The Experts below are selected from a list of 207 Experts worldwide ranked by ideXlab platform
Yves Bigot - One of the best experts on this subject based on the ideXlab platform.
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Symbiotic Virus at the Evolutionary Intersection of Three Types of Large DNA Viruses; Iridoviruses, Ascoviruses,
2013Co-Authors: Yves Bigot, Sylvaine Renault, Jacques Nicolas, Corinne Moundras, Marie-véronique Demattei, Sylvie Samain, Dennis K. Bideshi, 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). Methodology/Principal Findings: To clarify the evolutionary relationships of these large double-stranded DNA viruses, we sequenced the genome of DpAV4a and undertook phylogenetic analyses of the above viruses and others, including iridoviruses pathogenic to vertebrates. The DpAV4a genome consisted of 119,343 bp and contained at least 119 open reading frames (ORFs), the analysis of which confirmed the relatedness of this virus to iridoviruses and other ascoviruses. Conclusions: Analyses of core DpAV4a genes confirmed that ascoviruses and iridoviruses are evolutionary related. Nevertheless, our results suggested that the symbiotic DpAV4a had a separate origin in the iridoviruses from the pathogenic ascoviruses, and that these two types shared parallel evolutionary paths, which converged with respect to virion structure (icosahedral to bacilliform), genome configuration (linear to circular), and cytopathology (plasmalemma blebbing to virioncontainin
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Evolution of Immunosuppressive Organelles from DNA Viruses in Insects
Evolutionary Biology – Concepts Molecular and Morphological Evolution, 2010Co-Authors: Brian A. Federici, Yves BigotAbstract:Endoparasitic wasps inject particles into their lepidopteran hosts that enable these parasitoids to evade or directly suppress the hosts’ innate immune response, especially encapsulation by hemocytes. For decades, these particles have been considered virions produced by DNA viruses known as polydnaviruses (family Polydnaviridae). Structurally, there are two main types of particles, those resembling, respectively, virions of baculoviruses or ascoviruses. These particles contain double-stranded DNA in the form of multiple small circular molecules that are transcribed but not replicated in cells of the lepidopteran hosts. Instead particle DNA is replicated from the wasp genome and selectively amplified for packaging into the particles in the reproductive tract of female wasps. Once assembled and secreted into calyx lumen, the particles become mixed with eggs and injected into caterpillars during wasp oviposition. Particle DNA, referred to as the “viral genome,” has now been sequenced for several polydnaviruses. Annotation shows that most of this DNA consists of noncoding DNA or wasp genes, not viral genes. More significantly, recent studies have shown that particle structural proteins are coded by the wasp genome, not by particle DNA, but are of viral origin. Together, these findings provide strong evidence that these particles originated from viruses, but through symbiogenesis followed by gene deletion and acquisition evolved into transducing organelles that shuttle wasp immunosuppressive genes into their hosts, thereby enhancing wasp progeny survival and species radiation.
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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 Bigot, Sylvaine Renault, Jacques Nicolas, Corinne Moundras, Marie-véronique Demattei, Sylvie Samain, Dennis K. Bideshi, 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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Ascoviruses: Superb Manipulators of Apoptosis for Viral Replication and Transmission
Lesser Known Large dsDNA Viruses, 2009Co-Authors: Brian A. Federici, Dennis K. Bideshi, Yeping Tan, Tatsinda Spears, Yves BigotAbstract:Ascoviruses are members of a recently described new family (Ascoviridae) of large double-stranded DNA viruses that attack immature stages of insects belonging to the order Lepidoptera, in which they cause a chronic, fatal disease. Ascoviruses have several unusual characteristics not found among other viruses, the most novel of which are their transmission by endoparasitic wasps and a unique cytopathology that resembles apoptosis. Cell infection induces apoptosis and in some species is associated with synthesis of a virus-encoded executioner caspase and several lipid-metabolizing enzymes. Rather than leading directly to cell death, synthesis of viral proteins results in the rescue of developing apoptotic bodies that are converted into large vesicles in which virions accumulate and continue to assemble. In infected larvae, millions of these virion-containing vesicles begin to disperse from infected tissues 48-72 h after infection into the blood, making it milky white, a major characteristic of the disease. Circulation of virions and vesicles in the blood facilitates mechanical transmission by parasitic wasps. Although ascoviruses appear to be very common, only five species are currently recognized, with the type species being the Spodoptera frugiperda ascovirus 1a. Ascovirus virions are large, enveloped, typically bacilliform or reniform in shape, and, depending on the species, have genomes that range from 119 to 186 kbp. Molecular phylogenetic evidence indicates that ascoviruses evolved from iridoviruses (family Iridoviridae) that attack lepidopteran larvae and are likely the evolutionary source of ichnoviruses (family Polydnaviridae), which assist endoparasitic hymenopterans in overcoming the defense responses of their insect hosts. Thus, as other molecular evidence suggests that iridoviruses evolved from phycodnaviruses (family Phycodnaviridae), an evolutionary pathway is apparent from phycodnaviruses via iridoviruses and ascoviruses to ichnoviruses.
