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Elisabeth Huguet - One of the best experts on this subject based on the ideXlab platform.

  • Cotesia congregata Bracovirus Circles Encoding PTP and Ankyrin Genes Integrate into the DNA of Parasitized Manduca sexta Hemocytes.
    Journal of Virology, 2018
    Co-Authors: Germain Chevignon, Karine Musset, Jean-michel Drezen, Gabor Gyapay, Georges Periquet, Nathalie Vega-czarny, Elisabeth Huguet
    Abstract:

    Polydnaviruses (PDVs) are essential for the parasitism success of tens of thousands of species of parasitoid wasps. PDVs are present in wasp genomes as proviruses, which serve as the template for the production of double-stranded circular viral DNA carrying virulence genes that are injected into lepidopteran hosts. PDV circles do not contain genes coding for particle production, thereby impeding viral replication in caterpillar hosts during parasitism. Here, we investigated the fate of PDV circles of Cotesia congregata Bracovirus during parasitism of the tobacco hornworm, Manduca sexta, by the wasp Cotesia congregata Sequences sharing similarities with host integration motifs (HIMs) of Microplitis demolitor Bracovirus (MdBV) circles involved in integration into DNA could be identified in 12 CcBV circles, which encode PTP and VANK gene families involved in host immune disruption. A PCR approach performed on a subset of these circles indicated that they persisted in parasitized M. sexta hemocytes as linear forms, possibly integrated in host DNA. Furthermore, by using a primer extension capture method based on these HIMs and high-throughput sequencing, we could show that 8 out of 9 circles tested were integrated in M. sexta hemocyte genomic DNA and that integration had occurred specifically using the HIM, indicating that an HIM-mediated specific mechanism was involved in their integration. Investigation of BV circle insertion sites at the genome scale revealed that certain genomic regions appeared to be enriched in BV insertions, but no specific M. sexta target site could be identified.IMPORTANCE The identification of a specific and efficient integration mechanism shared by several Bracovirus species opens the question of its role in braconid parasitoid wasp parasitism success. Indeed, results obtained here show massive integration of Bracovirus DNA in somatic immune cells at each parasitism event of a caterpillar host. Given that Bracoviruses do not replicate in infected cells, integration of viral sequences in host DNA might allow the production of PTP and VANK virulence proteins within newly dividing cells of caterpillar hosts that continue to develop during parasitism. Furthermore, this integration process could serve as a basis to understand how PDVs mediate the recently identified gene flux between parasitoid wasps and Lepidoptera and the frequency of these horizontal transfer events in nature.

  • transcriptomic response of manduca sexta immune tissues to parasitization by the Bracovirus associated wasp cotesia congregata
    Insect Biochemistry and Molecular Biology, 2015
    Co-Authors: Germain Chevignon, Jean-michel Drezen, Elisabeth Huguet, Sebastien Cambier, Julie Poulain, Corinne Da Silva, Sébastien J.m. Moreau
    Abstract:

    During oviposition, Cotesia congregata parasitoid wasps inject into their host, Manduca sexta, some biological factors such as venom, ovarian fluid and a symbiotic polydnavirus (PDV) named Cotesia congregata Bracovirus (CcBV). During parasitism, complex interactions occur between wasp-derived factors and host targets that lead to important modifications in host physiology. In particular, the immune response leading to wasp egg encapsulation is inhibited allowing wasp survival. To date, the regulation of host genes during the interaction had only been studied for a limited number of genes. In this study, we analysed the global impact of parasitism on host gene regulation 24 h post oviposition by high throughput 454 transcriptomic analyses of two tissues known to be involved in the host immune response (hemocytes and fat body). To identify specific effects of parasitism on host transcription at this time point, transcriptomes were obtained from non-treated and parasitized larvae, and also from larvae injected with heat-killed bacteria and double stimulated larvae that were parasitized prior to bacterial challenge. Results showed that, immune challenge by bacteria leads to induction of certain antimicrobial peptide (AMP) genes in M. sexta larvae whether they were parasitized or not prior to bacterial challenge. These results show that at 24 h post oviposition pathways leading to expression of AMP genes are not all inactivated suggesting wasps are in an antiseptic environment. In contrast, at this time point genes involved in phenoloxidase activation and cellular immune responses were globally down-regulated after parasitism in accordance with the observed inhibition of wasp egg encapsulation.

  • Production of Bracovirus particles by the parasitoid wasp C. congregata and hypothesis on the process leading to transfer of Bracovirus sequences to lepidopteran genomes.
    2015
    Co-Authors: Laila Gasmi, Jérémy Gauthier, Karine Musset, Elisabeth Huguet, Helene Boulain, Aurelie Hua-van, Agata K. Jakubowska, Jean-marc Aury, Anne-nathalie Volkoff, Salvador Herrero
    Abstract:

