Protective potentials of a siderophore receptor against Acinetobacter baumannii infections

Abstract

Acinetobacter baumannii causes nosocomial infections and high mortality rates in the world. Since antibiotic treatment is complicated by extensive drug resistance in A. baumannii strains, other approaches such as vaccination can be a cost-effective solution. Siderophore receptor related to cluster 1 of iron uptake system (WP_000413999) is expressed in early stages of A. baumannii’s infection under iron restricted conditions. In this study, structural characterization and immunogenicity of the target protein in a murine sepsis model were assessed. Structural properties of the siderophore receptor were determined by bioinformatics tools. The gene encoding the antigen was cloned in E. coli BL21(DE3) and was then expressed. The purified recombinant protein was administered to the mice subcutaneously for antibody production. The immunized mice were challenged with the A. baumannii at lethal dose via intraperitoneal injection. Blast results revealed more than 97% identity of the protein in 3472 strains of A. baumannii. This receptor is a TonB-dependent transporter with a barrel domain composed of 22 β-strands connected by external loops and periplasmic turns. Experimental findings showed that the recombinant protein had no toxicity effect on A549 cells. Moreover, the studied protein was able to induce a specific antibody response in the mice. Survival rate of the passive immunized mice was improved against sepsis caused by A. baumannii ATCC 19606 and ABI022 clinical isolate. The study indicated that this siderophore receptor can be considered for further analysis as a potential vaccine target against A. baumannii.

Synergistic immunoprotection by Oma87 and Bap against Acinetobacter baumannii sepsis model

“…baumannii has developed antibiotic resistance at an alarming rate, especially in hospital settings, and becomes a major and challenging threat to communities due to the lack of effective treatment options (Kim et al 2021). The lack of treatment against this troublesome human pathogen and associated healthcare costs of treatments (Aghajani et al 2019a) have led to evaluate selected candidates for the development of novel therapeutics such as an e cient vaccine (Aghajani et al 2019b). A key step in the development of vaccines against pathogenic bacteria is the identi cation of appropriate antigens which may have the potential to be a vaccine candidate.…”