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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 Bigot, Sylvaine Renault, Jacques Nicolas, Corinne Moundras, Marie-véronique Demattei, Sylvie Samain, Dennis K. Bideshi, Brian A. FedericiAbstract: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). Methodology/Principal Findings: To clarify the evolutionary relationships of these large double-stranded DNA viruses, we sequenced the genome of DpAV4a and undertook phylogenetic analyses of the above viruses and others, including iridoviruses pathogenic to vertebrates. The DpAV4a genome consisted of 119,343 bp and contained at least 119 open reading frames (ORFs), the analysis of which confirmed the relatedness of this virus to iridoviruses and other ascoviruses. Conclusions : Analyses of core DpAV4a genes confirmed that ascoviruses and iridoviruses are evolutionary related. Nevertheless, our results suggested that the symbiotic DpAV4a had a separate origin in the iridoviruses from the pathogenic ascoviruses, and that these two types shared parallel evolutionary paths, which converged with respect to virion structure (icosahedral to bacilliform), genome configuration (linear to circular), and cytopathology (plasmalemma blebbing to virion-containing vesicles). Our analyses also revealed that DpAV4a shared more core genes with CIV than with other ascoviruses and iridoviruses, providing additional evidence that DpAV4a represents a separate lineage. Given the differences in the biology of the various iridoviruses and ascoviruses studied, these results provide an interesting model for how viruses of different families evolved from one another.
Elisabeth Huguet - One of the best experts on this subject based on the ideXlab platform.
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Origin and evolution of symbiotic viruses associated with parasitoid wasps
Current opinion in insect science, 2014Co-Authors: Jean-michel Drezen, Germain Chevignon, Faustine Louis, Elisabeth HuguetAbstract:The Polydnaviridae (PDV), including the Bracovirus (BV) and Ichnovirus (IV) genera, originated from the integration of viruses in the genomes of two parasitoid wasp lineages. In a remarkable example of convergent evolution BVs evolved from the domestication of a nudivirus, while IVs originate from a different ancestral virus belonging to a new virus entity. In both cases the ancestor genomes have been maintained in wasp genomes as endogenous viral elements involved in production of particles containing DNA encoding virulence genes that are injected into lepidopteran hosts. However many PDV virulence genes appear to be of eukaryotic origin, and expansion and diversification of these genes have led to the production of novel PDVs in different wasp species that promote survival of offspring in particular hosts.
