Intranasal DNA Vaccine for Protection against Respiratory Infectious Diseases: The Delivery Perspectives

Xu, Yingying; Yuen, Pak-Wai; Lam, Jenny Ka-Wing

With the emergence of new or antimicrobial-resistant bacteria and viruses, and the ease of transmission, especially the respiratory pathogens, respiratory infections are becoming serious threats to human health. Safe and effective vaccines are important to safeguard public health. Intranasal DNA vaccination appears to be a promising non-invasive approach to provide protection against various infectious diseases. Evidence shows that intranasal DNA vaccine could elicit strong and long-lasting humoral as well as cell-mediated immune responses in many animal models. DNA vaccines are already successfully used in veterinary products for protection against infections, but their immunogenicity needs to be further enhanced to make them suitable for human use. Improving DNA delivery and formulation is one of the several strategies to enhance the immune response. Various studies have demonstrated that significant improvement of immune response that could be achieved by the employment of DNA carrier system, or to target the DNA vaccines to APCs. DNA vaccines generally have good safety profile, but the potential toxicity associated with DNA delivery systems, especially when they are used at high concentration, must not be neglected. DNA vaccines may circumvent many problems associated with conventional vaccines such as high costs of protein vaccine purification and bacterial/viral inactivated or attenuated process, the incorrect folding of antigen and viral mutation risk, thereby offering a safer alternative to benefit humans. In addition, mass manufacture of DNA vaccine is easier and faster, and DNA product is usually highly stable. Once an effective intranasal DNA vaccine delivery system is identified and optimized, a delivery technology platform could be established to allow the development of DNA vaccine formulations for different infectious diseases in the future.