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Kim J, Rahman MM, Kim AY, Ramasamy S, Kwon M, Kim Y. Genome, host genome integration, and gene expression in Diadegma fenestrale ichnovirus from the perspective of coevolutionary hosts. Front Microbiol 2023; 14:1035669. [PMID: 36876096 PMCID: PMC9981800 DOI: 10.3389/fmicb.2023.1035669] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2022] [Accepted: 01/25/2023] [Indexed: 02/19/2023] Open
Abstract
Polydnaviruses (PDVs) exhibit species-specific mutualistic relationships with endoparasitoid wasps. PDVs can be categorized into bracoviruses and ichnoviruses, which have independent evolutionary origins. In our previous study, we identified an ichnovirus of the endoparasitoid Diadegma fenestrale and named it DfIV. Here, DfIV virions from the ovarian calyx of gravid female wasps were characterized. DfIV virion particles were ellipsoidal (246.5 nm × 109.0 nm) with a double-layered envelope. Next-generation sequencing of the DfIV genome revealed 62 non-overlapping circular DNA segments (A1-A5, B1-B9, C1-C15, D1-D23, E1-E7, and F1-F3); the aggregate genome size was approximately 240 kb, and the GC content (43%) was similar to that of other IVs (41%-43%). A total of 123 open reading frames were predicted and included typical IV gene families such as repeat element protein (41 members), cysteine motif (10 members), vankyrin (9 members), polar residue-rich protein (7 members), vinnexin (6 members), and N gene (3 members). Neuromodulin N (2 members) was found to be unique to DfIV, along with 45 hypothetical genes. Among the 62 segments, 54 showed high (76%-98%) sequence similarities to the genome of Diadegma semiclausum ichnovirus (DsIV). Three segments, namely, D22, E3, and F2, contained lepidopteran host genome integration motifs with homologous regions of about 36-46 bp between them (Diadegma fenestrale ichnovirus, DfIV and lepidopteran host, Plutella xylostella). Most of the DfIV genes were expressed in the hymenopteran host and some in the lepidopteran host (P. xylostella), parasitized by D. fenestrale. Five segments (A4, C3, C15, D5, and E4) were differentially expressed at different developmental stages of the parasitized P. xylostella, and two segments (C15 and D14) were highly expressed in the ovaries of D. fenestrale. Comparative analysis between DfIV and DsIV revealed that the genomes differed in the number of segments, composition of sequences, and internal sequence homologies.
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Affiliation(s)
- Juil Kim
- Agriculture and Life Science Research Institute, Kangwon National University, Chuncheon, Republic of Korea.,Program of Applied Biology, Division of Bio-Resource Sciences, College of Agriculture and Life Science, Kangwon National University, Chuncheon, Republic of Korea
| | - Md-Mafizur Rahman
- Agriculture and Life Science Research Institute, Kangwon National University, Chuncheon, Republic of Korea.,Department Biotechnology and Genetic Engineering, Faculty of Biological Science, Islamic University, Kushtia, Bangladesh
| | - A-Young Kim
- Ilsong Institute of Life Science, Hallym University, Seoul, Republic of Korea
| | | | - Min Kwon
- Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, Republic of Korea
| | - Yonggyun Kim
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong, Republic of Korea
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Parasitism and survival rate of Diadegma fenestrale (Hymenoptera: Ichneumonidae) and DfIV gene expression patterns in two lepidopteran hosts. Biochem Biophys Res Commun 2015; 459:579-84. [PMID: 25769948 DOI: 10.1016/j.bbrc.2015.02.150] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Accepted: 02/25/2015] [Indexed: 11/21/2022]
Abstract
The genus Diadegma is a well-known parasitoid group and some are known to have symbiotic virus, polydnavirus (PDV). A novel IV was discovered from the calyx of Diadegma fenestrale female and sequenced its genome. D. fenestrale has more than two hosts, including potato tuber moth (PTM) and diamondback moth (DBM). D. fenestrale preferred PTM to DBM as hosts based on the oviposition and survival rate. Nevertheless, the developmental period and morphology of D. fenestrale were not significantly different between PTM and DBM. We compared DfIV gene expression patterns between PTM and DBM under various conditions to understand the phenomena. DfIV genes were more widely expressed in PTM with large numbers than in DBM after parasitized by D. fenestrale, particularly at the initial point. They showed differential expression patterns between two lepidopteran hosts. This DfIV gene expression plasticity showed a dependency on the lepidopteran host species and parasitization time, suggesting that it may contribute to increase the parasitoid survival rate. This might be one of the key elements that determine the symbiotic relationship between PDV and parasitoid.