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functional annotation of cotesia congregata bracovirus identification of viral genes expressed in parasitized host immune tissues
Journal of Virology, 2014Co-Authors: Germain Chevignon, Annie Bezier, Karine Musset, Sébastien J.m. Moreau, Julien Thézé, Jean-michel Drezen, Sebastien Cambier, Julie Poulain, Corinne Da Silva, Elisabeth HuguetAbstract:Bracoviruses (BVs) from the Polydnaviridae family are symbiotic viruses used as biological weapons by parasitoid wasps to manipulate lepidopteran host physiology and induce parasitism success. BV particles are produced by wasp ovaries and injected along with the eggs into the caterpillar host body, where viral gene expression is necessary for wasp development. Recent sequencing of the proviral genome of Cotesia congregata BV (CcBV) identified 222 predicted virulence genes present on 35 proviral segments integrated into the wasp genome. To date, the expressions of only a few selected candidate virulence genes have been studied in the caterpillar host, and we lacked a global vision of viral gene expression. In this study, a large-scale transcriptomic analysis by 454 sequencing of two immune tissues (fat body and hemocytes) of parasitized Manduca sexta caterpillar hosts allowed the detection of expression of 88 CcBV genes expressed 24 h after the onset of parasitism. We linked the expression profiles of these genes to several factors, showing that different regulatory mechanisms control viral gene expression in the host. These factors include the presence of signal peptides in encoded proteins, diversification of promoter regions, and, more surprisingly, gene position on the proviral genome. Indeed, most genes for which expression could be detected are localized in particular proviral regions globally producing higher numbers of circles. Moreover, this polydnavirus (PDV) transcriptomic analysis also reveals that a majority of CcBV genes possess at least one intron and an arthropod transcription start site, consistent with an insect origin of these virulence genes. IMPORTANCE Bracoviruses (BVs) are symbiotic polydnaviruses used by parasitoid wasps to manipulate lepidopteran host physiology, ensuring wasp offspring survival. To date, the expressions of only a few selected candidate BV virulence genes have been studied in caterpillar hosts. We performed a large-scale analysis of BV gene expression in two immune tissues of Manduca sexta caterpillars parasitized by Cotesia congregata wasps. Genes for which expression could be detected corresponded to genes localized in particular regions of the viral genome globally producing higher numbers of circles. Our study thus brings an original global vision of viral gene expression and paves the way to the determination of the regulatory mechanisms enabling the expression of BV genes in targeted organisms, such as major insect pests. In addition, we identify sequence features suggesting that most BV virulence genes were acquired from insect genomes.
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Functional annotation of Cotesia congregata bracovirus: identification of the viral genes expressed in parasitized host immune tissues.
Journal of Virology, 2014Co-Authors: Chevignon Germain, Karine Musset, Julien Thézé, Jean-michel Drezen, Sebastien Cambier, Julie Poulain, Corinne Da Silva, Bézier Annie, J.m. Sébastien Moreau, Elisabeth HuguetAbstract:Bracoviruses (BV) from Polydnaviridae family are symbiotic viruses used as biological weapons by parasitoid wasps to manipulate lepidopteran host physiology and induce parasitism success. BV particles are produced by wasp ovaries and injected along with the eggs into the caterpillar host body where viral gene expression is necessary for wasp development. Recent sequencing of the proviral genome of Cotesia congregata BV (CcBV) identified 222 predicted virulence genes present on 35 proviral segments integrated in the wasp genome. To date, the expression of only a few selected candidate virulence genes had been studied in the caterpillar host, and we lacked a global vision of viral gene expression. In this study, a large-scale transcriptomic analysis by 454 sequencing of two immune tissues (fat body and hemocytes) of parasitized Manduca sexta caterpillar host allowed detection of expression of 88 CcBV genes expressed 24 h after the onset of parasitism. We could link the expression profile of these genes to several factors, showing that different regulatory mechanisms control viral gene expression in the host. These factors include presence of signal peptides in encoded proteins, diversification of promoter regions, and more surprisingly gene position on the proviral genome. Indeed, most genes for which expression could be detected are localized in particular proviral regions globally producing higher numbers of circles. Moreover this PDV transcriptomic analysis also reveals that a majority of CcBV genes possess at least one intron and an arthropod transcription start site consistent with an insect origin of these virulence genes.
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When parasitic wasps hijacked viruses: genomic and functional evolution of polydnaviruses.
Philosophical Transactions of the Royal Society B: Biological Sciences, 2013Co-Authors: Elisabeth A. Herniou, Annie Bezier, Julien Thézé, Elisabeth Huguet, Georges Periquet, Jean-michel DrezenAbstract:The Polydnaviridae (PDV), including the Bracovirus (BV) and Ichnovirus genera, originated from the integration of unrelated viruses in the genomes of two parasitoid wasp lineages, in a remarkable example of convergent evolution. Functionally active PDVs represent the most compelling evolutionary success among endogenous viral elements (EVEs). BV evolved from the domestication by braconid wasps of a nudivirus 100 Ma. The nudivirus genome has become an EVE involved in BV particle production but is not encapsidated. Instead, BV genomes have co-opted virulence genes, used by the wasps to control the immunity and development of their hosts. Gene transfers and duplications have shaped BV genomes, now encoding hundreds of genes. Phylogenomic studies suggest that BVs contribute largely to wasp diversification and adaptation to their hosts. A genome evolution model explains how multidirectional wasp adaptation to different host species could have fostered PDV genome extension. Integrative studies linking ecological data on the wasp to genomic analyses should provide new insights into the adaptive role of particular BV genes. Forthcoming genomic advances should also indicate if the associations between endoparasitoid wasps and symbiotic viruses evolved because of their particularly intimate interactions with their hosts, or if similar domesticated EVEs could be uncovered in other parasites.
