DNA vaccine: Mechanism of action and factors which increase its efficacy

DNA vaccine is a new promising vaccine type which has many advantages among various conventional vaccines. DNA vaccine could induce the cellular immune response beside the humoral immune response. This vaccine is more stable in production, storage and distribution, which makes it as a cheaper vaccine. Although it has many added values, so far there is no FDA accepted human vaccine. There are some hindering factors that affect the efficacy of the DNA vaccine, such as immunogenicity, delivery system, administration route, and adjuvant choices. This review aims to describe the DNA vaccine mechanism of action and several factors that have important roles to increase the DNA vaccine efficacy. By optimizing these factors, an effective DNA vaccine could be developed.