Abstract
Vaccination has led to the eradication of those diseases which had once claimed millions of lives worldwide; however, it is accompanied with a number of dis-advantages especially safety issues until the entry of DNA vaccines. The DNA vaccines have been emerged as the best remedy for problematic diseases being capable of producing humoral and cellular immune responses as well as the safest vaccines so far. However, the magnitude of immune responses produced in primates is lower than that in experimental animals. There are several reasons described theoretically for this limited efficacy and a number of novel approaches have been applied to boost their immune responses, e.g., use of more efficient promoters and coding optimization, addition of traditional or genetic adjuvants, electroporation, intradermal delivery and various prime-boost strategies. One of these strategies is controlled antigen administration of plasmid DNA through microspheres and nanoparticles. This approach is accompanied with a number of advantages to overcome the limitations of traditional delivery systems in terms of stability, solubility and pharmacology. Furthermore, the surface structure of a virus highly resembles with a nanoparticle because of their geometrical regularities and nanoscale dimensions; therefore, the engineering of nanoparticles is based upon principles of natural virus attack which will be the best tool for vaccination. There is evidence that these immune responses can be augmented by properly structured nanosized particles (nanoparticles) that may avoid DNA degradation and facilitate targeted delivery to antigen presenting cells. Adsorption, formulation or encapsulation with particles has been found to stabilize DNA formulations. The use of nanoparticles for DNA vaccine delivery is a platform technology and has been applied for delivery of a variety of existing and potential vaccines successfully.