Have you ever wondered whether the virus that gave you a nasty cold can catch one itself? It may comfort you to know that, yes, viruses can actually get sick. Even better, as karmic justice would have it, the culprits turn out to be other viruses.
Viruses can get sick in the sense that their normal function is impaired. When a virus enters a cell, it can either go dormant or start replicating right away. When replicating, the virus essentially commandeers the molecular factory of the cell to make lots of copies of itself, then breaks out of the cell to set the new copies free.
Sometimes a virus enters a cell only to find that its new temporary dwelling is already home to another dormant virus. Surprise, surprise. What follows is a battle for control of the cell that can be won by either party.