A delivery method that comprises bringing a composition comprising (a) a plurality of intact killed S. typhimurium cells that contain an agent selected from the group consisting of a functional nucleic acid, a therapeutic nucleic acid and a drug and (b) a ligand that carries specificity for a non-phagocytic mammalian cell surface receptor that activates receptor-mediated endocytosis into contact with endocytosis-competent mammalian cells, such that said intact killed S. typhimurium cells are endocytosed by said mammalian cells via receptor-mediated endocytosis, thereby delivering said agent to said mammalian cells.