After more than 15 years of experimentation,
DNA vaccines have become a promising perspective for tumour diseases, and animal models are widely used to study the
biological features of human
cancer progression and to test the efficacy of vaccination protocols. In recent years, immunisation with naked plasmid
DNA encoding tumour-associated
antigens or tumour-specific
antigens has revealed a number of advantages:
antigen-specific
DNA vaccination stimulates both cellular and humoral immune responses; multiple or multi-gene vectors encoding several
antigens/determinants and immune-modulatory molecules can be delivered as single administration;
DNA vaccination does not induce
autoimmune disease in normal animals;
DNA vaccines based on plasmid vectors can be produced and tested rapidly and economically. However,
DNA vaccines have shown low immunogenicity when tested in human clinical trials, and compared with traditional
vaccines, they induce weak immune responses. Therefore, the improvement of
vaccine efficacy has become a critical goal in the development of effective
DNA vaccination protocols for anti-tumour
therapy. Several strategies are taken into account for improving the
DNA vaccination efficacy, such as
antigen optimisation, use of adjuvants and delivery systems like electroporation, co-expression of
cytokines and co-stimulatory molecules in the same vector, different vaccination protocols. In this review we discuss how the combination of these approaches may contribute to the development of more effective
DNA vaccination protocols for the
therapy of
lymphoma in a mouse model.