http://www.nofc.forestry.ca/authors/read/18895 Publications by B.A. Webb en-ca 2012-01-11 14:47:44 MST 2012-01-11 14:47:44 MST webmaster@nofc.cfs.nrcan.gc.ca http://www.nofc.forestry.ca/publications?id=33022 A large number of genes encoding structural components of polydnaviruses associated with ichneumonid wasps of the subfamily Campopleginae have recently been identified (Volkoff et al., 2010). The genes involved in the production of ichnovirus particle proteins were shown to be localized in specific regions embedded in the genome of the wasp Hyposoter didymator. These specialized regions were named ‘IchnoVirus Structural Proteins Encoding Regions’ (IVSPERs). Three IVSPERs, representing over 60kb in length, were identified in the H. didymator genome. Although they are not packaged in the virus particles, the IVSPERs can be considered functionally as an integral part of the viral genome and are amplified during virus replication. Their particular genomic organization (high coding sequence density, single-exon predicted genes) suggests that IVSPERs represent fingerprints of an ancestor virus that integrated its own DNA into the genome of an ancestor wasp. The IVSPER genes constitute a set of genes specific to ichnoviruses and conserved among ichnovirus-associated wasps, as shown for the nudivirus-related genes involved in bracovirus particle production. However, their lack of similarity with genes from known pathogenic viruses suggests that ichnoviruses originated from a virus family that has yet to be described. Altogether these recent findings show that ichnoviruses and bracoviruses derive from independent evolutionary events and represent an example of convergent evolution in the use of virus particles to transfer virulence genes into the host caterpillar. Wed, 11 Jan 2012 http://www.nofc.forestry.ca/publications?id=33022 http://www.nofc.forestry.ca/publications?id=27202 During egg-laying, some endoparasitic wasps transmit a polydnavirus to their caterpillar host, causing physiological disturbances that benefit the wasp larva. Members of the two recognized polydnavirus taxa, ichnovirus (IV) and bracovirus (BV), have large, segmented, dsDNA genomes containing virulence genes expanded into families. A recent comparison of IV and BV genomes revealed taxon-specific features, but the IV database consisted primarily of the genome sequence of a single species, the Campoletis sonorensis IV (CsIV). Here we describe analyses of two additional IV genomes, the Hyposoter fugitivus IV (HfIV) and the Tranosema rostrale IV (TrIV), which we compare to the sequence previously reported for CsIV. The three IV genomes share several features including a low coding density, a strong A+T bias, similar estimated aggregate genome sizes (¡«250 kb) and the presence of nested genome segments. In addition, all three IV genomes contain members of six conserved gene families: repeat element, cysteine motif, viral innexin, viral ankyrin, N-family, and a newly defined putative family, the polar-residue-rich proteins. The three genomes, however, differ in their degree of segmentation, in within-family gene frequency and in the presence, in TrIV, of a unique gene family (TrV). These interspecific variations may reflect differences in parasite/host biology, including virus-induced pathologies in the latter. Thu, 31 May 2007 http://www.nofc.forestry.ca/publications?id=27202 http://www.nofc.forestry.ca/publications?id=22516 Tue, 22 Jul 2003 http://www.nofc.forestry.ca/publications?id=22516