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Polydnavirus genomes reflect their dual roles as mutualists and pathogens
Bruce A Webb1, Michael R Strand, Stephanie E Dickey
1Department of Entomology, University of Kentucky, Lexington, KY 40506, USA. bawebb@pop.uky.edu
Virology
|December 29, 2005
Summary
Polydnaviruses (PDVs) are viruses with a dual life cycle, acting as symbionts in wasps and pathogens in insects. Their genomes show shared features due to their life cycle, despite different evolutionary paths.
Area of Science:
- Virology
- Genomics
- Evolutionary Biology
Background:
- Symbionts typically simplify genomes, while pathogens increase complexity.
- Some organisms act as both symbionts and pathogens, creating conflicting evolutionary pressures.
- Polydnaviruses (PDVs) are double-stranded DNA viruses with a unique life cycle involving wasps and other insects.
Purpose of the Study:
- To investigate how the dual life cycle of PDVs influences their genome evolution.
- To compare the genomes of Campoletis sonorensis ichnovirus (CsIV) and Microplitis demolitor bracovirus (MdBV) to understand shared and divergent evolutionary strategies.
Main Methods:
- Comparative genomics of CsIV and MdBV.
- Analysis of genome organization, gene content, and virulence factors.
Main Results:
- CsIV and MdBV, despite lacking a common ancestor, share genome segmentation, diversified virulence genes, and lack replication genes.
- Few genes are shared between CsIV and MdBV in their expression within parasitized hosts.
- Both viruses exhibit features reflecting their shared parasitic wasp-insect life cycle.
Conclusions:
- Shared organizational features of PDV genomes are driven by their unique life cycle.
- PDVs associated with different wasp families (ichneumonid and braconid) have evolved distinct mechanisms for pathogenesis and parasitoid survival.
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