"Retroviruses are like a speedboat full of grinning Somali pirates who go careering hundreds of miles into the Atlantic to take over passing supertankers, by randomly firing off their ancient AK-47's at anybody on board. When they succeed, they get great big ransom payments from Lloyds of London. Everybody's happy, and the pirates go back to Mogadishu and make a lot of little baby pirates."
This may be a stretch, but a retrovirus is like a prankster who breaks into your house, turns on your computer, inserts a thumb drive with a picture of itself and then uses the computer to produce multiple copies of that picture.
METAMIA is a free database of analogy and metaphor. Anyone can contribute or search. The subject matter can be anything. Science is popular, but poetry is encouraged. The goal is to integrate our fluid muses with the stark literalism of a relational database. Metamia is like a girdle for your muses, a cognitive girdle.