The immunoprotective effect of a hybrid antigen from Omp۳۴ against A.baumannii in a murine model of pneumonia

Background and Aim : Acinetobacter baumannii is one of the most troublesome human infections. Researchers are looking for alternative therapeutic options, including immunization against the nosocomial bacterium, due to the emergence of antibiotic-resistant strains. Although no vaccine for this infection is currently available, various attempts have been made to develop one. Omp۳۴ is known as a specific antigen in Acinetobacter.Methods : In this study, the most immunogenic loop of Omp۳۴ protein was found to be loop ۳. The gene in the query was amplified and cloned into a predetermined position in loopless C lobe (LCL) of Neisseria meningitides and the construct was cloned into the ۵۰۴۴ plasmid. The purified recombinant protein was subsequently administered to mice. Results : According to an indirect ELISA test on the serum of mice given ۲۰ µg of Omp۳۴ protein and adjuvant , there was a substantial rise in antibody to Omp۳۴ compared to the control group. The active immunized mice were subjected to A.baumannii challenge. The mice group challenged with A.baumannii ATCC ۱۹۶۰۶ showed ۸۰, ۱۰۰, and ۶۰% survival rate in mice after nasal inoculation with loop۳ in positions ۱, ۳, and combination of the two positions while the clinical strain exhibited ۱۰۰, ۱۰۰, and ۸۰% survival rate at the same LCL positions respectively. In addition, the bacterial load in the lung was significantly reduced in all immunized groups.Conclusion : Our results showed that protein omp۳۴ as an immunogen can protect against A.baumannii.

Keywords:

Acinetobacter baumannii , Omp۳۴ , Immunogenicity