminished during the extrinsic incubation period of mosquitoes.
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Affiliation(s)
- Doug E. Brackney
- Department of Pathology, University of New Mexico School of Medicine, Albuquerque, New Mexico, United States of America
| | - Kendra N. Pesko
- Department of Pathology, University of New Mexico School of Medicine, Albuquerque, New Mexico, United States of America
| | - Ivy K. Brown
- Department of Pathology, University of New Mexico School of Medicine, Albuquerque, New Mexico, United States of America
| | - Eleanor R. Deardorff
- Department of Pathology, University of New Mexico School of Medicine, Albuquerque, New Mexico, United States of America
| | - Jon Kawatachi
- Department of Pathology, University of New Mexico School of Medicine, Albuquerque, New Mexico, United States of America
| | - Gregory D. Ebel
- Department of Pathology, University of New Mexico School of Medicine, Albuquerque, New Mexico, United States of America
- * E-mail:
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46
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Zwart MP, Daròs JA, Elena SF. One is enough: in vivo effective population size is dose-dependent for a plant RNA virus. PLoS Pathog 2011; 7:e1002122. [PMID: 21750676 PMCID: PMC3131263 DOI: 10.1371/journal.ppat.1002122] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2011] [Accepted: 05/02/2011] [Indexed: 11/19/2022] Open
Abstract
Effective population size (N(e)) determines the strength of genetic drift and the frequency of co-infection by multiple genotypes, making it a key factor in viral evolution. Experimental estimates of N(e) for different plant viruses have, however, rendered diverging results. The independent action hypothesis (IAH) states that each virion has a probability of infection, and that virions act independent of one another during the infection process. A corollary of IAH is that N(e) must be dose dependent. A test of IAH for a plant virus has not been reported yet. Here we perform a test of an IAH infection model using a plant RNA virus, Tobacco etch virus (TEV) variants carrying GFP or mCherry fluorescent markers, in Nicotiana tabacum and Capsicum annuum plants. The number of primary infection foci increased linearly with dose, and was similar to a Poisson distribution. At high doses, primary infection foci containing both genotypes were found at a low frequency (<2%). The probability that a genotype that infected the inoculated leaf would systemically infect that plant was near 1, although in a few rare cases genotypes could be trapped in the inoculated leaf by being physically surrounded by the other genotype. The frequency of mixed-genotype infection could be predicted from the mean number of primary infection foci using the independent-action model. Independent action appears to hold for TEV, and N(e) is therefore dose-dependent for this plant RNA virus. The mean number of virions causing systemic infection can be very small, and approaches 1 at low doses. Dose-dependency in TEV suggests that comparison of N(e) estimates for different viruses are not very meaningful unless dose effects are taken into consideration.
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Affiliation(s)
- Mark P Zwart
- Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-UPV, València, Spain.
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47
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Desbiez C, Moury B, Lecoq H. The hallmarks of "green" viruses: do plant viruses evolve differently from the others? INFECTION GENETICS AND EVOLUTION 2011; 11:812-24. [PMID: 21382520 DOI: 10.1016/j.meegid.2011.02.020] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Revised: 02/22/2011] [Accepted: 02/24/2011] [Indexed: 12/13/2022]
Abstract
All viruses are obligatory parasites that must develop tight interactions with their hosts to complete their infectious cycle. Viruses infecting plants share many structural and functional similarities with those infecting other organisms, particularly animals and fungi. Quantitative data regarding their evolutionary mechanisms--generation of variability by mutation and recombination, changes in populations by selection and genetic drift have been obtained only recently, and appear rather similar to those measured for animal viruses.This review presents an update of our knowledge of the phylogenetic and evolutionary characteristics of plant viruses and their relation to their plant hosts, in comparison with viruses infecting other organisms.
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Affiliation(s)
- C Desbiez
- INRA, Unité de Pathologie Végétale UR407, F-84140 Montfavet, France.
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48
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Elena SF, Bedhomme S, Carrasco P, Cuevas JM, de la Iglesia F, Lafforgue G, Lalić J, Pròsper A, Tromas N, Zwart MP. The evolutionary genetics of emerging plant RNA viruses. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2011; 24:287-93. [PMID: 21294624 DOI: 10.1094/mpmi-09-10-0214] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Over the years, agriculture across the world has been compromised by a succession of devastating epidemics caused by new viruses that spilled over from reservoir species or by new variants of classic viruses that acquired new virulence factors or changed their epidemiological patterns. Viral emergence is usually associated with ecological change or with agronomical practices bringing together reservoirs and crop species. The complete picture is, however, much more complex, and results from an evolutionary process in which the main players are ecological factors, viruses' genetic plasticity, and host factors required for virus replication, all mixed with a good measure of stochasticity. The present review puts emergence of plant RNA viruses into the framework of evolutionary genetics, stressing that viral emergence begins with a stochastic process that involves the transmission of a preexisting viral strain into a new host species, followed by adaptation to the new host.
