AUTHOR=Acar Mustafa Burak , Ayaz-Güner Şerife , Güner Hüseyin , Dinç Gökçen , Ulu Kılıç Ayşegül , Doğanay Mehmet , Özcan Servet 

TITLE=A subtractive proteomics approach for the identification of immunodominant Acinetobacter baumannii vaccine candidate proteins

JOURNAL=Frontiers in Immunology

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2022.1001633

DOI=10.3389/fimmu.2022.1001633

ISSN=1664-3224

ABSTRACT=<sec><title>Background</title><p><italic>Acinetobacter baumannii</italic> is one of the most life-threatening multidrug-resistant pathogens worldwide. Currently, 50%–70% of clinical isolates of <italic>A. baumannii</italic> are extensively drug-resistant, and available antibiotic options against <italic>A. baumannii</italic> infections are limited. There is still a need to discover specific <italic>de facto</italic> bacterial antigenic proteins that could be effective vaccine candidates in human infection. With the growth of research in recent years, several candidate molecules have been identified for vaccine development. So far, no public health authorities have approved vaccines against <italic>A. baumannii</italic>.</p></sec><sec><title>Methods</title><p>This study aimed to identify immunodominant vaccine candidate proteins that can be immunoprecipitated specifically with patients’ IgGs, relying on the hypothesis that the infected person’s IgGs can capture immunodominant bacterial proteins. Herein, the outer-membrane and secreted proteins of sensitive and drug-resistant <italic>A. baumannii</italic> were captured using IgGs obtained from patient and healthy control sera and identified by Liquid Chromatography- Tandem Mass Spectrometry (LC-MS/MS) analysis.</p></sec><sec><title>Results</title><p>Using the subtractive proteomic approach, we determined 34 unique proteins captured only in drug-resistant <italic>A. baumannii</italic> strain <italic>via</italic> patient sera. After extensively evaluating the predicted epitope regions, solubility, transverse membrane characteristics, and structural properties, we selected several notable vaccine candidates.</p></sec><sec><title>Conclusion</title><p>We identified vaccine candidate proteins that triggered a <italic>de facto</italic> response of the human immune system against the antibiotic-resistant <italic>A. baumannii</italic>. Precipitation of bacterial proteins <italic>via</italic> patient immunoglobulins was a novel approach to identifying the proteins that could trigger a response in the patient immune system.</p></sec>