A Multi-epitope Peptide rOmp22 Encapsulated in Chitosan-PLGA Nanoparticles as Vaccine Candidate Against Acinetobacter baumannii Infection

Abstract

Background: Development of vaccine is a promising and cost-effective strategy to prevent emerging multi-drug resistant (MDR) Acinetobacter baumannii infections. The purpose of this study was to prepare a multi-epitope peptide nanovaccine and evaluate its immunogenicity and protective effect in BALB/c mice.Results: The B-cell and T-cell epitopes of Omp22 from A. baumannii were predicted using bioinformatics method and identified by immunological experiments. Three dominant B-cell epitopes and two T-cell epitopes were linked in series and chemically synthesized to generate multi-epitope peptide rOmp22. Then, rOmp22 was encapsulated by chitosan (CS) and polylactic acid glycolic acid (PLGA) to prepare CS-PLGA-rOmp22 nanoparticles (NPs). CS-PLGA-rOmp22 NPs were small (mean size of 272.83 nm) with apparently spherical structural, positively charged (4.39 mV) and exhibited nontoxicity to A549 cells. We achieved a high encapsulation efficiency (54.94%) and a continuous slow release pattern. Compared with non-encapsulated rOmp22, CS-PLGA-rOmp22 induced more rOmp22-specific IgG in serum and IFN-γ in splenocyte supernatant. Vaccination with CS-PLGA-rOmp22 decreased lung injury, suppressed bacterial burdens in the lung and blood, provided potent protection (57.14%-83.3%) against acute lethal intratracheal A. baumannii challenge in BALB/c mice.Conclusions: CS-PLGA-rOmp22 NPs could elicit specific IgG antibody, Th1 cellular immunity and protection against acute lethal intratracheal A. baumannii challenge. Our results indicate this nanovaccine is a disirable candidate to prevent A. baumannii infection.

A clinical perspective of chitosan nanoparticles for infectious disease management

“…Acinetobacter baumannii has recently emerged as one of the most important health problems due to its propensity to acquire multidrug, extensive drug, and even pan-drug resistance. A multiepitope peptide, rOmp22, encapsulated in chitosan-PLGA nanoparticles is being investigated as a vaccine prospect against Acinetobacter baumannii infection [ 70 ]. Likewise, Brucella abortus antigen, malate dehydrogenase (Mdh) when loaded in mucoadhesive chitosan nanoparticles emerged as an effective intranasal nanovaccine candidate in the mouse model [ 71 ].…”