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Bruno Gronenborn - One of the best experts on this subject based on the ideXlab platform.
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ICTV Virus Taxonomy Profile: Nanoviridae.
The Journal of general virology, 2021Co-Authors: John E Thomas, Ioana Grigoras, Heinrich-josef Vetten, Bruno Gronenborn, John W. Randles, Robert M Harding, Bikash Mandal, Yoshitaka Sano, Tania Timchenko, Hsin-hung YehAbstract:Nanoviridae is a family of plant viruses (nanovirids) whose members have small isometric virions and multipartite, circular, single-stranded (css) DNA genomes. Each of the six (genus Babuvirus) or eight (genus Nanovirus) genomic DNAs is 0.9-1.1 kb and is separately encapsidated. Many isolates are associated with satellite-like cssDNAs (alphasatellites) of 1.0-1.1 kb. Hosts are eudicots, predominantly legumes (genus Nanovirus), and monocotyledons, predominantly in the order Zingiberales (genus Babuvirus). Nanovirids require a virus-encoded helper factor for transmission by aphids in a circulative, non-propagative manner. This is a summary of the ICTV Report on the family Nanoviridae, which is available at ictv.global/report/nanoviridae.
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Identification of a novel Nanovirus in parsley
Archives of Virology, 2019Co-Authors: Heinrich-josef Vetten, Dennis Knierim, Bruno Gronenborn, Stephan Winter, Mirko Sebastian Rakoski, Wulf Menzel, Edgar Maiss, Björn KrenzAbstract:Using next-generation sequencing to characterize agents associated with a severe stunting disease of parsley from Germany, we identified a hitherto undescribed virus. We sequenced total RNA and rolling-circle-amplified DNA from diseased plants. The genome sequence of the virus shows that it is a member of the genus Nanovirus , but it lacks DNA-U4. In addition to the seven genomic DNAs of the virus, we identified a second DNA-R and seven distinct alphasatellites associated with the disease. We propose the name “parsley severe stunt associated virus” (PSSaV) for this novel Nanovirus.
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Subterranean Clover Stunt Virus Revisited: Detection of Two Missing Genome Components
Viruses, 2019Co-Authors: Dennis Knierim, Quentin Barrière, Mark Schwinghamer, Paul Chu, Ioana Grigoras, Heinrich-josef Vetten, Bruno Gronenborn, Stephan Winter, John Thomas, Tatiana TimtchenkoAbstract:Subterranean clover stunt virus (SCSV) is a type species of the genus Nanovirus in the family Nanoviridae. It was the first single-stranded DNA plant virus with a multipartite genome, of which genomic DNA sequences had been determined. All Nanoviruses have eight genome components except SCSV, for which homologs of two genome components present in all other Nanovirus genomes, DNA-U2 and DNA-U4, were lacking. We analysed archived and more recent samples from SCSV-infected legume plants to verify its genome composition and found the missing genome components. These results indicated that SCSV also has eight genome components and is a typical member of the genus Nanovirus.
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Nanovirus DNA-N encodes a protein mandatory for aphid transmission
Virology, 2018Co-Authors: Ioana Grigoras, Heinrich-josef Vetten, Bruno Gronenborn, Ulrich Commandeur, Heiko Ziebell, Tatiana TimtchenkoAbstract:Nanoviruses possess a multipartite single-stranded DNA genome and are naturally transmitted to plants by various aphid species in a circulative non-propagative manner. Using the cloned genomic DNAs of faba bean necrotic stunt virus (FBNSV) for reconstituting Nanovirus infections we analyzed the necessity of different virus components for infection and transmission by aphids. We found that in the absence of DNA-U1 and DNA-U2 symptom severity decreased, and in the absence of DNA-U1 the transmission efficiency decreased. Most significantly, we demonstrated that the protein encoded by DNA-N (NSP) is mandatory for aphid transmission. Moreover, we showed that the NSP of FBNSV could substitute for that of a distantly related Nanovirus, pea necrotic yellow dwarf virus. Altering the FBNSV NSP by adding 13 amino acids to its carboxy-terminus resulted in an infectious but non-transmissible virus. We demonstrate that the NSP acts as a Nanovirus transmission factor, the existence of which had been hypothesized earlier.
