RESUMO
BACKGROUND: Generating vaccines is a promising and effective method for stopping the spread of Acinetobacter baumannii (A. baumannii) infections that are becoming more and more drug-resistant (MDR). Developing a DNA vaccine and testing its efficacy and protective effects in BALB/c mice were the goals of this research. METHODS: We examined the genomes of 35 different strains of A. baumannii using the Vaxign online program, and we selected outer membrane and secreted proteins as potential vaccine candidates. Next, the proteins' immunogenicity, antigenic features, physical and chemical characteristics, and B and MHCI/II cell epitope concentrations were assessed. The DNA vaccine was synthesized. Then, to generate CS-DNA nanoparticles, the DNA vaccine was e encapsulated by chitosan (CS) nanoparticles (NPs). BALB/c mice were used to assess the vaccine's immunogenicity and immunoprotective effectiveness. RESULTS: CS-DNA NPs were nontoxic, positively charged (4.39 mV), and small (mean size of 285-350 nm) with ostensibly spherical shapes. It was possible to establish a continuously slow release profile and a high entrapment efficiency (78.12 %). CS-DNA vaccinated BALB/c mice elicited greater levels of csuC-specific IgG in plasma and IFN-γ in splenocyte lysate compared with non-encapsulated DNA vaccine. In addition, BALB/c mice immunized with CS-DNA nanovaccine showed decreased lung damage and bacterial loads in the lung and blood, as well as significant immunity (87.5 %) versus acute fatal intratracheal A. baumannii challenge. CONCLUSION: In conclusion, acute fatal intratracheal A. baumannii exposure was prevented by CS-DNA NPs that induced specific IgG antibodies, Th1 cellular immunity, and other protective mechanisms. Our findings show that this nanovaccine is a promising contender for stopping the spread of A. baumannii infection.