Abstract

Objective: Vaccination of at-risk people against Acinetobacter baumannii is a promising method to inhibit infections. Mucociliary clearance in the nasal cavity and hard transportation of protein agents over the epithelial barrier are justifying the development of encapsulated vaccines. Methods: In this study, we used chitosan as an adjuvant and antigen delivery system. Mucosal immunity brought about by the conserved region of A. baumannii biofilm-associated Protein (Bap) loaded on chitosan was assessed following intranasal (i.n) inoculation of mice. Mucosal and systemic immune responses were evaluated. Passive immunization was studied both in vivo and in vitro. Results: Antigen-specific IgG and IgA antibodies were raised in serum and fecal and lung extractions in mice administered intranasally with Bap-chitosan particles. Passive immunization with serum obtained from chitosan-Bap immunized mice conferred higher survival compared to immunization with subcutaneously immunized mice serum. Conclusions: Passive immunization with antibodies triggered with chitosan-Bap could be an additional immunization strategy for preventing A. baumannii pneumonia.