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The RXL motif of the African cassava mosaic virus Rep protein is necessary for rereplication of yeast DNA and viral infection in plants.
Virology, 2014Co-Authors: Katharina Hipp, Bruno Gronenborn, Peter Rau, Benjamin Schäfer, Holger JeskeAbstract:Geminiviruses, single-stranded DNA plant viruses, encode a replication-initiator protein (Rep) that is indispensable for virus replication. A potential cyclin interaction motif (RXL) in the sequence of African cassava mosaic virus Rep may be an alternative link to cell cycle controls to the known interaction with plant homologs of retinoblastoma protein (pRBR). Mutation of this motif abrogated rereplication in fission yeast induced by expression of wildtype Rep suggesting that Rep interacts via its RXL motif with one or several yeast proteins. The RXL motif is essential for viral infection of Nicotiana benthamiana plants, since mutation of this motif in infectious clones prevented any symptomatic infection. The cell-cycle link (Clink) protein of a Nanovirus (faba bean necrotic yellows virus) was investigated that activates the cell cycle by binding via its LXCXE motif to pRBR. Expression of wildtype Clink and a Clink mutant deficient in pRBR-binding did not trigger rereplication in fission yeast.
Heinrich-josef Vetten - One of the best experts on this subject based on the ideXlab platform.
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ICTV Virus Taxonomy Profile: Nanoviridae.
The Journal of general virology, 2021Co-Authors: John E Thomas, Ioana Grigoras, Heinrich-josef Vetten, Bruno Gronenborn, John W. Randles, Robert M Harding, Bikash Mandal, Yoshitaka Sano, Tania Timchenko, Hsin-hung YehAbstract:Nanoviridae is a family of plant viruses (nanovirids) whose members have small isometric virions and multipartite, circular, single-stranded (css) DNA genomes. Each of the six (genus Babuvirus) or eight (genus Nanovirus) genomic DNAs is 0.9-1.1 kb and is separately encapsidated. Many isolates are associated with satellite-like cssDNAs (alphasatellites) of 1.0-1.1 kb. Hosts are eudicots, predominantly legumes (genus Nanovirus), and monocotyledons, predominantly in the order Zingiberales (genus Babuvirus). Nanovirids require a virus-encoded helper factor for transmission by aphids in a circulative, non-propagative manner. This is a summary of the ICTV Report on the family Nanoviridae, which is available at ictv.global/report/nanoviridae.
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Identification of a novel Nanovirus in parsley
Archives of Virology, 2019Co-Authors: Heinrich-josef Vetten, Dennis Knierim, Bruno Gronenborn, Stephan Winter, Mirko Sebastian Rakoski, Wulf Menzel, Edgar Maiss, Björn KrenzAbstract:Using next-generation sequencing to characterize agents associated with a severe stunting disease of parsley from Germany, we identified a hitherto undescribed virus. We sequenced total RNA and rolling-circle-amplified DNA from diseased plants. The genome sequence of the virus shows that it is a member of the genus Nanovirus , but it lacks DNA-U4. In addition to the seven genomic DNAs of the virus, we identified a second DNA-R and seven distinct alphasatellites associated with the disease. We propose the name “parsley severe stunt associated virus” (PSSaV) for this novel Nanovirus.
