Where did viruses come from, according to Young Earth Creationists?

Viruses are quite nasty germs. Whereas bacteria serve many useful purposes and we need them, I wonder what the purpose of viruses in God's creation could be. Does Young Earth Creationism address what role viruses have in the world? I'd like to hear the YEC view on the following points: 1. Where did viruses come from? 2. What is their purpose? 3. Were viruses created? If so, by whom? 4. Does the Bible say anything applicable? If the Old Earth Creationist view is significantly different, please notify me. I expect them to be similar, but might ask another question focused on OEC if relevant.