Characterization of Functional B-Cell Epitopes at the Amino Terminus of Shigella Invasion Plasmid Antigen B (IpaB).
Characterization of Functional B-Cell Epitopes at the Amino Terminus of Shigella Invasion Plasmid Antigen B (IpaB).
复制标题
志贺氏菌入侵质粒抗原 B (IpaB) 氨基末端功能性 B 细胞表位的表征。
DOI：
10.1128/aem.00384-22
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发表时间：
2022
影响因子：
4.4
通讯作者：
Zhang,Weiping
中科院分区：
文献类型：
--
作者：
Li,Siqi;Han,Xinfeng;Upadhyay,Ipshita;Zhang,Weiping
志贺菌侵袭质粒抗原B（Ipa B）在志贺菌病的发病中起重要作用。虽然IpaB的蛋白质结构、对疾病机制的贡献以及对志贺氏菌感染的保护性免疫已经得到了很好的研究，但是单个抗原结构域的意义，特别是在N末端的意义，还没有被系统地表征。为了筛选IpaB蛋白的功能表位，并构建优化的多价多表位融合抗原（MEFA）免疫原，用于开发基于蛋白质的交叉保护性志贺氏菌疫苗，本研究通过计算机模拟鉴定了IpaB N端的免疫优势B细胞表位，并将每个表位与载体蛋白CsaB融合，（肠致病性大肠杆菌CS4粘附素的主要亚基）的表位融合蛋白，用每种表位融合蛋白免疫小鼠，检测IpaB特异性抗体应答，并评估抗体对志贺氏菌侵袭的功能活性。从IpaB的N端共鉴定出10个B细胞连续表位，每个表位与载体蛋白CsaB融合后，均能诱导小鼠产生抗IpaB IgG抗体。体外抗体侵袭抑制试验表明，来自每个鉴定的表位的抗体是功能性的，表位1（LAKILASTELGDNTIQAA），2（HSTSNILIPELKAPKSL）和4（QARQQKNLEFSDKI）诱导的抗体以与重组IpaB蛋白相似的水平抑制宋内志贺菌和福氏志贺菌侵袭，提示这三个IpaB表位可潜在地用作IpaB代表性抗原以诱导保护性抗IpaB抗体和用于构建表位-重要的是，目前还没有有效的措施来控制或预防志贺氏菌感染，志贺氏菌感染是发展中国家3至5岁儿童腹泻的最常见原因。志贺氏菌疫苗开发面临的挑战包括种属和血清型之间的毒力异质性。为了克服毒力异质性的挑战并开发基于蛋白质的多价志贺氏菌疫苗，我们靶向了一组毒力因子，包括侵入质粒抗原，鉴定了作为代表性抗原的功能性抗原结构域或表位，并应用新型基于表位和结构的疫苗学平台多表位融合抗原（MEFA）将功能性抗原结构域或表位整合到骨架免疫原中以产生交叉保护性抗体的多价免疫原。本研究中功能性IpaB表位的鉴定增强了我们对IpaB免疫原性的理解，使我们能够直接利用IpaB表位构建交叉保护性多价志贺氏菌免疫原，并加速基于蛋白质的志贺氏菌疫苗的开发。
Shigellainvasion plasmid antigen B (IpaB) plays an important role in causing shigellosis. While IpaB’s protein structure, contribution to disease mechanism, and protective immunity againstShigellainfection have been well studied, the significance of individual antigenic domains, especially at the N terminus, has not been systematically characterized. In an attempt to identify IpaB protein functional epitopes and to construct an optimized polyvalent multiepitope fusion antigen (MEFA) immunogen for development of a protein-based cross protectiveShigellavaccine, in this study, wein silicoidentified immunodominant B-cell epitopes from the IpaB N terminus, fused each epitope to carrier protein CsaB (the major subunit of enterotoxigenic Escherichia coli CS4 adhesin) for epitope fusion proteins, immunized mice with each epitope fusion protein, examined IpaB-specific antibody responses, and assessed antibody functional activity againstShigellabacterial invasion. A total of 10 B-cell continuous epitopes were identified from IpaB N terminus, and after being fused to carrier protein CsaB, each epitope induced anti-IpaB IgG responses in the intramuscularly immunized mice. Whilein vitroantibody invasion inhibition assays demonstrated that antibodies derived from each identified epitope were functional, epitopes 1 (LAKILASTELGDNTIQAA), 2 (HSTSNILIPELKAPKSL), and 4 (QARQQKNLEFSDKI) induced antibodies to inhibit Shigella sonnei and Shigella flexneri invasion at levels similar to those of recombinant IpaB protein, suggesting that these three IpaB epitopes can be used potentially as IpaB-representing antigens to induce protective anti-IpaB antibodies and for construction of an epitope-based polyvalent MEFA protein immunogen forShigellavaccine development.IMPORTANCECurrently, there are no effective measures for control or prevention ofShigellainfection, the most common cause of diarrhea in children 3 to 5 years of age in developing countries. Challenges in developingShigellavaccines include virulence heterogeneity among species and serotypes. To overcome virulence heterogeneity challenge and to develop a protein-based multivalentShigellavaccine, we targeted a panel of virulence factors, including invasion plasmid antigens, identified functional antigenic domains or epitopes as representative antigens, and applied the novel epitope- and structure-based vaccinology platform multiepitope fusion antigen (MEFA) to integrate functional antigenic domains or epitopes into a backbone immunogen to produce a polyvalent immunogen for cross protective antibodies. Identification of functional IpaB epitopes from this study enhances our understanding of IpaB immunogenicity and allows us to directly utilize IpaB epitopes for construction of a cross protective polyvalentShigellaimmunogen and to accelerate development of a protein-basedShigellavaccine.