Protective Efficacy of a Divalent Candidate Vaccine Consisting of Type A Flagellin and Pilin Against Dermal Pseudomonas aeruginosa Infection in a Murine Burn Model

Background and Aims: Pseudomonas aeruginosa is an opportunistic pathogen that causes serious infections and high mortality among burn patients. The aim of this study is to evaluate the protective effects of a candidate divalent vaccine containing type A flagellin and pilin of P. aeruginosa in a burn wound mouse model. Materials and Methods: Recombinant flagellin A and pilin proteins were generated by expressing fliC and pilA genes (cloned in pET-28a and pET-22b vectors, respectively) in E. coli BL-21. Groups of mice were immunized by injection of 10 µg of either flagellin A and pilin, or flagellin A, or pilin. Specific IgG titer was measured by ELISA. The functional activity of antibodies was evaluated by opsonophagocytosis assay. The protective effects of the vaccine were evaluated by measuring mortality and bacterial load in mice. Results: Immunization with flagellin A and pilin mixture significantly increased the specific IgG antibody titer as well as opsonophagocytosis compared to monovalent antigens (P<0.05). Immunization with flagellin A and pilin mixture significantly reduced the bacterial load, and increased the survival of mice challenged with P. aeruginosa, as compared to the monovalent antigens (P<0.05). Conclusions: Immunization with flagellin A and pilin mixture provides effective protection against P. aeruginosa wound infection in burned mice. Reduced bacterial load, and high survival rates among immunized mice suggest that flagellin A and pilin candidate vaccine shows therapeutic potential against P. aeruginosa infections among burn patients.