Division of Viral Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, MD 20993.
Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037.
Proc Natl Acad Sci U S A. 2019 Jul 23;116(30):15194-15199. doi: 10.1073/pnas.1821317116. Epub 2019 Jul 11.
Several next-generation (universal) influenza vaccines and broadly neutralizing antibodies (bNAbs) are in clinical development. Some of these mediate inhibitions of virus replication at the postentry stage or use Fc-dependent mechanisms. Nonneutralizing antibodies have the potential to mediate enhancement of viral infection or disease. In the current study, two monoclonal antibodies (MAbs) 72/8 and 69/1, enhanced respiratory disease (ERD) in mice following H3N2 virus challenge by demonstrating increased lung pathology and changes in lung cytokine/chemokine levels. MAb 78/2 caused changes in the lung viral loads in a dose-dependent manner. Both MAbs increased HA sensitivity to trypsin cleavage at a higher pH range, suggesting MAb-induced conformational changes. pHrodo-labeled virus particles' entry and residence time in the endocytic compartment were tracked during infection of Madin-Darby canine kidney (MDCK) cells. Both MAbs reduced H3N2 virus residence time in the endocytic pathway, suggesting faster virus fusion kinetics. Structurally, 78/2 and 69/1 Fabs bound the globular head or base of the head domain of influenza hemagglutinin (HA), respectively, and induced destabilization of the HA stem domain. Together, this study describes Mab-induced destabilization of the influenza HA stem domain, faster kinetics of influenza virus fusion, and ERD in vivo. The in vivo animal model and in vitro assays described could augment preclinical safety evaluation of antibodies and next-generation influenza vaccines that generate antibodies which do not block influenza virus-receptor interaction.
几种下一代（通用）流感疫苗和广泛中和抗体（bNAbs）正在临床开发中。其中一些在进入后阶段介导病毒复制的抑制作用，或使用 Fc 依赖性机制。非中和抗体有可能介导病毒感染或疾病的增强。在当前的研究中，两种单克隆抗体（MAb）72/8 和 69/1 通过显示增加的肺部病理学和肺部细胞因子/趋化因子水平的变化，在 H3N2 病毒攻击后增强了小鼠的呼吸道疾病（ERD）。MAb 78/2 以剂量依赖的方式引起肺部病毒载量的变化。两种 MAbs 均增加了 HA 在更高 pH 范围下对胰蛋白酶切割的敏感性，表明 MAb 诱导的构象变化。在 Madin-Darby 犬肾 (MDCK) 细胞感染过程中，用 pHrodo 标记的病毒颗粒在细胞内体中的进入和停留时间进行了跟踪。两种 MAbs 均缩短了 H3N2 病毒在细胞内体途径中的停留时间，表明病毒融合动力学更快。结构上，78/2 和 69/1 Fab 分别结合流感血凝素 (HA) 的球形头部或头部域的基部，并诱导 HA 茎域的不稳定性。总的来说，这项研究描述了 Mab 诱导的流感 HA 茎域的不稳定性、流感病毒融合的更快动力学以及体内 ERD。描述的体内动物模型和体外测定可以增强不会阻断流感病毒受体相互作用的抗体和下一代流感疫苗的临床前安全性评估。
