According to Central Intelligence and Spying Stuff of the Idaho Legion (CISSofIL) the personnel staffing the Intergalactic Dreadnoughts and Ships of the Line of the Galactic Overlord ARE viruses (or, for language purists, virii). Their motto is "If Not Us, Who?." There are no "variants" and all of them do what they are trained to do. Any "variants" are thrown into a spleen full of lymphocytes and phagocytes.