Vollmer Benjamin, Ebel Henriette, Rees Renate, Nentwig Julia, Mulvaney Thomas, Schünemann Jürgen, Krull Jens, Topf Maya, Görlich Dirk, Grünewald Kay
Centre for Structural Systems Biology (CSSB), Hamburg, Germany.
Department of Chemistry, University of Hamburg, Hamburg, Germany.
Nature. 2025 Sep 3. doi: 10.1038/s41586-025-09438-5.
The nine human herpesviruses, including herpes simplex virus 1 and 2, human cytomegalovirus and Epstein-Barr virus, present a significant burden to global public health. Their envelopes contain at least ten different glycoproteins, which are necessary for host cell tropism, attachment and entry. The best conserved among them, glycoprotein B (gB), is essential as it performs membrane fusion by undergoing extensive rearrangements from a prefusion to postfusion conformation. At present, there are no antiviral drugs targeting gB or neutralizing antibodies directed against its prefusion form, because of the difficulty in structurally determining and using this metastable conformation. Here we show the isolation of prefusion-specific nanobodies, one of which exhibits strong neutralizing and cross-species activity. By mutational stabilization we solved the herpes simplex virus 1 gB full-length prefusion structure, which allowed the bound epitope to be determined. Our analyses show the membrane-embedded regions of gB and previously unresolved structural features, including a new fusion loop arrangement, providing insights into the initial conformational changes required for membrane fusion. Binding an epitope spanning three domains, proximal only in the prefusion state, the nanobody keeps wild-type HSV-2 gB in this conformation and enabled its native prefusion structure to be determined. This also indicates the mode of neutralization and an attractive avenue for antiviral interventions.
包括单纯疱疹病毒1型和2型、人巨细胞病毒和爱泼斯坦-巴尔病毒在内的九种人类疱疹病毒给全球公共卫生带来了沉重负担。它们的包膜包含至少十种不同的糖蛋白，这些糖蛋白对于宿主细胞嗜性、附着和进入至关重要。其中保守性最好的糖蛋白B（gB）至关重要，因为它通过从融合前构象到融合后构象的广泛重排来进行膜融合。目前，由于难以在结构上确定和使用这种亚稳态构象，因此没有针对gB的抗病毒药物或针对其融合前形式的中和抗体。在这里，我们展示了融合前特异性纳米抗体的分离，其中一种表现出强大的中和和跨物种活性。通过突变稳定化，我们解析了单纯疱疹病毒1型gB的全长融合前结构，从而确定了结合的表位。我们的分析揭示了gB的膜嵌入区域以及先前未解析的结构特征，包括一种新的融合环排列，为膜融合所需的初始构象变化提供了见解。该纳米抗体结合了一个跨越三个结构域的表位，该表位仅在融合前状态下是近端的，它使野生型HSV-2 gB保持在这种构象，并使其天然融合前结构得以确定。这也表明了中和模式以及抗病毒干预的一个有吸引力的途径。
