Enhanced efficacy of DNA vaccines against an intracellular bacterial pathogen by genetic adjuvants

After 200 years of practice, vaccinology has proved to be very effective in preventing infectious diseases. However, several human and animal pathogens exist for which vaccines need to be improved or simply have not yet been discovered. The era of molecular genetic has given a new breath for vaccine development with the achievement of the "Third Generation of Vaccines": the DNA vaccine. In this article, we reviewed strategies that have been used to improve and modulate the immune response induced by DNA vaccines, using as a model the intracellular bacterial pathogen Brucella abortus. First, we described different approaches used to isolate and to identify genes that encode potential immunogens. Secondly, we reported the use of cytokine genes and genetic adjuvants that could improve the immunogenicity of target genes. And finally, we discussed the "Expression Library Immunization"-(ELI) strategy and the recent results obtained against Brucella abortus infection.