Its not so hard to get your head around endogenous retroviruses once you get the gist of them. RNA virus turns itself into DNA, inserts itself into your genome, makes babby viruses. Sometimes the RNA virus infects an egg/sperm, turns itself into DNA, inserts itself into the genome, and that egg/sperm goes on to create an organism that has the retrovirus permanently integrated into every cell of said organism.
But, generally, the viruses we find in an organisms genome are the kinds of viruses that infect that organism. We dont find insect viruses in people or people viruses in plants or plant viruses in insects…
Because many plant viruses are transmitted by insect vectors – although often without active replication – it is also theoretically possible that plant viruses may also be integrated into insect genomes, and vice versa.
I love this! “Are there any plant viruses in insect DNA?” Its a weird, interesting question, but I wouldnt have really bothered investigating it. Like they said, its theoretically maybe possible, but it seems like the event would be so rare and so off the wall, it would hardly seem worth the effort to seriously investigate it.
I should take my own advice: “When youre dealing with a 4.2 billion year time-frame, random, low probability accidents happen all the time.” There are endogenous viral elements, or EVEs, from plant viruses in the genomes of a multitude of insects:
This BLAST protocol revealed that the genomes of mosquito (Aedes aegypti), fruit flies (Drosophila rhopaloa, D. ananassae, and D. ficusphila), bees (Bombus terrestris, B. impatiens, and Megachile rotundata), ant (Pogonomyrmex barbatus), silkworm (Bombyx mori), pea aphid (Acyrthosiphon pisum), Monarch butterfly (Danaus plexippus), and wasps (Nasonia vitripennis, N. longicornis, and N. giraulti) contain EVEs that exhibit the closest relationship to plant viruses (protein sequence similarities of 50%-22%; e-values 0.81-2e− 39; Table S1)
And even better– This group of scientists doesnt overstate what they found (plant viruses in insects… OMG GMO GENES FROM CORN IN MOSQUITOES GIVING KIDS AUTISM!!!!). They point out a good alternative explanation in their discussion: There is still the possibility that while the EVEs in these insects *look* like they are related to plant viruses, they might actually belong to a family of not-yet-characterized insect viruses. We generally only find viruses we are looking for, and we only look for the ones that make us/our crops/our livestock sick. Good on this group of scientists for looking outside the box and finding something cool, whether they ultimately end up finding plant viruses in insects, or a new family of viruses in insects 🙂