system
Given the following post, respond as if you're commenting on Reddit:
human
Under what conditions does a virus "die"?

Viruses (bacteriophages specifically) are energetically neutral. Given that they can effectively just float around until they encounter a host cell, do they deteriorate after a while? What determines how or when they are destroyed?
gpt
A virus is inactivated when one or more of several things happen. The structure of the virion can be damaged to the point where it can no longer contain its genetic material, for example, the lipid envelope of the influenza virus can be disrupted by detergents. The binding proteins on the surface can be damaged, or otherwise permanently prevented from the ability to bind to their receptor on the target cell. Also, the genetic material itself can be damaged to the point of being nonfunctional, like with UV radiation. 

A virus lacks the ability to repair or replace components of itself once it has left the host, so any damage to the binding ability or reproductive ability renders it effectively dead.