What is the main role of a virus in relation to a host?

The main role of a virus in relation to a host is to use the host as a home and food source. Viruses are non-living entities that require a host cell to replicate and propagate. When a virus infects a host, it enters the host's cells and commandeers the cellular machinery to produce more copies of itself. In doing so, the virus utilizes the resources of the host, such as its proteins and nucleotides, essentially feeding off the host’s cellular activities to sustain its own life cycle.

This relationship drastically alters the normal function of the host cells, often leading to cell damage or death in the process. Unlike repair, protection, or curing functions, the primary interaction is one of exploitation, where the virus leverages the host's biological systems for its reproduction and survival.