Strategies to increase DNA vaccines resistance to nucleases

The past several years have witnessed an increase in the number of reports tackling the use of plasmid DNA for gene therapy and vaccines. These are used as vectors, for the introduction of genes into the host cells, allowing this immunisation strategy to be more rapid, simple and to be able to obtain immune responses against native protein antigens with complex structures and skills to obtain both humoral and cellular immune responses without the need for live vectors or complex biochemical techniques. N owadays, due to intense R&D, three veterinary DNA vaccines have reached the market. Nonetheless, the accessibility and specific characteristics of the vaccine target may impose barriers along e.g. trafficking and nuclear delivery pathway of the immunogeni c and/or therapeutic genes. Furthermore, the upgrading of antigen presentation into the immune system is equally considered to be fundamental in the development of DNA vaccines, since the localization of the expressed protein can significantly influence t he efficacy of DNA vaccines. In order to achieve the protective and therapeutic level for the necessary vaccination efficacy, improved delivery platforms are necessary. These include improvement of the immunological properties of the vector itself (by ad ding antigen-targeting sequences for lysosomes (Lamp), extracellular space (Sc) or endoplasmic reticulum (e1A) or by modification of the polyA signal and origin of replication in order to increase pDNA resistance to nucleases. At Nofima, inhibitors of ma mmalian DNases will be sought in selected (sub) Artic marine invertebrates and fish species. Moreover, strategies to extract the desired compounds must be settled as well as the establishment of robust and specific screening assays of bioactivities. In th e end, these combined strategies, as the combined administration of DNA with these molecules, are also sought to increase transfection and expression efficiencies.