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Subterranean Clover Stunt Virus Revisited: Detection of Two Missing Genome Components
Viruses, 2019Co-Authors: Dennis Knierim, Quentin Barrière, Mark Schwinghamer, Paul Chu, Ioana Grigoras, Heinrich-josef Vetten, Bruno Gronenborn, Stephan Winter, John Thomas, Tatiana TimtchenkoAbstract:Subterranean clover stunt virus (SCSV) is a type species of the genus Nanovirus in the family Nanoviridae. It was the first single-stranded DNA plant virus with a multipartite genome, of which genomic DNA sequences had been determined. All Nanoviruses have eight genome components except SCSV, for which homologs of two genome components present in all other Nanovirus genomes, DNA-U2 and DNA-U4, were lacking. We analysed archived and more recent samples from SCSV-infected legume plants to verify its genome composition and found the missing genome components. These results indicated that SCSV also has eight genome components and is a typical member of the genus Nanovirus.
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Nanovirus DNA-N encodes a protein mandatory for aphid transmission
Virology, 2018Co-Authors: Ioana Grigoras, Heinrich-josef Vetten, Bruno Gronenborn, Ulrich Commandeur, Heiko Ziebell, Tatiana TimtchenkoAbstract:Nanoviruses possess a multipartite single-stranded DNA genome and are naturally transmitted to plants by various aphid species in a circulative non-propagative manner. Using the cloned genomic DNAs of faba bean necrotic stunt virus (FBNSV) for reconstituting Nanovirus infections we analyzed the necessity of different virus components for infection and transmission by aphids. We found that in the absence of DNA-U1 and DNA-U2 symptom severity decreased, and in the absence of DNA-U1 the transmission efficiency decreased. Most significantly, we demonstrated that the protein encoded by DNA-N (NSP) is mandatory for aphid transmission. Moreover, we showed that the NSP of FBNSV could substitute for that of a distantly related Nanovirus, pea necrotic yellow dwarf virus. Altering the FBNSV NSP by adding 13 amino acids to its carboxy-terminus resulted in an infectious but non-transmissible virus. We demonstrate that the NSP acts as a Nanovirus transmission factor, the existence of which had been hypothesized earlier.
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High Variability and Rapid Evolution of a Nanovirus
Journal of virology, 2010Co-Authors: Ioana Grigoras, Tatiana Timchenko, Heinrich-josef Vetten, L. Katul, Ana Grande-pérez, Bruno GronenbornAbstract:Nanoviruses are multipartite single-stranded DNA (ssDNA) plant viruses that cause important diseases of leguminous crops and banana. Little has been known about the variability and molecular evolution of these viruses. Here we report on the variability of faba bean necrotic stunt virus (FBNSV), a Nanovirus from Ethiopia. We found mutation frequencies of 7.52 x 10(-4) substitutions per nucleotide in a field population of the virus and 5.07 x 10(-4) substitutions per nucleotide in a laboratory-maintained population derived thereof. Based on virus propagation for a period of more than 2 years, we determined a nucleotide substitution rate of 1.78 x 10(-3) substitutions per nucleotide per year. This high molecular evolution rate places FBNSV, as a representative of the family Nanoviridae, among the fastest-evolving ssDNA viruses infecting plants or vertebrates.
Ioana Grigoras - One of the best experts on this subject based on the ideXlab platform.
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ICTV Virus Taxonomy Profile: Nanoviridae.
The Journal of general virology, 2021Co-Authors: John E Thomas, Ioana Grigoras, Heinrich-josef Vetten, Bruno Gronenborn, John W. Randles, Robert M Harding, Bikash Mandal, Yoshitaka Sano, Tania Timchenko, Hsin-hung YehAbstract:Nanoviridae is a family of plant viruses (nanovirids) whose members have small isometric virions and multipartite, circular, single-stranded (css) DNA genomes. Each of the six (genus Babuvirus) or eight (genus Nanovirus) genomic DNAs is 0.9-1.1 kb and is separately encapsidated. Many isolates are associated with satellite-like cssDNAs (alphasatellites) of 1.0-1.1 kb. Hosts are eudicots, predominantly legumes (genus Nanovirus), and monocotyledons, predominantly in the order Zingiberales (genus Babuvirus). Nanovirids require a virus-encoded helper factor for transmission by aphids in a circulative, non-propagative manner. This is a summary of the ICTV Report on the family Nanoviridae, which is available at ictv.global/report/nanoviridae.
