wiki to ma pekne strucne opisane:
Whether or not viruses should be considered as alive is controversial. They are most often considered as just replicators rather than forms of life. They have been described as "organisms at the edge of life" because they possess genes, evolve by natural selection, and replicate by creating multiple copies of themselves through self-assembly. However, viruses do not metabolize and they require a host cell to make new products. Virus self-assembly within host cells has implications for the study of the origin of life, as it may support the hypothesis that life could have started as self-assembling organic molecules.

Virus nema vlastny metabolizmus ci procesy mimo hostitelskej bunky. Jedine co dokaze je infikovat, hijacknut aparat bunky na tvorbu bielkovin a DNA, vygenerovat tak kopie svojej DNA a potrebne proteiny, ktore sa pomocou self-assembly poskladaju do virionov (virusovych castic) a uvolnia z bunky.