| persistence and expression of microplitis demolitor polydnavirus in pseudoplusia includens. | persistence and expression of microplitis demolitor polydnavirus (mdpdv) was examined in parasitized and virus-injected pseudoplusia includens larvae. viral dna persisted in p. includens larvae for 6 days, but no increase in the amount of viral dna present was detected. viral transcripts were observed in parasitized and virus-injected larvae 4 h post-parasitism and expression continued for 6 days. when specific host tissues were examined, more viral dna and rna was detected in haemocytes than in ... | 1992 | 1629694 |
| microplitis demolitor polydnavirus induces apoptosis of a specific haemocyte morphotype in pseudoplusia includens. | microplitis demolitor polydnavirus (mdpdv) is associated with microplitis demolitor, a parasitic wasp that attacks the larval stage of the lepidopteran pseudoplusia includens. previously, we observed that mdpdv induced several alterations in the granular cells and plasmatocytes of p. includens, the primary haemocytes involved in regulating the cellular immune response toward m. demolitor and other parasites. in examining the mechanisms underlying immunosuppression of this host, we found that mdp ... | 1995 | 7844550 |
| microplitis demolitor polydnavirus infects and expresses in specific morphotypes of pseudoplusia includens haemocytes. | microplitis demolitor is a polydnavirus-carrying wasp that parasitizes the larval stage of pseudoplusia includens. m. demolitor eggs are never encapsulated by host haemocytes when coinfected with its associated polyndnavirus (mdpdv) whereas eggs are encapsulated within 36 h when injected into hosts without virus. in this study, infection of specific classes of p. includens haemocytes by mdpdv was examined. electron microscopic studies indicated that mdpdv entered all haemocyte morphotypes. north ... | 1994 | 7964610 |
| two microplitis demolitor polydnavirus mrnas expressed in hemocytes of pseudoplusia includens contain a common cysteine-rich domain. | microplitis demolitor is a polydnavirus-carrying wasp that parasitizes the larval stage of pseudoplusia includens. a previous study indicated that m. demolitor polydnavirus (mdpdv) infects primarily hemocytes in parasitized hosts. thereafter, several alterations that compromise the immune response of p. includens toward the developing parasitoid occur in hemocytes. in this study, we identified two mdpdv mrnas (1.0 and 1.5 kb) expressed in p. includens hemocytes that have homology to the viral ge ... | 1997 | 9032348 |
| plasmatocyte spreading peptide does not induce microplitis demolitor polydnavirus-infected plasmatocytes to spread on foreign surfaces. | capsule formation by the moth pseudopulsia includens requires that plasmatocytes change from being nonadhesive cells in circulation to strongly adhesive cells capable of attaching to the foreign target and one another. this change in adhesive state is induced by plasmatocyte spreading peptide (psp1); a 23 amino acid peptide isolated from p. includens plasma. plasmatocytes from hosts parasitized by microplitis demolitor remain in a nonadhesive state after infection by microplitis demolitor polydn ... | 1999 | 9987820 |
| characterization of two novel microplitis demolitor polydnavirus mrnas expressed in pseudoplusia includens haemocytes. | the braconid wasp microplitis demolitor carries m. demolitor polydnavirus (mdpdv) and parasitizes the larval stage of the moth pseudoplusia includens. m. demolitor injects mdpdv into p. includens larvae when it lays an egg and the virus infects various cells including haemocytes. two new mdpdv transcripts expressed in host haemocytes were characterized in this study. screening of an mdpdv-infected haemocyte cdna library identified a 0.4 kb cdna encoding a predicted protein of 103 amino acids whi ... | 2000 | 11086136 |
| a limited role in parasitism for microplitis demolitor polydnavirus. | spodoptera frugiperda larvae stung by microplitis demolitor undergo physiological alterations characteristic of parasitism. however, despite these physiological modifications, parasitized s. frugiperda larvae never yield adult wasps. our original hypothesis that unsuccessful parasitism was due to a transcriptionally inactive polydnavirus proved untrue. microplitis demolitor polydnavirus (mdpdv) successfully infected and expressed, albeit transiently, in s. frugiperda hemocytes. mdpdv expression ... | 1998 | 12769875 |
