scholarly journals Transcriptional Regulation of the Outer Membrane Protein A in Acinetobacter baumannii

2020 ◽  
Vol 8 (5) ◽  
pp. 706
Author(s):  
Kyu-Wan Oh ◽  
Kyeongmin Kim ◽  
Md. Maidul Islam ◽  
Hye-Won Jung ◽  
Daejin Lim ◽  
...  
Keyword(s):  
Transcriptional Regulation ◽  
Membrane Protein ◽  
Acinetobacter Baumannii ◽  
Outer Membrane ◽  
Binding Affinity ◽  
Outer Membrane Protein ◽  
Protein A ◽  
Regulatory Factors ◽  
Promotor Region ◽  
Outer Membrane Protein A

Acinetobacter baumannii is known for its virulence in severely ill, hospitalized patients and for exhibiting multidrug resistance. A. baumannii infection treatment poses a serious problem in clinical environments. The outer membrane protein A (OmpA) of the Acinetobacter genus is involved in bacterial virulence. Regulatory factors of OmpA in the post-transcriptional stage have been previously identified. However, the regulatory factors that act before the transcriptional stage remain unclear. We investigated the A1S_0316 gene that encodes a putative transcription factor for OmpA expression in A. baumannii. A1S_0316 was purified and examined using size-exclusion chromatography, which revealed that it forms an oligomer. The binding affinity of A1S_0316 to the OmpA promoter region was also examined. We compared the binding affinity to the OmpA promotor region between A1S_0316 and the AbH-NS protein. A1S_0316 showed higher binding affinity to the OmpA promotor region than did H-NS. We examined the regulatory effect of these proteins on OmpA expression in A. baumannii using real-time qPCR and various in vitro tools. Our results indicated that A1S_0316 acts as an anti-repressor on the promotor region of the OmpA gene by inhibiting the binding of the AbH-NS protein. This study was the first demonstration of the transcriptional regulation of OmpA expression.

scholarly journals Evaluation of the New Outer Membrane Protein A Epitope-based Vaccines for Mice Model of Acinetobacter baumannii Associated Pneumonia and Sepsis Infection

2021 ◽  
Author(s):  
Kobra Mehdinejadiani ◽  
Ali Hashemi ◽  
Mojgan Bandehpour ◽  
Hoda Rahmani ◽  
Mohammad Mehdi Ranjbar ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Acinetobacter Baumannii ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Protein A ◽  
Survival Rates ◽  
The Other ◽  
Dependent Manner ◽  
Protective Function ◽  
Outer Membrane Protein A

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, their survival rates were compared with the non-infected controls.Based on the results, activated spleen cells in P127 peptide-immunized mice exhibited an increased level of IFN-γ compared with the other experimental groups, but not about the IL-4 concentration. The results of the opsonophagocytic assay revealed an appropriate killing the 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 of the other peptide-immunized group.In conclusion, findings indicated that peptides derived from OmpA can be used as a promising tool for designing the epitope-based vaccines against infections caused by A. baumannii.   

scholarly journals In Silico Design and Evaluation of Acinetobacter baumannii Outer Membrane Protein A (OmpA) Antigenic Peptides as Vaccine Candidate in Immunized Mice

2020 ◽  
Author(s):  
Kobra Mehdinejadiani ◽  
Mojgan Bandehpour ◽  
Ali Hashemi ◽  
Mohammad Mehdi Ranjbar ◽  
Sodabeh Taheri ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Acinetobacter Baumannii ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Protein A ◽  
Epitope Prediction ◽  
Effective Vaccine ◽  
Enzyme Linked Immunosorbent Assay ◽  
Antigenic Peptides ◽  
Outer Membrane Protein A

Acinetobacter baumannii is a Gram-negative bacterium that has recently been identified as a leading nosocomial pathogen. Infections by this pathogen result in significant mortality due to antibiotic resistance. An effective vaccine would help alleviate the burden of disease incurred by this pathogen; however, there are currently no licensed vaccines offering protection against Acinetobacter baumannii infection. In this study, considering the fact that outer membrane protein A is one of the most promising vaccine candidates, we predicted T cell and B cell epitopes on this protein using sequence-based epitope prediction tools and determined whether or not mice immunized with these peptides induce an immune response. We selected consensus epitopes including five peptides in different tools with the highest score. 48 female C5BL/6 SPF injected subcutaneously with the peptides (peptide1 to peptide 5 separately) in 100 μL of the solution and sham groups received adjuvant and PBS alone on the same schedule: on day 0 (primary dose) and two booster doses were administered on days 14 and 28. At the end of time, animals euthanized by Isoflurane, and collected sera for assessment of specific antibodies against each peptide by ELISA (Enzyme-linked immunosorbent assay). Immunization of mice showed one of the novel synthetic peptides (peptide 1 (24-50 amino acids)) elicited immune responses. We conclude to combine theoretical methods of epitope prediction and evaluating the potential of immunogenicity for developing vaccines is important.

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