Preparation of a nanovaccine against Brucella melitensis M16 based on PLGA nanoparticles and oligopolysaccharide antigen.

Brucellosis is one of the most common and important diseases between humans and animals. Herein, we developed a nanovaccine against Brucella melitensis based on oligopolysaccharide (OPS) antigen and PLGA nanoparticles. The conjugation of extracted OPS with poly lactic-co-glycolic acid was performed. The antigenicity evaluation was conducted in 4 groups of 5 female BALB/c mice including OPS-PLGA conjugate, OPS alone, PLGA alone and PBS as a control. The mice were vaccinated intra-peritoneal three times with two-week intervals. To determine the immune response and functional capacity of the antibodies, the enzyme linked immunosorbent, opsonophagocytosis and challenge tests were performed. For checking the immunization ability of the nanovaccine, the challenge test was performed. The results showed a significant increase in the total IgG and IgM antibody titres in the mice vaccinated with OPS-PLGA conjugate in comparison with other groups. The sera of animals immunized with OPS-PLGA conjugate promoted efficient opsonophagocytosis of Brucella bacteria. The results of challenge assay showed that the immunization with OPS-PLGA conjugate gave a high level of protection in comparison with other groups. These findings showed that the new nanovaccine can be considered as a candidate for immunization of animals and humans against the diseases caused by B. melitensis that needs further investigations.