Tobacco mosaic virus is used to deliver genetic information to plants. I believe that the genetic information is in the form of a plasmid.
Ouch, viruses do not carry plasmids. You are confusing it with Agrobacterium tumefacies, an alpha-proteobacterium and its Ti-plasmid.
A virus itself is a vector. Certain areas of the viral (RNA-)genome can be replaced with other sequences with a variety of function. This may include, but not be limited to fluorescent proteins for visualization and tagging or to use it as siRNA to shut down protein expression.