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Affiliation(s)
- Santiago F Elena
- Instituto de Biologia Molecular, Consejo Superior de Investigaciones Cientificas, Valencia, Spain.
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Gutiérrez S, Yvon M, Thébaud G, Monsion B, Michalakis Y, Blanc S. Dynamics of the multiplicity of cellular infection in a plant virus. PLoS Pathog 2010; 6:e1001113. [PMID: 20862320 PMCID: PMC2940754 DOI: 10.1371/journal.ppat.1001113] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2010] [Accepted: 08/18/2010] [Indexed: 01/22/2023] Open
Abstract
Recombination, complementation and competition profoundly influence virus evolution and epidemiology. Since viruses are intracellular parasites, the basic parameter determining the potential for such interactions is the multiplicity of cellular infection (cellular MOI), i.e. the number of viral genome units that effectively infect a cell. The cellular MOI values that prevail in host organisms have rarely been investigated, and whether they remain constant or change widely during host invasion is totally unknown. Here, we fill this experimental gap by presenting the first detailed analysis of the dynamics of the cellular MOI during colonization of a host plant by a virus. Our results reveal ample variations between different leaf levels during the course of infection, with values starting close to 2 and increasing up to 13 before decreasing to initial levels in the latest infection stages. By revealing wide dynamic changes throughout a single infection, we here illustrate the existence of complex scenarios where the opportunity for recombination, complementation and competition among viral genomes changes greatly at different infection phases and at different locations within a multi-cellular host. Viruses are fast evolving organisms for which changes in fitness and virulence are driven by interactions between genomes such as recombination, functional complementation, and competition. Viruses being intra-cellular parasites, one basic parameter determines the potential for such interactions: the cellular multiplicity of infection (cellular MOI), defined as the number of genome units actually penetrating and co-replicating within individual cells of the host. Despite its importance for virus evolution, this trait has scarcely been investigated. For example, there are only three point estimates for eukaryote-infecting viruses while the possibility that the cellular MOI may vary during the infection or across organs of a given host individual has never been conclusively addressed. By monitoring the cellular MOI in plants infected by the Cauliflower mosaic virus we found remarkably ample variations during the development of the infection process in successive leaf levels. Our results reveal that the opportunities for recombination, complementation and competition among viral genomes can greatly change at different infection phases and at different locations within a multi-cellular host.
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Affiliation(s)
- Serafín Gutiérrez
- Unité Mixte de Recherche BGPI, INRA-CIRAD-SupAgro, TA A-54/K, Campus International de Baillarguet, Montpellier, France
| | - Michel Yvon
- Unité Mixte de Recherche BGPI, INRA-CIRAD-SupAgro, TA A-54/K, Campus International de Baillarguet, Montpellier, France
| | - Gaël Thébaud
- Unité Mixte de Recherche BGPI, INRA-CIRAD-SupAgro, TA A-54/K, Campus International de Baillarguet, Montpellier, France
| | - Baptiste Monsion
- Unité Mixte de Recherche BGPI, INRA-CIRAD-SupAgro, TA A-54/K, Campus International de Baillarguet, Montpellier, France
| | - Yannis Michalakis
- Unité Mixte de Recherche GEMI 2724, CNRS-IRD, Avenue Agropolis, B.P. 64501, Montpellier, France
| | - Stéphane Blanc
- Unité Mixte de Recherche BGPI, INRA-CIRAD-SupAgro, TA A-54/K, Campus International de Baillarguet, Montpellier, France
- * E-mail:
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50
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Abstract
Cross-protection is a phenomenon in which infection of a plant with a mild virus or viroid strain protects it from disease resulting from a subsequent encounter with a severe strain of the same virus or viroid. In this chapter, we review the history of cross-protection with regard to the development of ideas concerning its likely mechanisms, including RNA silencing and exclusion, and its influence on the early development of genetically engineered virus resistance. We also examine examples of the practical use of cross-protection in averting crop losses due to viruses, as well as the use of satellite RNAs to ameliorate the impact of virus-induced diseases. We also discuss the potential of cross-protection to contribute in future to the maintenance of crop health in the face of emerging virus diseases and related threats to agricultural production.
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