DNA vaccination.

Few advances in the history of vaccination have had as quick a passage (approximately 10 years) from their discovery to clinical trials and, hopefully soon, registration as DNA immunisation. A very clear picture has now emerged of the recognition of the CpG-motif rich, chimaeric bacterial DNA by dendritic cells (antigen-presenting cells [APCs]) and the subsequent activation of T lymphocytes. Both humoral and comprehensive cell-mediated responses occur in both mice and primates. No significant safety concerns have been observed following administration to several hundred human volunteers, including some children. Of special interest is the generation of strong and high avidity CD8+ cytotoxic T lymphocyte (CTL) responses in primates, following priming with chimaeric DNA and subsequent boosting with a chimaeric live viral vector, such as an attenuated poxvirus or adenovirus. The DNA may also be used as a highly potent adjuvant, inducing mainly T helper (Th)1 responses. Advantages include its potential use in the presence of antibody to the targeted infectious agent and a generally simple manufacturing process.