DNA vaccines are third generation vaccines, made up of small, circular pieces of bacterial DNA, plasmids. These plasmids are genetically engineered to produce specific antigens from a pathogen. The DNA is injected into the cells of the body where the host cell then interprets the DNA and uses it to synthesize the pathogen’s proteins. An immune response is then triggered when the pathogen’s proteins are recognized as foreign to the immune system.DNA vaccines are effective in stimulating antibody responses to attack infectious diseases as they enter the body, before they can infect cells, therefore acting as a preventive vaccine.DNA vaccines are efficient at generating T-cell responses that may kill targeted cancerous cells or cells infected by the targeted virus or bacteria. DNA vaccines may therefore also be used as a therapeutic to treat existing disease.