    The BV genome is integrated in the wasp genome (in grey). It is composed of proviral segments (in blue) used to produce dsDNA circles (blue circles) packaged in nucleocapsids (grey cylinders) that encode virulence genes introduced into the host (coloured rectangles) and of BV genes that are involved in particle production (grey rectangles). The latter originate from a nudivirus and encode structural proteins, they are expressed in wasp ovaries where production of Bracovirus circles also occurs. Direct Repeat Junctions (DRJ, red triangles) are involved in site-specific recombination allowing circularisation of linear molecules from proviral segments. The circles thus produced are packaged in BV particles that also contain several integrase proteins. The particles are injected in the lepidopteran host during wasp oviposition. Once in the host BV particles infect many lepidopteran cell types but do not replicate. BV circles can integrate into lepidopteran host genomic DNA (in light blue) by a mechanism involving most likely an integrase and mediated by Host Integration Motifs (HIM) indicated by dark blue lines. When injected into a regular host (1) BV virulence gene (coloured squares) expression leads to modifications in lepidopteran host physiology, such as inhibition of wasp egg encapsulation and alteration of developmental programming allowing wasp larvae to complete their development safely in the host body. Hypothesis: when integration of viral circles occurs in the germline the integrated forms are not transmitted because the host dies. When Bracoviruses are injected into a caterpillar, which is not a regular host species (2) or is a resistant host (interrupting oviposition, destroying wasp eggs, etc.) the integrated viral form in germline DNA can be transmitted vertically. As Bracovirus genes are adapted for expression in lepidopteran cells they can be readily domesticated. Once integrated in lepidopteran genomes the Bracovirus sequences undergo rearrangements. Ultimately, after several million years, only the domesticated genes remain from the original integrated circle. We propose that stinging of non-host species could be the main route for Bracovirus sequence transfer to Lepidoptera. This is based on the fact that the genome of M. sexta which is the regular host of Cotesia congregata does not contain genes acquired from CcBV, conversely genes found in Spodoptera exigua, which is not a host of Cotesia congregata, are more closely related to CcBV. This figure is mostly based on the life cycle of CcBV associated with C. congregata parasitoid wasp of M. sexta, HIM motifs have been identified in the Bracovirus of M. demolitor, the picture of S. exigua is shown as an example of C. congregata non-host species.

  • functional annotation of cotesia congregata Bracovirus identification of viral genes expressed in parasitized host immune tissues
    Journal of Virology, 2014
    Co-Authors: Germain Chevignon, Annie Bezier, Karine Musset, Sébastien J.m. Moreau, Julien Thézé, Jean-michel Drezen, Sebastien Cambier, Julie Poulain, Corinne Da Silva, Elisabeth Huguet
    Abstract:

    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.

  • Viral cystatin evolution and three-dimensional structure modelling: A case of directional selection acting on a viral protein involved in a host-parasitoid interaction
    BMC Biology, 2008
    Co-Authors: Céline Serbielle, Jerome Lesobre, Stéphane Dupas, Shafinaz Chowdhury, Samuel Pichon, Enrico O Purisima, Elisabeth Huguet
    Abstract:

    Background In pathogens, certain genes encoding proteins that directly interact with host defences coevolve with their host and are subject to positive selection. In the lepidopteran host-wasp parasitoid system, one of the most original strategies developed by the wasps to defeat host defences is the injection of a symbiotic polydnavirus at the same time as the wasp eggs. The virus is essential for wasp parasitism success since viral gene expression alters the immune system and development of the host. As a wasp mutualist symbiont, the virus is expected to exhibit a reduction in genome complexity and evolve under wasp phyletic constraints. However, as a lepidopteran host pathogenic symbiont, the virus is likely undergoing strong selective pressures for the acquisition of new functions by gene acquisition or duplication. To understand the constraints imposed by this particular system on virus evolution, we studied a polydnavirus gene family encoding cyteine protease inhibitors of the cystatin superfamily. Results We show that cystatins are the first Bracovirus genes proven to be subject to strong positive selection within a host-parasitoid system. A generated three-dimensional model of Cotesia congregata Bracovirus cystatin 1 provides a powerful framework to position positively selected residues and reveal that they are concentrated in the vicinity of actives sites which interact with cysteine proteases directly. In addition, phylogenetic analyses reveal two different cystatin forms which evolved under different selective constraints and are characterized by independent adaptive duplication events. Conclusion Positive selection acts to maintain cystatin gene duplications and induces directional divergence presumably to ensure the presence of efficient and adapted cystatin forms. Directional selection has acted on key cystatin active sites, suggesting that cystatins coevolve with their host target. We can strongly suggest that cystatins constitute major virulence factors, as was already proposed in previous functional studies.

Jean-michel Drezen - One of the best experts on this subject based on the ideXlab platform.

  • genome wide patterns of Bracovirus chromosomal integration into multiple host tissues during parasitism
    Journal of Virology, 2021
    Co-Authors: Heloise Muller, Laure Kaiser, Georges Periquet, Mohamed Amine Chebbi, Clemence Bouzar, Taiadjana M Fortuna, Paulandre Calatayud, Julius Obonyo, Jean-michel Drezen
    Abstract:

    Bracoviruses are domesticated viruses found in parasitic wasp genomes. They are composed of genes of nudiviral origin involved in particle production and proviral segments encoding virulence genes necessary for parasitism success. During particle production, proviral segments are amplified and individually packaged as DNA circles in nucleocapsids. These particles are injected by parasitic waspstogether with their eggs into host larvae. Bracovirus circles of two wasp species were reported toundergo chromosomal integration in parasitized host hemocytes, through a conserved sequence named Host Integration Motif (HIM). Here, we used bulk Illumina sequencing to survey integrations of Cotesia typhae Bracovirus circles in the DNA of its host, the maize corn borer (Sesamia nonagrioides) seven days after parasitism. First, assembly and annotation of a high-quality genome for C. typhae enabled us to characterize 27 proviral segments clustered in proviral loci. Using these data, we characterized large numbers of chromosomal integrations (from 12 to 85 events per host haploid genome) for all 16 Bracovirus circles containing a HIM. Integrations were found in four S. nonagrioides tissues and in the body of a caterpillar in which parasitism had failed. The 12 remaining circles do not integrate but are maintained at high levels in host tissues. Surprisingly, we found that HIM-mediated chromosomal integration has occurred at least six times accidentally in thewasp germline during evolution. Overall, our study furthers our understanding of wasp-host genome interactions and supports HIM-mediated chromosomal integration as a possible mechanism ofhorizontal transfer from wasps to their hosts. Importance Bracoviruses are endogenous domesticated viruses of parasitoid wasps that are injected together with wasp eggs into wasp host larvae during parasitism. Several studies have shown that some DNA circles packaged into Bracovirus particles become integrated into host somatic genomes during parasitism, but the phenomenon has never been studied using non-targeted approaches. Here we use bulk Illumina sequencing to systematically characterize and quantify Bracovirus circle integrations that occur in four tissues of the Mediterranean corn borer (Sesamia nonagrioides) during parasitism by the Cotesia typhae wasp. Our analysis reveals that all circles containing a host integration motif (HIM) integrate at substantial levels (from 12 to 85 integrations per host cell in total) in all tissues while other circles do not integrate. In addition to shedding new light on wasp-Bracovirus-host interaction, our study supports HIM-mediated chromosomal integration of Bracovirus as a possible source of wasp-to-host horizontal transfer with long term evolutionary consequences.

