Protein Analysis Group, Department of Pharmacy, University of Copenhagen, 2100 Copenhagen O, Denmark.
GSK, Siena 53100, Italy.
J Am Soc Mass Spectrom. 2021 Jul 7;32(7):1575-1582. doi: 10.1021/jasms.0c00431. Epub 2021 Mar 8.
Characterization of antigen-antibody interactions is crucial for understanding antibody-mediated protection against pathogens, biopharmaceutical development, as well as evaluation of the immune response post vaccination. Bexsero is a multicomponent vaccine against serogroup B in which one of the key vaccine antigens is Neisserial adhesin A (NadA), a trimeric coiled-coil protein. Two NadA-specific monoclonal antibodies (mAbs) isolated from Bexsero-vaccinated individuals have been shown to have similar binding affinity and appear to recognize a similar antigen region, yet only one of the mAbs is bactericidal. In this study, we use hydrogen/deuterium exchange mass spectrometry (HDX-MS) to perform an in-depth study of the interaction of the two mAbs with NadA antigen using a combined epitope and paratope mapping strategy. In addition, we use surface plasmon resonance (SPR) to investigate the stoichiometry of the binding of the two mAbs to NadA. While epitope mapping only identifies a clear binding impact of one of the mAbs on NadA, the paratope mapping analyses shows that both mAbs are binding to NadA through several complementarity determining regions spanning both heavy and light chains. Our results highlight the advantage of combined epitope and paratope mapping HDX-MS experiments and supporting biochemical experiments to characterize antigen-antibody interactions. Through this combined approach, we provide a rationale for how the binding stoichiometry of the two mAbs to the trimeric NadA antigen can explain the difference in bactericidal activity of the two mAbs.
抗原-抗体相互作用的特性对于理解抗体介导的针对病原体的保护作用、生物制药的开发以及评估疫苗接种后的免疫反应至关重要。Bexsero 是一种针对 B 群脑膜炎奈瑟菌的多组分疫苗，其中一种关键的疫苗抗原是奈瑟氏菌黏附素 A（NadA），这是一种三聚体螺旋卷曲蛋白。从 Bexsero 疫苗接种个体中分离出的两种 NadA 特异性单克隆抗体（mAb）已显示出相似的结合亲和力，并且似乎识别相似的抗原区域，但只有一种 mAb 具有杀菌活性。在这项研究中，我们使用氘代/氢交换质谱（HDX-MS）结合表位和互补位作图策略，对两种 mAb 与 NadA 抗原的相互作用进行深入研究。此外，我们还使用表面等离子体共振（SPR）研究两种 mAb 与 NadA 结合的化学计量。虽然表位作图仅确定了一种 mAb 对 NadA 的明确结合影响，但互补位作图分析表明，两种 mAb 都通过跨越重链和轻链的几个互补决定区结合 NadA。我们的研究结果强调了结合表位和互补位作图 HDX-MS 实验以及支持的生化实验来表征抗原-抗体相互作用的优势。通过这种联合方法，我们提供了一个合理的解释，说明两种 mAb 与三聚体 NadA 抗原的结合化学计量如何解释两种 mAb 杀菌活性的差异。