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Dorémus T, Darboux I, Cusson M, Ravallec M, Jouan V, Frayssinet M, Stoltz DB, Webb BA, Volkoff AN. Specificities of ichnoviruses associated with campoplegine wasps: genome, genes and role in host-parasitoid interaction. CURRENT OPINION IN INSECT SCIENCE 2014; 6:44-51. [PMID: 32846675 DOI: 10.1016/j.cois.2014.09.017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Revised: 09/23/2014] [Accepted: 09/24/2014] [Indexed: 06/11/2023]
Abstract
Ichnoviruses (IVs), unique symbiotic viruses carried by ichneumonid campoplegine wasps, derive from integration of a paleo-ichnovirus into an ancestral wasp genome. The modern 'genome' is composed of both regions that are amplified, circularized and encapsidated into viral particles and non-encapsidated viral genomic regions involved in particle morphogenesis. Packaged genomes include multiple circular dsDNAs encoding many genes mostly organized in gene families. Virus particles are assembled in specialized ovarian cells from which they exit into the oviduct lumen; mature virions are injected during oviposition into the insect host. Expression of viral proteins in infected cells correlates with physiological alterations of the host enabling success of parasitism.
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Affiliation(s)
- Tristan Dorémus
- "Diversity, Genomes & Interactions Microorganisms Insects" Laboratory, INRA (UMR 1333), Université de Montpellier 2, Place Eugène Bataillon, CC101, 34095 Montpellier Cedex, France
| | - Isabelle Darboux
- "Diversity, Genomes & Interactions Microorganisms Insects" Laboratory, INRA (UMR 1333), Université de Montpellier 2, Place Eugène Bataillon, CC101, 34095 Montpellier Cedex, France
| | - Michel Cusson
- Laurentian Forestry Centre, Canadian Forest Service, Natural Resources Canada, 1055 du P.E.P.S., P.O. Box 10380, Stn. Ste. Foy, Quebec G1V 4C7, Canada
| | - Marc Ravallec
- "Diversity, Genomes & Interactions Microorganisms Insects" Laboratory, INRA (UMR 1333), Université de Montpellier 2, Place Eugène Bataillon, CC101, 34095 Montpellier Cedex, France
| | - Véronique Jouan
- "Diversity, Genomes & Interactions Microorganisms Insects" Laboratory, INRA (UMR 1333), Université de Montpellier 2, Place Eugène Bataillon, CC101, 34095 Montpellier Cedex, France
| | - Marie Frayssinet
- "Diversity, Genomes & Interactions Microorganisms Insects" Laboratory, INRA (UMR 1333), Université de Montpellier 2, Place Eugène Bataillon, CC101, 34095 Montpellier Cedex, France
| | - Don B Stoltz
- Department of Microbiology and Immunology, Dalhousie University, Sir Charles Tupper Medical Building, 5850 College Street, P.O. Box 15000, Halifax, Nova Scotia B3H 4R2, Canada
| | - Bruce A Webb
- Department of Entomology, S-225 Agricultural Science Center N, University of Kentucky, Lexington, KY 40546-0091, USA
| | - Anne-Nathalie Volkoff
- "Diversity, Genomes & Interactions Microorganisms Insects" Laboratory, INRA (UMR 1333), Université de Montpellier 2, Place Eugène Bataillon, CC101, 34095 Montpellier Cedex, France.
