Canadian Forest Service Publications
Genomics and replication of polydnaviruses. 2012. Dupuy, C.; Gundersen-Rindal, D.; Cusson, M. Chapter 4, pp. 47-61, in N.E. Beckage and J.-M. Drezen, eds. Parasitoid Viruses: Symbionts and Pathogens, Academic Press, London.
Issued by: Laurentian Forestry Centre
Catalog ID: 33023
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Most large DNA viruses have a pathogenic association with their hosts, with symbiosis being a rare exception. A striking example of the latter, however, is found among DNA viruses of the family Polydnaviridae (PDV), which have evolved a complex association with wasps that live as endoparasitoids of lepidopteran larvae. PDVs replicate asymptomatically in their wasp hosts but infect and cause severe disease in parasitized caterpillars. The two recognized PDV taxa, ichnoviruses (IVs) and bracoviruses (BVs), are associated with endoparasitic wasps of the families Ichneumonidae and Braconidae, respectively, and have distinct ancestors. Here, we survey the available data on the genome sequence and gene content of members of these two taxa. A comparison of the two groups shows that, despite their distinct origins, IV and BV genomes display similar organizational features. However, they share relatively few genes, which have diversified into multigene families in both taxa. We also review what is known about mechanisms of PDV replication in the wasp host. These viruses constitute a versatile, replication-defective system for delivery of virulence genes to parasitized host insects.