  • Cotesia congregata Bracovirus Circles Encoding PTP and Ankyrin Genes Integrate into the DNA of Parasitized Manduca sexta Hemocytes.
    Journal of Virology, 2018
    Co-Authors: Germain Chevignon, Karine Musset, Jean-michel Drezen, Gabor Gyapay, Georges Periquet, Nathalie Vega-czarny, Elisabeth Huguet
    Abstract:

    Polydnaviruses (PDVs) are essential for the parasitism success of tens of thousands of species of parasitoid wasps. PDVs are present in wasp genomes as proviruses, which serve as the template for the production of double-stranded circular viral DNA carrying virulence genes that are injected into lepidopteran hosts. PDV circles do not contain genes coding for particle production, thereby impeding viral replication in caterpillar hosts during parasitism. Here, we investigated the fate of PDV circles of Cotesia congregata Bracovirus during parasitism of the tobacco hornworm, Manduca sexta, by the wasp Cotesia congregata Sequences sharing similarities with host integration motifs (HIMs) of Microplitis demolitor Bracovirus (MdBV) circles involved in integration into DNA could be identified in 12 CcBV circles, which encode PTP and VANK gene families involved in host immune disruption. A PCR approach performed on a subset of these circles indicated that they persisted in parasitized M. sexta hemocytes as linear forms, possibly integrated in host DNA. Furthermore, by using a primer extension capture method based on these HIMs and high-throughput sequencing, we could show that 8 out of 9 circles tested were integrated in M. sexta hemocyte genomic DNA and that integration had occurred specifically using the HIM, indicating that an HIM-mediated specific mechanism was involved in their integration. Investigation of BV circle insertion sites at the genome scale revealed that certain genomic regions appeared to be enriched in BV insertions, but no specific M. sexta target site could be identified.IMPORTANCE The identification of a specific and efficient integration mechanism shared by several Bracovirus species opens the question of its role in braconid parasitoid wasp parasitism success. Indeed, results obtained here show massive integration of Bracovirus DNA in somatic immune cells at each parasitism event of a caterpillar host. Given that Bracoviruses do not replicate in infected cells, integration of viral sequences in host DNA might allow the production of PTP and VANK virulence proteins within newly dividing cells of caterpillar hosts that continue to develop during parasitism. Furthermore, this integration process could serve as a basis to understand how PDVs mediate the recently identified gene flux between parasitoid wasps and Lepidoptera and the frequency of these horizontal transfer events in nature.

  • Adaptive Selection on Bracovirus Genomes Drives the Specialization of Cotesia Parasitoid Wasps
    2016
    Co-Authors: Corentin Paillusson, Jean-michel Drezen, Laure Kaiser, Georges Periquet, Bruno Pierre, Elisabeth A Herniou
    Abstract:

    The geographic mosaic of coevolution predicts parasite virulence should be locally adapted to the host community. Cotesia parasitoid wasps adapt to local lepidopteran species possibly through their symbiotic Bracovirus. The virus, essential for the parasitism success, is at the heart of the complex coevolutionary relationship linking the wasps and their hosts. The large segmented genome contained in the virus particles encodes virulence genes involved in host immune and developmental suppression. Coevolutionary arms race should result in the positive selection of particular beneficial alleles. To understand the global role of Bracoviruses in the local adaptation or specialization of parasitoid wasps to their hosts, we studied the molecular evolution of four Bracoviruses associated with wasps of the genus Cotesia, including C congregata, C vestalis and new data and annotation on two ecologically differentiated populations of C sesamie, Kitale and Mombasa. Paired orthologs analyses revealed more genes under positive selection when comparing the two C sesamiae Bracoviruses belonging to the same species, and more genes under strong evolutionary constraint between species. Furthermore branch-site evolutionary models showed that 17 genes, out of the 54 currently available shared by the four Bracoviruses, harboured sites under positive selection including: the histone H4-like, a C-type lectin, two ep1-like, ep2, a viral ankyrin, CrV1, a ben-domain, a Serine-rich, and eight unknown genes. Lastly the phylogenetic analyses of the histone, ep2 and CrV1 genes in different African

  • transcriptomic response of manduca sexta immune tissues to parasitization by the Bracovirus associated wasp cotesia congregata
    Insect Biochemistry and Molecular Biology, 2015
    Co-Authors: Germain Chevignon, Jean-michel Drezen, Elisabeth Huguet, Sebastien Cambier, Julie Poulain, Corinne Da Silva, Sébastien J.m. Moreau
    Abstract:

    During oviposition, Cotesia congregata parasitoid wasps inject into their host, Manduca sexta, some biological factors such as venom, ovarian fluid and a symbiotic polydnavirus (PDV) named Cotesia congregata Bracovirus (CcBV). During parasitism, complex interactions occur between wasp-derived factors and host targets that lead to important modifications in host physiology. In particular, the immune response leading to wasp egg encapsulation is inhibited allowing wasp survival. To date, the regulation of host genes during the interaction had only been studied for a limited number of genes. In this study, we analysed the global impact of parasitism on host gene regulation 24 h post oviposition by high throughput 454 transcriptomic analyses of two tissues known to be involved in the host immune response (hemocytes and fat body). To identify specific effects of parasitism on host transcription at this time point, transcriptomes were obtained from non-treated and parasitized larvae, and also from larvae injected with heat-killed bacteria and double stimulated larvae that were parasitized prior to bacterial challenge. Results showed that, immune challenge by bacteria leads to induction of certain antimicrobial peptide (AMP) genes in M. sexta larvae whether they were parasitized or not prior to bacterial challenge. These results show that at 24 h post oviposition pathways leading to expression of AMP genes are not all inactivated suggesting wasps are in an antiseptic environment. In contrast, at this time point genes involved in phenoloxidase activation and cellular immune responses were globally down-regulated after parasitism in accordance with the observed inhibition of wasp egg encapsulation.

  • functional annotation of cotesia congregata Bracovirus identification of viral genes expressed in parasitized host immune tissues
    Journal of Virology, 2014
    Co-Authors: Germain Chevignon, Annie Bezier, Karine Musset, Sébastien J.m. Moreau, Julien Thézé, Jean-michel Drezen, Sebastien Cambier, Julie Poulain, Corinne Da Silva, Elisabeth Huguet
    Abstract:

    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.

Michael R Strand - One of the best experts on this subject based on the ideXlab platform.

  • MdBVe46 is an envelope protein that is required for virion formation by Microplitis demolitor Bracovirus.
    The Journal of general virology, 2021
    Co-Authors: Michael J. Arvin, Gaelen R Burke, Ange Lorenzi, Michael R Strand
    Abstract:

    Bracoviruses (BVs) are endogenized nudiviruses that braconid parasitoid wasps have coopted for functions in parasitizing hosts. Microplitis demolitor is a braconid wasp that produces Microplitis demolitor Bracovirus (MdBV) and parasitizes the larval stage of the moth Chrysodeixis includens. Some BV core genes are homologs of genes also present in baculoviruses while others are only known from nudiviruses or other BVs. In this study, we had two main goals. The first was to separate MdBV virions into envelope and nucleocapsid fractions before proteomic analysis to identify core gene products that were preferentially associated with one fraction or the other. Results indicated that nearly all MdBV baculovirus-like gene products that were detected by our proteomic analysis had similar distributions to homologs in the occlusion-derived form of baculoviruses. Several core gene products unknown from baculoviruses were also identified as envelope or nucleocapsid components. Our second goal was to functionally characterize a core gene unknown from baculoviruses that was originally named HzNVorf64-like. Immunoblotting assays supported our proteomic data that identified HzNVorf64-like as an envelope protein. We thus renamed HzNVorf64-like as MdBVe46, which we further hypothesized was important for infection of C. includens. Knockdown of MdBVe46 by RNA interference (RNAi) greatly reduced transcript and protein abundance. Knockdown of MdBVe46 also altered virion morphogenesis, near-fully inhibited infection of C. includens, and significantly reduced the proportion of hosts that were successfully parasitized by M. demolitor.

  • Permissiveness of lepidopteran hosts is linked to differential expression of Bracovirus genes.
    Virology, 2016
    Co-Authors: Kavita Bitra, Gaelen R Burke, Michael R Strand
    Abstract:

    Polydnaviruses in the genus Bracovirus (BV) are associated with parasitoid wasps in the family Braconidae. BV-carrying wasps rely on their associated viruses to parasitize permissive hosts but also occasionally oviposit into host species that are non-permissive. Here, we studied Microplitis demolitor and M. demolitor Bracovirus (MdBV) in Chrysodeixis includens, a permissive host, and Trichoplusia ni, which is usually non-permissive. M. demolitor laid eggs and injected MdBV into both hosts but almost no wasp offspring developed in T. ni. MdBV DNA similarly persisted in both host species, but deep sequencing data showed that transcript abundance for most viral genes was higher in C. includens than T. ni. Overall, our results identify lower expression of MdBV genes as an important factor in the non-permissiveness of T. ni. However, certain genes with functions in immunosuppression were sufficiently expressed to have similar effect in T. ni and C. includens.

  • microplitis demolitor Bracovirus proviral loci and clustered replication genes exhibit distinct dna amplification patterns during replication
    Journal of Virology, 2015
    Co-Authors: Gaelen R Burke, Tyler J Simmonds, Sarah A Thomas, Michael R Strand
    Abstract:

    UNLABELLED Polydnaviruses are large, double-stranded DNA viruses that are beneficial symbionts of parasitoid wasps. Polydnaviruses in the genus Bracovirus (BVs) persist in wasps as proviruses, and their genomes consist of two functional components referred to as proviral segments and nudivirus-like genes. Prior studies established that the DNA domains where proviral segments reside are amplified during replication and that segments within amplified loci are circularized before packaging into nucleocapsids. One DNA domain where nudivirus-like genes are located is also amplified but never packaged into virions. We recently sequenced the genome of the braconid Microplitis demolitor, which carries M. demolitor Bracovirus (MdBV). Here, we took advantage of this resource to characterize the DNAs that are amplified during MdBV replication using a combination of Illumina and Pacific Biosciences sequencing approaches. The results showed that specific nucleotide sites identify the boundaries of amplification for proviral loci. Surprisingly, however, amplification of loci 3, 4, 6, and 8 produced head-to-tail concatemeric intermediates; loci 1, 2, and 5 produced head-to-head/tail-to-tail concatemers; and locus 7 yielded no identified concatemers. Sequence differences at amplification junctions correlated with the types of amplification intermediates the loci produced, while concatemer processing gave rise to the circularized DNAs that are packaged into nucleocapsids. The MdBV nudivirus-like gene cluster was also amplified, albeit more weakly than most proviral loci and with nondiscrete boundaries. Overall, the MdBV genome exhibited three patterns of DNA amplification during replication. Our data also suggest that PacBio sequencing could be useful in studying the replication intermediates produced by other DNA viruses. IMPORTANCE Polydnaviruses are of fundamental interest because they provide a novel example of viruses evolving into beneficial symbionts. All polydnaviruses are associated with insects called parasitoid wasps, which are of additional applied interest because many are biological control agents of pest insects. Polydnaviruses in the genus Bracovirus (BVs) evolved ~100 million years ago from an ancestor related to the baculovirus-nudivirus lineage but have also established many novelties due to their symbiotic lifestyle. These include the fact that BVs are transmitted only vertically as proviruses and produce replication-defective virions that package only a portion of the viral genome. Here, we studied Microplitis demolitor Bracovirus (MdBV) and report that its genome exhibits three distinct patterns of DNA amplification during replication. We also identify several previously unknown features of BV genomes that correlate with these different amplification patterns.

  • Virulence gene families in the encapsidated genomes of BVs.
    2013
    Co-Authors: Michael R Strand, Gaelen R Burke
    Abstract:

    Each BV isolate is indicated to the left in relation to phylogenetic placement of its associated wasp. The isolates are: Cotesia congregata Bracovirus (CcBV), C. vestalis Bracovirus (CvBV), Glyptapanteles indiensis Bracovirus (GiBV), G. flavicoxis Bracovirus (GfBV), Microplitis demolitor Bracovirus (MdBV), and Chelonus inanitus Bracovirus (CiBV). C. inanitus resides in the subfamily Cheloninae while the other wasp species shown are in the subfamily Microgastrinae. The 20 gene families identified from BVs are listed above the figure. Family names derive from predicted function or the presence of a distinguishing motif: 1) protein tyrosine phosphatases; 2) ankyrin-repeat; 3) cysteine-rich; 4) BEN domain; 5) BV4; 6) EP-1 like, homologs of “early expressed protein 1” of CcBV; 7) cystatins; 8) histone-like; 9) C-type lectin; 10) ribonuclease T2; 11) 94K-like, related to baculovirus 94K protein; 12) CrV1-like, homologs of a gene in CrBV; 13) BV2; 14) BV3; 15) Duffy binding-like; 16) BV1; 17) sugar transporter; 18) serine rich; 19) Egf, epidermal growth factor-like; 20) Glc, glycosylated central domain proteins. A circle to the right of an isolate indicates that the gene family is present, while the number inside the circle indicates the number of family members encoded by that isolate. Phylogenetic evidence further suggests families to the left are more ancient, while families to the right have been more recently acquired by particular BV isolates. *The encapsidated genome of CiBV is only partially sequenced. To date, 16 single copy genes are described in the CiBV genome but none of these genes are present in BV isolates outside the genus Chelonus.

  • Polydnavirus Gene Products that Interact with the Host Immune System
    Parasitoid Viruses, 2012
    Co-Authors: Michael R Strand
    Abstract:

    Publisher Summary This chapter discusses the polydnavirus gene products that interact with the host immune system. The Polydnaviridae is divided into the genus Bracovirus (BV), which is associated with wasps in seven subfamilies of the Braconidae and the genus ichnovirus (IV), which is associated with wasps in two subfamilies of the Ichneumonidae. Strict vertical transmission as proviruses results in each wasp species carrying a genetically unique polydnavirus (PDV) isolate. Most PDV-carrying wasps also parasitize only one or a small number of host species, which are primarily larval or egg stage Lepidoptera. All PDV-carrying wasps inject the encapsidated form of their virus into host insects when they oviposit. Virions rapidly infect different host tissues and within 1–2 h begin expressing viral gene products. PDVs do not replicate in the wasp's host but a number of the genes they express are implicated in causing physiological alterations of benefit to developing offspring. Among the most important of these alterations is preventing the host's immune system from killing wasp eggs and larvae.

Yonggyun Kim - One of the best experts on this subject based on the ideXlab platform.

  • Persistent expression of Cotesia plutellae Bracovirus genes in parasitized host, Plutella xylostella
    2018
    Co-Authors: Yonggyun Kim, Sunil Kumar
    Abstract:

    Cotesia plutellae (= vestalis) Bracovirus (CpBV) is symbiotic to an endoparasitoid wasp, C. plutellae, and plays crucial roles in parasitism against the diamondback moth, Plutella xylostella. CpBV virion genome consists of 35 circular DNAs encoding 157 putative open reading frames (ORFs). This study re-annotated 157 ORFs with update genome database and analyzed their gene expressions at early and late parasitic stages. Re-annotation has established 15 different viral gene families, to which 83 ORFs are assigned with remaining 74 hypothetical genes. Among 157 ORFs, 147 genes were expressed at early or late parasitic stages, among which 141 genes were expressed in both parasitic stages, indicating persistent nature of gene expression. Relative frequencies of different viral circles present in the ovarian lumen did not explain the expression variation of the viral ORFs. Furthermore, expression level of each viral gene was varied during parasitism along with host development. Highly up-regulated CpBV genes at early parasitic stage included BEN (BANP, E5R and NAC1), ELP (EP1-like protein), IkB (inhibitor kB), P494 (protein 494 kDa) family genes, while those at late stage were mostly hypothetical genes. Along with the viral gene expression, 362 host genes exhibited more than two fold changes in expression levels at early parasitic stage compared to nonparasitized host. At late stage, more number (1,858) of host genes was regulated. These results suggest that persistent expression of most CpBV genes may be necessary to regulate host physiological processes during C. plutellae parasitism.