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Dorémus T, Cousserans F, Gyapay G, Jouan V, Milano P, Wajnberg E, Darboux I, Cônsoli FL, Volkoff AN. Extensive transcription analysis of the Hyposoter didymator Ichnovirus genome in permissive and non-permissive lepidopteran host species. PLoS One 2014; 9:e104072. [PMID: 25117496 PMCID: PMC4130501 DOI: 10.1371/journal.pone.0104072] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Accepted: 07/07/2014] [Indexed: 01/10/2023] Open
Abstract
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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Affiliation(s)
- Tristan Dorémus
- INRA - Université de Montpellier 2, Unité « Diversité, Génomes et Interactions Insectes-Microorganismes », Place Eugène Bataillon, CC101, Montpellier, France
| | - François Cousserans
- INRA - Université de Montpellier 2, Unité « Diversité, Génomes et Interactions Insectes-Microorganismes », Place Eugène Bataillon, CC101, Montpellier, France
| | - Gabor Gyapay
- France Génomique - Commissariat à l'Energie Atomique - Institut de Génomique, Génoscope, 2, Evry, France
| | - Véronique Jouan
- INRA - Université de Montpellier 2, Unité « Diversité, Génomes et Interactions Insectes-Microorganismes », Place Eugène Bataillon, CC101, Montpellier, France
| | - Patricia Milano
- Escola Superior de Agricultura Luiz de Queiroz - Universidade de Sao Paulo, Departamento de Entomologia e Acarologia, Laboratório de Interações em Insetos, Piracicaba, Sao Paulo, Brazil
| | - Eric Wajnberg
- INRA - CNRS - Université Nice Sophia Antipolis, Institut Sophia Agrobiotech, Sophia Antipolis, France
| | - Isabelle Darboux
- INRA - Université de Montpellier 2, Unité « Diversité, Génomes et Interactions Insectes-Microorganismes », Place Eugène Bataillon, CC101, Montpellier, France
| | - Fernando Luis Cônsoli
- Escola Superior de Agricultura Luiz de Queiroz - Universidade de Sao Paulo, Departamento de Entomologia e Acarologia, Laboratório de Interações em Insetos, Piracicaba, Sao Paulo, Brazil
| | - Anne-Nathalie Volkoff
- INRA - Université de Montpellier 2, Unité « Diversité, Génomes et Interactions Insectes-Microorganismes », Place Eugène Bataillon, CC101, Montpellier, France
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Gill TA, Webb BA. Analysis of gene transcription and relative abundance of the cys-motif gene family from Campoletis sonorensis ichnovirus (CsIV) and further characterization of the most abundant cys-motif protein, WHv1.6. INSECT MOLECULAR BIOLOGY 2013; 22:341-353. [PMID: 23614457 DOI: 10.1111/imb.12022] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The cys-motif gene family associated with Campoletis sonorensis ichnovirus contains 10 members, WHv1.6, WHv1.0, VHv1.1, VHv1.4, AHv1.0, A'Hv0.8, FHv1.4, LHv2.8, UHv0.8, and UHv0.8a. The results of this study indicated that, within the encapsidated virion, WHv1.6 is the most abundant cys-motif gene, while the combined AHv genes are the least abundant. During parasitization of Heliothis virescens by Campoletis sonorenis, WHv1.6 transcripts were the mostly highly expressed, while the combined UHv genes had the lowest expression. Further proteomic analysis of WHv1.6 showed that it accumulates at high levels in parasitized plasma by 6 h, and is detectable in the haemocytes, fat body, malpighian tubules, nerve cord and epidermis by 2 days after parasitization. Localization experiments led us to conclude that WHv1.6 interacts with the cell membrane along with other organelles within a virus-infected cell and prevents immunocytes from spreading or adhering to a foreign surface. Similarly to VHv1.4 and VHv1.1, WHv1.6 is able to inhibit the translation of haemocyte and Malpighian tubule RNAs. Our results showed that the expression of cys-motif genes during parasitization is related to the gene copy number of each gene within the encapsidated virion and may also be dependent upon cis-regulatory element activity in different target tissues. In addition, WHv1.6 plays a major role in inhibiting the cellular encapsulation response by H. virescens.
