Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, USA.
Centro Nacional de Microbiología, Instituto de Salud Carlos III, Madrid, Spain.
Nat Commun. 2022 Mar 14;13(1):1299. doi: 10.1038/s41467-022-28931-3.
The human metapneumovirus (hMPV) fusion (F) protein is essential for viral entry and is a key target of neutralizing antibodies and vaccine development. The prefusion conformation is thought to be the optimal vaccine antigen, but previously described prefusion F proteins expressed poorly and were not well stabilized. Here, we use structures of hMPV F to guide the design of 42 variants containing stabilizing substitutions. Through combinatorial addition of disulfide bonds, cavity-filling substitutions, and improved electrostatic interactions, we describe a prefusion-stabilized F protein (DS-CavEs2) that expresses at 15 mg/L and has a melting temperature of 71.9 °C. Crystal structures of two prefusion-stabilized hMPV F variants reveal that antigenic surfaces are largely unperturbed. Importantly, immunization of mice with DS-CavEs2 elicits significantly higher neutralizing antibody titers against hMPV A1 and B1 viruses than postfusion F. The improved properties of DS-CavEs2 will advance the development of hMPV vaccines and the isolation of therapeutic antibodies.
人偏肺病毒（hMPV）融合（F）蛋白对于病毒进入宿主细胞至关重要，是中和抗体和疫苗开发的关键靶点。融合前构象被认为是最佳的疫苗抗原，但先前描述的融合前 F 蛋白表达不佳，且稳定性也不好。在这里，我们使用 hMPV F 的结构来指导设计包含稳定化取代的 42 种变体。通过组合添加二硫键、填补腔的取代以及改善静电相互作用，我们描述了一种融合前稳定化的 F 蛋白（DS-CavEs2），其表达量为 15mg/L，熔点为 71.9°C。两种融合前稳定化的 hMPV F 变体的晶体结构表明，抗原表面基本未受影响。重要的是，用 DS-CavEs2 免疫小鼠可引发针对 hMPV A1 和 B1 病毒的中和抗体滴度显著高于融合后 F 蛋白。DS-CavEs2 的这些改善特性将推动 hMPV 疫苗的开发和治疗性抗体的分离。
