A DNA vaccine consists of a suitable gene encoding an antigenic protein, inserted into a plasmid, and then incorporated into the cells in a target animal. The plasmid vaccine carrying the DNA (gene) enters the nucleus of target cells and produces RNA, and in turn the specific antigenic protein, because these proteins are recognized as foreign. When they are processed by the host cells and displayed on their surface, the immune system is alerted, which then triggers a range of immune responses.