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Affiliation(s)
- T A Gill
- Department of Entomology, University of Kentucky, Lexington, KY 40503, USA
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Djoumad A, Dallaire F, Lucarotti CJ, Cusson M. Characterization of the polydnaviral ‘T. rostrale virus’ (TrV) gene family: TrV1 expression inhibits in vitro cell proliferation. J Gen Virol 2013; 94:1134-1144. [DOI: 10.1099/vir.0.049817-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Tranosema rostrale ichnovirus (TrIV) is a polydnavirus (PDV) transmitted by the endoparasitic wasp T. rostrale to its host Choristoneura fumiferana during oviposition. PDV genes are expressed in infected caterpillars, causing physiological disturbances that promote the survival of the developing endoparasite. The previously sequenced genome of TrIV contains ~86 genes organized in multigene families and distributed on multiple segments of circular dsDNA. Among these, the ‘T. rostrale virus’ (TrV) family comprises seven genes that are absent in other PDV genomes examined to date and whose function(s) remain(s) unknown. Here, we initiated a functional analysis of the TrV family using qPCR, transfection and RNAi approaches. TrV family genes were weakly expressed in wasp ovaries, but some displayed high transcript abundance in parasitized caterpillars. Whilst TrV1 was the most highly transcribed TrV gene in infected caterpillars, transcript levels for TrV5 and TrV6 were nearly undetectable, indicating that they may be pseudogenes. Temporal and tissue-specific patterns of transcript abundance were similar for all expressed TrV family genes, indicative of an apparent lack of difference in function or tissue specificity. Infection of Cf-203 and Sf-21 insect cells with TrIV led to a dose-dependent inhibition of cell proliferation with no sign of apoptosis. Whilst similar inhibition was observed following transfection of cells with a cloned genome segment carrying the TrV1 gene, RNA interference targeting TrV1 largely restored cell growth in TrIV-infected cells, indicating that TrV1 expression was responsible for the observed inhibition. We suggest that TrV genes may contribute to host developmental disruption by interfering with host-cell proliferation during parasitism.
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Affiliation(s)
- Abdelmadjid Djoumad
- Natural Resources Canada, Canadian Forest Service, Laurentian Forestry Centre, 1055 du PEPS, PO Box 10380, Stn. Sainte‐Foy, Québec, Quebec G1V 4C7, Canada
| | - Fréderic Dallaire
- Natural Resources Canada, Canadian Forest Service, Laurentian Forestry Centre, 1055 du PEPS, PO Box 10380, Stn. Sainte‐Foy, Québec, Quebec G1V 4C7, Canada
| | - Christopher J. Lucarotti
- Natural Resources Canada, Canadian Forest Service, Atlantic Forestry Centre, 1350 Regent Street, Fredericton, New Brunswick E3C 2G6, Canada
| | - Michel Cusson
- Natural Resources Canada, Canadian Forest Service, Laurentian Forestry Centre, 1055 du PEPS, PO Box 10380, Stn. Sainte‐Foy, Québec, Quebec G1V 4C7, Canada
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Etebari K, Hussain M, Asgari S. Suppression of scavenger receptors transcription by parasitoid factors. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2012; 38:517-524. [PMID: 23000265 DOI: 10.1016/j.dci.2012.08.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2012] [Revised: 08/28/2012] [Accepted: 08/28/2012] [Indexed: 06/01/2023]
Abstract
Scavenger receptors (SR) are a group of membrane proteins that play central roles in various functions, such as immune responses in insects. Members of different SR classes were identified from Plutella xylostella larval transcriptome. SR B1 and B3 were found to be differentially expressed in larvae and pupae. Expression of P. xylostella SR genes was significantly altered during immune challenge induced in P. xylostella cells (Px) and parasitized larvae. Maternal factors injected into the larvae by the endoparasitoid wasp Diadegma semiclausum at oviposition include venom and ichnovirus (DsIV) genes to suppress the host immune system. Transient expression of two DsIV genes, Vankyrin1 and Repeat element 4 (Rep4), in Px cells led to significant down-regulation of both SR B1 and B3 transcript levels, while DsIV Rep4 expression did not change the relative transcription levels of SR B3. In conclusion, it appears that the two members of the SR family play important roles in innate immune responses in P. xylostella and that each member of this group may play different roles in the host-parasitoid interaction.
