Intranasal Immunization with Chitosan-PLGA-rOmp22 Protects Against Multidrug-Resistant Acinetobacter baumannii-Associated Pneumonia

Acinetobacter baumannii has become a challenge to treat clinically because of the increased number of extensively drug-resistant strains. Vaccination is an effective way to prevent and control A. baumannii infection. In this study, we constructed an A. baumannii nanovaccine Chitosan-PLGA-rOmp22 (CS-PLGA-rOmp22), and evaluated its immunogenicity and protective effects after intranasal immunization. BALB/c mice that received intranasal immunization with the CS-PLGA-rOmp22 nanovaccine displayed long-lasting local mucosal and systemic immunity, and could resist A. baumannii challenge. The CS-PLGA-rOmp22 penetrated the nasal mucosa and promoted the maturation and activation of dendritic cells (DCs) in vitro. Moreover, the immunoprotective effect of intranasal vaccination was comparable to that of subcutaneous immunization. Our findings suggest that this nanovaccine is a potential candidate for preventing A. baumannii infection after mucosal administration.