Impact of Immunoglobulin Isotype and Epitope on the Functional Properties of Vibrio cholerae O-Specific Polysaccharide-Specific Monoclonal Antibodies.
Impact of Immunoglobulin Isotype and Epitope on the Functional Properties of Vibrio cholerae O-Specific Polysaccharide-Specific Monoclonal Antibodies.
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DOI：
10.1128/mbio.03679-20
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发表时间：
2021-04-20
期刊：
影响因子：
6.4
通讯作者：
Wrammert J
中科院分区：
文献类型：
--
作者：
Kauffman RC;Adekunle O;Yu H;Cho A;Nyhoff LE;Kelly M;Harris JB;Bhuiyan TR;Qadri F;Calderwood SB;Charles RC;Ryan ET;Kong J;Wrammert J
对严重腹泻病霍乱的免疫主要是由脂多糖（LPS）特异性抗体介导的。然而，功能相关抗体的性质和保护机制尚未明确。霍乱弧菌引起严重的腹泻疾病霍乱。临床疾病和目前的口服霍乱疫苗产生与保护相关的抗体反应。免疫被认为主要是由脂多糖（LPS）特异性抗体介导的，主要针对o抗原。然而，功能相关抗体的性质和保护机制尚未明确。我们之前报道了孟加拉国一组患者对霍乱的早期B细胞反应，并从急性诱导的浆母细胞中分离出一组人单克隆抗体（mab）。在先前的研究中，所有抗体都在IgG1主干中表达，而不考虑其原始同型。为了清楚地确定亲和力、免疫球蛋白同型和亚类对这些单克隆抗体功能特性的影响，我们在不同的免疫球蛋白同型和亚类中重新设计了一组低亲和力和高亲和力的抗体，并表征了这些变化对结合、杀弧菌、凝集和运动抑制活性的影响。高亲和抗体与o抗原结合相似，而低亲和抗体与o抗原结合明显不同。有趣的是，尽管表现出较低的结合特性，低亲和力单克隆抗体衍生的变体具有与强结合抗体相当的凝集和运动抑制特性，这表明单克隆抗体如何与o抗原结合可能对功能至关重要。此外，不仅五聚体IgM和二聚体IgA，单体IgA在抑制运动方面也明显强于IgG。最后，通过分析这些抗体的高纯度F（ab）版本，我们发现LPS交联对运动抑制至关重要。
Immunity to the severe diarrheal disease cholera is largely mediated by lipopolysaccharide (LPS)-specific antibodies. However, the properties and protective mechanism of functionally relevant antibodies have not been well defined. Vibrio cholerae causes the severe diarrheal disease cholera. Clinical disease and current oral cholera vaccines generate antibody responses associated with protection. Immunity is thought to be largely mediated by lipopolysaccharide (LPS)-specific antibodies, primarily targeting the O-antigen. However, the properties and protective mechanism of functionally relevant antibodies have not been well defined. We previously reported on the early B cell response to cholera in a cohort of Bangladeshi patients, from which we characterized a panel of human monoclonal antibodies (MAbs) isolated from acutely induced plasmablasts. All antibodies in that previous study were expressed in an IgG1 backbone irrespective of their original isotype. To clearly determine the impact of affinity, immunoglobulin isotype and subclass on the functional properties of these MAbs, we re-engineered a subset of low- and high-affinity antibodies in different isotype and subclass immunoglobulin backbones and characterized the impact of these changes on binding, vibriocidal, agglutination, and motility inhibition activity. While the high-affinity antibodies bound similarly to O-antigen, irrespective of isotype, the low-affinity antibodies displayed significant avidity differences. Interestingly, despite exhibiting lower binding properties, variants derived from the low-affinity MAbs had comparable agglutination and motility inhibition properties to the potently binding antibodies, suggesting that how the MAb binds to the O-antigen may be critical to function. In addition, not only pentameric IgM and dimeric IgA, but also monomeric IgA, was remarkably more potent than their IgG counterparts at inhibiting motility. Finally, analyzing highly purified F(ab) versions of these antibodies, we show that LPS cross-linking is essential for motility inhibition.