| cross-protection experiments with parasitoids in the genus microplitis (hymenoptera: braconidae) suggest a high level of specificity in their associated bracoviruses. | the immunological and developmental effects of bracoviruses (bvs) from three parasitoids in the genus microplitis (braconidae: microgastrinae) were compared in the hosts pseudoplusia includens and heliothis virescens (lepidoptera: noctuidae). southern blotting experiments indicated that viral dnas from microplitis demolitor bracovirus (mdbv) cross-hybridized with viral dnas from microplitis croceipes bracovirus (mcbv) and microplitis mediator bracovirus (mmbv) under conditions of high stringency ... | 2003 | 12770626 |
| rna interference silences microplitis demolitor bracovirus genes and implicates glc1.8 in disruption of adhesion in infected host cells. | the family polydnaviridae consists of ds-dna viruses that are symbiotically associated with certain parasitoid wasps. pdvs are transmitted vertically but also are injected by wasps into hosts where they cause several physiological alterations including immunosuppression. the pdv genes responsible for mediating immunosuppression and other host alterations remain poorly characterized in large measure because viral mutants cannot be produced to study gene function. here we report the use of rna int ... | 2003 | 14554081 |
| glc1.8 from microplitis demolitor bracovirus induces a loss of adhesion and phagocytosis in insect high five and s2 cells. | polydnaviridae is a unique family of dna viruses that are symbiotically associated with parasitoid wasps. upon oviposition, wasps inject these viruses into their hosts, where they cause several physiological alterations, including suppression of the cellular immune response. here we report that expression of the glc1.8 gene from microplitis demolitor bracovirus (mdbv) causes a loss of adhesion by two hemocyte-like cell lines, namely, high five cells from the lepidopteran trichoplusia ni and s2 c ... | 2005 | 15650210 |
| inhibitor kappab-like proteins from a polydnavirus inhibit nf-kappab activation and suppress the insect immune response. | complex signaling pathways regulate the innate immune system of insects, with nf-kappab transcription factors playing a central role in the activation of antimicrobial peptides and other immune genes. although numerous studies have characterized the immune responses of insects to pathogens, comparatively little is known about the counter-strategies pathogens have evolved to circumvent host defenses. among the most potent immunosuppressive pathogens of insects are polydnaviruses that are symbioti ... | 2005 | 16061795 |
| polydnavirus genomes reflect their dual roles as mutualists and pathogens. | symbionts often exhibit significant reductions in genome complexity while pathogens often exhibit increased complexity through acquisition and diversification of virulence determinants. a few organisms have evolved complex life cycles in which they interact as symbionts with one host and pathogens with another. how the predicted and opposing influences of symbiosis and pathogenesis affect genome evolution in such instances, however, is unclear. the polydnaviridae is a family of double-stranded ( ... | 2006 | 16380146 |
| microplitis demolitor bracovirus inhibits phagocytosis by hemocytes from pseudoplusia includens. | the braconid wasp microplitis demolitor carries microplitis demolitor bracovirus (mdbv) and parasitizes the larval stage of several noctuid moths. a key function of mdbv in parasitism is suppression of the host's cellular immune response. prior studies in the host pseudoplusia includens indicated that mdbv blocks encapsulation by preventing two types of hemocytes, plasmatocytes and granulocytes, from adhering to foreign targets. the other main immune response mediated by insect hemocytes is phag ... | 2006 | 16482578 |
| microplitis demolitor bracovirus genome segments vary in abundance and are individually packaged in virions. | polydnaviruses (pdvs) are distinguished by their unique association with parasitoid wasps and their segmented, double-stranded (ds) dna genomes that are non-equimolar in abundance. relatively little is actually known, however, about genome packaging or segment abundance of these viruses. here, we conducted electron microscopy (em) and real-time polymerase chain reaction (pcr) studies to characterize packaging and segment abundance of microplitis demolitor bracovirus (mdbv). like other pdvs, mdbv ... | 2007 | 17034828 |