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Subterranean Clover Stunt Virus Revisited: Detection of Two Missing Genome Components
Viruses, 2019Co-Authors: Dennis Knierim, Quentin Barrière, Mark Schwinghamer, Paul Chu, Ioana Grigoras, Heinrich-josef Vetten, Bruno Gronenborn, Stephan Winter, John Thomas, Tatiana TimtchenkoAbstract:Subterranean clover stunt virus (SCSV) is a type species of the genus Nanovirus in the family Nanoviridae. It was the first single-stranded DNA plant virus with a multipartite genome, of which genomic DNA sequences had been determined. All Nanoviruses have eight genome components except SCSV, for which homologs of two genome components present in all other Nanovirus genomes, DNA-U2 and DNA-U4, were lacking. We analysed archived and more recent samples from SCSV-infected legume plants to verify its genome composition and found the missing genome components. These results indicated that SCSV also has eight genome components and is a typical member of the genus Nanovirus.
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Nanovirus DNA-N encodes a protein mandatory for aphid transmission
Virology, 2018Co-Authors: Ioana Grigoras, Heinrich-josef Vetten, Bruno Gronenborn, Ulrich Commandeur, Heiko Ziebell, Tatiana TimtchenkoAbstract:Nanoviruses possess a multipartite single-stranded DNA genome and are naturally transmitted to plants by various aphid species in a circulative non-propagative manner. Using the cloned genomic DNAs of faba bean necrotic stunt virus (FBNSV) for reconstituting Nanovirus infections we analyzed the necessity of different virus components for infection and transmission by aphids. We found that in the absence of DNA-U1 and DNA-U2 symptom severity decreased, and in the absence of DNA-U1 the transmission efficiency decreased. Most significantly, we demonstrated that the protein encoded by DNA-N (NSP) is mandatory for aphid transmission. Moreover, we showed that the NSP of FBNSV could substitute for that of a distantly related Nanovirus, pea necrotic yellow dwarf virus. Altering the FBNSV NSP by adding 13 amino acids to its carboxy-terminus resulted in an infectious but non-transmissible virus. We demonstrate that the NSP acts as a Nanovirus transmission factor, the existence of which had been hypothesized earlier.
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High Variability and Rapid Evolution of a Nanovirus
Journal of virology, 2010Co-Authors: Ioana Grigoras, Tatiana Timchenko, Heinrich-josef Vetten, L. Katul, Ana Grande-pérez, Bruno GronenbornAbstract:Nanoviruses are multipartite single-stranded DNA (ssDNA) plant viruses that cause important diseases of leguminous crops and banana. Little has been known about the variability and molecular evolution of these viruses. Here we report on the variability of faba bean necrotic stunt virus (FBNSV), a Nanovirus from Ethiopia. We found mutation frequencies of 7.52 x 10(-4) substitutions per nucleotide in a field population of the virus and 5.07 x 10(-4) substitutions per nucleotide in a laboratory-maintained population derived thereof. Based on virus propagation for a period of more than 2 years, we determined a nucleotide substitution rate of 1.78 x 10(-3) substitutions per nucleotide per year. This high molecular evolution rate places FBNSV, as a representative of the family Nanoviridae, among the fastest-evolving ssDNA viruses infecting plants or vertebrates.
