The Experts below are selected from a list of 201 Experts worldwide ranked by ideXlab platform
Yves Le Bigot - One of the best experts on this subject based on the ideXlab platform.
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ICTV virus taxonomy profile: Ascoviridae
Journal of General Virology, 2017Co-Authors: Sassan Asgari, Brian A. Federici, Yves Le Bigot, Dennis K Bideshi, Xiaowen ChengAbstract:The family Ascoviridae includes viruses with circular dsDNA genomes of 100–200 kbp characterized by oblong enveloped virions of 200–400 nm in length. Ascoviruses mainly infect lepidopteran larvae and are mechanically transmitted by parasitoid wasps in which they may also replicate. Most known members belong to the genus Ascovirus, except one virus, that of the genus Toursvirus, which replicates in both its lepidopteran and parasitoid vector hosts. Ascoviruses cause high mortality among economically important insect pests, thereby controlling insect populations. This is a summary of the current International Committee on Taxonomy of Viruses (ICTV) Report on the taxonomy of the Ascoviridae, which is available at www.ictv.global/report/Ascoviridae.
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Evolutionary relationships of iridoviruses and divergence of ascoviruses from invertebrate iridoviruses in the superfamily Megavirales.
Molecular phylogenetics and evolution, 2015Co-Authors: Benoit Piegu, Sassan Asgari, Brian A. Federici, Dennis K Bideshi, Yves Le BigotAbstract:The family Iridoviridae of the superfamily Megavirales currently consists of five genera. Three of these, Lymphocystivirus, Megalocytivirus and Ranavirus, are composed of species that infect vertebrates, and the other two, Chloriridovirus and Iridovirus, contain species that infect invertebrates. Until recently, the lack of genomic sequence data limited investigation of the evolutionary relationships between the invertebrate iridoviruses (IIVs) and vertebrate iridoviruses (VIVs), as well as the relationship of these viruses to those of the closely related family Ascoviridae, which only contains species that infect insects. To help clarify the phylogenetic relationships of these viruses, we recently published the annotated genome sequences of five additional IIV isolates. Here, using classical approaches of phylogeny via maximum likelihood, a Bayesian approach, and resolution of a core protein tree, we demonstrate that the invertebrate and vertebrate IV species constitute two lineages that diverged early during the evolution of the family Iridoviridae, before the emergence of the four IIV clades, previously referred to as Chloriridoviruses, Polyiridoviruses, Oligoiridoviruses and Crustaceoiridoviruses. In addition, we provide evidence that species of the family Ascoviridae have a more recent origin than most iridoviruses, emerging just before the differentiation between the Oligoiridoviruses and Crustaceoiridovirus clades. Our results also suggest that after emergence, based on their molecular clock, the ascoviruses evolved more quickly than their closest iridovirus relatives.
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megavirales a proposed new order for eukaryotic nucleocytoplasmic large dna viruses
Archives of Virology, 2013Co-Authors: Philippe Colson, Sassan Asgari, Xiaowen Cheng, Brian A. Federici, Yves Le Bigot, Xavier De Lamballerie, Dennis K Bideshi, Natalya Yutin, James L Van Etten, Eugene V. KooninAbstract:The nucleocytoplasmic large DNA viruses (NCLDVs) comprise a monophyletic group of viruses that infect animals and diverse unicellular eukaryotes. The NCLDV group includes the families Poxviridae, Asfarviridae, Iridoviridae, Ascoviridae, Phycodnaviridae, Mimiviridae and the proposed family “Marseilleviridae”. The family Mimiviridae includes the largest known viruses, with genomes in excess of one megabase, whereas the genome size in the other NCLDV families varies from 100 to 400 kilobase pairs. Most of the NCLDVs replicate in the cytoplasm of infected cells, within so-called virus factories. The NCLDVs share a common ancient origin, as demonstrated by evolutionary reconstructions that trace approximately 50 genes encoding key proteins involved in viral replication and virion formation to the last common ancestor of all these viruses. Taken together, these characteristics lead us to propose assigning an official taxonomic rank to the NCLDVs as the order “Megavirales”, in reference to the large size of the virions and genomes of these viruses.
