Kedari Ashwini, Iheozor-Ejiofor Rommel, Salminen Petja, Uğurlu Hasan, Mäkelä Anna R, Levanov Lev, Vapalahti Olli, Hytönen Vesa P, Saksela Kalle, Rissanen Ilona
Institute of Biotechnology, Helsinki Institute of Life Science (HiLIFE), University of Helsinki, Helsinki, Finland.
Department of Virology, University of Helsinki, Helsinki, Finland.
Structure. 2024 Dec 5;32(12):2220-2230.e4. doi: 10.1016/j.str.2024.10.002. Epub 2024 Oct 28.
Host-cell entry of the highly pathogenic rabies virus (RABV) is mediated by glycoprotein (G) spikes, which also comprise the primary target for the humoral immune response. RABV glycoprotein (RABV-G) displays several antigenic sites that are targeted by neutralizing monoclonal antibodies (mAbs). In this study, we determined the epitope of a potently neutralizing human mAb, CR57, which we engineered into a diabody format to facilitate crystallization. We report the crystal structure of the CR57 diabody alone at 2.38 Å resolution, and in complex with RABV-G domain III at 2.70 Å resolution. The CR57-RABV-G structure reveals critical interactions at the antigen interface, which target the conserved "KLCGVL" peptide and residues proximal to it on RABV-G. Structural analysis combined with a cell-cell fusion assay demonstrates that CR57 effectively inhibits RABV-G-mediated fusion by obstructing the fusogenic transitions of the spike protein. Altogether, this investigation provides a structural perspective on RABV inhibition by a potently neutralizing human antibody.
高致病性狂犬病病毒（RABV）进入宿主细胞是由糖蛋白（G）刺突介导的，糖蛋白刺突也是体液免疫反应的主要靶点。狂犬病病毒糖蛋白（RABV-G）具有多个被中和性单克隆抗体（mAb）靶向的抗原位点。在本研究中，我们确定了一种高效中和性人源单克隆抗体CR57的表位，并将其改造成双体形式以利于结晶。我们报告了单独的CR57双体在2.38 Å分辨率下的晶体结构，以及与RABV-G结构域III形成复合物在2.70 Å分辨率下的晶体结构。CR57-RABV-G结构揭示了抗原界面处的关键相互作用，这些相互作用靶向RABV-G上保守的“KLCGVL”肽及其附近的残基。结构分析结合细胞-细胞融合试验表明，CR57通过阻碍刺突蛋白的融合转变有效抑制RABV-G介导的融合。总之，本研究为一种高效中和性人源抗体抑制RABV提供了结构视角。
