Improving the immunogenicity of DNA vaccines: A nano-sized task?

A major biotechnological revolution of the last two decades has resulted in the novel application of DNA as a vaccine to prevent or treat disease. This has progressed from principle to product in only 20 years. However, the wider application of DNA vaccines is reliant on improving their immunogenicity, as while DNA vaccination can provide a broad inunune response to an antigen, the magnitude is often less than optimal. This has led to many studies into improving the immunogenicity by using different delivery methods, targeting to specific cells in the host and by co-delivery with potent immune stimulators. Here we will review the different methodologies used to improve the immunogenicity of DNA vaccines, designed to maximise irnmunogenicity without changing the fundamental simplicity and usability of this type of vaccine. The most recent innovations, of delivery using nanoparticles, are also highlighted.