Originally Posted by
roger wiegand
The question of "are viruses alive?" is an interesting philosophical one. Here's the dictionary definition of life: the condition that distinguishes animals and plants from inorganic matter, including the capacity for growth, reproduction, functional activity, and continual change preceding death. Viruses are a little borderline on some of those criteria, they replicate in a very host-dependent fashion, I don't know that they change much during their existence, they certainly reproduce. A functional virus like MS2 can get by with only four genes, so not much there to work with, but much closer to "alive" than, say prions, which you can't really effectively kill without complete destruction of the molecule. Viroids are a whole other question, only a couple hundred bases long.
I use a very pragmatic definition of life, to wit, if I can kill it, it was alive. It's pretty easy to render a virus unable to infect and replicate (a dash of Lysol, or a bit of heat will do it), so I'd give them the benefit of the doubt and say they were alive. Something like a viroid or prion, just a bit of infectious RNA or protein that gums up the works, I would say no.