  • Translational Control of Host Gene Expression by a Cys-Motif Protein Encoded in a Bracovirus
    2016
    Co-Authors: Eunseong Kim, Yonggyun Kim
    Abstract:

    Translational control is a strategy that various viruses use to manipulate their hosts to suppress acute antiviral response. Polydnaviruses, a group of insect double-stranded DNA viruses symbiotic to some endoparasitoid wasps, are divided into two genera: ichnovirus (IV) and Bracovirus (BV). In IV, some Cys-motif genes are known as host translation-inhibitory factors (HTIF). The genome of endoparasitoid wasp Cotesia plutellae contains a Cys-motif gene (Cp-TSP13) homologous to an HTIF known as teratocyte-secretory protein 14 (TSP14) of Microplitis croceipes. Cp-TSP13 consists of 129 amino acid residues with a predicted molecular weight of 13.987 kDa and pI value of 7.928. Genomic DNA region encoding its open reading frame has three introns. Cp-TSP13 possesses six conserved cysteine residues as other Cys-motif genes functioning as HTIF. Cp-TSP13 was expressed in Plutella xylostella larvae parasitized by C. plutellae. C. plutellae Bracovirus (CpBV) was purified and injected into non-parasitized P. xylostella that expressed Cp-TSP13. Cp-TSP13 was cloned into a eukaryotic expression vector and used to infect Sf9 cells to transiently express Cp-TSP13. The synthesized Cp-TSP13 protein was detected in culture broth. An overlaying experiment showed that the purified Cp-TSP13 entered hemocytes. It was localized in the cytosol. Recombinant Cp-TSP13 significantly inhibited protein synthesis of secretory proteins when it was added to in vitro cultured fat body. In addition, the recombinant Cp-TSP13 directly inhibited the translation of fat body mRNAs in in vitro translation assay using rabbit reticulocyte lysate. Moreover, the recombinant Cp-TSP13 significantly suppressed cellular immune responses by inhibiting hemocyte-spreading behavior. It also exhibited significant insecticidal activities by both injection and feeding routes. These results indicate that Cp-TSP13 is a viral HTIF.

  • analysis of promoter activity of selected cotesia plutellae Bracovirus genes
    Journal of General Virology, 2009
    Co-Authors: Jae Young Choi, Soo-jin Kwon, Beom-seok Park, Tae Jin Yang, Yonggyun Kim, Jong Yul Roh, Soodong Woo, Byung Rae Jin
    Abstract:

    In a previous study, we cloned 27 discrete genome segments of Cotesia plutellae Bracovirus (CpBV) and provided the complete nucleotide sequences and annotation. Seven putative coding regions were predicted from one of the largest segments, CpBV-S30. The activity of promoters associated with six predicted ORFs from this segment were investigated using both transient and baculovirus expression assays with enhanced green fluorescent protein as a reporter gene. CpBV promoters showed activity earlier than the polyhedrin promoter and the activity of some of these promoters was superior to that of the Autographa californica multiple nucleopolyhedrovirus (AcMNPV) ie-1 promoter in the baculovirus expression assays. The promoter of ORF3004 showed the highest level of activity in insect cells, exhibiting 24 % of the activity obtained with the AcMNPV polyhedrin promoter in Sf9 cells. In Spodoptera exigua larvae, the ORF3006 promoter showed the highest activity, with about 35 % of the activity measured with the polyhedrin promoter. In addition, analysis of the ORF3006 promoter revealed that the region between -382 and -422 from the translation start point was critical for activity of this promoter. These results suggest that the CpBV-S30 promoters characterized here could be useful tools in a variety of biotechnological applications, such as gene expression analyses and insecticide development.

  • a putative actin destabilizer cpbv rtx encoded in cotesia plutellae Bracovirus and its expression in the parasitized plutella xylostella
    Journal of Asia-pacific Entomology, 2008
    Co-Authors: Hosanna H Kim, Karen P. Barandoc, Yonggyun Kim
    Abstract:

    Abstract A novel gene was identified in Cotesia plutellae Bracovirus (CpBV), which acts as a symbiotic virus of the endoparasitoid wasp C. plutellae. The gene was encoded in the genome of CpBV, but not in the genome of its natural host, Plutella xylostella. The gene has an open reading frame comprised of 94 amino acids. A bioinformatic analysis indicated that the gene encodes a signal peptide comprised of 18 residues at its amino terminus and 4 glycosylation sites at threonine and serine residues, as well as two asparagine residues. The expression of the gene by C. plutellae was specific in parasitized P. xylostella, but not in unparasitized larvae. In parasitized larvae, the expression of the gene occurred on the first day after parasitization, and its expression resumed on the fourth day. The gene showed tissue specific expression in the fat body and epidermis, but not in hemocytes and gut tissue. Its sequence showed some similarity with that of a bacterial toxin, RTX, of Vibrio spp., especially in its actin cross-linking domain. The viral gene has been named CpBV-RTX, and its putative physiological function is discussed in terms of host-parasite molecular interactions.

