The replication of <i>Hyposoter didymator</i> polydnavirus: Cytopathology of the calyx cells in the parasitoid

Volkoff, Anne-Nathalie; Ravallec, Marc; Bossy, J.P.; Cérutti, Pierre; Rocher, Janick; Cérutti, Martine; Devauchelle, G.

doi:10.1016/0248-4900(96)89926-6

Cited by 53 publications

(48 citation statements)

References 35 publications

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“…As has been shown for both IVs (26,31) and BVs (7,25,39), GfV morphogenesis takes place within the nuclei of calyx epithelial cells. Like the ichnoviruses (26), the mature GfV particle possesses two unit membrane envelopes.…”

Section: Resultsmentioning

confidence: 92%

Genomic and Morphological Features of a Banchine Polydnavirus: Comparison with Bracoviruses and Ichnoviruses

Lapointe

Tanaka

Barney

et al. 2007

J Virol

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Many ichneumonid and braconid endoparasitoids inject a polydnavirus (PDV) into their caterpillar hosts during oviposition. The viral entities carried by wasps of these families are referred to as "ichnoviruses" (IVs) and "bracoviruses" (BVs), respectively. All IV genomes characterized to date are found in wasps of the subfamily Campopleginae; consequently, little is known about PDVs found in wasps of the subfamily Banchinae, the only other ichneumonid taxon thus far shown to carry these viruses. Here we report on the genome sequence and virion morphology of a PDV carried by the banchine parasitoid Glypta fumiferanae. With an aggregate genome size of ϳ290 kb and 105 genome segments, this virus displays a degree of genome segmentation far greater than that reported for BVs or IVs. The size range of its genome segments is also lower than those in the latter two groups. As reported for other PDVs, the predicted open reading frames of this virus cluster into gene families, including the protein tyrosine phosphatase (PTP) and viral ankyrin (ank) families, but phylogenetic analysis indicates that ank genes of the G. fumiferanae virus are not embedded within the IV lineage, while its PTPs and those of BVs form distinct clusters. The banchine PDV genome also encodes a novel family of NTPase-like proteins displaying a pox-D5 domain. The unique genomic features of the first banchine virus examined, along with the morphological singularities of its virions (IV-like nucleocapsids, but enveloped in groups like some of the BVs), suggest that they could have an origin distinct from those of IVs and BVs.

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Section: Resultsmentioning

confidence: 92%

Genomic and Morphological Features of a Banchine Polydnavirus: Comparison with Bracoviruses and Ichnoviruses

Lapointe

Tanaka

Barney

et al. 2007

J Virol

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“…The morphology and formation of viral particles is different between ichnoviruses and bracoviruses. Ichnoviruses are released continuously from calyx cells by budding and their nucleocapsids are surrounded by two membranes (Volkoff et al, 1995). Bracoviruses on the other hand are fully formed in the highly swollen nuclei of calyx cells and are then released by cell lysis; their nucleocapsids are surrounded by one membrane .…”

mentioning

confidence: 99%

Genome organization of the Chelonus inanitus polydnavirus: excision sites, spacers and abundance of proviral and excised segments

Annaheim¹,

Lanzrein²

2007

Journal of General Virology

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Polydnaviruses are only found in symbiotic association with parasitic wasps within the families Ichneumonidae and Braconidae (ichnoviruses and bracoviruses). They have a segmented genome consisting of circular double-stranded DNA. In the proviral linear form they are integrated in the wasp's genome; in two bracoviruses, segments were found to be clustered. Proviral segments have direct terminal repeats. Segment excision has been proposed to occur through juxtaposition of these repeats by formation of a loop and recombination; one copy of the repeat then ends up in the circular segment and one in the rejoined DNA. Here we analysed the excision/circularization site of four segments of the Chelonus inanitus bracovirus (CiV) and found that they are similar to the two already known sites; on the basis of the combined data an extended excision site motif was found. Analyses of segment flanking sequences led to the first identification of one complete and several partial spacers between proviral segments in a polydnavirus. The spacer between the proviral segments CiV14 and CiV22.5 has a length of 2065 bp; the terminal repeats of CiV14 and CiV22.5 were seen to have an opposite orientation and from this a model on the spacial organization of the loops of the proviral cluster is proposed. Through various approaches it was shown that spacers are not excised or injected into the host. Measurement of relative abundances of various segments in proviral and excised form indicates for the first time that abundant segments are present in multiple copies in the proviral form. INTRODUCTIONPolydnaviruses represent a unique type of virus which is found only in parasitic wasps of the families Ichneumonidae and Braconidae; accordingly they are classified as ichnoviruses and bracoviruses (Webb et al., 2000). These viruses are formed in the calyx cells of the wasp's ovary and are injected along with the eggs into the host insects, mostly lepidopteran larvae or eggs (Webb, 1998). Polydnaviruses do not replicate in the lepidopteran host but are essential for survival of the wasp larva within the host; they play an important role in abrogation of the host's immune reaction (Schmidt et al., 2001) and in various aspects of host regulation (Lawrence & Lanzrein, 1993). We are working with the egg-larval parasitoid Chelonus inanitus (Braconidae) and its natural host Spodoptera littoralis (Noctuidae). In this system the bracovirus prevents encapsulation of the parasitoid larva (Stettler et al., 1998), affects feeding and nutritional physiology of the last instar host (Kaeslin et al., 2005) and induces a developmental arrest of the host in the prepupal stage (Soller & Lanzrein, 1996) by interference with the ecdysteroid system (Grossniklaus-Bürgin et al., 1998). Ichnoviruses and bracoviruses have different evolutionary origins (Whitfield & Asgari, 2003). The bracovirus-braconid association arose approximately 74 million years ago in a monophyletic lineage (microgastroid braconids) that consists of over 17 000 species (Whitfield, 2002); much less ...

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“…Deux principaux groupes de virus à ADN multiples phylogénétiquement et morphologiquement distincts, les Ichnoviridae et les Bracoviridae, ont été caractérisés (Fleming 1992 ;Shelby & Webb 1999 ;Federici & Bigot 2003). L'expression des gènes de ces virus se fait durant leur cycle de réplication, exclusivement réalisé dans les cellules du calice des femelles parasitoïdes, ou dans certains tissus hôtes tels que les hémocytes (Fleming & Summers 1991 ;Strand et al 1992 ;Harwood et al 1994 ;Volkoff et al 1995 ;Cui & Webb 1996 ;Gruber et al 1996 ;Yamanaka et al 1996, Cui et al 1997Stoltz & Makkay 2000 ;Trudeau et al 2000 ;Pasquier-Barre et al 2002).…”

Section: Ii2 Immunosuppression Totaleunclassified

Interactions Hyménoptères parasitoïdes – systèmes immunitaires hôtes: Les mécanismes «actifs» et «passifs» redéfinis

Moreau

2003

Annales de la Société entomologique de France (N.S.)

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The replication of Hyposoter didymator polydnavirus: Cytopathology of the calyx cells in the parasitoid

Cited by 53 publications

References 35 publications

Genomic and Morphological Features of a Banchine Polydnavirus: Comparison with Bracoviruses and Ichnoviruses

Genomic and Morphological Features of a Banchine Polydnavirus: Comparison with Bracoviruses and Ichnoviruses

Genome organization of the Chelonus inanitus polydnavirus: excision sites, spacers and abundance of proviral and excised segments

Interactions Hyménoptères parasitoïdes – systèmes immunitaires hôtes: Les mécanismes «actifs» et «passifs» redéfinis

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