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

BACKGROUND: Influenza outbreak has become a great lifethreateningdisease in the world. Nasal vaccines can inducesystemic IgG and mucosal IgA antibody responses, whichestablish two layers of immune defense against the infectiouspathogens like influenza. Mucosal vaccines must overcomeseveral limitations, including the mucociliary clearance andinefficient uptake of soluble antigens. Therefore, nasal vaccinesrequire potent adjuvants and delivery systems. OBJECTIVES: Inthis study we evaluated the effect of N-trimethyl chitosan (TMC)as a potent vehicle for DNA encoding M2e/HSP70c in order forintranasal administration in mice. METHODS:Ectodomain of theconserved influenza matrix protein 2 (M2e), which has beenfound to induce heterosubtypic immunity, was fused toHSP70359-610 or C-terminus of Mycobacterium tuberculosisHSP70 (HSP70c) in pcDNA3.1 vector (pcDNA/M2e-HSP70c)and then encapsulated into a derivative of chitosan, N-trimethylchitosan (TMC). After encapsulation of the plasmid, physicalproperties of the particles were investigated using Zetasizer®3000 the particles were then administered through the intranasaldelivery in BALB/c mice. RESULTS: It was found that theparticles had a size ranging between 90-120nm and positivesurface charge. The intranasal immunization with M2e-HSP70c+TMC in BALB/c mice significantly induced higherM2e specific IgG than those induced in control groups(pcDNA/M2e-HSP70c without TMC, pcDNA/M2e, bearingM2e alone, and PBS).CONCLUSIONS: The present study showedthat the encapsulation of M2e/ HSP70c into N-trimethylchitosan (TMC) could strongly induce the humoral immuneresponse against the M2e-HSP70c plasmid without lowering theadjuvant efficacy of HSP70c.