Synthesis and immunological evaluation of a nanovaccine based on PLGA nanoparticles and alginate antigen against infections caused by Pseudomonas aeruginosa

Mucoid strains of P. aeruginosa are the major causes of morbidity and mortality in patients with cystic fibrosis. Recently, the application of nanocarriers was considered as a promising method in drug and vaccine delivery. The aim of this study was to develop an immunogenic nanovaccine against P. aeruginosa based on PLGA nanoparticles as a carrier and alginate (ALG) extracted from PAO1 strain of P. aeruginosa as an immunogen. The conjugation of alginate with PLGA nanoparticles was performed to develop the new nanovaccine and physiochemical analyses including FTIR spectroscopy, AFM, Zeta sizer, elemental and HNMR were performed to characterize the ALG-PLGA conjugate. The antigenicity evaluation was conducted in four groups of 5 BALB/c mice including: ALG-PLGA conjugate, alginate alone, PLGA alone and normal saline (as a control group). The mice were vaccinated intra-peritoneal three times with two-week intervals and the blood samples were collected via the mice hearts two weeks after the last administration. To determine the immune response total IgG, IgG2a, IgG2b, IgG3, IgA, IgG1 and IgM titers were determined in the serum samples using indirect ELISA method. A significant increase in total IgG and IgM antibodies was observed in mice vaccinated with ALG-PLGA conjugate in comparison with other groups. The histopathological study of mice treated with the new nanovaccine showed no toxicity in lung, kidney and liver. The findings showed the potential of ALG-PLGA conjugate as a reliable vaccine against the infections caused by P. aeruginosa.