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Symbiotic virus at the evolutionary intersection of three types of large DNA viruses; iridoviruses, ascoviruses, and ichnoviruses.
PLoS ONE, 2009Co-Authors: Yves Le Bigot, Marie-véronique Demattei, Sylvaine Renault, Dennis K Bideshi, Jacques Nicolas, Corinne Moundras, Sylvie Samain, Brian A. FedericiAbstract:Background The ascovirus, DpAV4a (family Ascoviridae), is a symbiotic virus that markedly increases the fitness of its vector, the parasitic ichneumonid wasp, Diadromus puchellus, by increasing survival of wasp eggs and larvae in their lepidopteran host, Acrolepiopsis assectella. Previous phylogenetic studies have indicated that DpAV4a is related to the pathogenic ascoviruses, such as the Spodoptera frugiperda ascovirus 1a (SfAV1a) and the lepidopteran iridovirus (family Iridoviridae), Chilo iridescent virus (CIV), and is also likely related to the ancestral source of certain ichnoviruses (family Polydnaviridae).
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Communication Proteomic analysis of the Spodoptera frugiperda
2008Co-Authors: Yeping Tan, Brian A. Federici, Yves Le Bigot, Dennis K Bideshi, Jeffrey J. JohnsonAbstract:The Spodoptera frugiperda ascovirus 1a (SfAV-1a) is a double-stranded DNA virus that attacks lepidopteran larvae, in which it produces enveloped virions with complex symmetry which have an average diameter of 130 nm and length of 400 nm. Here, we report identification of 21 SfAV-1a-encoded proteins that occur in the virion, as determined by nano-liquid chromatography/tandem mass spectrometry. These included a helicase (ORF009), nuclease (ORF075), ATPase (ORF047), serine/threonine-like protein kinase (ORF064), inhibitor of apoptosis-like protein (ORF015), thiol oxidoreductase-like protein (ORF061), CTD phosphatase (ORF109), major capsid protein (ORF041) and a highly basic protein, P64 (ORF048). The latter two were the most abundant. Apart from ascoviruses, the closest orthologues were found in iridoviruses, providing further evidence that ascoviruses evolved from invertebrate iridoviruses. These results establish a foundation for investigating how ascovirus virion proteins interact to form their complex asymmetrical structure, as well as for elucidating the mechanisms involved in SfAV-1a virion morphogenesis. The family Ascoviridae comprises large double-stranded DNA viruses with circular genomes ranging from 100 to 186 kb (Asgari et al., 2007; Bideshi et al., 2006; Bigot et al., 1997a, b; Wang et al., 2006). Four species of ascoviruses (AVs) are recognized, Spodoptera frugiperda AV (SfAV-1)
Brian A. Federici - One of the best experts on this subject based on the ideXlab platform.
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ICTV virus taxonomy profile: Ascoviridae
Journal of General Virology, 2017Co-Authors: Sassan Asgari, Brian A. Federici, Yves Le Bigot, Dennis K Bideshi, Xiaowen ChengAbstract:The family Ascoviridae includes viruses with circular dsDNA genomes of 100–200 kbp characterized by oblong enveloped virions of 200–400 nm in length. Ascoviruses mainly infect lepidopteran larvae and are mechanically transmitted by parasitoid wasps in which they may also replicate. Most known members belong to the genus Ascovirus, except one virus, that of the genus Toursvirus, which replicates in both its lepidopteran and parasitoid vector hosts. Ascoviruses cause high mortality among economically important insect pests, thereby controlling insect populations. This is a summary of the current International Committee on Taxonomy of Viruses (ICTV) Report on the taxonomy of the Ascoviridae, which is available at www.ictv.global/report/Ascoviridae.
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Evolutionary relationships of iridoviruses and divergence of ascoviruses from invertebrate iridoviruses in the superfamily Megavirales.
