Role of glycosylation mutations at the N-terminal domain of SARS-CoV-2 XEC variant in immune evasion, cell-cell fusion, and spike stability.

IF 4 2区 医学 Q2 VIROLOGY
Pei Li, Julia N Faraone, Cheng Chih Hsu, Michelle Chamblee, Yajie Liu, Yi-Min Zheng, Yan Xu, Claire Carlin, Jeffrey C Horowitz, Rama K Mallampalli, Linda J Saif, Eugene M Oltz, Daniel Jones, Jianrong Li, Richard J Gumina, Joseph S Bednash, Kai Xu, Shan-Lu Liu
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引用次数: 0

Abstract

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to evolve, producing new variants that drive global coronavirus disease 2019 surges. XEC, a recombinant of KS.1.1 and KP.3.3, contains T22N and F59S mutations in the spike protein's N-terminal domain (NTD). The T22N mutation, similar to the DelS31 mutation in KP.3.1.1, introduces a potential N-linked glycosylation site in XEC. In this study, we examined the neutralizing antibody (nAb) response and mutation effects in sera from bivalent-vaccinated healthcare workers, BA.2.86/JN.1 wave-infected patients, and XBB.1.5 monovalent-vaccinated hamsters, assessing responses to XEC alongside D614G, JN.1, KP.3, and KP.3.1.1. XEC demonstrated significantly reduced neutralization titers across all cohorts, largely due to the F59S mutation. Notably, removal of glycosylation sites in XEC and KP.3.1.1 substantially restored nAb titers. Antigenic cartography analysis revealed XEC to be more antigenically distinct from its common ancestral BA.2.86/JN.1 compared to KP.3.1.1, with the F59S mutation as a determining factor. Similar to KP.3.1.1, XEC showed reduced cell-cell fusion relative to its parental KP.3, a change attributed to the T22N glycosylation. We also observed reduced S1 shedding for XEC and KP.3.1.1, which was reversed by ablation of T22N and DelS31 glycosylation mutations, respectively. Molecular modeling suggests that T22N and F59S mutations of XEC alter hydrophobic interactions with adjacent spike protein residues, impacting both conformational stability and neutralization. Overall, our findings underscore the pivotal role of NTD mutations in shaping SARS-CoV-2 spike biology and immune escape mechanisms.IMPORTANCEThe continuous evolution of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to the emergence of novel variants with enhanced immune evasion properties, posing challenges for current vaccination strategies. This study identifies key N-terminal domain (NTD) mutations, particularly T22N and F59S in the recent XEC variant, which significantly impacts antigenicity, neutralization, and spike protein stability. The introduction of an N-linked glycosylation site through T22N, along with the antigenic shift driven by F59S, highlights how subtle mutations can drastically alter viral immune recognition. By demonstrating that glycosylation site removal restores neutralization sensitivity, this work provides crucial insights into the molecular mechanisms governing antibody escape. Additionally, the observed effects on spike protein shedding and cell-cell fusion contribute to a broader understanding of variant fitness and transmissibility. These findings emphasize the importance of monitoring NTD mutations in emerging SARS-CoV-2 lineages and support the need for adaptive vaccine designs to counteract ongoing viral evolution.

SARS-CoV-2 XEC变异n端糖基化突变在免疫逃避、细胞-细胞融合和刺突稳定性中的作用
严重急性呼吸综合征冠状病毒2 (SARS-CoV-2)继续进化,产生新的变体,推动2019年全球冠状病毒疾病激增。XEC是KS.1.1和KP.3.3的重组蛋白,在刺突蛋白n端结构域(NTD)中含有T22N和F59S突变。T22N突变类似于KP.3.1.1中的DelS31突变,在XEC中引入了一个潜在的n -连锁糖基化位点。在这项研究中,我们检测了二价疫苗接种的医护人员血清中的中和抗体(nAb)反应和突变效应,BA.2.86/JN。1波感染患者和XBB.1.5单价疫苗接种仓鼠,评估XEC与D614G、JN.1、KP.3和KP.3.1.1的反应。XEC在所有队列中表现出显著降低的中和效价,主要是由于F59S突变。值得注意的是,去除XEC和KP.3.1.1中的糖基化位点可以显著恢复nAb滴度。抗原制图分析显示,XEC与其共同祖先BA.2.86/JN的抗原差异更大。1与KP.3.1.1相比,F59S突变是一个决定因素。与KP.3.1.1类似,XEC表现出相对于亲本KP.3的细胞-细胞融合减少,这一变化归因于T22N糖基化。我们还观察到XEC和KP.3.1.1的S1脱落减少,这分别通过T22N和DelS31糖基化突变的消融而逆转。分子模型表明,XEC的T22N和F59S突变改变了与相邻刺突蛋白残基的疏水相互作用,影响了构象稳定性和中和作用。总的来说,我们的研究结果强调了NTD突变在形成SARS-CoV-2刺突生物学和免疫逃逸机制中的关键作用。严重急性呼吸综合征冠状病毒2 (SARS-CoV-2)的持续进化导致了具有增强免疫逃避特性的新变体的出现,对当前的疫苗接种策略提出了挑战。本研究确定了关键n端结构域(NTD)突变,特别是最近的XEC变异中的T22N和F59S,它们显著影响抗原性、中和性和刺突蛋白稳定性。通过T22N引入n链糖基化位点,以及F59S驱动的抗原转移,突出了微妙的突变如何极大地改变病毒免疫识别。通过证明糖基化位点去除可以恢复中和敏感性,这项工作为控制抗体逃逸的分子机制提供了重要的见解。此外,观察到的对刺突蛋白脱落和细胞-细胞融合的影响有助于更广泛地了解变异适应度和传播性。这些发现强调了在新出现的SARS-CoV-2谱系中监测NTD突变的重要性,并支持有必要设计适应性疫苗来对抗正在进行的病毒进化。
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来源期刊
Journal of Virology
Journal of Virology 医学-病毒学
CiteScore
10.10
自引率
7.40%
发文量
906
审稿时长
1 months
期刊介绍: Journal of Virology (JVI) explores the nature of the viruses of animals, archaea, bacteria, fungi, plants, and protozoa. We welcome papers on virion structure and assembly, viral genome replication and regulation of gene expression, genetic diversity and evolution, virus-cell interactions, cellular responses to infection, transformation and oncogenesis, gene delivery, viral pathogenesis and immunity, and vaccines and antiviral agents.
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