Novel chitosan particles and chitosan-coated emulsions inducing immune response via intranasal vaccine delivery

Purpose. The aim of this study was to prepare a novel vaccine carrier particulate system (nanoparticles and emulsions) with chitosan and to evaluate the effect of this system on the immune response for intranasal delivery. Methods. Chitosan nanoparticles (NP) and chitosan-coated emulsions (CC-Emul) were prepared by improvement of the method previously reported and by modified ethanol injection methods, respectively. The rats were immunized with the particles adsorbed with ovalbumin ( OVA) and cholera toxin (CT) by intranasal (i.n.) and intraperitoneal (i.p.) administration. Results. NP and CC-Emul could be prepared with particle diameter from about 0.4 mum to 3 mum. IgG induced by i.n. of NP was comparable with that by i.p., and IgA induced by i.n. of 0.4-mum- and 1-mum-size NP was significantly higher than control ( OVA and CT). IgG and IgA induced by i.n. of 2-mum-size CC-Emul were significantly higher than those with control. Conclusions. The novel chitosan particles used simple preparation methods showed high OVA adsorption. When administered intranasally, NP and CC-Emul induced systemic immune response in rats. These findings suggested that CC-Emul and the smaller-size (0.4 mum) NP are effective for targeting to nasal-associated lymphoid tissues (NALTs) in nasal vaccine delivery.