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Arvind Varsani - One of the best experts on this subject based on the ideXlab platform.
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Novel nanovirus and associated alphasatellites identified in milk vetch plants with chlorotic dwarf disease in Iran.
Virus research, 2019Co-Authors: Parisa Hassan-sheikhi, Simona Kraberger, Jahangir Heydarnejad, Hossain Massumi, Arvind VarsaniAbstract:Abstract Members of the family Nanoviridae are multi-component single-stranded DNA viruses that infect a variety of plant species. Using a combination of conventional PCR and high throughput sequencing-based approach, we identified a novel nanovirus infecting two symptomatic milk vetch plants (Astragalus myriacanthus Boiss.; family Fabaceae) showing marginal leaf chlorosis, little leaves and dwarfing in Iran. All eight segments (DNA-C, DNA-M, DNA-N, DNA-R, DNA-S, DNA-U1, DNA-U2 and DNAU4) were recovered and Sanger sequenced. The genome of this new nanovirus, hereby referred to as milk vetch chlorotic dwarf virus (MVCDV), shares 62.2–74.7 % nucleotide pairwise identity with the genomes of other nanoviruses. DNA-C, DNA-M, DNA-N, DNA-S components are most closely related to those of black medic leaf roll virus (BMLRV), sharing between 67.8–81.2 % identity. We also identified three nanoalphasatellites (family Alphasatellitidae) associated with the nanovirus which belong to species Faba bean necrotic yellows alphasatellite 1 (genus Subclovsatellite), Faba bean necrotic yellows alphasatellite 2 (genus Fabenesatellite) and Sophora yellow stunt alphasatellite 5 (genus Clostunsatellite). Given the significant diversity of Astragalus spp. in Iran, it is likely that there could be more nanoviruses circulating in these plants and that these may play a role in the spread of these nanovirus to cultivated fabaceous hosts.
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Unravelling the Single-Stranded DNA Virome of the New Zealand Blackfly.
Viruses, 2019Co-Authors: Simona Kraberger, Matthew Walters, Kara Schmidlin, Rafaela S. Fontenele, Arvind VarsaniAbstract:Over the last decade, arthropods have been shown to harbour a rich diversity of viruses. Through viral metagenomics a large diversity of single-stranded (ss) DNA viruses have been identified. Here we examine the ssDNA virome of the hematophagous New Zealand blackfly using viral metagenomics. Our investigation reveals a plethora of novel ssDNA viral genomes, some of which cluster in the viral families Genomoviridae (n = 9), Circoviridae (n = 1), and Microviridae (n = 108), others in putative families that, at present, remain unclassified (n = 20) and one DNA molecule that only encodes a replication associated protein. Among these novel viruses, two putative multi-component virus genomes were recovered, and these are most closely related to a Tongan flying fox faeces-associated multi-component virus. Given that the only other known multi-component circular replication-associated (Rep) protein encoding single-stranded (CRESS) DNA viruses infecting plants are in the families Geminiviridae (members of the genus Begomovirus) and Nanoviridae, it appears these are likely a new multi-component virus group which may be associated with animals. This study reiterates the diversity of ssDNA viruses in nature and in particular with the New Zealand blackflies.
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Pervasive Chimerism in the Replication-Associated Proteins of Uncultured Single-Stranded DNA Viruses
Viruses, 2018Co-Authors: Darius Kazlauskas, Arvind Varsani, Mart KrupovicAbstract:Numerous metagenomic studies have uncovered a remarkable diversity of circular replication-associated protein (Rep)-encoding single-stranded (CRESS) DNA viruses, the majority of which are uncultured and unclassified. Unlike capsid proteins, the Reps show significant similarity across different groups of CRESS DNA viruses and have conserved domain organization with the N-terminal nuclease and the C-terminal helicase domain. Consequently, Rep is widely used as a marker for identification, classification and assessment of the diversity of CRESS DNA viruses. However, it has been shown that in certain viruses the Rep nuclease and helicase domains display incongruent evolutionary histories. Here, we systematically evaluated the co-evolutionary patterns of the two Rep domains across classified and unclassified CRESS DNA viruses. Our analysis indicates that the Reps encoded by members of the families Bacilladnaviridae, Circoviridae, Geminiviridae, Genomoviridae, Nanoviridae and Smacoviridae display largely congruent evolutionary patterns in the two domains. By contrast, among the unclassified CRESS DNA viruses, 71% appear to have chimeric Reps. Such massive chimerism suggests that unclassified CRESS DNA viruses represent a dynamic population in which exchange of gene fragments encoding the nuclease and helicase domains is extremely common. Furthermore, purging of the chimeric sequences uncovered six monophyletic Rep groups that may represent new families of CRESS DNA viruses.