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Affiliation(s)
- Kayvan Etebari
- School of Biological Sciences, The University of Queensland, St. Lucia, Australia
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Clavijo G, Dorémus T, Ravallec M, Mannucci MA, Jouan V, Volkoff AN, Darboux I. Multigenic families in Ichnovirus: a tissue and host specificity study through expression analysis of vankyrins from Hyposoter didymator Ichnovirus. PLoS One 2011; 6:e27522. [PMID: 22087334 PMCID: PMC3210807 DOI: 10.1371/journal.pone.0027522] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Accepted: 10/18/2011] [Indexed: 11/18/2022] Open
Abstract
The viral ankyrin (vankyrin) gene family is represented in all polydnavirus (PDVs) genomes and encodes proteins homologous to I-kappaBs, inhibitors of NF-kappaB transcription factors. The structural similarities led to the hypothesis that vankyrins mimic eukaryotic factors to subvert important physiological pathways in the infected host. Here, we identified nine vankyrin genes in the genome of the Hyposoter didymator Ichnovirus (HdIV). Time-course gene expression experiments indicate that all members are expressed throughout parasitism of Spodoptera frugiperda, as assessed using RNA extracted from whole larvae. To study tissue and/or species specificity transcriptions, the expression of HdIV vankyrin genes were compared between HdIV-injected larvae of S. frugiperda and S. littoralis. The transcriptional profiles were similar in the two species, including the largely predominant expression of Hd27-vank1 in all tissues examined. However, in various insect cell lines, the expression patterns of HdIV vankyrins differed according to species. No clear relationship between vankyrin expression patterns and abundance of vankyrin-bearing genomic segments were found in the lepidopteran cell lines. Moreover, in these cells, the amount of vankyrin-bearing genomic segments differed substantially between cytosol and nuclei of infected cells, implying the existence of an unexpected step regulating the copy number of HdIV segments in cell nuclei. Our in vitro results reveal a host-specific transcriptional profile of vankyrins that may be related to the success of parasitism in different hosts. In Spodoptera hosts, the predominant expression of Hd27-vank1 suggests that this protein might have pleiotropic functions during parasitism of these insect species.
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Affiliation(s)
- Gabriel Clavijo
- INRA, UMR 1333- Diversité, Génomes et Interactions Microorganismes-Insectes, Montpellier, France
- Université Montpellier 2, UMR 1333- Diversité, Génomes et Interactions Microorganismes-Insectes, Montpellier, France
| | - Tristan Dorémus
- INRA, UMR 1333- Diversité, Génomes et Interactions Microorganismes-Insectes, Montpellier, France
- Université Montpellier 2, UMR 1333- Diversité, Génomes et Interactions Microorganismes-Insectes, Montpellier, France
| | - Marc Ravallec
- INRA, UMR 1333- Diversité, Génomes et Interactions Microorganismes-Insectes, Montpellier, France
- Université Montpellier 2, UMR 1333- Diversité, Génomes et Interactions Microorganismes-Insectes, Montpellier, France
| | - Marie-Anne Mannucci
- INRA, UMR 1333- Diversité, Génomes et Interactions Microorganismes-Insectes, Montpellier, France
- Université Montpellier 2, UMR 1333- Diversité, Génomes et Interactions Microorganismes-Insectes, Montpellier, France
| | - Véronique Jouan
- INRA, UMR 1333- Diversité, Génomes et Interactions Microorganismes-Insectes, Montpellier, France
- Université Montpellier 2, UMR 1333- Diversité, Génomes et Interactions Microorganismes-Insectes, Montpellier, France
| | - Anne-Nathalie Volkoff
- INRA, UMR 1333- Diversité, Génomes et Interactions Microorganismes-Insectes, Montpellier, France
- Université Montpellier 2, UMR 1333- Diversité, Génomes et Interactions Microorganismes-Insectes, Montpellier, France
| | - Isabelle Darboux
- INRA, UMR 1333- Diversité, Génomes et Interactions Microorganismes-Insectes, Montpellier, France
- Université Montpellier 2, UMR 1333- Diversité, Génomes et Interactions Microorganismes-Insectes, Montpellier, France
- * E-mail:
