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DNA immunization was discovered in early s and its use has been expanded from vaccine studies to a broader range of biomedical research, such as the generation of high quality polyclonal and monoclonal antibodies as research reagents. In this unit, three common DNA immunization methods are described: needle injection, electroporation and gene gun. In addition, several common considerations related to DNA immunization are discussed.
DNA vaccination was discovered in the early s when it was demonstrated that direct inoculation of antigen-expressing DNA plasmids could induce humoral and cellular immune responses in a mammalian host against the protein antigens expressed from the inoculating plasmids Fynan et al. This discovery was a major breakthrough in the history of vaccines. For the first time, a gene segment encoding a particular protein antigen, instead of the antigen itself, was delivered to elicit antigen-specific immune responses.
In the last twenty years since these initial reports, great progress has been made on DNA immunization techniques, including optimized vector design, better selection, and engineering of antigen gene inserts, and improved DNA plasmid delivery approaches. As part of DNA vaccines, newly produced antigens undergo additional post-translational processing as part of trafficking within eukaryotic cells, which is similar to what occurs with live attenuated vaccines; however, DNA vaccines are safer as they are without concern of infection by the pathogen that is used to make traditional vaccines.
Antigens produced by DNA vaccines usually maintain their conformation due to the fact that they do not go through in vitro protein production and purification. In addition, since DNA vaccine plasmids can be easily produced and the DNA immunization process is relatively simple, DNA vaccines can be used for quick and large scale screening to determine immunogenicity of novel antigens.