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Molecular characterization of faba bean necrotic yellows viruses in Tunisia
Archives of Virology, 2018Co-Authors: Simona Kraberger, Safaa G. Kumari, Asma Najar, Daisy Stainton, Darren P. Martin, Arvind VarsaniAbstract:Faba bean necrotic yellows virus (FBNYV) (genus Nanovirus ; family Nanoviridae ) has a genome comprising eight individually encapsidated circular single-stranded DNA components. It has frequently been found infecting faba bean ( Vicia faba L.) and chickpea ( Cicer arietinum L.) in association with satellite molecules (alphasatellites). Genome sequences of FBNYV from Azerbaijan, Egypt, Iran, Morocco, Spain and Syria have been determined previously and we now report the first five genome sequences of FBNYV and associated alphasatellites from faba bean sampled in Tunisia. In addition, we have determined the genome sequences of two additional FBNYV isolates from chickpea plants sampled in Syria and Iran. All individual FBNYV genome component sequences that were determined here share > 84% nucleotide sequence identity with FBNYV sequences available in public databases, with the DNA-M component displaying the highest degree of diversity. As with other studied nanoviruses, recombination and genome component reassortment occurs frequently both between FBNYV genomes and between genomes of nanoviruses belonging to other species.
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Identification of a Nanovirus-Alphasatellite Complex in Sophora alopecuroides
Virus research, 2017Co-Authors: Jahangir Heydarnejad, Simona Kraberger, Daisy Stainton, Darren P. Martin, Hossain Massumi, Mehdi Kamali, Anders Kvarnheden, Maketalena F. Male, Arvind VarsaniAbstract:Viruses in the genus Nanovirus of the family Nanoviridae generally have eight individually encapsidated circular genome components and have been predominantly found infecting Fabaceae plants in Europe, Australia, Africa and Asia. For over a decade Sophora alopecuroides L. (Fabaceae) plants have been observed across Iran displaying dwarfing, yellowing, stunted leaves and yellow vein banding. Using a high-throughput sequencing approach, sequences were identified within one such plant that had similarities to nanovirus genome components. From this plant, the nanovirus-like molecules DNA-R (n=4), DNA-C (n=2), DNA-S (n=1), DNA-M (n=1), DNA-N (n=1), DNA-U1 (n=1), DNA-U2 (n=1) and DNA-U4 (n=1) were amplified, cloned and sequenced. Other than for the DNA-R, these components share less than 71% identity with those of other known nanoviruses. The four DNA-R molecules were highly diverse, sharing only 65-71% identity with each other and 64-86% identity with those of other nanoviruses. In the S. alopecuroides plant 14 molecules sharing 57.7-84.6% identity with previously determined sequences of nanovirus-associated alphasatellites were also identified. Given the research activity in the nanovirus field during the last five years coupled with high-throughput sequence technologies, many more diverse nanoviruses and nanovirus-associated satellites are likely to be identified.
Alberto Bressan - One of the best experts on this subject based on the ideXlab platform.
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Localization of Banana bunchy top virus and cellular compartments in gut and salivary gland tissues of the aphid vector Pentalonia nigronervosa.
Insect science, 2015Co-Authors: Shizu Watanabe, Dulal Borthakur, Alberto BressanAbstract:Banana bunchy top virus (BBTV) (Nanoviridae: Babuvirus) is transmitted by aphids of the genus Pentalonia in a circulative manner. The cellular mechanisms by which BBTV translocates from the anterior midgut to the salivary gland epithelial tissues are not understood. Here, we used multiple fluorescent markers to study the distribution and the cellular localization of early and late endosomes, macropinosomes, lysosomes, microtubules, actin filaments, and lipid raft subdomains in the gut and principal salivary glands of Pentalonia nigronervosa. We applied colabeling assays, to colocalize BBTV viral particles with these cellular compartments and structures. Our results suggest that multiple potential cellular processes, including clathrin- and caveolae-mediated endocytosis and lipid rafts, may not be involved in BBTV internalization.