Molecular phylogenetics and evolution, 2015Co-Authors: Benoit Piegu, Sassan Asgari, Brian A. Federici, Dennis K Bideshi, Yves Le BigotAbstract:The family Iridoviridae of the superfamily Megavirales currently consists of five genera. Three of these, Lymphocystivirus, Megalocytivirus and Ranavirus, are composed of species that infect vertebrates, and the other two, Chloriridovirus and Iridovirus, contain species that infect invertebrates. Until recently, the lack of genomic sequence data limited investigation of the evolutionary relationships between the invertebrate iridoviruses (IIVs) and vertebrate iridoviruses (VIVs), as well as the relationship of these viruses to those of the closely related family Ascoviridae, which only contains species that infect insects. To help clarify the phylogenetic relationships of these viruses, we recently published the annotated genome sequences of five additional IIV isolates. Here, using classical approaches of phylogeny via maximum likelihood, a Bayesian approach, and resolution of a core protein tree, we demonstrate that the invertebrate and vertebrate IV species constitute two lineages that diverged early during the evolution of the family Iridoviridae, before the emergence of the four IIV clades, previously referred to as Chloriridoviruses, Polyiridoviruses, Oligoiridoviruses and Crustaceoiridoviruses. In addition, we provide evidence that species of the family Ascoviridae have a more recent origin than most iridoviruses, emerging just before the differentiation between the Oligoiridoviruses and Crustaceoiridovirus clades. Our results also suggest that after emergence, based on their molecular clock, the ascoviruses evolved more quickly than their closest iridovirus relatives.
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megavirales a proposed new order for eukaryotic nucleocytoplasmic large dna viruses
Archives of Virology, 2013Co-Authors: Philippe Colson, Sassan Asgari, Xiaowen Cheng, Brian A. Federici, Yves Le Bigot, Xavier De Lamballerie, Dennis K Bideshi, Natalya Yutin, James L Van Etten, Eugene V. KooninAbstract:The nucleocytoplasmic large DNA viruses (NCLDVs) comprise a monophyletic group of viruses that infect animals and diverse unicellular eukaryotes. The NCLDV group includes the families Poxviridae, Asfarviridae, Iridoviridae, Ascoviridae, Phycodnaviridae, Mimiviridae and the proposed family “Marseilleviridae”. The family Mimiviridae includes the largest known viruses, with genomes in excess of one megabase, whereas the genome size in the other NCLDV families varies from 100 to 400 kilobase pairs. Most of the NCLDVs replicate in the cytoplasm of infected cells, within so-called virus factories. The NCLDVs share a common ancient origin, as demonstrated by evolutionary reconstructions that trace approximately 50 genes encoding key proteins involved in viral replication and virion formation to the last common ancestor of all these viruses. Taken together, these characteristics lead us to propose assigning an official taxonomic rank to the NCLDVs as the order “Megavirales”, in reference to the large size of the virions and genomes of these viruses.
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Symbiotic virus at the evolutionary intersection of three types of large DNA viruses; iridoviruses, ascoviruses, and ichnoviruses.
PLoS ONE, 2009Co-Authors: Yves Le Bigot, Marie-véronique Demattei, Sylvaine Renault, Dennis K Bideshi, Jacques Nicolas, Corinne Moundras, Sylvie Samain, Brian A. FedericiAbstract:Background The ascovirus, DpAV4a (family Ascoviridae), is a symbiotic virus that markedly increases the fitness of its vector, the parasitic ichneumonid wasp, Diadromus puchellus, by increasing survival of wasp eggs and larvae in their lepidopteran host, Acrolepiopsis assectella. Previous phylogenetic studies have indicated that DpAV4a is related to the pathogenic ascoviruses, such as the Spodoptera frugiperda ascovirus 1a (SfAV1a) and the lepidopteran iridovirus (family Iridoviridae), Chilo iridescent virus (CIV), and is also likely related to the ancestral source of certain ichnoviruses (family Polydnaviridae).
