@indigomoth - That's not quite right. A cloning vector isn't deactivated. You're thinking of another kind of cloning, where they insert DNA into an empty host cell with the intention of growing an embryo, I think.
I think the purpose of a cloning vector is to provide a space in a DNA sequence that is able to invade a cell and replicate, but not much else, so that you can stick whatever DNA you like in there and have it replicated.
So, you modify bacteria DNA, for example, to accept the bit of DNA you want copied, then insert the whole thing into a cell. The bacteria just gets on with copying itself like usual, except now it is copying your DNA along with it.
In fact, I think people should be more worried about the fact that antibiotic resistance is considered desirable for a cloning vector. That seems like a recipe for disaster if you happen to have one careless scientist...