“…DNA vaccines continue to raise considerable interest due to the ease of production and administration, genetic stability, no requirement for a cold chain, and activation of humoral, cell-mediated, and innate immunity. However, despite promising results in preclinical trials, the clinical application of traditional DNA vaccines has been limited due to various factors including low DNA uptake, low immunogenicity in humans and the need of repeated booster vaccinations with considerable quantities of DNA, as reviewed elsewhere [1, 4, 5]. Furthermore, traditional DNA vaccines are designed to express a single vaccine-relevant antigen in the tissues of vaccine recipient, essentially serving as a vector for transient expression of the subunit antigen vaccine.…”