Nosocomial infections caused by Acinetobacter baumannii (A. baumannii)
nosocomial infections caused by Acinetobacter baumannii (A. baumannii) are considered as a global serious problem in hospitalized patients because of emerging antibiotic resistance.
Immunotherapy approaches are promising to prevent such
infections. In our previous study, five antigenic
epitopes of
outer membrane protein A (OmpA), as the most dangerous virulence molecule in A. baumanii, were predicted in silico. In this study, the investigators evaluated some immunological aspects of the
peptides. Five
peptides were separately injected into C5BL/6 mice; then the
cytokine production (interleukin-4 and interferon-gamma) of splenocytes and opsonophagocytic activity of immunized serum were assessed. To identify the protective function of the
peptides, animal models of
sepsis and
pneumonia infections were actively and passively immunized with selected
peptides and pooled sera of immunized mice, respectively. Then, survival rates of them were compared with the non-infected controls. Based on the results, activated spleen cells in P127
peptide-immunized mice exhibited an increase level of IFN-γ compared with the other experimental groups, but not about the
IL-4 concentration. The results of opsonophagocytic assay revealed an appropriate killing activity of produced
antibodies against A. baumannii in a dose-dependent manner. Further, the survival rates of the mice under passive immunization with the immunized sera or active immunization with P127
peptide were significantly more than those in the control group. Moreover, the survival rate of the P127
peptide immunized group was considerably higher than that among the other
peptide-immunized group. In conclusion, findings indicated that
peptides derived from
outer membrane protein-A can be used as a promising tool for designing the
epitope-based
vaccines against
infections caused by A. baumannii.