Synthesis of Trimethyl Chitosan Nanoparticles Containing Recombinant BLF1-stxB Protein of Burkholderia Pseudomallei and Evaluation of its Immunogenicity in Mice

 The bacterium Burkholderia Pseudomallei is the cause of melioidosis disease. BLF1 plays an important role in the pathogenesis and infection of B. Pseudomallei. STxB has an adjuvant and carrier role and can be produced by mixing vaccine-candidate antigens with this adjuvant to produce a suitable vaccine. This study aimed to construct and evaluate the immunogenicity of trimethyl chitosan nanoparticles containing BLF1-stxB protein by subcutaneous injection.

 In this study, the expression of recombinant BLF1-stxB protein was induced in the expression host, and the protein was purified by affinity chromatography. Then, nanoparticles were fabricated by ion gelation method and the size and shape of nanoparticles were assessed by electron microscopy and injected subcutaneously into mice four times. Antibody titration was evaluated by indirect ELISA. BLF1 toxin was used for immunogenicity.

 The results of this study showed that protein-containing nanoparticles have higher size and PDI, and lower zeta potential than protein-free nanoparticles. The protein charge in nanoparticles was about 65%. The highest antibody titer belonged to the group receiving protein without nanoparticles. The results showed a 75% conservation challenge of the nanoparticle-free protein group.

 This study showed that the nanoparticle form containing this recombinant protein leads to a weaker immune response, compared to the non-nanoparticle form by injection. The results of the challenge showed that this recombinant chimeric protein provides better protection when subcutaneously injected with an adjuvant.