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Lack of evidence for an interaction between Buchnera GroEL and Banana bunchy top virus (Nanoviridae)
Virus research, 2013Co-Authors: Shizu Watanabe, Dulal Borthakur, Alberto BressanAbstract:Abstract Circulative plant viruses such as luteovirids and geminiviruses have been shown to bind to GroEL proteins produced by endosymbiotic bacteria harboured within hemipteran vectors. These interactions seem to prevent the degradation of the viral particles in the aphid's haemocoel. Similarly to luteovirids and geminiviruses, Banana bunchy top virus (BBTV), a member of the Nanoviridae family, is transmitted in a persistent, circulative manner and can be detected in the haemolymph of the aphid vector, Pentalonia nigronervosa. To date, it is not known if BBTV can interact with GroEL. In this study, we localised and inferred the phylogeny of a Buchnera aphidicola endosymbiont inhabiting P. nigronervosa. Furthermore, we predicted the 3D structure of Buchnera GroEL and detected the protein in the haemolymph of P. nigronervosa. Interactions were tested using 3 different assays: immunocapture PCR, dot blot, and far-western blot assays; however, none of them showed evidence of a BBTV–GroEL interaction. We concluded that it was unlikely that BBTV interacted with Buchnera GroEL either in vitro or in vivo and we discuss possible alternatives by which BBTV viral particles are able to avoid the process of degradation in the aphid haemocoel.
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Tropism, compartmentalization and retention of banana bunchy top virus (Nanoviridae) in the aphid vector Pentalonia nigronervosa.
The Journal of general virology, 2012Co-Authors: Shizu Watanabe, Alberto BressanAbstract:Plant viruses of the families Luteoviridae and Geminiviridae rely on hemipteran vectors for the infection of their hosts. Several lines of evidence have revealed that these viruses are transmitted by competent vectors in a circulative manner, involving entry into the vector's body and the crossing of epithelial tissues forming the alimentary tract and the salivary glands. Similar to luteovirids and geminiviruses, a third family of plant viruses, the family Nanoviridae, have also been reported to be transmitted by aphids in a circulative manner. However, there is limited direct evidence of a possible path of translocation through the aphid vectors. Here, we used time-course experiments and transmission assays coupled with real-time PCR and immunofluorescence assays on dissected tissues to examine the translocation, compartmentalization and retention of banana bunchy top virus (BBTV) into the aphid vector Pentalonia nigronervosa. Our results indicate that BBTV translocates rapidly through the aphid vector; it is internalized into the anterior midgut in which it accumulates and is retained at concentrations higher than either the haemolymph or the principal salivary glands. Despite the large increase in viral concentration, we have failed to detect BBTV transcripts with RT-PCR. When tissues were not permeabilized, BBTV localized as distinct puncta in the proximity of the basal surface of the cells forming the anterior midgut and principal salivary glands, suggesting an on-going process of virion escape and internalization, respectively. Interestingly, we document that those organs can have direct contact within the aphid body, suggesting a possible haemolymph-independent translocation path.
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Immunofluorescence localisation of Banana bunchy top virus (family Nanoviridae) within the aphid vector, Pentalonia nigronervosa, suggests a virus tropism distinct from aphid-transmitted luteoviruses.
Virus research, 2010Co-Authors: Alberto Bressan, Shizu WatanabeAbstract:We have applied immunocapture PCR and developed an immunofluorescence assay to specifically detect Banana bunchy top virus (BBTV; family Nanoviridae, genus Babuvirus) within its aphid vector, Pentalonia nigronervosa (Hemiptera, Aphididae). BBTV was localised using either monoclonal or polyclonal antibodies into the anterior midgut (stomach) and into specific cells forming the principal salivary glands. These results suggest a distinct path of virus translocation that likely differs from the one described for aphid-transmitted luteovirus, which enter hemocoels through the hindguts and posterior midguts and that penetrate the accessory salivary glands of their competent vectors. To our understanding, this is the first work analysing the localisation of a virus member of the family Nanoviridae within an aphid vector.
Shizu Watanabe - One of the best experts on this subject based on the ideXlab platform.
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Localization of Banana bunchy top virus and cellular compartments in gut and salivary gland tissues of the aphid vector Pentalonia nigronervosa.
