Integrated Glyptapanteles braconid polydnavirus genomes

Certain parasitoid wasps possess obligate endosymbiont polydnaviruses (PDVs) essential for their successful parasitization of lepidopteran larvae. In such braconid parasitoids, variable sized circular dsDNA segments are encapsidated into infectious particles in a process dependent upon the linear provirus form of the virus integrated chromosomally within the wasp. Once formed, PDV particles are injected into larval hosts during oviposition where virus-associated immunosuppression and other negative effects within the host ensure survival of the parasitoid and, thus, survival of the integrated provirus form. Recent analyses of Glyptapanteles (Braconidae, Hymenoptera) parasitoid species (parasites of larval Lymantria dispar gypsy moths) have characterized genome sequences for both encapsidated PDV and chromosomally integrated provirus forms. Encapsidated Glyptapanteles PDV genomes encode numerous genes conserved among braconid PDVs, as well as unique genes. The encapsidated PDVs lack genes for most structural proteins, which were shown recently by Bezier et al (Science 323: 926 – 930; 2009) for braconid PDVs to be encoded within the wasp genetic material and no longer packaged into the PDV particles. Integrated proviral segments are organized as multiple loci containing viral segments that are separated from each other by flanking parasitoid gene-encoding chromosomal DNA and share structural and organizational features.