> so it could never be brought back to life in an environment where nothing is already alive

I always thought of a virus as purely a "modifier", not having the characteristics of "life" independently. If this was a game, the virus might be a runestone or skin for your character.

Anything that doesn't need external "life" to come alive, I would consider as "life" in various states. Maybe it's in hibernation, or stasis, or dormant but the life is there. Maybe to keep the silly game analogy, this might be the extra character on your roster.