Seminar

Lessons learned from using DNA vaccines

Dr. Fernando Rodriguez

Despite the dramatic advancement of vaccine technology in the last decades, few recombinant vaccines are currently available on the market. Most of the vaccines used today are still produced by classical procedures such as those based on inactivation or attenuation of the given pathogen, with all the disadvantages associated to these technologies, including failures on the inactivation or reversion to virulence. Recombinant technology is knocking at the door to fight against both animal and human diseases. The time has arrived to put them on the market.

One of the most novel and promising vaccine technologies are those based on nucleic acids. To illustrate some of these possibilities, we will show some results obtained in our lab while trying to develop DNA vaccines against several pathogens (mainly viruses), relevant for Animal Health.

 One of the main criticisms to DNA vaccines is the low immunogenicity they seem to induce, overall in large animals, including humans. Here we demonstrate that similar as it has been demonstrated for mice, the immune responses induced upon DNA immunization of pigs, can be exponentially improved by using diverse strategies. On one hand, T-cell responses can be exponentially improved after DNA immunization by targeting the encoded antigens to specific intracellular pathways. On the other hand, both humoral (antibodies) and cellular responses could be improved by targeting the vaccine antigens to the professional antigen presenting cells (APCs).

Apart from the practical lessons learned from these experiments, DNA vaccination has been very useful to carefully dissect some of the intrinsic mechanisms involved in protection and has allowed us to confirm that for each pathogen and animal host, there is one optimal vaccine approach to be followed. There is not a universal answer to fight against pathogens but at least there are partial answers.