DNA vaccines

Humoral and cellular immune responses to protein antigens can be efficiently primed by nucleic acid or DNA vaccination. In DNA-based vaccination, immunogenic proteins are expressed with correct posttranslational modification, conformation or oligomerization; this ensures the integrity of epitopes that stimulate neutralizing antibody (B cell) responses. DNA (or RNA) immunization is exceptionally potent in stimulating T cell responses because antigenic peptides are efficiently generated in (endogenous or exogenous) processing pathways (without interference by viral proteins) from intracellular or extracellular protein antigens expressed after transient in vivo transfection. Both features are difficult to achieve with recombinant subunit vaccines produced in eukaryotic or prokaryotic expression systems. The current state of vector designs, strategies for delivery of DNA vaccines, priming humoral and cellular immune responses by DNA vaccines, experimental strategies facilitated by DNA vaccines, unique advantages of DNA vaccination, experience of DNA vaccination in preclinical animal models and clinical trials, and potential risks of DNA vaccination are discussed. Excellent reviews on DNA-based vaccination have been published recently [1-3].