Insect science, 2015Co-Authors: Shizu Watanabe, Dulal Borthakur, Alberto BressanAbstract:Banana bunchy top virus (BBTV) (Nanoviridae: Babuvirus) is transmitted by aphids of the genus Pentalonia in a circulative manner. The cellular mechanisms by which BBTV translocates from the anterior midgut to the salivary gland epithelial tissues are not understood. Here, we used multiple fluorescent markers to study the distribution and the cellular localization of early and late endosomes, macropinosomes, lysosomes, microtubules, actin filaments, and lipid raft subdomains in the gut and principal salivary glands of Pentalonia nigronervosa. We applied colabeling assays, to colocalize BBTV viral particles with these cellular compartments and structures. Our results suggest that multiple potential cellular processes, including clathrin- and caveolae-mediated endocytosis and lipid rafts, may not be involved in BBTV internalization.
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Lack of evidence for an interaction between Buchnera GroEL and Banana bunchy top virus (Nanoviridae)
Virus research, 2013Co-Authors: Shizu Watanabe, Dulal Borthakur, Alberto BressanAbstract:Abstract Circulative plant viruses such as luteovirids and geminiviruses have been shown to bind to GroEL proteins produced by endosymbiotic bacteria harboured within hemipteran vectors. These interactions seem to prevent the degradation of the viral particles in the aphid's haemocoel. Similarly to luteovirids and geminiviruses, Banana bunchy top virus (BBTV), a member of the Nanoviridae family, is transmitted in a persistent, circulative manner and can be detected in the haemolymph of the aphid vector, Pentalonia nigronervosa. To date, it is not known if BBTV can interact with GroEL. In this study, we localised and inferred the phylogeny of a Buchnera aphidicola endosymbiont inhabiting P. nigronervosa. Furthermore, we predicted the 3D structure of Buchnera GroEL and detected the protein in the haemolymph of P. nigronervosa. Interactions were tested using 3 different assays: immunocapture PCR, dot blot, and far-western blot assays; however, none of them showed evidence of a BBTV–GroEL interaction. We concluded that it was unlikely that BBTV interacted with Buchnera GroEL either in vitro or in vivo and we discuss possible alternatives by which BBTV viral particles are able to avoid the process of degradation in the aphid haemocoel.
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Tropism, compartmentalization and retention of banana bunchy top virus (Nanoviridae) in the aphid vector Pentalonia nigronervosa.
The Journal of general virology, 2012Co-Authors: Shizu Watanabe, Alberto BressanAbstract:Plant viruses of the families Luteoviridae and Geminiviridae rely on hemipteran vectors for the infection of their hosts. Several lines of evidence have revealed that these viruses are transmitted by competent vectors in a circulative manner, involving entry into the vector's body and the crossing of epithelial tissues forming the alimentary tract and the salivary glands. Similar to luteovirids and geminiviruses, a third family of plant viruses, the family Nanoviridae, have also been reported to be transmitted by aphids in a circulative manner. However, there is limited direct evidence of a possible path of translocation through the aphid vectors. Here, we used time-course experiments and transmission assays coupled with real-time PCR and immunofluorescence assays on dissected tissues to examine the translocation, compartmentalization and retention of banana bunchy top virus (BBTV) into the aphid vector Pentalonia nigronervosa. Our results indicate that BBTV translocates rapidly through the aphid vector; it is internalized into the anterior midgut in which it accumulates and is retained at concentrations higher than either the haemolymph or the principal salivary glands. Despite the large increase in viral concentration, we have failed to detect BBTV transcripts with RT-PCR. When tissues were not permeabilized, BBTV localized as distinct puncta in the proximity of the basal surface of the cells forming the anterior midgut and principal salivary glands, suggesting an on-going process of virion escape and internalization, respectively. Interestingly, we document that those organs can have direct contact within the aphid body, suggesting a possible haemolymph-independent translocation path.
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Immunofluorescence localisation of Banana bunchy top virus (family Nanoviridae) within the aphid vector, Pentalonia nigronervosa, suggests a virus tropism distinct from aphid-transmitted luteoviruses.