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Parasitoid polydnaviruses: evolution, pathology and applications
Biocontrol Science and Technology, 2013Co-Authors: Dawn Gundersen-rindal, Elisabeth Huguet, Catherine Dupuy, Jean-michel DrezenAbstract:One of the more unusual groups of insect pathogens consists of members of the family Polydnaviridae, insect DNA viruses that live in mutual symbioses with their associated parasitoid wasp (Hymentoptera) carriers until they are injected into specific lepidopteran hosts. Once inside this secondary host, polydnaviruses cause a wide variety of negative effects that ultimately ensure the survival of the parasitoid larvae. Because of their unusual life strategy and genetic features, it had been difficult to fully characterise polydnaviruses in terms of evolutionary history, replication cycle and functions in the host that might normally be well characterised for more conventional viruses. Recently, our understanding of polydnavirus evolutionary origins, gene content, genome organisation and functions in parasitism has greatly increased. Key findings are summarised in this review with emphasis on evolution of polydnavirus genes and genomes, their functional roles in insect pathology and their potential applications in insect biological control and biotechnology
Brian A. Federici - One of the best experts on this subject based on the ideXlab platform.
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Symbiotic Virus at the Evolutionary Intersection of Three Types of Large DNA Viruses; Iridoviruses, Ascoviruses,
2013Co-Authors: Yves Bigot, Sylvaine Renault, Jacques Nicolas, Corinne Moundras, Marie-véronique Demattei, Sylvie Samain, Dennis K. Bideshi, 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). Methodology/Principal Findings: To clarify the evolutionary relationships of these large double-stranded DNA viruses, we sequenced the genome of DpAV4a and undertook phylogenetic analyses of the above viruses and others, including iridoviruses pathogenic to vertebrates. The DpAV4a genome consisted of 119,343 bp and contained at least 119 open reading frames (ORFs), the analysis of which confirmed the relatedness of this virus to iridoviruses and other ascoviruses. Conclusions: Analyses of core DpAV4a genes confirmed that ascoviruses and iridoviruses are evolutionary related. Nevertheless, our results suggested that the symbiotic DpAV4a had a separate origin in the iridoviruses from the pathogenic ascoviruses, and that these two types shared parallel evolutionary paths, which converged with respect to virion structure (icosahedral to bacilliform), genome configuration (linear to circular), and cytopathology (plasmalemma blebbing to virioncontainin
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Evolution of Immunosuppressive Organelles from DNA Viruses in Insects
Evolutionary Biology – Concepts Molecular and Morphological Evolution, 2010Co-Authors: Brian A. Federici, Yves BigotAbstract:Endoparasitic wasps inject particles into their lepidopteran hosts that enable these parasitoids to evade or directly suppress the hosts’ innate immune response, especially encapsulation by hemocytes. For decades, these particles have been considered virions produced by DNA viruses known as polydnaviruses (family Polydnaviridae). Structurally, there are two main types of particles, those resembling, respectively, virions of baculoviruses or ascoviruses. These particles contain double-stranded DNA in the form of multiple small circular molecules that are transcribed but not replicated in cells of the lepidopteran hosts. Instead particle DNA is replicated from the wasp genome and selectively amplified for packaging into the particles in the reproductive tract of female wasps. Once assembled and secreted into calyx lumen, the particles become mixed with eggs and injected into caterpillars during wasp oviposition. Particle DNA, referred to as the “viral genome,” has now been sequenced for several polydnaviruses. Annotation shows that most of this DNA consists of noncoding DNA or wasp genes, not viral genes. More significantly, recent studies have shown that particle structural proteins are coded by the wasp genome, not by particle DNA, but are of viral origin. Together, these findings provide strong evidence that these particles originated from viruses, but through symbiogenesis followed by gene deletion and acquisition evolved into transducing organelles that shuttle wasp immunosuppressive genes into their hosts, thereby enhancing wasp progeny survival and species radiation.
