RESUMO
Background and purpose: Acinetobacter baumannii (A. baumannii) is known as a pathogen with antibiotic resistance, causing respiratory infections. PLGA has been approved for use in vaccines as well as drug delivery. This study was performed to evaluate PLGA nanoparticles containing the outer membrane proteins (OMPs) of A. baumannii in stimulating the mice's immune system and improving pneumonia. Experimental approach: Double emulsion solvent evaporation technique was used. The properties of the obtained nanospheres were determined using a zetasizer, FTIR, and AFM devices. Nanoparticles were administered to mice BALB/c by applying the intramuscular route. ELISA was used to measure the amounts of immunoglobulins produced; also, an opsonophagocytic killing assay was used to measure the effectiveness of immunoglobulins. Immunized mice were then challenged with live A. baumannii through the lungs; their internal organs were also removed for bacteriological studies. Findings/Results: The prepared particles were 550 nm in diameter with a negative surface charge. The production of the OMPs specific IgG was much higher in the group receiving nanoparticles containing antigen as compared to those getting pure antigen. The immunoglobulins produced against nanoparticles were superior to those developed against pure antigens. Mice that received the new nanovaccine were more resistant to pneumonia caused by this bacterium than those that received pure antigen. Conclusion and implication: Overall, it can be said that PLGA nanoparticles could deliver their internal antigens (OMPs) well to the immune system of mice and stimulate humoral immunity in these animals, thus protecting them against pneumonia caused by A. baumannii.
RESUMO
BACKGROUND: Pseudomonas aeruginosa has an important role in nosocomial infections. OBJECTIVE: To evaluate biological activity of the detoxified LPS (D-LPS) entrapped into Poly lactic-co-glycolic acid (PLGA) nanoparticles. MATERIALS: LPS was extracted and detoxified from the P. aeruginosa strain PAO1. The D-LPS, conjugated to the PLGA nanoparticles with 1-ethyl-3-dimethyl aminopropyl carbodiimide (EDAC) and N-hydroxy-succinimide (NHS). The connection was evaluated by FTIR (Fourier transform infrared), Zetasizer, and Atomic Force Microscope (AFM). The BALB/c mice injected intramuscularly with the D-LPS-PLGA with two-week intervals and then challenged two weeks after the last immunization. The bioactivity of the induced specific antisera and cytokines responses against D-LPS-PLGA antigen was assessed by ELISA. RESULTS: D-LPS-PLGA conjugation was confirmed by FTIR, Zetasizer, and AFM. The ELISA results showed that D-LPS was successful in the stimulation of the humoral immune response. The immune responses raised against the D-LPS-PLGA, significantly decreased bacterial titer in the spleen of the immunized mice after challenge with PAO1 strain in comparison with the control groups. CONCLUSION: The conjugation of the bacterial LPS to the PLGA nanoparticle increased their functional activity by decrease in bacterial dissemination and increase the killing of opsonized bacteria.