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Rasoolizadeh A, Béliveau C, Stewart D, Cloutier C, Cusson M. Tranosema rostrale ichnovirus repeat element genes display distinct transcriptional patterns in caterpillar and wasp hosts. J Gen Virol 2009; 90:1505-1514. [PMID: 19264643 DOI: 10.1099/vir.0.008664-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The endoparasitic wasp Tranosema rostrale transmits an ichnovirus to its lepidopteran host, Choristoneura fumiferana, during parasitization. As shown for other ichnoviruses, the segmented dsDNA genome of the T. rostrale ichnovirus (TrIV) features several multi-gene families, including the repeat element (rep) family, whose products display no known similarity to non-ichnovirus proteins, except for a homologue encoded by the genome of the Helicoverpa armigera granulovirus; their functions remain unknown. This study applied linear regression of efficiency analysis to real-time PCR quantification of transcript abundance for all 17 TrIV rep open reading frames (ORFs) in parasitized and virus-injected C. fumiferana larvae, as well as in T. rostrale ovaries and head-thorax complexes. Although transcripts were detected for most rep ORFs in infected caterpillars, two of them clearly outnumbered the others in whole larvae, with a tendency for levels to drop over time after infection. The genome segments bearing the three most highly expressed rep genes in parasitized caterpillars were present in higher proportions than other rep-bearing genome segments in TrIV DNA, suggesting a possible role for gene dosage in the regulation of transcription level. TrIV rep genes also showed important differences in the relative abundance of their transcripts in specific tissues (cuticular epithelium, the fat body, haemocytes and the midgut), implying tissue-specific roles for individual members of this gene family. Significantly, no rep transcripts were detected in T. rostrale head-thorax complexes, whereas some were abundant in ovaries. There, the transcription pattern was completely different from that observed in infected caterpillars, suggesting that some rep genes have wasp-specific functions.
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Affiliation(s)
- Asieh Rasoolizadeh
- Département de Biologie, Université Laval, QC G1V 0A6, Canada.,Natural Resources Canada, Canadian Forest Service, Laurentian Forestry Centre, 1055 du PEPS, PO Box 10380, Stn Sainte-Foy, QC G1V 4C7, Canada
| | - Catherine Béliveau
- Natural Resources Canada, Canadian Forest Service, Laurentian Forestry Centre, 1055 du PEPS, PO Box 10380, Stn Sainte-Foy, QC G1V 4C7, Canada
| | - Don Stewart
- Natural Resources Canada, Canadian Forest Service, Laurentian Forestry Centre, 1055 du PEPS, PO Box 10380, Stn Sainte-Foy, QC G1V 4C7, Canada
| | - Conrad Cloutier
- Département de Biologie, Université Laval, QC G1V 0A6, Canada
| | - Michel Cusson
- Département de Biologie, Université Laval, QC G1V 0A6, Canada.,Natural Resources Canada, Canadian Forest Service, Laurentian Forestry Centre, 1055 du PEPS, PO Box 10380, Stn Sainte-Foy, QC G1V 4C7, Canada
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Weber B, Annaheim M, Lanzrein B. Transcriptional analysis of polydnaviral genes in the course of parasitization reveals segment-specific patterns. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2007; 66:9-22. [PMID: 17694561 DOI: 10.1002/arch.20190] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Polydnaviruses are symbiotic viruses of endoparasitic wasps, which are formed in their ovary and injected along with the eggs into the host. They manipulate the host in a way to allow successful parasitoid development. A hallmark of polydnaviruses is their segmented genome consisting of several circles of double-stranded DNA. We are studying the solitary egg-larval parasitoid Chelonus inanitus (Braconidae) parasitizing Spodoptera littoralis (Noctuidae). The polydnavirus of Chelonus inanitus (CiV) protects the parasitoid larva from encapsulation by the host's immune system, slightly modifies host nutritional physiology, and induces a developmental arrest of the host in the prepupal stage. Here we present data on newly identified CiV genes and their expression patterns in the course of parasitization. None of these genes has similarity to other genes and so far no gene families could be found. A rough estimation of transcript quantities revealed that even the most highly expressed CiV genes reach maximal values, which are 250 times lower than actin. This indicates that the CiV-induced alterations of the host are brought about by a concerted action of low levels of transcripts. In an overview, we show the expression patterns of all CiV genes analysed up to now; they indicate that several genes with similar expression patterns (early, persistent, intermediate, or late) are grouped together on the same segment. This is the first observation of this type. It suggests that one function of the segmentation of the polydnavirus genome may be the grouping together of genes, which are regulated in a similar manner.
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Affiliation(s)
- Benjamin Weber
- Institute of Cell Biology, University of Bern, Bern, Switzerland
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