Many bacteria have adaptive immune systems, the kind with a library of previous attackers. I was a bit surprised. I thought something that cool at least took being multi-cellular, but what do I know?
So far, they haven't found a virus which builds a library, but there's a virus which keeps a copy of part of a cholera bacteria's immune system, apparently so that it can recognize and target the immune system.
Link thanks to Diane Duane on Facebook.
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