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Communication Proteomic analysis of the Spodoptera frugiperda
2008Co-Authors: Yeping Tan, Brian A. Federici, Yves Le Bigot, Dennis K Bideshi, Jeffrey J. JohnsonAbstract:The Spodoptera frugiperda ascovirus 1a (SfAV-1a) is a double-stranded DNA virus that attacks lepidopteran larvae, in which it produces enveloped virions with complex symmetry which have an average diameter of 130 nm and length of 400 nm. Here, we report identification of 21 SfAV-1a-encoded proteins that occur in the virion, as determined by nano-liquid chromatography/tandem mass spectrometry. These included a helicase (ORF009), nuclease (ORF075), ATPase (ORF047), serine/threonine-like protein kinase (ORF064), inhibitor of apoptosis-like protein (ORF015), thiol oxidoreductase-like protein (ORF061), CTD phosphatase (ORF109), major capsid protein (ORF041) and a highly basic protein, P64 (ORF048). The latter two were the most abundant. Apart from ascoviruses, the closest orthologues were found in iridoviruses, providing further evidence that ascoviruses evolved from invertebrate iridoviruses. These results establish a foundation for investigating how ascovirus virion proteins interact to form their complex asymmetrical structure, as well as for elucidating the mechanisms involved in SfAV-1a virion morphogenesis. The family Ascoviridae comprises large double-stranded DNA viruses with circular genomes ranging from 100 to 186 kb (Asgari et al., 2007; Bideshi et al., 2006; Bigot et al., 1997a, b; Wang et al., 2006). Four species of ascoviruses (AVs) are recognized, Spodoptera frugiperda AV (SfAV-1)
Xiaowen Cheng - One of the best experts on this subject based on the ideXlab platform.
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genomic analysis of a novel isolate heliothis virescens ascovirus 3i hvav 3i and identification of ascoviral repeat orfs aros
Archives of Virology, 2018Co-Authors: Zishu Chen, Xiaowen Cheng, Xing Wang, Guohua HuangAbstract:Ascoviruses are circular double-stranded DNA viruses that infect insects. Herein we sequenced and analyzed the genome of the previously unrecorded ascovirus isolate Heliothis virescens ascovirus 3i (HvAV-3i). The genome size is 185,650 bp with 181 hypothetical open reading frames (ORFs). Additionally, definition based on ascovirus repeated ORFs (aros) is proposed; whereby the 29 aros from all sequenced Ascoviridae genomes are divided into six distinct groups. The topological relationship among the isolates of Heliothis virescens ascovirus 3a is (HvAV-3f, {HvAV-3h, [HvAV-3e, (HvAV-3g, HvAV-3i)]}) with every clade well supported by a Bayesian posterior probability of 1.00 and a Bootstrap value of 100%.
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ICTV virus taxonomy profile: Ascoviridae
Journal of General Virology, 2017Co-Authors: Sassan Asgari, Brian A. Federici, Yves Le Bigot, Dennis K Bideshi, Xiaowen ChengAbstract:The family Ascoviridae includes viruses with circular dsDNA genomes of 100–200 kbp characterized by oblong enveloped virions of 200–400 nm in length. Ascoviruses mainly infect lepidopteran larvae and are mechanically transmitted by parasitoid wasps in which they may also replicate. Most known members belong to the genus Ascovirus, except one virus, that of the genus Toursvirus, which replicates in both its lepidopteran and parasitoid vector hosts. Ascoviruses cause high mortality among economically important insect pests, thereby controlling insect populations. This is a summary of the current International Committee on Taxonomy of Viruses (ICTV) Report on the taxonomy of the Ascoviridae, which is available at www.ictv.global/report/Ascoviridae.
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megavirales a proposed new order for eukaryotic nucleocytoplasmic large dna viruses
Archives of Virology, 2013Co-Authors: Philippe Colson, Sassan Asgari, Xiaowen Cheng, Brian A. Federici, Yves Le Bigot, Xavier De Lamballerie, Dennis K Bideshi, Natalya Yutin, James L Van Etten, Eugene V. KooninAbstract:The nucleocytoplasmic large DNA viruses (NCLDVs) comprise a monophyletic group of viruses that infect animals and diverse unicellular eukaryotes. The NCLDV group includes the families Poxviridae, Asfarviridae, Iridoviridae, Ascoviridae, Phycodnaviridae, Mimiviridae and the proposed family “Marseilleviridae”. The family Mimiviridae includes the largest known viruses, with genomes in excess of one megabase, whereas the genome size in the other NCLDV families varies from 100 to 400 kilobase pairs. Most of the NCLDVs replicate in the cytoplasm of infected cells, within so-called virus factories. The NCLDVs share a common ancient origin, as demonstrated by evolutionary reconstructions that trace approximately 50 genes encoding key proteins involved in viral replication and virion formation to the last common ancestor of all these viruses. Taken together, these characteristics lead us to propose assigning an official taxonomic rank to the NCLDVs as the order “Megavirales”, in reference to the large size of the virions and genomes of these viruses.
