Title: Genomics and Replication of Polydnaviruses Authors
Submitted to: Parasitoid Viruses: Symbionts and Pathogens
Publication Type: Book / Chapter
Publication Acceptance Date: July 15, 2011
Publication Date: January 1, 2012
Citation: Dupuy, C., Gundersen, D.E., Cusson, M. 2012. Genomics and Replication of Polydnaviruses. In: Beckage, N.E., Drezen, J.M., editors. Parasitoid Viruses: Symbionts and Pathogens. London, England: Elsevier. p. 47-61. Technical Abstract: 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, ichnovirus (IV) and bracovirus (BV), 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.