[DNA vaccines]

DNA vaccination is a new vaccine approach used to induce an immune response to an antigen protein expressed in vivo. It is based on the introduction, via intramuscular injections, particle bombardment, or nasal spray, of a purified DNA plasmid encoding for the polypeptide sequence. The resulting in situ protein synthesis involves biosynthetic processing and post-translational modifications. The effectiveness of DNA vaccines has been demonstrated in many animal models. Cell-mediated immunity (Th1 and Th2 responses) and humoral immunity can be obtained. B-cell production of antibodies is generally weaker than induced by traditional vaccines. Various approaches to boost the immune response have been studied, including co-administration of cytokines, co-stimulation with specific genes, and addition of targeting molecules. Research with animal models has shown that DNA vaccines are safe. Deleterious immune responses, such as autoimmunity and development of tolerance in response to persistent expression of a foreign antigen, have not been observed. Phase I and Phase II clinical trials with DNA vaccines have been conducted for HIV, HBV, HVC, HSV, tuberculosis, and malaria. Clinical trials are also in hand for cancer and the treatment of allergies. This new approach of DNA vaccination offers new hope because of their low cost and manufacturing stability at ambient temperature.