Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.
Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA.
Cell Rep. 2021 Jan 26;34(4):108682. doi: 10.1016/j.celrep.2020.108682.
Novel influenza A virus (IAV) strains elicit recall immune responses to conserved epitopes, making them favorable antigenic choices for universal influenza virus vaccines. Evaluating these immunogens requires a thorough understanding of the antigenic sites targeted by the polyclonal antibody (pAb) response, which single-particle electron microscopy (EM) can sensitively detect. In this study, we employ EM polyclonal epitope mapping (EMPEM) to extensively characterize the pAb response to hemagglutinin (HA) after H5N1 immunization in humans. Cross-reactive pAbs originating from memory B cells immediately bound the stem of HA and persisted for more than a year after vaccination. In contrast, de novo pAb responses to multiple sites on the head of HA, targeting previously determined key neutralizing sites on H5 HA, expanded after the second immunization and waned quickly. Thus, EMPEM provides a robust tool for comprehensively tracking the specificity and durability of immune responses elicited by novel universal influenza vaccine candidates.
新型甲型流感病毒（IAV）株引发针对保守表位的回忆性免疫应答，使其成为通用流感病毒疫苗的理想抗原选择。评估这些免疫原需要深入了解多克隆抗体（pAb）反应所针对的抗原表位，而单颗粒电子显微镜（EM）可以敏感地检测到这些表位。在这项研究中，我们采用 EM 多克隆表位作图（EMPEM）技术，广泛分析人类接种 H5N1 疫苗后针对血凝素（HA）的 pAb 反应。源自记忆 B 细胞的交叉反应性 pAb 立即结合 HA 的茎部，并在接种疫苗后持续存在一年以上。相比之下，针对 HA 头部多个位点的新产生的 pAb 反应在第二次免疫后扩展，并迅速衰减，这些位点针对之前确定的 H5 HA 的关键中和位点。因此，EMPEM 为全面跟踪新型通用流感疫苗候选物引发的免疫应答的特异性和持久性提供了一种强大的工具。
