Vaccination with a combination of planktonic and biofilm virulence factors confers protection against carbapenem-resistant Acinetobacter baumannii strains

Acinetobacter baumannii is a multi-drug resistant pathogen with the ability to switch between planktonic and biofilm phenotypes. Although there is no vaccine against A. baumannii infections, many attempts have been made to develop vaccines using planktonic or biofilm antigens. To cover the different phenotypes of A. baumannii during growth and attachment, we combined planktonic upregulated antigens of iron receptors with biofilm upregulated antigens of pilus rods and evaluated immune responses and protective efficacies of the combined vaccine using lethal and sub-lethal murine sepsis models. The results showed that the combined vaccine elicited high IgG antibody titers and conferred protection against lethal doses of two Carbapenem-resistant high adherent A. baumannii strains. Complete bacterial clearance from all the affected tissues of the mice challenged with A. baumannii was an excellent achievement with our quadrivalent immunogen. These results demonstrate both planktonic and biofilm antigens are important during antigen selection for vaccine design.

Automated summary

In this study, a combined vaccine using planktonic and biofilm antigens of Acinetobacter baumannii was evaluated for its immune response and protective efficacy against lethal doses of two Carbapenem-resistant high adherent A. baumannii strains in a murine sepsis model. The results showed that the combined vaccine elicited high antibody titers and achieved complete bacterial clearance in affected tissues, highlighting the importance of considering both planktonic and biofilm antigens in vaccine design.