Polydnavirus-wasp associations: evolution, genome organization, and function.

Viruses replicate to produce virions that transfer the viral genome among hosts, while endogenous viral elements (EVEs) are DNA sequences derived from viruses that integrate into the germline of multicellular organisms and are thereafter inherited like host alleles. Viruses in the family Polydnaviridae are specifically associated with insects called parasitoid wasps and exhibit many traits associated with other viruses. Polydnavirus genomes also persist as EVEs. In this short review we discuss polydnavirus evolution, compare polydnaviruses to other known EVEs of ancient origin, and examine some of the functional similarities polydnaviruses share with phage-like gene transfer agents (GTAs) from prokaryotes.