| ptp-h2 and ptp-h3 from microplitis demolitor bracovirus localize to focal adhesions and are antiphagocytic in insect immune cells. | viruses in the family polydnaviridae are symbiotically associated with parasitoid wasps. wasps inject polydnaviruses (pdvs) when laying an egg into their insect host, and expression of viral gene products causes several physiological alterations, including immunosuppression, that allow the wasp's progeny to develop. as with other pdvs, most microplitis demolitor bracovirus (mdbv) genes are related variants that form gene families. the largest mdbv gene family includes 13 members that encode pred ... | 2007 | 17121799 |
| a novel polydnavirus protein inhibits the insect prophenoloxidase activation pathway. | pathogens often suppress the melanization response of host insects, but the underlying molecular mechanisms are largely unknown. here we report that microplitis demolitor bracovirus (mdbv) carried by the wasp m. demolitor produces a protein, egf1.0, which inhibits the phenoloxidase (po) cascade. egf1.0 belongs to a larger gene family that shares a cysteine-rich motif with similarities to the trypsin inhibitor-like (til) domains of small serine proteinase inhibitors (smapins). gain-of-function an ... | 2007 | 18032603 |
| protein tyrosine phosphatase-h2 from a polydnavirus induces apoptosis of insect cells. | the family polydnaviridae is a large group of immunosuppressive insect viruses that are symbiotically associated with parasitoid wasps. the polydnavirus microplitis demolitor bracovirus (mdbv) causes several alterations that disable the cellular and humoral immune defences of host insects, including apoptosis of the primary phagocytic population of circulating immune cells (haemocytes), called granulocytes. here, we show that mdbv infection causes granulocytes in the lepidopteran spodoptera frug ... | 2008 | 18474557 |
| the viral protein egf1.0 is a dual activity inhibitor of prophenoloxidase-activating proteinases 1 and 3 from manduca sexta. | some pathogens are capable of suppressing the melanization response of host insects, but the virulence factors responsible are largely unknown. the insect pathogen microplitis demolitor bracovirus encodes the egf family of small serine proteinase inhibitors. one family member, egf1.0, was recently shown to suppress melanization of hemolymph in manduca sexta in part by inhibiting the enzymatic activity of prophenoloxidase activating proteinase 3 (pap3). however, other experiments suggested this v ... | 2008 | 18519564 |
| egf1.5 is a second phenoloxidase cascade inhibitor encoded by microplitis demolitor bracovirus. | the three-member egf gene family from the polydnavirus microplitis demolitor bracovirus (mdbv) encodes novel proteins distinguished by a shared cysteine-rich motif. prior studies determined that one family member, egf1.0, inhibits melanization of hemolymph from the moth manduca sexta by disabling phenoloxidase activating proteinases (paps). here we characterized a second family member, egf1.5, which shares an identical cysteine-rich motif with egf1.0, but possesses an extended c-terminal repeat ... | 2010 | 20417280 |
| characterization and kinetic analysis of protein tyrosine phosphatase-h2 from microplitis demolitor bracovirus. | the polydnavirus microplitis demolitor bracovirus (mdbv) encodes 13 genes that share homology with classical protein tyrosine phosphatases (ptps). prior sequence analysis suggested that five members of the mdbv ptp gene family (ptp-h2, -h3, -h5, -n1 and -n2) encode ptps, seven family members encode pseudophosphatases, and one family member is a pseudogene. prior experimental studies further implicated ptp-h2 in disabling the function of host hemocytes following infection by mdbv. here we report ... | 2010 | 20691785 |
| lepidopteran transcriptome analysis following infection by phylogenetically unrelated polydnaviruses highlights differential and common responses. | the polydnaviridae is a family of double-stranded dna viruses that are symbionts of parasitoid wasps. the family is currently divided into two genera, the ichnovirus (iv) and bracovirus (bv), which are associated with wasps in the families ichneumonidae and braconidae, respectively. ivs and bvs have similar immunosuppressive and developmental effects on parasitized hosts but their encapsidated genomes largely encode different genes. to assess whether iv and bv infection has similar or disparate ... | 2011 | 21457783 |
