Can a bacteria carry a virus?

Hi everyone,

I know that bacterial cells can be infected and killed by viruses. I also recently learned that many bacteria carry viral DNA within them that has been incorporated from viruses that attacked them in the past.

What I'm wondering is, is it possible for bacteria to be "carriers" for viruses the way multicellular organisms can be? Could a bacteria, in infecting a host, inadvertently release the virus into that host's system?

This isn't in regard to the flu virus or any particular known virus. It's just a hypothetical question. Have there been any known incidence of bacterial infection spreading a virus from host to host, or is it theoretically possible?

On a related note, is it possible for bacteria to substantially alter their hosts' DNA? I know some theories of cancer have microbes (not viruses) invading cells and causing DNA disruption, but I don't know how common or widely accepted that theory is.

Any input on the subject would be appreciated. Thanks so much!