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first report of a Nanovirus disease of pea in germany
Plant Disease, 2010Co-Authors: Ioana Grigoras, Bruno Gronenborn, Heinrich-josef VettenAbstract:During the growing season of 2009, a disease consisting of leaf rolling, top yellows, and plant stunting affected pea (Pisum sativum) in fields near Aschersleben, Saxony-Anhalt, Germany. Samples from symptomatic plants collected in July 2009 were analyzed at the JKI in Braunschweig for infections by various legume viruses by ELISA, immunoelectron microscopy, and transmission assays by sap and aphids. Of 23 samples, 9 were shown to contain Pea enation mosaic virus and three samples each contained Bean leafroll virus and Soybean dwarf virus. From two further samples that had tested negative for the aforementioned viruses, we succeeded in transferring a disease agent to faba bean (Vicia faba) seedlings by giving 50 to 100 individuals of the pea aphid (Acyrthosiphon pisum) acquisition and inoculation access feedings each of ~48 h. Following vector transmission, the agent caused severe yellowing and stunting in pea and faba bean, sometimes followed by necrosis. Attempts at mechanical transmission of the agent failed, and isolation of double-stranded RNA from infected tissue was not successful. Therefore, we considered the possible presence of a Nanovirus (4). When using polyclonal antibodies (PAbs) against Faba bean necrotic yellows virus (FBNYV) for double-antibody sandwich (DAS)-ELISA analysis of the two isolates of the disease agent we observed weak but clearly positive reactions. To confirm these weak DAS-ELISA reactions, we used all available monoclonal antibodies (MAbs) raised against FBNYV (1) and faba bean necrotic stunt virus (FBNSV) (3) individually in triple-antibody sandwich (TAS)-ELISA in combination with the FBNYV PAbs for plate coating. Six of 26 MAbs reacted from weak to strong with the two pea isolates, with MAbs FBNYV-3-1F7 and FBNSV-5-1G8 giving the strongest reactions and none of the MAbs giving a differential reaction with the two pea isolates. Employing rolling circle amplification of total DNA extracted from symptomatic leaves of one of the pea isolates yielded a substantial amount of high molecular weight DNA, whereas little or no amplification occurred when using DNA from noninoculated pea leaves. Restriction of the amplified DNA in a Nanovirus iteron-specific manner by AatII endonuclease yielded a predominant and abundant product of ~1 kb (3). Sequence comparisons of eight cloned DNAs of 1,002 nucleotides long unequivocally identified them as complete DNA-R component of a new member of the genus Nanovirus (2,4). Its DNA-R sequence (GenBank No. GU553134) is nearly equidistant from the DNA-R sequences of FBNYV (Y11405), FBNSV (GQ150778), Milk vetch dwarf virus (MDV) (AB027511) and Subterranean clover stunt virus (SCSV) (AJ290434), sharing with them respective sequence identities of 79, 78, 79, and 73%. Moreover, it is more distinct from the DNA-R sequences of FBNYV, FBNSV, and MDV than the three latter are from each other (86 to 91%). This together with the serological data relating to the capsid protein properties of this virus strongly suggest that it is distinct from the hitherto described Nanoviruses FBNYV, MDV, FBNSV, and SCSV. Therefore, we propose the name pea necrotic yellow dwarf virus (PNYDV) for this new Nanovirus naturally infecting pea in Germany. References: (1) A. Franz et al. Ann. Appl. Biol. 128:255, 1996. (2) I. Grigoras et al. J. Gen. Virol. 89:583, 2008. (3) I. Grigoras et al. J. Virol. 83:10778, 2009. (4) H. J. Vetten et al. Page 343 in: Virus Taxonomy. Elsevier/Academic Press, London, 2005.
John Stanley - One of the best experts on this subject based on the ideXlab platform.