| transcriptomic profiling of microplitis demolitor bracovirus reveals host, tissue, and stage-specific patterns of activity. | the polydnaviridae is a family of dna viruses that are symbiotically associated with parasitoid wasps. the transcription of particular genes or gene family members have been reported for several pdvs, but no studies have characterized spatio-temporal patterns of expression for the entire complement of predicted genes in the encapsidated genome of any pdv isolate. the braconid wasp microplitis demolitor carries the pdv microplitis demolitor bracovirus (mdbv) and parasitizes the larval stage pseud ... | 2011 | 21613444 |
| the encapsidated genome of microplitis demolitor bracovirus integrates into the host pseudoplusia includens. | polydnaviruses (pdvs) are symbionts of parasitoid wasps that function as gene delivery vehicles in the insects (hosts) that the wasps parasitize. pdvs persist in wasps as integrated proviruses but are packaged as circularized and segmented double-stranded dnas into the virions that wasps inject into hosts. in contrast, little is known about how pdv genomic dnas persist in host cells. microplitis demolitor carries microplitis demolitor bracovirus (mdbv) and parasitizes the host pseudoplusia inclu ... | 2011 | 21880747 |
| analysis of genetic variation across the encapsidated genome of microplitis demolitor bracovirus in parasitoid wasps. | insect parasitoids must complete part of their life cycle within or on another insect, ultimately resulting in the death of the host insect. one group of parasitoid wasps, the 'microgastroid complex' (hymenoptera: braconidae), engage in an association with beneficial symbiotic viruses that are essential for successful parasitism of hosts. these viruses, known as bracoviruses, persist in an integrated form in the wasp genome, and activate to replicate in wasp ovaries during development to ultimat ... | 2016 | 27390861 |
| microplitis demolitor bracovirus proviral loci and clustered replication genes exhibit distinct dna amplification patterns during replication. | 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. ... | 2015 | 26157119 |
| mutualistic polydnaviruses share essential replication gene functions with pathogenic ancestors. | viruses are usually thought to form parasitic associations with hosts, but all members of the family polydnaviridae are obligate mutualists of insects called parasitoid wasps. phylogenetic data founded on sequence comparisons of viral genes indicate that polydnaviruses in the genus bracovirus (bv) are closely related to pathogenic nudiviruses and baculoviruses. however, pronounced differences in the biology of bvs and baculoviruses together with high divergence of many shared genes make it uncle ... | 2013 | 23671417 |
| polydnavirus ank proteins bind nf-κb homodimers and inhibit processing of relish. | recent studies have greatly increased understanding of how the immune system of insects responds to infection, whereas much less is known about how pathogens subvert immune defenses. key regulators of the insect immune system are rel proteins that form nuclear factor-κb (nf-κb) transcription factors, and inhibitor κb (iκb) proteins that complex with and regulate nf-κbs. major mortality agents of insects are parasitoid wasps that carry immunosuppressive polydnaviruses (pdvs). most pdvs encode ank ... | 2012 | 22654665 |
| deep sequencing identifies viral and wasp genes with potential roles in replication of microplitis demolitor bracovirus. | viruses in the genus bracovirus (bv) (polydnaviridae) are symbionts of parasitoid wasps that specifically replicate in the ovaries of females. recent analysis of expressed sequence tags from two wasp species, cotesia congregata and chelonus inanitus, identified transcripts related to 24 different nudivirus genes. these results together with other data strongly indicate that bvs evolved from a nudivirus ancestor. however, it remains unclear whether bv-carrying wasps contain other nudivirus-like g ... | 2012 | 22238295 |