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genomic sequence of heliothis virescens ascovirus 3g isolated from spodoptera exigua
Journal of Virology, 2012Co-Authors: Guohua Huang, Tyler A Garretson, Xiaowen Cheng, Chuanxi Zhang, Yunsheng Wang, Xing WangAbstract:Heliothis virescens ascovirus 3a (HvAV-3a), a member of the family Ascoviridae, has the highest diversity among ascovirus species that have been reported in Australia, Indonesia, China, and the United States. To understand the diversity and origin of this important ascovirus, the complete genome of the HvAV Indonesia strain (HvAV-3g), isolated from Spodoptera exigua, was determined to be 199,721 bp, with a G+C content of 45.9%. Therefore, HvAV-3g has the largest genome among the reported ascovirus genomes to date. There are 194 predicted open reading frames (ORFs) encoding proteins of 50 or more amino acid residues. In comparison to HvAV-3e reported from Australia, HvAV-3g has all the ORFs in HvAV-3e with 6 additional ORFs unique to HvAV-3g, including 1 peptidase C26 gene with the highest identity to Drosophila spp. and 2 gas vesicle protein U (GvpU) genes with identities to Bacillus megaterium. The five unique homologous regions (hrs) and 25 baculovirus repeat ORFs (bro) of HvAV-3g are highly variable.
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Comparative analysis of a highly variable region within the genomes of Spodoptera frugiperda ascovirus 1d (SfAV-1d) and SfAV-1a.
Journal of General Virology, 2011Co-Authors: Jianli Xue, Xiaowen ChengAbstract:The recently discovered ascoviruses have a worldwide distribution. Here we report a new member of the family Ascoviridae, Spodoptera frugiperda ascovirus 1d (SfAV-1d) with a variable region in the genome. Restriction fragment length polymorphism, Southern hybridization and genome sequencing analyses confirmed that SfAV-1d and the earlier reported SfAV-1a are closely related but are not identical. The genome size of SfAV-1d is approximately 100 kbp, which is about 57 kbp smaller than SfAV-1a. The SfAV-1d genome has a major deletion of 14 kbp that corresponds to one of the inverted repeat (IR) regions of SfAV-1a. Cloning and sequencing revealed that the region flanking the deletion within the SfAV-1d genome is highly variable. In all the variants of this region, the whole IR region is missing, with 88.2 % of the variants missing part of or the whole adjacent SfAV-1a ORF71, 94.1 % missing part of or the whole of adjacent ORF72 and 64.6 % missing part of or the whole of ORF73.
Sassan Asgari - One of the best experts on this subject based on the ideXlab platform.
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ICTV virus taxonomy profile: Ascoviridae
Journal of General Virology, 2017Co-Authors: Sassan Asgari, Brian A. Federici, Yves Le Bigot, Dennis K Bideshi, Xiaowen ChengAbstract:The family Ascoviridae includes viruses with circular dsDNA genomes of 100–200 kbp characterized by oblong enveloped virions of 200–400 nm in length. Ascoviruses mainly infect lepidopteran larvae and are mechanically transmitted by parasitoid wasps in which they may also replicate. Most known members belong to the genus Ascovirus, except one virus, that of the genus Toursvirus, which replicates in both its lepidopteran and parasitoid vector hosts. Ascoviruses cause high mortality among economically important insect pests, thereby controlling insect populations. This is a summary of the current International Committee on Taxonomy of Viruses (ICTV) Report on the taxonomy of the Ascoviridae, which is available at www.ictv.global/report/Ascoviridae.
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Evolutionary relationships of iridoviruses and divergence of ascoviruses from invertebrate iridoviruses in the superfamily Megavirales.
