This application provides a method to form non-infectious Biological Carrier that may be used to deliver signals to cells either in vitro or in vivo. The Biological Carriers are inactivated virus particles that have been specifically modified to give biological properties different from the virus particles deriving from an unmodified host cell that (i) expresses at least one co-stimulatory molecule and (iia) at least one antigen that can initiate an immune response, and/or (iib) express surface molecules that suppress viral replication.