Cool story about a common virus that seems to target cancerous cells. The virus exists in a large majority of the population with no pathological effects. Theory goes that it is far better for a body to harmless with respect to its host. The whole bite-the-hand-that-feeds just doesn't work in the long term.
The mechanism for the virus is that it needs other viruses to carry it into cells. The story says that it kills cancer cells, but it seems that the actual mechanism is that it prevents viruses that cause cancer from gaining a foothold. I would think what happens is that AAV-2 hijacks the hijacker, and AAV-2 replicates itself while preventing the other virus from doing so. The rate of intruder propogation and virus load would be lower than it otherwise would be. If I am right, this is a symbiotic relationship that would be worth general innoculation beyond viral therapy.
I always appreciate feedback in the case that I am mistaken about any particulars.