Molecular phylogenetics and evolution, 2015Co-Authors: Benoit Piegu, Sassan Asgari, Brian A. Federici, Dennis K Bideshi, Yves Le BigotAbstract:The family Iridoviridae of the superfamily Megavirales currently consists of five genera. Three of these, Lymphocystivirus, Megalocytivirus and Ranavirus, are composed of species that infect vertebrates, and the other two, Chloriridovirus and Iridovirus, contain species that infect invertebrates. Until recently, the lack of genomic sequence data limited investigation of the evolutionary relationships between the invertebrate iridoviruses (IIVs) and vertebrate iridoviruses (VIVs), as well as the relationship of these viruses to those of the closely related family Ascoviridae, which only contains species that infect insects. To help clarify the phylogenetic relationships of these viruses, we recently published the annotated genome sequences of five additional IIV isolates. Here, using classical approaches of phylogeny via maximum likelihood, a Bayesian approach, and resolution of a core protein tree, we demonstrate that the invertebrate and vertebrate IV species constitute two lineages that diverged early during the evolution of the family Iridoviridae, before the emergence of the four IIV clades, previously referred to as Chloriridoviruses, Polyiridoviruses, Oligoiridoviruses and Crustaceoiridoviruses. In addition, we provide evidence that species of the family Ascoviridae have a more recent origin than most iridoviruses, emerging just before the differentiation between the Oligoiridoviruses and Crustaceoiridovirus clades. Our results also suggest that after emergence, based on their molecular clock, the ascoviruses evolved more quickly than their closest iridovirus relatives.
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megavirales a proposed new order for eukaryotic nucleocytoplasmic large dna viruses
Archives of Virology, 2013Co-Authors: Philippe Colson, Sassan Asgari, Xiaowen Cheng, Brian A. Federici, Yves Le Bigot, Xavier De Lamballerie, Dennis K Bideshi, Natalya Yutin, James L Van Etten, Eugene V. KooninAbstract:The nucleocytoplasmic large DNA viruses (NCLDVs) comprise a monophyletic group of viruses that infect animals and diverse unicellular eukaryotes. The NCLDV group includes the families Poxviridae, Asfarviridae, Iridoviridae, Ascoviridae, Phycodnaviridae, Mimiviridae and the proposed family “Marseilleviridae”. The family Mimiviridae includes the largest known viruses, with genomes in excess of one megabase, whereas the genome size in the other NCLDV families varies from 100 to 400 kilobase pairs. Most of the NCLDVs replicate in the cytoplasm of infected cells, within so-called virus factories. The NCLDVs share a common ancient origin, as demonstrated by evolutionary reconstructions that trace approximately 50 genes encoding key proteins involved in viral replication and virion formation to the last common ancestor of all these viruses. Taken together, these characteristics lead us to propose assigning an official taxonomic rank to the NCLDVs as the order “Megavirales”, in reference to the large size of the virions and genomes of these viruses.
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An Ascovirus-Encoded RNase III Autoregulates Its Expression and Suppresses RNA Interference-Mediated Gene Silencing
Journal of virology, 2010Co-Authors: Mazhar Hussain, Alexander M. Abraham, Sassan AsgariAbstract:RNase III proteins play vital roles in processing of several types of RNA molecules and gene silencing. Recently, it has been discovered that some plant and animal viruses encode RNase III-like proteins as well. Genome sequencing of four virus species belonging to the Ascoviridae family has revealed sequence conservation of an RNase III open reading frame among the viruses. These have not been explored in ascoviruses, and therefore their role in host-virus interaction is unknown. Here, we confirmed expression of Heliothis virescens ascovirus (HvAV-3e) open reading frame 27 (orf27) that encodes an RNase III-like protein after infection and demonstrated dsRNA specific endoribonuclease activity of the encoded protein. Analysis of the expression patterns of orf27 in virus-infected insect cells and a bacterial expression system revealed autoregulation of this protein over time. Moreover, HvAV-3e RNase III was found essential for virus DNA replication and infection using RNA interference (RNAi)-mediated gene silencing. In addition, using green fluorescent protein gene as a marker, we provide evidence that RNase III is involved in the suppression of gene silencing. To our knowledge, this is the first insect virus-encoded RNase III described and shown to suppress host cell RNAi defense mechanism.
