In vitro assay of immunostimulatory activities of plasmid vectors

DNA vaccination represents a powerful new approach for the elicitation of long-lived protective immunity against a broad range of protein antigens (1,2). In this approach, the vaccine is a plasmid DNA vector that encodes a foreign protein to be targeted for the induction of humoral or cellular responses. Following administration by various routes, the plasmid is taken up by cells to allow intracellular production of the protein for presentation to the immune system. Although the trafficking of the plasmid and its protein product is not well understood, the generation of responses ultimately involves a bone marrow-derived antigen presenting cell (3).