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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 Bigot, Sylvaine Renault, Jacques Nicolas, Corinne Moundras, Marie-véronique Demattei, Sylvie Samain, Dennis K. Bideshi, 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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Ascoviruses: Superb Manipulators of Apoptosis for Viral Replication and Transmission
Lesser Known Large dsDNA Viruses, 2009Co-Authors: Brian A. Federici, Dennis K. Bideshi, Yeping Tan, Tatsinda Spears, Yves BigotAbstract:Ascoviruses are members of a recently described new family (Ascoviridae) of large double-stranded DNA viruses that attack immature stages of insects belonging to the order Lepidoptera, in which they cause a chronic, fatal disease. Ascoviruses have several unusual characteristics not found among other viruses, the most novel of which are their transmission by endoparasitic wasps and a unique cytopathology that resembles apoptosis. Cell infection induces apoptosis and in some species is associated with synthesis of a virus-encoded executioner caspase and several lipid-metabolizing enzymes. Rather than leading directly to cell death, synthesis of viral proteins results in the rescue of developing apoptotic bodies that are converted into large vesicles in which virions accumulate and continue to assemble. In infected larvae, millions of these virion-containing vesicles begin to disperse from infected tissues 48-72 h after infection into the blood, making it milky white, a major characteristic of the disease. Circulation of virions and vesicles in the blood facilitates mechanical transmission by parasitic wasps. Although ascoviruses appear to be very common, only five species are currently recognized, with the type species being the Spodoptera frugiperda ascovirus 1a. Ascovirus virions are large, enveloped, typically bacilliform or reniform in shape, and, depending on the species, have genomes that range from 119 to 186 kbp. Molecular phylogenetic evidence indicates that ascoviruses evolved from iridoviruses (family Iridoviridae) that attack lepidopteran larvae and are likely the evolutionary source of ichnoviruses (family Polydnaviridae), which assist endoparasitic hymenopterans in overcoming the defense responses of their insect hosts. Thus, as other molecular evidence suggests that iridoviruses evolved from phycodnaviruses (family Phycodnaviridae), an evolutionary pathway is apparent from phycodnaviruses via iridoviruses and ascoviruses to ichnoviruses.
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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 Bigot, Sylvaine Renault, Jacques Nicolas, Corinne Moundras, Marie-véronique Demattei, Sylvie Samain, Dennis K. Bideshi, Brian A. FedericiAbstract: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). Methodology/Principal Findings: To clarify the evolutionary relationships of these large double-stranded DNA viruses, we sequenced the genome of DpAV4a and undertook phylogenetic analyses of the above viruses and others, including iridoviruses pathogenic to vertebrates. The DpAV4a genome consisted of 119,343 bp and contained at least 119 open reading frames (ORFs), the analysis of which confirmed the relatedness of this virus to iridoviruses and other ascoviruses. Conclusions : Analyses of core DpAV4a genes confirmed that ascoviruses and iridoviruses are evolutionary related. Nevertheless, our results suggested that the symbiotic DpAV4a had a separate origin in the iridoviruses from the pathogenic ascoviruses, and that these two types shared parallel evolutionary paths, which converged with respect to virion structure (icosahedral to bacilliform), genome configuration (linear to circular), and cytopathology (plasmalemma blebbing to virion-containing vesicles). Our analyses also revealed that DpAV4a shared more core genes with CIV than with other ascoviruses and iridoviruses, providing additional evidence that DpAV4a represents a separate lineage. Given the differences in the biology of the various iridoviruses and ascoviruses studied, these results provide an interesting model for how viruses of different families evolved from one another.
Annenathalie Volkoff - One of the best experts on this subject based on the ideXlab platform.
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The dual life of ichnoviruses
Current Opinion in Insect Science, 2019Co-Authors: Isabelle Darboux, Michel Cusson, Annenathalie VolkoffAbstract:Ichnoviruses (IVs) are mutualistic, double-stranded DNA viruses playing a key role in the successful parasitism of thousands of endoparasitoid wasp species. IV particles are produced exclusively in the female wasp reproductive tract. They are co-injected along with the parasitoid egg into caterpillar hosts upon parasitization. The expression of viral genes by infected host cells leads to an immunosuppressive state and delayed development of the host, two pathologies that are critical to the successful development of the wasp egg and larva. Ichnovirus is one of the two recognized genera within the family Polydnaviridae (polydnaviruses or PDVs), the other genus being Bracovirus (BV), associated with braconid wasps. IVs are associated with ichneumonid wasps belonging to the subfamilies Campopleginae and Banchinae; attempts to identify IV particles in other ichneumonid subfamilies have so far been unsuccessful. Functional studies targeting IV genes expressed in parasitized hosts, along with investigations of the molecular mechanisms responsible for viral morphogenesis in the female wasp, have resulted in a better understanding of the biology of these atypical viruses.
