The idea that viruses are self-contained entities separate from the organisms they infect is an artifact of the human mind's power-saving system of modelling the world in terms of functional-decomposition. Viruses are non-living extraorganism messages crucial as a source of novelty in evolution. Nevertheless, it would be nice to find cures for them.
The 'inividualistic' feature of viruses is their genome, which is what gets replicated when they take over a cell, and which is subject to evolution itself, not just an agent in the evolution of 'true' organisms.