Preparation of ESAT-6 Nanoparticles and Evaluation of Humoral Immunity after Intranasal Administration

Introduction: Among several tuberculosis vaccine candidates for replacement of BCG, ESAT-6 protein has a special role. Since mycobacterium tuberculosis infection most often attacks the lungs, intranasal rout can be regarded as appropriate methods for tuberculosis vaccines and drug delivery. One of the appropriate systems for intranasal vaccine delivery is using biodegradable nanoparticles. Among biodegradable polymers, chitosan polymer has great features to increase the response of immunity system. This study aimed to investigate the specific humoral immune response of mice model after encapsulation of recombinant ESAT-6 antigen in chitosan nanoparticles. Methods: The chitosan nanoparticles containing ESAT-6 antigen were synthesized by ionic gelation. Nanoparticle properties including morphology, particle size, zeta potential, encapsulation rates, and protein release were measured in vitro. The immunization was performed through the nose for 3 times on days 0 and 14 and 28. 2 weeks after last administration, blood samples were collected and specific IgG titers were measured by indirect ELISA. Results: The nanoparticles synthesized had appropriate properties. The mean size of resulting nanoparticles was 242.8 nm by excellent antigen loading capacity (95.23 %). The vitro release of antigen from nanoparticles after 200 hours was detected as 67.5%. The Level of IgG antibody showed significant increase in the group that had received chitosan nanoparticles containing ESAT-6 compared with other groups. Conclusion: ESAT-6 protein was encapsulated in chitosan nanoparticles successfully. Administration of chitosan nanoparticles can be a suitable method for administration of humoral immunity antigens of Mycobacterium tuberculosis through intranasal rout.