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Downloaded from www.microbiologyresearch.org by
2016Co-Authors: Keith Saunders, Ian D. Bedford, John StanleyAbstract:Adaptation from whitefly to leafhopper transmission of an autonomously replicating Nanovirus-like DNA component associated with ageratum yellow vein diseas
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Adaptation from whitefly to leafhopper transmission of an autonomously replicating Nanovirus-like DNA component associated with ageratum yellow vein disease
Journal of General Virology, 2002Co-Authors: Keith Saunders, Ian D. Bedford, John StanleyAbstract:Ageratum yellow vein disease is caused by the whitefly-transmitted monopartite begomovirus Ageratum yellow vein virus and a DNA β satellite component. Naturally occurring symptomatic plants also contain an autonomously replicating Nanovirus-like DNA 1 component that relies on the begomovirus and DNA β for systemic spread and whitefly transmission but is not required for maintenance of the disease. Here, we show that systemic movement of DNA 1 occurs in Nicotiana benthamiana when co-inoculated with the bipartite begomovirus Tomato golden mosaic virus and the curtovirus Beet curly top virus (BCTV), but not with the mastrevirus Bean yellow dwarf virus. BCTV also mediates the systemic movement of DNA 1 in sugar beet, and the Nanovirus-like component is transmitted between plants by the BCTV leafhopper vector Circulifer tenellus. We also describe a second Nanovirus-like component, referred to as DNA 2, that has only 47% nucleotide sequence identity with DNA 1. The diversity and adaptation of Nanovirus components are discussed.
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a unique virus complex causes ageratum yellow vein disease
Proceedings of the National Academy of Sciences of the United States of America, 2000Co-Authors: Keith Saunders, Ian D. Bedford, Rob W. Briddon, Peter G. Markham, Sekman Wong, John StanleyAbstract:Ageratum conyzoides L., a weed species widely distributed throughout southeast Asia, frequently exhibits striking yellow vein symptoms associated with infection by Ageratum yellow vein virus (AYVV), a member of the Geminiviridae (genus Begomovirus). Most begomoviruses have bipartite genomes (DNAs A and B), but only a DNA A has been identified for AYVV. We demonstrate that yellow vein disease of A. conyzoides results from co-infection by AYVV DNA A (2,741 nt) and a circular DNA that is approximately half its size (1,347 nt) that we designate DNA β. Apart from the sequence TAATATTAC, common to all geminiviruses and containing the initiation site of rolling circle replication, DNA β shows negligible sequence homology either to AYVV DNA A or to DNA B associated with bipartite begomoviruses. DNA β depends on DNA A for replication and is encapsidated by DNA A-encoded coat protein and so has characteristics of a DNA satellite. However, systemic infection of A. conyzoides by DNA A alone is sporadic and asymptomatic, and DNA A accumulation is reduced to 5% or less of its accumulation in the presence of DNA β. Therefore, DNA A and DNA β together form a previously unrecognized disease-inducing complex. Our data also demonstrate that the Nanovirus-like DNA 1 component associated with infected A. conyzoides plays no essential role in the disease and represents a satellite-like DNA. Furthermore, the satellite DNA previously found associated with tomato leaf curl virus is probably a defective DNA β homologue.
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Association of a Begomovirus and Nanovirus-like Molecule with Ageratum Yellow Vein Disease in Pakistan.
Plant disease, 2000Co-Authors: Shahid Mansoor, John Stanley, Yusuf Zafar, Rob W. Briddon, Habibullah Khan, Mazhar Hussain, Marion S. Pinner, Peter G. MarkhamAbstract:Whitefly-transmitted geminiviruses (begomoviruses) cause heavy losses to many food and fiber crops in Pakistan. Many weeds also show symptoms typical of begomoviruses. Ageratum (Ageratum conyzoides) is a common perennial weed in Pakistan, growing along irrigation canals, that often shows symptoms, such as yellow vein and mosaic, suggesting infection by a begomovirus. To confirm this, symptomatic and asymptomatic ageratum plants were collected from three locations in the Punjab Province of Pakistan, and total DNA was isolated, subjected to agarose gel electrophoresis, transferred to a nylon membrane, and Southern blotted. Total DNA isolated from cotton infected with Cotton leaf curl virus (CLCuV), tomato infected with Tomato leaf curl virus from Pakistan (TLCV-Pak), tobacco infected with African cassava mosaic virus (ACMV) from Nigeria, and healthy tobacco were included as controls. A full-length clone of CLCuV DNA A was labeled with [32P]dCTP by oligo-labeling and hybridized at medium stringency. The prob...