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An Ascovirus-encoded RNase III autoregulates its expression and suppresses RNA interference-mediated gene silencing
2010Co-Authors: Mazhar Hussain, Er M. Abraham, Sassan AsgariAbstract:RNase III proteins play vital roles in processing of several types of RNA molecules and gene silencing. Recently, it has been discovered that some plant and animal viruses encode RNase III-like proteins as well. Genome sequencing of four virus species belonging to the Ascoviridae family has revealed sequence conserva-tion of an RNase III open reading frame among the viruses. These have not been explored in ascoviruses, and therefore their role in host-virus interaction is unknown. Here, we confirmed expression of Heliothis virescens ascovirus (HvAV-3e) open reading frame 27 (orf27) that encodes an RNase III-like protein after infection and demonstrated dsRNA specific endoribonuclease activity of the encoded protein. Analysis of the expression patterns of orf27 in virus-infected insect cells and a bacterial expression system revealed autoregulation of this protein over time. Moreover, HvAV-3e RNase III was found essential for virus DNA replication and infection using RNA interference (RNAi)-mediated gene silencing. In addition, using green fluorescent protein gene as a marker, we provide evidence that RNase III is involved in the suppression of gene silencing. To our knowledge, this is the first insect virus-encoded RNase III described and shown to suppress host cell RNAi defense mechanism. RNases III are double-stranded RNA (dsRNA)-specific processing enzymes present in prokaryotes, eukaryotes, an
Dennis K Bideshi - One of the best experts on this subject based on the ideXlab platform.
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ICTV virus taxonomy profile: Ascoviridae
Journal of General Virology, 2017Co-Authors: Sassan Asgari, Brian A. Federici, Yves Le Bigot, Dennis K Bideshi, Xiaowen ChengAbstract:The family Ascoviridae includes viruses with circular dsDNA genomes of 100–200 kbp characterized by oblong enveloped virions of 200–400 nm in length. Ascoviruses mainly infect lepidopteran larvae and are mechanically transmitted by parasitoid wasps in which they may also replicate. Most known members belong to the genus Ascovirus, except one virus, that of the genus Toursvirus, which replicates in both its lepidopteran and parasitoid vector hosts. Ascoviruses cause high mortality among economically important insect pests, thereby controlling insect populations. This is a summary of the current International Committee on Taxonomy of Viruses (ICTV) Report on the taxonomy of the Ascoviridae, which is available at www.ictv.global/report/Ascoviridae.
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Evolutionary relationships of iridoviruses and divergence of ascoviruses from invertebrate iridoviruses in the superfamily Megavirales.
Molecular phylogenetics and evolution, 2015Co-Authors: Benoit Piegu, Sassan Asgari, Brian A. Federici, Dennis K Bideshi, Yves Le BigotAbstract:The family Iridoviridae of the superfamily Megavirales currently consists of five genera. Three of these, Lymphocystivirus, Megalocytivirus and Ranavirus, are composed of species that infect vertebrates, and the other two, Chloriridovirus and Iridovirus, contain species that infect invertebrates. Until recently, the lack of genomic sequence data limited investigation of the evolutionary relationships between the invertebrate iridoviruses (IIVs) and vertebrate iridoviruses (VIVs), as well as the relationship of these viruses to those of the closely related family Ascoviridae, which only contains species that infect insects. To help clarify the phylogenetic relationships of these viruses, we recently published the annotated genome sequences of five additional IIV isolates. Here, using classical approaches of phylogeny via maximum likelihood, a Bayesian approach, and resolution of a core protein tree, we demonstrate that the invertebrate and vertebrate IV species constitute two lineages that diverged early during the evolution of the family Iridoviridae, before the emergence of the four IIV clades, previously referred to as Chloriridoviruses, Polyiridoviruses, Oligoiridoviruses and Crustaceoiridoviruses. In addition, we provide evidence that species of the family Ascoviridae have a more recent origin than most iridoviruses, emerging just before the differentiation between the Oligoiridoviruses and Crustaceoiridovirus clades. Our results also suggest that after emergence, based on their molecular clock, the ascoviruses evolved more quickly than their closest iridovirus relatives.
