M Taghizadeh - Medical Vaccine Department, Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran
M Dabaghian - Department of Biotechnology, Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran

The nasal passage is the primary entry point for many infectious agents. Therefore, nasal vaccines that can overcome the limitations associated with antigen uptake are likely to play an important role in protecting these infectious agents. Thus, adjuvants and antigen-carrying systems that can induce a suitable mucosal and systemic immune response against their accompanying antigens are highly important. In this study, synthetic oligodeoxynucleotides containing CpG motifs (CpG-ODN) accompanied by the recombinant ectodomain of influenza M۲ protein were encapsulated in N-trimethyl chitosan (TMC) nanoparticles. After the preparation of TMC nanoparticles, the morphological characteristics and loading efficiency and in vitro antigen release, as well as their ability to induce efficient immune responses against M۲e in intranasal inoculation in the mouse model, were studied. Based on the size and zeta potential of the nanoparticles prepared in this study, it was determined that they were all nanosized, and their positive zeta potential ranged from ۲۵ to ۲۸ mV, while their polydispersity index was between ۰.۱ to ۰.۲, indicating a narrow range of particle sizes. A significant increase in serum levels of the total M۲e-specific IgG antibody and BALF anti-M۲e IgA was observed in mice intranasally immunized with M۲e/CpG-ODN/TMC as opposed to those that were intranasally immunized with M۲e/TMC, M۲e/CpG-ODN, free M۲e, and CpG-ODN/TMC. There was also a significant change in the IgG۲a/IgG۱ ratio in favour of IgG۲a seems that CpG-ODN is responsible for directing the immune system towards Th۱. Our findings show that CpG-ODN can significantly enhance the mucosal and systemic humoral immune response against M۲e when encapsulated in a suitable carrier such as TMC for intranasal administration. In conclusion, when combined with a suitable carrier, CpG-ODN can be considered an effective adjuvant for mucosal administration.

CpG-ODN ۲۰۰۶, M۲e, TMC