Chitosan stabilized nasal emulsion delivery system for effective humoral and cellular response against recombinant tetravalent dengue antigen

Nasal vaccine delivery systems are emerging alternatives to the conventional sub unit vaccine delivery systems owing to their ability to stimulate potent antigen specific humoral and cellular immune responses. Additional virtue of nasal delivery is its close proximity of immune cells to external epithelial layer which is the route of entry to pathogens. Toxicity of emulsion based vaccine delivery systems may be attributed to the presence of high quantities of surfactants used for stabilizing the emulsions. A safer approach would be to reduce physiologically unwanted surfactant burden in the emulsion to the bare limit to necessity. Oleic acid was used as oil phase due to its ability to enhance penetration of system in nasal mucosa. This emulsion was designed with the purpose that it activates the innate (TLR 4) and adaptive immune systems apart from performing its antigen delivery function. Proving the hypothesis, emulsion when immunized along with recombinant tetravalent dengue antigen has elicited a profound antigen specific humoral and cellular response. Antigen cross presenting and sustained release of antigen by emulsion is the key factor in shaping this immune response. Moreover, the dose sparing effect of emulsion has also been proven which has a crucial role in modern day vaccine delivery. This significant humoral and cellular response elicited proves the suitability of this emulsion system for enhancing the protective effect of vaccines against various intracellular pathogens.