Immunogenic reactivity of recombinant PKF and AbOmpA proteins as serum resistance factors against sepsis of Acinetobacter baumannii

Acinetobacter baumannii is considered as a major cause of nosocomial infection worldwide. Various vaccine formulations have been mostly studied based on secreted or surface-exposed proteins of A. baumannii in murine models. Serum resistance proteins are critical virulence factors in bloodstream infections. AbOmpA and PKF are two major factors involved in serum resistance and could be considered as promising vaccine targets. In this study IgG1, IgG2c, Total-IgG concentrations, survival rates and spleen bacterial loads were studied in C57/BL mice model according to PKF, AbOmpA and AbOmpA + PKF vaccine formulations. The findings showed significant raises of IgG2c and Total-IgG in all three vaccinated groups in comparison with the control group. Whereas, there were low concentrations of IgG1 in all immunization plans. Colony counts of mice spleen showed the bacterial load of PKF plan had the most decrease of bacterial load (DBL = 5 log10 CFU/g). Taken together, this evaluation indicated that PKF vaccination plan induced a polarized Th1 response and rendered an effective protection against bloodstream infection caused by A. baumannii. •In vivo immunogenic reactivity of PKF, AbOmpA and PKF + AbOmpA were evaluated against sepsis of Acinetobacter baumannii.•High concentration of Total-IgG and IgG2c and low concentration of IgG1 were detected in all immunization plans.•PKF immunization plan fulfilled a more efficient protection against sepsis of A. baumannii.