Use of N-trimethyl chitosan for intranasal delivery of DNAencoding M2e-HSP70c in mice

BACKGROUND: Influenza outbreak has become a great lifethreatening disease in the world. Nasal vaccines can induce systemic IgG and mucosal IgA antibody responses, which establish two layers of immune defense against the infectious pathogens like influenza. Mucosal vaccines must overcomeseveral limitations, including the mucociliary clearance and inefficient uptake of soluble antigens. Therefore, nasal vaccines require potent adjuvants and delivery systems. OBJECTIVES: In this study we evaluated the effect of N-trimethyl chitosan (TMC) as a potent vehicle for DNA encoding M2e/HSP70c in order for intranasal administration in mice. METHODS:Ectodomain of the conserved influenza matrix protein 2 (M2e), which has been found to induce heterosubtypic immunity, was fused to HSP70359-610 or C-terminus of Mycobacterium tuberculosis HSP70 (HSP70c) in pcDNA3.1 vector (pcDNA/M2e-HSP70c)and then encapsulated into a derivative of chitosan, N-trimethyl chitosan (TMC). After encapsulation of the plasmid, physical properties of the particles were investigated using Zetasizer® 3000 the particles were then administered through the intranasal delivery in BALB/c mice. RESULTS: It was found that theparticles had a size ranging between 90-120nm and positive surface charge. The intranasal immunization with M2e- HSP70c+TMC in BALB/c mice significantly induced higher M2e specific IgG than those induced in control groups (pcDNA/M2e-HSP70c without TMC, pcDNA/M2e, bearing M2e alone, and PBS).CONCLUSIONS: The present study showed that the encapsulation of M2e/ HSP70c into N-trimethyl chitosan (TMC) could strongly induce the humoral immune response against the M2e-HSP70c plasmid without lowering the adjuvant efficacy of HSP70c.