“Textbooks define viruses as infectious agents with nucleic acid genomes (RNA or DNA), which replicate inside living host cells to produce particles (virions) that can transfer the genome to other cells , . The Polydnaviridae was recognized as a family of viruses in 1995, and is currently divided into two genera named the Bracovirus and Ichnovirus . Polydnavirus (PDV) virions consist of enveloped nucleocapsids and package multiple circular, double-stranded (ds) DNAs with aggregate sizes that range from 190 to more than 500 kbp . PDVs are also strictly associated with insects called parasitoid wasps (Hymenoptera), which are free living nectar feeders as adults but which develop during their immature stages by feeding inside the body of another insect (the host) , . Recent studies, however, indicate that PDVs differ from all other known viruses in ways that challenge traditional views of what viruses are and how they function.”
Great review on a group of viruses that has fascinated me since I first heard of them – mainly because there seemed to be no end to the discovery of new bits of genome, and no-one could ever seem to clone a whole one.
I especially like this quote:
“The novelty is that BVs today are obligate beneficial symbionts, which persist entirely from a proviral genome yet produce virions that efficiently deliver genes to other organisms wasps depend upon for survival. Are PDVs still viruses? If we can accept that viruses are not always obligate intracellular parasites, we would suggest the answer is yes.”
See on www.plospathogens.org