DNA immunization as an efficient strategy for vaccination.

The field of vaccinology provides excellent promises to control different infectious and non-infectious diseases. Genetic immunization as a new tool in this area by using naked DNA has been shown to induce humoral as well as cellular immune responses with high efficiency. This demonstrates the enormous potential of this strategy for vaccination purposes. DNA vaccines have been widely used to develop vaccines against various pathogens as well as cancer, autoimmune diseases and allergy. However, despite their successful application in many pre-clinical disease models, their potency in human clinical trials has been insufficient to provide protective immunity. Several strategies have been applied to increase the potency of DNA vaccine. Among these strategies, the linkage of antigens to Heat Shock Proteins (HSPs) and the utilization of different delivery systems have been demonstrated as efficient approaches for increasing the potency of DNA vaccines. The uptake of DNA plasmids by cells upon injection is inefficient. Two basic delivery approaches including physical delivery to achieve higher levels of antigen production and formulation with microparticles to target Antigen-Presenting Cells (APCs) are effective in animal models. Alternatively, different regimens called prime-boost vaccination are also effective. In this regimen, naked DNA is utilized to prime the immune system and either recombinant viral vector or purified recombinant protein with proper adjuvant is used for boosting. In this review, we discuss recent advances in upgrading the efficiency of DNA vaccination in animal models.