[DNA vaccines].

Immunization with plasmid DNA is a new trend in vaccine development that could enhance the safety and efficacy of currently used vaccines. Simultaneously, it will enable preparation of new vaccines that could not be developed by existing procedures. The main methods of plasmid-DNA application are intramuscular injection and intradermal delivery into skin by a gene gun. As a protein antigen is produced inside host cells, both humoral and cell-mediated immunity are significantly activated. The dominant role is played by dendritic cells presenting an antigen. The type and intensity of immune reaction induced can be influenced by various ways. Modification of gene coding for immunization antigen, combination with genes for immunostimulatory factors, and utilization of adjuvant effect of stimulatory CpG motifs are the major methods of improvement of immunization with plasmid DNA. Immune reactions against viral, bacterial, and parasitic infectious agents were successfully stimulated in many experimental systems. Other experiments are under way utilizing DNA vaccines for treatment of malignant tumors, autoimmune diseases, and allergy. The fast progress in DNA-vaccine development resulted in continually increasing number of clinical trials.