Immunogenicity Effect of Chitosan Nanoparticles Containing Botulinum Neurotoxin E binding Domain Recombinant Protein in Mice

Background and Clostridium botulinum neurotoxins are the most potent toxins that cause the life-threatening botulism syndrome in humans and animals. Researches have shown that the binding domain of the botulinum neurotoxin type E has a high immunogenicity effect that could be used as an efficient recombinant vaccine. The recombinant vaccines are not potent enough to stimulate the immune responses, therefore, the use of biocompatible and safe adjuvants is inevitable. In recent years, there have been many studies on the adjuvanticity effect of nanoparticles and their role as delivery vehicles of recombinant vaccines. This study investigated the vaccine delivery effect of chitosan nanoparticles for administration of a recombinant candidate vaccine against Clostridium botulinum type E. The expression and purification of botulinum neurotoxin type E was done in E. coli BL21 (DE3). Chitosan nanoparticles were synthesized by ionic gelation method. The protein containing nanoparticles were administered to mice subcutaneously. At the same time, a control group received the candidate vaccine in combination with the Freund adjuvant. Finally, the IgG titers of immunized mice were assayed by ELISA. The recombinant protein was successfully expressed and purified and was subsequently confirmed by western blot analysis. The loading capacity of the recombinant antigen into nanocapsules was calculated as 90%. ELISA results showed an increase in the IgG titer after each administration. The present study shows that the chitosan nanoparticles containing a recombinant vaccine could efficiently stimulate the humoral immune responses.