"The authors solve a long-standing mystery, and at the same time establish a new paradigm in virology," add Stoltz and Whitfield, in a more congratulatory vein. Episodes of "horizontal" transfer of genes, wholesale borrowing of useful ones, are common among microbes, and genome researchers have long shown that animal genomes, including ours, are riddled with remnants of viral DNA that blundered their way into our genes and sometimes play useful roles, for example in the development of the placenta in pregnant women. But the wasp-virus incorporations "represent the only example, so far," say the study authors, of a creature lifting gene machinery that allows it to inject and fire off genes into another creature. The finding, they suggest, opens a new avenue for gene therapy.
More broadly, the virus finding reveals a new way for viruses and the hosts to make a living off each other, suggest Stoltz and Whitfield. The original virus doesn't seem to be around any more, but its genes live on in the belly of the wasp. "Were the (virus-like) polydnaviruses really viruses?" they ask? It all depends on how virologists define viruses, they conclude, something neglected in the most recent 1,259-page Virus Taxonomy: VIIIth Report, the bible of virology.
"The more interesting lesson here for virologists and for evolutionary biologists may be that there is now reason to start thinking about virus-host relationships in much broader terms," adds the commentary. The wasp polydnavirus-style mutual back-scratching among viruses and their victims may be more common than previously supposed. "How did this kind of relationship arise?" they ask.
In the Taming of The Shrew, the play's shrew, Katharina, instead locates the wasp's sting, "In his tongue." The sarcastic rejoinder to Shakespeare's tail suggestion may contain a hint of the answer to viruses' origin. Most likely, concludes the commentary, larval wasps long ago munching on caterpillars infected with the original virus imbibed the same infection, which made its way, eventually, into their sting.