  • a viral lectin encoded in cotesia plutellae Bracovirus and its immunosuppressive effect on host hemocytes
    Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 2008
    Co-Authors: Sunyoung Lee, Madanagopal Nalini, Yonggyun Kim
    Abstract:

    An endoparasitoid wasp, Cotesia plutellae, induces immunosuppression of the host diamondback moth, Plutella xylostella. To identify an immunosuppressive factor, the parasitized hemolymph of P. xylostella was separated into plasma and hemocyte fractions. When nonparasitized hemocytes were overlaid with parasitized plasma, they showed significant reduction in bacterial binding efficacy. Here, we considered a viral lectin previously known in other Cotesia species as a humoral immunosuppressive candidate in C. plutellae parasitization. Based on consensus regions of the viral lectins, the corresponding lectin gene was cloned from P. xylostella parasitized by C. plutellae. Its cDNA is 674 bp long and encodes 157 amino acid residues containing a signal peptide (15 residues) and one carbohydrate recognition domain. Open reading frame is divided by one intron (156 bp) in its genomic DNA. Amino acid sequence shares 80% homology with that of C. ruficrus Bracovirus lectin and is classified into C-type lectin. Southern hybridization analysis indicated that the cloned lectin gene was located at C. plutellae Bracovirus (CpBV) genome. Both real-time quantitative RT-PCR and immunoblotting assays indicated that CpBV-lectin showed early expression during the parasitization. A recombinant CpBV-lectin was expressed in a bacterial system and the purified protein significantly inhibited the association between bacteria and hemocytes of nonparasitized P. xylostella. In the parasitized P. xylostella, CpBV-lectin was detected on the surface of parasitoid eggs after 24 h parasitization by its specific immunostaining. The 24 h old eggs were not encapsulated in vitro by hemocytes of P. xylostella, compared to newly laid parasitoid eggs showing no CpBV-lectin detectable and easily encapsulated. These results support an existence of a polydnaviral lectin family among Cotesia-associated Bracovirus and propose its immunosuppressive function.

Georges Periquet - One of the best experts on this subject based on the ideXlab platform.

  • genome wide patterns of Bracovirus chromosomal integration into multiple host tissues during parasitism
    Journal of Virology, 2021
    Co-Authors: Heloise Muller, Laure Kaiser, Georges Periquet, Mohamed Amine Chebbi, Clemence Bouzar, Taiadjana M Fortuna, Paulandre Calatayud, Julius Obonyo, Jean-michel Drezen
    Abstract:

    Bracoviruses are domesticated viruses found in parasitic wasp genomes. They are composed of genes of nudiviral origin involved in particle production and proviral segments encoding virulence genes necessary for parasitism success. During particle production, proviral segments are amplified and individually packaged as DNA circles in nucleocapsids. These particles are injected by parasitic waspstogether with their eggs into host larvae. Bracovirus circles of two wasp species were reported toundergo chromosomal integration in parasitized host hemocytes, through a conserved sequence named Host Integration Motif (HIM). Here, we used bulk Illumina sequencing to survey integrations of Cotesia typhae Bracovirus circles in the DNA of its host, the maize corn borer (Sesamia nonagrioides) seven days after parasitism. First, assembly and annotation of a high-quality genome for C. typhae enabled us to characterize 27 proviral segments clustered in proviral loci. Using these data, we characterized large numbers of chromosomal integrations (from 12 to 85 events per host haploid genome) for all 16 Bracovirus circles containing a HIM. Integrations were found in four S. nonagrioides tissues and in the body of a caterpillar in which parasitism had failed. The 12 remaining circles do not integrate but are maintained at high levels in host tissues. Surprisingly, we found that HIM-mediated chromosomal integration has occurred at least six times accidentally in thewasp germline during evolution. Overall, our study furthers our understanding of wasp-host genome interactions and supports HIM-mediated chromosomal integration as a possible mechanism ofhorizontal transfer from wasps to their hosts. Importance Bracoviruses are endogenous domesticated viruses of parasitoid wasps that are injected together with wasp eggs into wasp host larvae during parasitism. Several studies have shown that some DNA circles packaged into Bracovirus particles become integrated into host somatic genomes during parasitism, but the phenomenon has never been studied using non-targeted approaches. Here we use bulk Illumina sequencing to systematically characterize and quantify Bracovirus circle integrations that occur in four tissues of the Mediterranean corn borer (Sesamia nonagrioides) during parasitism by the Cotesia typhae wasp. Our analysis reveals that all circles containing a host integration motif (HIM) integrate at substantial levels (from 12 to 85 integrations per host cell in total) in all tissues while other circles do not integrate. In addition to shedding new light on wasp-Bracovirus-host interaction, our study supports HIM-mediated chromosomal integration of Bracovirus as a possible source of wasp-to-host horizontal transfer with long term evolutionary consequences.

  • Cotesia congregata Bracovirus Circles Encoding PTP and Ankyrin Genes Integrate into the DNA of Parasitized Manduca sexta Hemocytes.
    Journal of Virology, 2018
    Co-Authors: Germain Chevignon, Karine Musset, Jean-michel Drezen, Gabor Gyapay, Georges Periquet, Nathalie Vega-czarny, Elisabeth Huguet
    Abstract:

    Polydnaviruses (PDVs) are essential for the parasitism success of tens of thousands of species of parasitoid wasps. PDVs are present in wasp genomes as proviruses, which serve as the template for the production of double-stranded circular viral DNA carrying virulence genes that are injected into lepidopteran hosts. PDV circles do not contain genes coding for particle production, thereby impeding viral replication in caterpillar hosts during parasitism. Here, we investigated the fate of PDV circles of Cotesia congregata Bracovirus during parasitism of the tobacco hornworm, Manduca sexta, by the wasp Cotesia congregata Sequences sharing similarities with host integration motifs (HIMs) of Microplitis demolitor Bracovirus (MdBV) circles involved in integration into DNA could be identified in 12 CcBV circles, which encode PTP and VANK gene families involved in host immune disruption. A PCR approach performed on a subset of these circles indicated that they persisted in parasitized M. sexta hemocytes as linear forms, possibly integrated in host DNA. Furthermore, by using a primer extension capture method based on these HIMs and high-throughput sequencing, we could show that 8 out of 9 circles tested were integrated in M. sexta hemocyte genomic DNA and that integration had occurred specifically using the HIM, indicating that an HIM-mediated specific mechanism was involved in their integration. Investigation of BV circle insertion sites at the genome scale revealed that certain genomic regions appeared to be enriched in BV insertions, but no specific M. sexta target site could be identified.IMPORTANCE The identification of a specific and efficient integration mechanism shared by several Bracovirus species opens the question of its role in braconid parasitoid wasp parasitism success. Indeed, results obtained here show massive integration of Bracovirus DNA in somatic immune cells at each parasitism event of a caterpillar host. Given that Bracoviruses do not replicate in infected cells, integration of viral sequences in host DNA might allow the production of PTP and VANK virulence proteins within newly dividing cells of caterpillar hosts that continue to develop during parasitism. Furthermore, this integration process could serve as a basis to understand how PDVs mediate the recently identified gene flux between parasitoid wasps and Lepidoptera and the frequency of these horizontal transfer events in nature.

  • Adaptive Selection on Bracovirus Genomes Drives the Specialization of Cotesia Parasitoid Wasps
    2016
    Co-Authors: Corentin Paillusson, Jean-michel Drezen, Laure Kaiser, Georges Periquet, Bruno Pierre, Elisabeth A Herniou
    Abstract:

    The geographic mosaic of coevolution predicts parasite virulence should be locally adapted to the host community. Cotesia parasitoid wasps adapt to local lepidopteran species possibly through their symbiotic Bracovirus. The virus, essential for the parasitism success, is at the heart of the complex coevolutionary relationship linking the wasps and their hosts. The large segmented genome contained in the virus particles encodes virulence genes involved in host immune and developmental suppression. Coevolutionary arms race should result in the positive selection of particular beneficial alleles. To understand the global role of Bracoviruses in the local adaptation or specialization of parasitoid wasps to their hosts, we studied the molecular evolution of four Bracoviruses associated with wasps of the genus Cotesia, including C congregata, C vestalis and new data and annotation on two ecologically differentiated populations of C sesamie, Kitale and Mombasa. Paired orthologs analyses revealed more genes under positive selection when comparing the two C sesamiae Bracoviruses belonging to the same species, and more genes under strong evolutionary constraint between species. Furthermore branch-site evolutionary models showed that 17 genes, out of the 54 currently available shared by the four Bracoviruses, harboured sites under positive selection including: the histone H4-like, a C-type lectin, two ep1-like, ep2, a viral ankyrin, CrV1, a ben-domain, a Serine-rich, and eight unknown genes. Lastly the phylogenetic analyses of the histone, ep2 and CrV1 genes in different African

  • functional endogenous viral elements in the genome of the parasitoid wasp cotesia congregata insights into the evolutionary dynamics of Bracoviruses
    Philosophical Transactions of the Royal Society B, 2013
    Co-Authors: Annie Bezier, Jerome Lesobre, Severine Jancek, Karine Musset, Julien Thézé, Gabor Gyapay, Georges Periquet, Faustine Louis, Patricia Lenoble
    Abstract:

    Bracoviruses represent the most complex endogenous viral elements (EVEs) described to date. Nudiviral genes have been hosted within parasitoid wasp genomes since approximately 100 Ma. They play a crucial role in the wasp life cycle as they produce Bracovirus particles, which are injected into parasitized lepidopteran hosts during wasp oviposition. Bracovirus particles encapsidate multiple dsDNA circles encoding virulence genes. Their expression in parasitized caterpillars is essential for wasp parasitism success. Here, we report on the genomic organization of the proviral segments (i.e. master sequences used to produce the encapsidated dsDNA circles) present in the Cotesia congregata parasitoid wasp genome. The provirus is composed of a macrolocus, comprising two-thirds of the proviral segments and of seven dispersed loci, each containing one to three segments. Comparative genomic analyses with closely related species gave insights into the evolutionary dynamics of Bracovirus genomes. Conserved synteny in the different wasp genomes showed the orthology of the proviral macrolocus across different species. The nudiviral gene odv-e66-like1 is conserved within the macrolocus, suggesting an ancient co-localization of the nudiviral genome and Bracovirus proviral segments. By contrast, the evolution of proviral segments within the macrolocus has involved a series of lineage-specific duplications.

  • the Bracovirus genome of the parasitoid wasp cotesia congregata is amplified within 13 replication units including sequences not packaged in the particles
    Journal of Virology, 2013
    Co-Authors: Faustine Louis, Annie Bezier, Georges Periquet, Cristina Ferras, Jean-michel Drezen
    Abstract:

    The relationship between parasitoid wasps and polydnaviruses constitutes one of the few known mutualisms between viruses and eukaryotes. Viral particles are injected with the wasp eggs into parasitized larvae, and the viral genes thus introduced are used to manipulate lepidopteran host physiology. The genome packaged in the particles is composed of 35 double-stranded DNA (dsDNA) circles produced in wasp ovaries by amplification of viral sequences from proviral segments integrated in tandem arrays in the wasp genome. These segments and their flanking regions within the genome of the wasp Cotesia congregata were recently isolated, allowing extensive mapping of amplified sequences. The Bracovirus DNAs packaged in the particles were found to be amplified within more than 12 replication units. Strikingly, the nudiviral cluster, the genes of which encode particle structural components, was also amplified, although not encapsidated. Amplification of bracoviral sequences was shown to involve successive head-to-head and tail-to-tail concatemers, which was not expected given the nudiviral origin of Bracoviruses.