Virus research, 2010Co-Authors: Alberto Bressan, Shizu WatanabeAbstract:We have applied immunocapture PCR and developed an immunofluorescence assay to specifically detect Banana bunchy top virus (BBTV; family Nanoviridae, genus Babuvirus) within its aphid vector, Pentalonia nigronervosa (Hemiptera, Aphididae). BBTV was localised using either monoclonal or polyclonal antibodies into the anterior midgut (stomach) and into specific cells forming the principal salivary glands. These results suggest a distinct path of virus translocation that likely differs from the one described for aphid-transmitted luteovirus, which enter hemocoels through the hindguts and posterior midguts and that penetrate the accessory salivary glands of their competent vectors. To our understanding, this is the first work analysing the localisation of a virus member of the family Nanoviridae within an aphid vector.
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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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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analysis of dnas associated with coconut foliar decay disease implicates a unique single stranded dna virus representing a new taxon
Scientific Reports, 2018Co-Authors: Bruno Gronenborn, Quentin Barrière, Dennis Knierim, Stephan Winter, J W Randles, Josef H Vetten, Norman Warthmann, David Cornu, Tiata Sileye, Tatiana TimchenkoAbstract:The unique ecology, pathology and undefined taxonomy of coconut foliar decay virus (CFDV), found associated with coconut foliar decay disease (CFD) in 1986, prompted analyses of old virus samples by modern methods. Rolling circle amplification and deep sequencing applied to nucleic acid extracts from virion preparations and CFD-affected palms identified twelve distinct circular DNAs, eleven of which had a size of about 1.3 kb and one of 641 nt. Mass spectrometry-based protein identification proved that a 24 kDa protein encoded by two 1.3 kb DNAs is the virus capsid protein with highest sequence similarity to that of grabloviruses (family Geminiviridae), even though CFDV particles are not geminate. The nine other 1.3 kb DNAs represent alphasatellites coding for replication initiator proteins that differ clearly from those encoded by nanovirid DNA-R. The 641 nt DNA-gamma is unique and may encode a movement protein. Three DNAs, alphasatellite CFDAR, capsid protein encoding CFDV DNA-S.1 and DNA-gamma share sequence motifs near their replication origins and were consistently present in all samples analysed. These DNAs appear to be integral components of a possibly tripartite CFDV genome, different from those of any Geminiviridae or Nanoviridae family member, implicating CFDV as representative of a new genus and family.
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High Variability and Rapid Evolution of a Nanovirus
Journal of virology, 2010Co-Authors: Ioana Grigoras, Heinrich-josef Vetten, Tatiana Timchenko, Ana Grande-pérez, L. Katul, 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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Genome diversity and evidence of recombination and reassortment in nanoviruses from Europe
Journal of General Virology, 2014Co-Authors: Ioana Grigoras, Arvind Varsani, Darren P. Martin, Ana Isabel Del Cueto Ginzo, Javier Romero, Alamdar Ch. Mammadov, Irada M. Huseynova, Jalal A. Aliyev, A. Kheyr-pour, Herbert HussAbstract:The recent identification of a new nanovirus, pea necrotic yellow dwarf virus, from pea in Germany prompted us to survey wild and cultivated legumes for nanovirus infections in several European countries. This led to the identification of two new nanoviruses: black medic leaf roll virus (BMLRV) and pea yellow stunt virus (PYSV), each considered a putative new species. The complete genomes of a PYSV isolate from Austria and three BMLRV isolates from Austria, Azerbaijan and Sweden were sequenced. In addition, the genomes of five isolates of faba bean necrotic yellows virus (FBNYV) from Azerbaijan and Spain and those of four faba bean necrotic stunt virus (FBNSV) isolates from Azerbaijan were completely sequenced, leading to the first identification of FBNSV occurring in Europe. Sequence analyses uncovered evolutionary relationships, extensive reassortment and potential remnants of mixed nanovirus infections, as well as intra- and intercomponent recombination events within the nanovirus genomes. In some virus isolates, diverse types of the same genome component (paralogues) were observed, a type of genome complexity not described previously for any member of the family Nanoviridae. Moreover, infectious and aphid-transmissible nanoviruses from cloned genomic DNAs of FBNYV and BMLRV were reconstituted that, for the first time, allow experimental reassortments for studying the genome functions and evolution of these nanoviruses.
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High Variability and Rapid Evolution of a Nanovirus
Journal of virology, 2010Co-Authors: Ioana Grigoras, Heinrich-josef Vetten, Tatiana Timchenko, Ana Grande-pérez, L. Katul, 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.
