In virotherapy does the virus reproduce in the body or no? also if a virus has proteins to bind only to certain recepteors how does it bind to cancer?

See below: Viruses may be used in certain types of experimental therapy- using ocolytic viruses; the strategy involves transfer of some dna material that is incorporated into the tumor genetic make up thereby causing changes in the tumor leading to killing the tumor cells; there are various strategies for viral entry and beyond the scope of this 400 word discussion;.