Liu Yuhang, Heim Kyle P, Che Ye, Chi Xiaoyuan, Qiu Xiayang, Han Seungil, Dormitzer Philip R, Yang Xinzhen
Discovery Sciences, Pfizer Inc., Groton, CT 06340, USA.
Vaccine Research and Development, Pfizer Inc., Pearl River, NY 10965, USA.
Sci Adv. 2021 Mar 5;7(10). doi: 10.1126/sciadv.abf3178. Print 2021 Mar.
Human cytomegalovirus (HCMV) causes congenital disease with long-term morbidity. HCMV glycoprotein B (gB) transitions irreversibly from a metastable prefusion to a stable postfusion conformation to fuse the viral envelope with a host cell membrane during entry. We stabilized prefusion gB on the virion with a fusion inhibitor and a chemical cross-linker, extracted and purified it, and then determined its structure to 3.6-Å resolution by electron cryomicroscopy. Our results revealed the structural rearrangements that mediate membrane fusion and details of the interactions among the fusion loops, the membrane-proximal region, transmembrane domain, and bound fusion inhibitor that stabilized gB in the prefusion state. The structure rationalizes known gB antigenic sites. By analogy to successful vaccine antigen engineering approaches for other viral pathogens, the high-resolution prefusion gB structure provides a basis to develop stabilized prefusion gB HCMV vaccine antigens.
人巨细胞病毒（HCMV）可导致先天性疾病，并伴有长期发病。HCMV糖蛋白B（gB）在病毒进入宿主细胞过程中，会从亚稳态的预融合构象不可逆地转变为稳定的融合后构象，从而使病毒包膜与宿主细胞膜融合。我们使用融合抑制剂和化学交联剂将预融合的gB稳定在病毒粒子上，提取并纯化后，通过电子冷冻显微镜以3.6埃的分辨率确定了其结构。我们的结果揭示了介导膜融合的结构重排，以及融合环、膜近端区域、跨膜结构域和结合的融合抑制剂之间相互作用的细节，这些相互作用使gB在预融合状态下保持稳定。该结构解释了已知的gB抗原位点。类比于针对其他病毒病原体成功的疫苗抗原工程方法，高分辨率的预融合gB结构为开发稳定的预融合gB HCMV疫苗抗原提供了基础。
