The promise of nucleic acid vaccines.

Establishing the effective use of 'naked' nucleic acids as vaccines would undoubtedly be one of the most important advances in the history of vaccinology. While nucleic acids show much promise for use as vaccine vectors in experimental animals, not a single naked nucleic acid vector has been approved for use in humans. Indeed, data from human clinical trials is scant: nucleic acid vaccines have not been clearly demonstrated to have any convincing efficacy in the prevention or treatment of infectious disease or cancer. Here we illustrate possible mechanisms underlying effective nucleic acid vaccination. We focus on progress that has been made in the improvement of their function. Additionally, we identify promising new strategies and try to forecast future developments that could lead to the real success of nucleic acid vaccines in the prevention and treatment of human disease.