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Extensive Transcription Analysis of the Hyposoter didymator Ichnovirus Genome in Permissive and Non- Permissive Lepidopteran Host Species
2016Co-Authors: Gabor Gyapay, Isabelle Darboux, Patricia Milano, Eric Wajnberg, Luis O Cônsoli, Annenathalie VolkoffAbstract:Ichnoviruses are large dsDNA viruses that belong to the Polydnaviridae family. They are specifically associated with endoparasitic wasps of the family Ichneumonidae and essential for host parasitization by these wasps. We sequenced the Hyposoter didymator Ichnovirus (HdIV) encapsidated genome for further analysis of the transcription pattern of the entire set of HdIV genes following the parasitization of four different lepidopteran host species. The HdIV genome was found to consist of at least 50 circular dsDNA molecules, carrying 135 genes, 98 of which formed 18 gene families. The HdIV genome had general features typical of Ichnovirus (IV) genomes and closely resembled that of the IV carried by Hyposoter fugitivus. Subsequent transcriptomic analysis with Illumina technology during the course of Spodoptera frugiperda parasitization led to the identification of a small subset of less than 30 genes with high RPKM values in permissive hosts, consisting with these genes encoding crucial virulence proteins. Comparisons of HdIV expression profiles between host species revealed differences in transcript levels for given HdIV genes between two permissive hosts, S. frugiperda and Pseudoplusia includens. However, we found no evident intrafamily gene-specific transcription pattern consistent with the presence of multigenic families within IV genomes reflecting an ability of the wasps concerned to exploit different host species. Interestingly, in two non-permissive hosts, Mamestra brassiccae and Anticarsia gemmatalis (most of the parasitoid eggs were eliminated by th
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Extensive transcription analysis of the Hyposoter didymator Ichnovirus genome in permissive and non-permissive lepidopteran host species.
PLoS ONE, 2014Co-Authors: Tristan Dorémus, Isabelle Darboux, Gabor Gyapay, Patricia Milano, Eric Wajnberg, Véronique Jouan, Francois Cousserans, Fernando L. Cônsoli, Annenathalie VolkoffAbstract:Ichnoviruses are large dsDNA viruses that belong to the Polydnaviridae family. They are specifically associated with endoparasitic wasps of the family Ichneumonidae and essential for host parasitization by these wasps. We sequenced the Hyposoter didymator Ichnovirus (HdIV) encapsidated genome for further analysis of the transcription pattern of the entire set of HdIV genes following the parasitization of four different lepidopteran host species. The HdIV genome was found to consist of at least 50 circular dsDNA molecules, carrying 135 genes, 98 of which formed 18 gene families. The HdIV genome had general features typical of Ichnovirus (IV) genomes and closely resembled that of the IV carried by Hyposoter fugitivus. Subsequent transcriptomic analysis with Illumina technology during the course of Spodoptera frugiperda parasitization led to the identification of a small subset of less than 30 genes with high RPKM values in permissive hosts, consisting with these genes encoding crucial virulence proteins. Comparisons of HdIV expression profiles between host species revealed differences in transcript levels for given HdIV genes between two permissive hosts, S. frugiperda and Pseudoplusia includens. However, we found no evident intrafamily gene-specific transcription pattern consistent with the presence of multigenic families within IV genomes reflecting an ability of the wasps concerned to exploit different host species. Interestingly, in two non-permissive hosts, Mamestra brassiccae and Anticarsia gemmatalis (most of the parasitoid eggs were eliminated by the host cellular immune response), HdIV genes were generally less strongly transcribed than in permissive hosts. This suggests that successful parasitism is dependent on the expression of given HdIV genes exceeding a particular threshold value. These results raise questions about the mecanisms involved in regulating IV gene expression according to the nature of the lepidopteran host species encountered.