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a Nanovirus like dna component associated with yellow vein disease of ageratum conyzoides evidence for interfamilial recombination between plant dna viruses
Virology, 1999Co-Authors: Keith Saunders, John StanleyAbstract:Yellow vein disease of Ageratum conyzoides, a weed species that is widely distributed throughout Asia, has been attributed to infection by the geminivirus Ageratum yellow vein virus (AYVV). In addition to a single AYVV genomic component (DNA A), we have previously demonstrated that infected plants contain chimeric defective viral components, comprising DNA A and nongeminiviral sequences, that act as defective interfering DNAs. A database search has revealed that the nongeminiviral sequences of one such defective component (def19) show significant homology with sequences of Nanovirus components that encode replication-associated proteins (Reps). Primers designed to hybridise to the nongeminiviral DNA were used to PCR-amplify a full-length Nanovirus-like component, referred to as DNA 1, from an extract of infected A. conyzoides. DNA 1 is unrelated to AYVV DNA A but resembles Nanovirus components that encode Reps and is most closely related (73% identity) to a Nanovirus-like DNA recently isolated from geminivirus-infected cotton. DNA 1 is dependent on AYVV DNA A for systemic infection of A. conyzoides and Nicotiana benthamiana and can systemically infect N. benthamiana in the presence of the bipartite geminivirus African cassava mosaic virus. A. conyzoides plants coinfected with AYVV DNA A and DNA 1 remain asymptomatic, indicating that additional factors are required to elicit yellow vein disease. Our results provide direct evidence for recombination between distinct families of plant single-stranded DNA viruses and suggest that coinfection by geminivirus and Nanovirus-like pathogens may be a widespread phenomenon. The ability of plant DNA viruses to recombine in this way may greatly increase their scope for diversification.
Tatiana Timchenko - One of the best experts on this subject based on the ideXlab platform.
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Gene copy number is differentially regulated in a multipartite virus
Nature Communications, 2013Co-Authors: Anne Sicard, Tatiana Timchenko, Bruno Gronenborn, Michel Yvon, Yannis Michalakis, Serafin Gutierrez-simon, Stéphane BlancAbstract:Multipartite viruses have a genome divided into several nucleic acid segments, each encapsidated separately. An evident cost for these viral systems, particularly if some segments are rare, is the difficulty of gathering one copy of each segment to ensure infection. Here, we investigate the segment frequency-related cost by monitoring the copy number of the eight single-gene segments composing the genome of a plant Nanovirus. We show that some viral genes accumulate at low frequency, whereas others dominate. We further show that the relative frequency of viral genes impacts both viral accumulation and symptom expression, and changes specifically in different hosts. Earlier proposed benefits of viral genome segmentation do not depend on the segments' frequency and cannot explain our observations. We propose that the differential control of gene/segment copy number may represent an unforeseen benefit for multipartite viruses, which may compensate for the extra costs induced by the low-frequency segments.
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High Variability and Rapid Evolution of a Nanovirus
Journal of virology, 2010Co-Authors: Ioana Grigoras, Tatiana Timchenko, Heinrich-josef Vetten, L. Katul, Ana Grande-pérez, Bruno GronenbornAbstract:Nanoviruses are multipartite single-stranded DNA (ssDNA) plant viruses that cause important diseases of leguminous crops and banana. Little has been known about the variability and molecular evolution of these viruses. Here we report on the variability of faba bean necrotic stunt virus (FBNSV), a Nanovirus from Ethiopia. We found mutation frequencies of 7.52 x 10(-4) substitutions per nucleotide in a field population of the virus and 5.07 x 10(-4) substitutions per nucleotide in a laboratory-maintained population derived thereof. Based on virus propagation for a period of more than 2 years, we determined a nucleotide substitution rate of 1.78 x 10(-3) substitutions per nucleotide per year. This high molecular evolution rate places FBNSV, as a representative of the family Nanoviridae, among the fastest-evolving ssDNA viruses infecting plants or vertebrates.
