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

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

Apart from TB vaccine, there are studies that reported the use of liposome to deliver influenza DNA vaccine [177, 178] . Cationic liposomes DODAC/DOPE/PEG (1,2-dioleoyl-sn-glycero-3- phosphoethanolmine/dioleylphosphatidylethanolamine/polyethylene glycol) were used to encapsulate plasmid DNA encoding influenza virus HA. After intranasal immunization in mice, the liposome system was effective at eliciting both IgG and IgA humoral responses systemically. Local IgA level was enhanced. Cell-mediated immune response was also successfully induced. In addition, the immunized mice were able to withstand a lethal challenge of influenza virus. On the other hand, intramuscular immunization of the same system enhanced IgG level only with no effect on IgA level either locally or systemically. Intranasal administration of naked DNA failed to induce antibody response. The promising results demonstrated the potential of the intranasal liposomal DNA vaccine system. To improve the DNA vaccine delivery efficiency of liposomes for intranasal administration, Khatri et al. modified the surface of liposomes by coating with glycol chitosan [173] . The major function of glycol chitosan is to provide mucoadhesive and immune stimulating property [179] . In the study, cationic liposomes, PC/DOPE/Chol (Phosphatidylcholine/dioleylphosphatidylethanolamine/cholesterol) were used to entrap plasmid encoding the S region of hepatitis B antigen, and the glycol chitosan was adsorbed on the liposome surfaces through electrostatic interaction and hydrogen bonding. Following intranasal administration in mice, the surface modified liposomes could elicit both humoral mucosal and cell-mediated immune responses which were better than the uncoated liposomes. Such system has the potential to be exploited for intranasal DNA vaccine of respiratory infectious diseases.