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functional gap junction genes are encoded by insect viruses
Current Biology, 2005Co-Authors: Matthew W Turnbull, Annenathalie Volkoff, Bruce A Webb, Pauline PhelanAbstract:Ichnoviruses belong to the virus family Polydnaviridae, whose members are obligately associated with certain endoparasitoid wasps. Expression of ichnovirus genes in parasitized lepidopteran hosts leads to immune suppression and is essential for successful parasitization. To date, the role of specific ichnovirus genes in alteration of host physiology has been unclear, and no cellular homologues have been described. Here, we describe the isolation of a gene family from two ichnoviruses that is homologous to the innexin gene family, which encodes gap junctions in invertebrates. Campoletis sonorensis ichnovirus (CsIV) innexins are expressed in multiple tissues in infected lepidopterans, including haemocytes, the primary immunocytes of the host. Two of the CsIV proteins have been expressed and shown to form functional gap junctions in Xenopus oocytes. To our knowledge this is the first study to describe gap junction genes in any virus. We hypothesize that the virus innexins disrupt cellular immunity in infected insects by altering normal gap junctional intercellular communication. This would represent a novel mechanism of viral alteration of host physiology, and suggests that gap junctions play a crucial role in coordinating cellular immune responses.
Jean-michel Drezen - One of the best experts on this subject based on the ideXlab platform.
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Origin and evolution of symbiotic viruses associated with parasitoid wasps
Current opinion in insect science, 2014Co-Authors: Jean-michel Drezen, Germain Chevignon, Faustine Louis, Elisabeth HuguetAbstract:The Polydnaviridae (PDV), including the Bracovirus (BV) and Ichnovirus (IV) genera, originated from the integration of viruses in the genomes of two parasitoid wasp lineages. In a remarkable example of convergent evolution BVs evolved from the domestication of a nudivirus, while IVs originate from a different ancestral virus belonging to a new virus entity. In both cases the ancestor genomes have been maintained in wasp genomes as endogenous viral elements involved in production of particles containing DNA encoding virulence genes that are injected into lepidopteran hosts. However many PDV virulence genes appear to be of eukaryotic origin, and expansion and diversification of these genes have led to the production of novel PDVs in different wasp species that promote survival of offspring in particular hosts.
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functional annotation of cotesia congregata bracovirus identification of viral genes expressed in parasitized host immune tissues
Journal of Virology, 2014Co-Authors: Germain Chevignon, Annie Bezier, Karine Musset, Sébastien J.m. Moreau, Julien Thézé, Jean-michel Drezen, Sebastien Cambier, Julie Poulain, Corinne Da Silva, Elisabeth HuguetAbstract:Bracoviruses (BVs) from the Polydnaviridae family are symbiotic viruses used as biological weapons by parasitoid wasps to manipulate lepidopteran host physiology and induce parasitism success. BV particles are produced by wasp ovaries and injected along with the eggs into the caterpillar host body, where viral gene expression is necessary for wasp development. Recent sequencing of the proviral genome of Cotesia congregata BV (CcBV) identified 222 predicted virulence genes present on 35 proviral segments integrated into the wasp genome. To date, the expressions of only a few selected candidate virulence genes have been studied in the caterpillar host, and we lacked a global vision of viral gene expression. In this study, a large-scale transcriptomic analysis by 454 sequencing of two immune tissues (fat body and hemocytes) of parasitized Manduca sexta caterpillar hosts allowed the detection of expression of 88 CcBV genes expressed 24 h after the onset of parasitism. We linked the expression profiles of these genes to several factors, showing that different regulatory mechanisms control viral gene expression in the host. These factors include the presence of signal peptides in encoded proteins, diversification of promoter regions, and, more surprisingly, gene position on the proviral genome. Indeed, most genes for which expression could be detected are localized in particular proviral regions globally producing higher numbers of circles. Moreover, this polydnavirus (PDV) transcriptomic analysis also reveals that a majority of CcBV genes possess at least one intron and an arthropod transcription start site, consistent with an insect origin of these virulence genes. IMPORTANCE Bracoviruses (BVs) are symbiotic polydnaviruses used by parasitoid wasps to manipulate lepidopteran host physiology, ensuring wasp offspring survival. To date, the expressions of only a few selected candidate BV virulence genes have been studied in caterpillar hosts. We performed a large-scale analysis of BV gene expression in two immune tissues of Manduca sexta caterpillars parasitized by Cotesia congregata wasps. Genes for which expression could be detected corresponded to genes localized in particular regions of the viral genome globally producing higher numbers of circles. Our study thus brings an original global vision of viral gene expression and paves the way to the determination of the regulatory mechanisms enabling the expression of BV genes in targeted organisms, such as major insect pests. In addition, we identify sequence features suggesting that most BV virulence genes were acquired from insect genomes.