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megavirales a proposed new order for eukaryotic nucleocytoplasmic large dna viruses
Archives of Virology, 2013Co-Authors: Philippe Colson, Sassan Asgari, Xiaowen Cheng, Brian A. Federici, Yves Le Bigot, Xavier De Lamballerie, Dennis K Bideshi, Natalya Yutin, James L Van Etten, Eugene V. KooninAbstract:The nucleocytoplasmic large DNA viruses (NCLDVs) comprise a monophyletic group of viruses that infect animals and diverse unicellular eukaryotes. The NCLDV group includes the families Poxviridae, Asfarviridae, Iridoviridae, Ascoviridae, Phycodnaviridae, Mimiviridae and the proposed family “Marseilleviridae”. The family Mimiviridae includes the largest known viruses, with genomes in excess of one megabase, whereas the genome size in the other NCLDV families varies from 100 to 400 kilobase pairs. Most of the NCLDVs replicate in the cytoplasm of infected cells, within so-called virus factories. The NCLDVs share a common ancient origin, as demonstrated by evolutionary reconstructions that trace approximately 50 genes encoding key proteins involved in viral replication and virion formation to the last common ancestor of all these viruses. Taken together, these characteristics lead us to propose assigning an official taxonomic rank to the NCLDVs as the order “Megavirales”, in reference to the large size of the virions and genomes of these viruses.
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Symbiotic virus at the evolutionary intersection of three types of large DNA viruses; iridoviruses, ascoviruses, and ichnoviruses.
PLoS ONE, 2009Co-Authors: Yves Le Bigot, Marie-véronique Demattei, Sylvaine Renault, Dennis K Bideshi, Jacques Nicolas, Corinne Moundras, Sylvie Samain, Brian A. FedericiAbstract:Background The ascovirus, DpAV4a (family Ascoviridae), is a symbiotic virus that markedly increases the fitness of its vector, the parasitic ichneumonid wasp, Diadromus puchellus, by increasing survival of wasp eggs and larvae in their lepidopteran host, Acrolepiopsis assectella. Previous phylogenetic studies have indicated that DpAV4a is related to the pathogenic ascoviruses, such as the Spodoptera frugiperda ascovirus 1a (SfAV1a) and the lepidopteran iridovirus (family Iridoviridae), Chilo iridescent virus (CIV), and is also likely related to the ancestral source of certain ichnoviruses (family Polydnaviridae).
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Communication Proteomic analysis of the Spodoptera frugiperda
2008Co-Authors: Yeping Tan, Brian A. Federici, Yves Le Bigot, Dennis K Bideshi, Jeffrey J. JohnsonAbstract:The Spodoptera frugiperda ascovirus 1a (SfAV-1a) is a double-stranded DNA virus that attacks lepidopteran larvae, in which it produces enveloped virions with complex symmetry which have an average diameter of 130 nm and length of 400 nm. Here, we report identification of 21 SfAV-1a-encoded proteins that occur in the virion, as determined by nano-liquid chromatography/tandem mass spectrometry. These included a helicase (ORF009), nuclease (ORF075), ATPase (ORF047), serine/threonine-like protein kinase (ORF064), inhibitor of apoptosis-like protein (ORF015), thiol oxidoreductase-like protein (ORF061), CTD phosphatase (ORF109), major capsid protein (ORF041) and a highly basic protein, P64 (ORF048). The latter two were the most abundant. Apart from ascoviruses, the closest orthologues were found in iridoviruses, providing further evidence that ascoviruses evolved from invertebrate iridoviruses. These results establish a foundation for investigating how ascovirus virion proteins interact to form their complex asymmetrical structure, as well as for elucidating the mechanisms involved in SfAV-1a virion morphogenesis. The family Ascoviridae comprises large double-stranded DNA viruses with circular genomes ranging from 100 to 186 kb (Asgari et al., 2007; Bideshi et al., 2006; Bigot et al., 1997a, b; Wang et al., 2006). Four species of ascoviruses (AVs) are recognized, Spodoptera frugiperda AV (SfAV-1)