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reconstitution of authentic Nanovirus from multiple cloned dnas
Journal of Virology, 2009Co-Authors: Ioana Grigoras, Lina Katul, Tatiana Timchenko, Heinrich-josef Vetten, Ana Grandeperez, Bruno GronenbornAbstract:We describe a new plant single-stranded DNA (ssDNA) virus, a Nanovirus isolate originating from the faba bean in Ethiopia. We applied rolling circle amplification (RCA) to extensively copy the individual circular DNAs of the Nanovirus genome. By sequence analyses of more than 208 individually cloned genome components, we obtained a representative sample of eight polymorphic swarms of circular DNAs, each about 1 kb in size. From these heterogeneous DNA populations after RCA, we inferred consensus sequences of the eight DNA components of the virus genome. Based on the distinctive molecular and biological properties of the virus, we propose to consider it a new species of the genus Nanovirus and to name it faba bean necrotic stunt virus (FBNSV). Selecting a representative clone of each of the eight DNAs for transfer by T-DNA plasmids of Agrobacterium tumefaciens into Vicia faba plants, we elicited the development of the typical FBNSV disease symptoms. Moreover, we showed that the virus thus produced was readily transmitted by two different aphid vector species, Aphis craccivora and Acyrthosiphon pisum. This represents the first reconstitution of a fully infectious and sustainably insect-transmissible Nanovirus from its cloned DNAs and provides compelling evidence that the genome of a legume-infecting Nanovirus is typically comprised of eight distinct DNA components.
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transcripts encoding the Nanovirus master replication initiator proteins are terminally redundant
Journal of General Virology, 2008Co-Authors: Ioana Grigoras, Tatiana Timchenko, Bruno GronenbornAbstract:The multicomponent single-stranded DNA plant Nanoviruses encode unique master replication initiator (Rep) proteins. We have mapped the 5' and 3' termini of the corresponding polyadenylated mRNAs from faba bean necrotic yellows virus (FBNYV) and subterranean clover stunt virus and found that these are terminally redundant by up to about 160 nt. Moreover, the origin of viral DNA replication is transcribed into RNA that is capable of folding into extended secondary structures. Other Nanovirus genome components, such as the FBNYV DNA encoding the protein Clink or an FBNYV DNA encoding a non-essential para-Rep protein, are not transcribed in such a unique fashion. Thus, terminally redundant mRNAs and the resulting transcription of the replication origin appear to be restricted to Nanovirus master Rep DNAs. We speculate that this may be a way to regulate the expression of the essential master Rep protein.
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A Functional Histidine-Tagged Replication Initiator Protein: Implications for the Study of Single-Stranded DNA Virus Replication In Planta
Journal of Virology, 2005Co-Authors: Julio Vega-arreguín, Tatiana Timchenko, Bruno Gronenborn, Bertha Cecilia RamirezAbstract:Replication initiation of Nanoviruses, plant viruses with a multipartite circular single-stranded DNA genome, is triggered by the master Rep (M-Rep) protein. To enable the study of interactions between M-Rep and viral or host factors involved in replication, we designed oligohistidine-tagged variants of the Nanovirus Faba bean necrotic yellows virus (FBNYV) M-Rep protein that allow affinity purification of enzymatically active M-Rep from plant tissue. The tagged M-Rep protein was able to initiate replication of its cognate and other FBNYV DNAs in Nicotiana benthamiana leaf disks and plants. The replicon encoding the tagged M-Rep protein multiplied and moved systemically in FBNYV-infected Vicia faba plants and was transmitted by the aphid vector of the virus. Using the tagged M-Rep protein, we demonstrated the in planta interaction between wild-type M-Rep and its tagged counterpart. Such a tagged and fully functional replication initiator protein will have bearings on the isolation of protein complexes from plants.