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Functional annotation of Cotesia congregata bracovirus: identification of the viral genes expressed in parasitized host immune tissues.
Journal of Virology, 2014Co-Authors: Chevignon Germain, Karine Musset, Julien Thézé, Jean-michel Drezen, Sebastien Cambier, Julie Poulain, Corinne Da Silva, Bézier Annie, J.m. Sébastien Moreau, Elisabeth HuguetAbstract:Bracoviruses (BV) from Polydnaviridae family are symbiotic viruses used as biological weapons by parasitoid wasps to manipulate lepidopteran host physiology and induce parasitism success. BV particles are produced by wasp ovaries and injected along with the eggs into the caterpillar host body where viral gene expression is necessary for wasp development. Recent sequencing of the proviral genome of Cotesia congregata BV (CcBV) identified 222 predicted virulence genes present on 35 proviral segments integrated in the wasp genome. To date, the expression of only a few selected candidate virulence genes had been studied in the caterpillar host, and we lacked a global vision of viral gene expression. In this study, a large-scale transcriptomic analysis by 454 sequencing of two immune tissues (fat body and hemocytes) of parasitized Manduca sexta caterpillar host allowed detection of expression of 88 CcBV genes expressed 24 h after the onset of parasitism. We could link the expression profile of these genes to several factors, showing that different regulatory mechanisms control viral gene expression in the host. These factors include presence of signal peptides in encoded proteins, diversification of promoter regions, and more surprisingly gene position on the proviral genome. Indeed, most genes for which expression could be detected are localized in particular proviral regions globally producing higher numbers of circles. Moreover this PDV transcriptomic analysis also reveals that a majority of CcBV genes possess at least one intron and an arthropod transcription start site consistent with an insect origin of these virulence genes.
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When parasitic wasps hijacked viruses: genomic and functional evolution of polydnaviruses.
Philosophical Transactions of the Royal Society B: Biological Sciences, 2013Co-Authors: Elisabeth A. Herniou, Annie Bezier, Julien Thézé, Elisabeth Huguet, Georges Periquet, Jean-michel DrezenAbstract:The Polydnaviridae (PDV), including the Bracovirus (BV) and Ichnovirus genera, originated from the integration of unrelated viruses in the genomes of two parasitoid wasp lineages, in a remarkable example of convergent evolution. Functionally active PDVs represent the most compelling evolutionary success among endogenous viral elements (EVEs). BV evolved from the domestication by braconid wasps of a nudivirus 100 Ma. The nudivirus genome has become an EVE involved in BV particle production but is not encapsidated. Instead, BV genomes have co-opted virulence genes, used by the wasps to control the immunity and development of their hosts. Gene transfers and duplications have shaped BV genomes, now encoding hundreds of genes. Phylogenomic studies suggest that BVs contribute largely to wasp diversification and adaptation to their hosts. A genome evolution model explains how multidirectional wasp adaptation to different host species could have fostered PDV genome extension. Integrative studies linking ecological data on the wasp to genomic analyses should provide new insights into the adaptive role of particular BV genes. Forthcoming genomic advances should also indicate if the associations between endoparasitoid wasps and symbiotic viruses evolved because of their particularly intimate interactions with their hosts, or if similar domesticated EVEs could be uncovered in other parasites.
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Parasitoid polydnaviruses: evolution, pathology and applications
Biocontrol Science and Technology, 2013Co-Authors: Dawn Gundersen-rindal, Elisabeth Huguet, Catherine Dupuy, Jean-michel DrezenAbstract:One of the more unusual groups of insect pathogens consists of members of the family Polydnaviridae, insect DNA viruses that live in mutual symbioses with their associated parasitoid wasp (Hymentoptera) carriers until they are injected into specific lepidopteran hosts. Once inside this secondary host, polydnaviruses cause a wide variety of negative effects that ultimately ensure the survival of the parasitoid larvae. Because of their unusual life strategy and genetic features, it had been difficult to fully characterise polydnaviruses in terms of evolutionary history, replication cycle and functions in the host that might normally be well characterised for more conventional viruses. Recently, our understanding of polydnavirus evolutionary origins, gene content, genome organisation and functions in parasitism has greatly increased. Key findings are summarised in this review with emphasis on evolution of polydnavirus genes and genomes, their functional roles in insect pathology and their potential applications in insect biological control and biotechnology