Real and Apparent Complexity in Polydnavirus Genomes

  • Webb, Bruce (PI)

Grants and Contracts Details


This research will elucidate the role of polydnavirus (PDV) genome structure in generating viral gene variants. PDV genome structure appears to promote variability within viral gene families, facilitate alteration of the level to which genes are expressed and allow for acquisition of novel genes. Evidence in support of this hypothesis the: 1) identification of functionally significant variants in PDV genomes, 2) conservation of PDV genome and segment structure and 3) functional specialization among segment types. The preliminary data suggest that regulation of gene expression by changing copy number in ichnoviruses is but one part of a larger PDV organizational paradigm. These data support the more general hypothesize that PDV genome segmentation not only influences gene expression levels but also facilitates production of gene variants and acquisition of novel genes from the host genome. This hypothesis is tested under three research objectives intended to: 1) determine if Campoletis sonorensis ichnovirus (CsIV) genetic variation impacts virus function and parasite host range, 2) To determine if the structural organization of CsIV is representative of other ichnoviruses, 3) To determine if integration-competent segments support gene entry into viral genomes. Polydnaviruses must suppress host immunity and alter other host physiological systems in support of parasite development for the virus to be vertically transmitted. A parisite's ability to counter evolving host resistance mechanisms may require continual production of functional variants that enable continued host exploitation or invasion of new host species. In wasp parasites, where host and parasite life cycles are synchronized, PDVs may provide a highly mutable genome co-opted by the parasite to allow continual production of immunosuppressive gene variants that confer a sustainable evolutionary advantage. In a broader context, this work will elucidate some of the critical contributions of captive genomes to the evolution of highly variable traits in eukaryotic organisms. Transposable elements, retroviral and non-coding sequence comprise over 90% of the DNA in humans and other organisms but this type of DNA is often described as junk DNA because its functional role is not clearly understood. This research may also elucidate the role of viral and non-coding sequences in the evolution of biologically relevant traits in polydnaviruses and thereby contribute to a better understanding of these apparently non-essential sequences in other organisms.
Effective start/end date2/1/011/31/05


Explore the research topics touched on by this project. These labels are generated based on the underlying awards/grants. Together they form a unique fingerprint.