Viruses are a special little topic indeed. Here we are talking about life in one of its most bizarre, misunderstood and disturbing expressions. Viruses are the stuff of horror movies.
They are tiny microscopic entities that have absolutely no activity whatsoever. In the presence of a larger organism of their specific fit (and there are viruses to target anything), they come alive by hijacking its life tools: nutrients, energy, ribosomes, you name it.
They only carry the genetic information they need to invade and replicate. Invade and replicate. A bit of a glitch of life, or the perfect expression of it?