If you accept viruses as "life", do you accept prions?

When discussing reality, instead of fiction, we can get by with a fairly arbitrary choice between considering only cellular life as living, and also including viruses. At least, until we start getting data back from interstellar probes about alien worlds. But I think we are a few centuries away from that. Maybe, if we are very lucky (or very unlucky), we will detect life-like phenomena in the subsurface ocean of one of the moons of the outer planets.

In the meantime, we can come up with various definitions with all of the flaws of defining humans as "featherless bipeds".