Isolation and Characterization of Human Monoclonal Antibodies to Pneumococcal Capsular Polysaccharide 3.
Isolation and Characterization of Human Monoclonal Antibodies to Pneumococcal Capsular Polysaccharide 3.
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DOI：
10.1128/spectrum.01446-21
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发表时间：
2021-12-22
影响因子：
3.7
通讯作者：
Pirofski LA
中科院分区：
文献类型：
--
作者：
Babb R;Doyle CR;Pirofski LA
目前的肺炎球菌荚膜多糖 (PPS) 结合疫苗 (PCV13) 对肺炎链球菌血清型 3 (ST3) 的效果较差，而后者仍然是肺炎球菌疾病和死亡的主要原因。因此，剖析人ST3肺炎球菌荚膜多糖（PPS3）抗体的结构-功能关系可能揭示保护性抗体的特征。使用流式细胞术，我们从肺炎球菌疫苗接受者中分离出 PPS3 结合记忆 B 细胞，并生成了七种 PPS3 特异性人单克隆抗体 (humAb)。 5 种人类抗体表现出 ST3 调理吞噬活性，四种在体外诱导 ST3 凝集，四种介导这两种活性。两种人抗体，即 C10 和 C27，使用相同的可变重 (VH) 和轻 (VL) 链结构域 (VH3-9*01/VL2-14*03)，均在体外改变 ST3 基因表达；然而，C10 具有较少的 VL 体细胞突变、较高的 PPS3 亲和力，并促进体外 ST3 调理吞噬和凝集活性，而 C27 则不然。在 C57BL/6 小鼠中，两种人抗体均减少了 ST3 A66 和临床菌株 B2 的鼻咽定植，并延长了致命性 A66 腹膜内感染后的存活时间，但只有 C10 能够防止临床菌株的致命鼻内感染。进行 VL 交换后，C10VH/C27VL 表现出 ST3 结合和凝集减少，但 C27VH/C10VL 结合没有变化。然而，当轻链被替换时，两种人抗体都失去了减少体内定植的能力。我们的研究结果将 PPS3 特异性 humAb 减少定植的能力与 ST3 凝集和调理吞噬活性联系起来，并揭示了 VL 在其体外和体内功能活性中的意想不到的作用。这些发现还提供了一些见解，可以为基于抗体的治疗和 ST3 疫苗功效替代物的鉴定提供信息。重要性 尽管肺炎球菌结合疫苗接种在全球取得了成功，但血清型 3 (ST3) 肺炎球菌仍然是发病和死亡的主要原因。与其他疫苗包含的血清型相比，ST3 肺炎球菌荚膜多糖 (PPS3) 诱导较弱的调理吞噬反应，这被认为与疫苗功效相关。先前对小鼠 PPS3 单克隆抗体的研究发现，ST3 凝集与小鼠中 ST3 鼻咽定植减少有关。然而，人类疫苗引发的 PPS3 抗体的凝集能力和预防实验性小鼠鼻咽定植的能力均尚未研究。我们生成并分析了人疫苗引发的 PPS3 单克隆抗体的功能和体内功效，发现 ST3 凝集与抗体亲和力、体内保护以及轻链可变区的有限体细胞突变相关。这些发现提供了新的见解，可以为基于抗体的疗法和下一代 ST3 疫苗的开发提供信息。
The current pneumococcal capsular polysaccharide (PPS) conjugate vaccine (PCV13) is less effective against Streptococcus pneumoniae serotype 3 (ST3), which remains a major cause of pneumococcal disease and mortality. Therefore, dissecting structure-function relationships of human ST3 pneumococcal capsular polysaccharide (PPS3) antibodies may reveal characteristics of protective antibodies. Using flow cytometry, we isolated PPS3-binding memory B cells from pneumococcal vaccine recipients and generated seven PPS3-specific human monoclonal antibodies (humAbs). Five humAbs displayed ST3 opsonophagocytic activity, four induced ST3 agglutination in vitro, and four mediated both activities. Two humAbs, namely, C10 and C27, that used the same variable heavy (VH) and light (VL) chain domains (VH3-9*01/VL2-14*03) both altered ST3 gene expression in vitro; however, C10 had fewer VL somatic mutations, higher PPS3 affinity, and promoted in vitro ST3 opsonophagocytic and agglutinating activity, whereas C27 did not. In C57BL/6 mice, both humAbs reduced nasopharyngeal colonization with ST3 A66 and a clinical strain, B2, and prolonged survival following lethal A66 intraperitoneal infection, but only C10 protected against lethal intranasal infection with the clinical strain. After performing VL swaps, C10VH/C27VL exhibited reduced ST3 binding and agglutination, but C27VH/C10VL binding was unchanged. However, both humAbs lost the ability to reduce colonization in vivo when their light chains were replaced. Our findings associate the ability of PPS3-specific humAbs to reduce colonization with ST3 agglutination and opsonophagocytic activity, and reveal an unexpected role for the VL in their functional activity in vitro and in vivo. These findings also provide insights that may inform antibody-based therapy and identification of surrogates of vaccine efficacy against ST3. IMPORTANCE Despite the global success of vaccination with pneumococcal conjugate vaccines, serotype 3 (ST3) pneumococcus remains a leading cause of morbidity and mortality. In comparison to other vaccine-included serotypes, the ST3 pneumococcal capsular polysaccharide (PPS3) induces a weaker opsonophagocytic response, which is considered a correlate of vaccine efficacy. Previous studies of mouse PPS3 monoclonal antibodies identified ST3 agglutination as a correlate of reduced ST3 nasopharyngeal colonization in mice; however, neither the agglutinating ability of human vaccine-elicited PPS3 antibodies nor their ability to prevent experimental murine nasopharyngeal colonization has been studied. We generated and analyzed the functional and in vivo efficacy of human vaccine-elicited PPS3 monoclonal antibodies and found that ST3 agglutination associated with antibody affinity, protection in vivo, and limited somatic mutations in the light chain variable region. These findings provide new insights that may inform the development of antibody-based therapies and next-generation vaccines for ST3.
影响因子：
15.3
作者：
Bull, C G
通讯作者：
Bull, C G
影响因子：
15.3
作者：
Bull, C G
通讯作者：
Bull, C G