Liang Ruonan, Peccati Francesca, Ponse Niels L D, Uslu Elif, de Rooij Annelies J H, Han Alvin X, Boons Geert-Jan, Unione Luca, de Vries Robert P
Department of Chemical Biology & Drug Discovery, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Universiteitsweg 99, 3584CG Utrecht, the Netherlands.
CICbioGUNE, Basque Research & Technology Alliance (BRTA), Bizkaia Technology Park, Building 800, Bizkaia, 48160 Derio, Spain; Ikerbasque, Basque Foundation for Science, 48013 Bilbao, Spain.
Cell Rep. 2025 Jul 17;44(8):116007. doi: 10.1016/j.celrep.2025.116007.
Since their introduction into humans, H3N2 influenza A viruses have evolved continuously to escape immunity through antigenic drift, driven by mutations in and around the receptor-binding site. Recently, these changes resulted in viruses that recognize elongated glycans, which are less abundant in the human respiratory tract, complicating vaccine strain propagation. This study employed ELISA, glycan arrays, tissue staining, flow cytometry, and hemagglutinin (HA) assays to demonstrate the molecular determinants of recent H3N2 viruses that regained recognition of shorter glycans. Mutations Y159N/T160I in contemporary strains replace Y159/T160, weakening receptor binding. However, this is compensated by Y195F in the 190-helix. These findings highlight epistasis across critical residues in the HA receptor-binding site, including the 130-loop, 150-loop, and 190-helix. Interestingly, a positive correlation exists between binding to an asymmetrical N-glycan and binding to human and ferret respiratory tract tissues. These results elucidate the epistatic nature of receptor-binding specificity during influenza A virus H3N2 evolution.
自甲型H3N2流感病毒传入人类以来，它们不断进化，通过抗原漂移逃避免疫，这是由受体结合位点及其周围的突变驱动的。最近，这些变化导致病毒能够识别在人类呼吸道中含量较少的细长聚糖，这使得疫苗毒株的繁殖变得复杂。本研究采用酶联免疫吸附测定（ELISA）、聚糖阵列、组织染色、流式细胞术和血凝素（HA）测定，以证明近期重新获得对较短聚糖识别能力的H3N2病毒的分子决定因素。当代毒株中的Y159N/T160I突变取代了Y159/T160，削弱了受体结合。然而，这被190螺旋中的Y195F所补偿。这些发现突出了HA受体结合位点中关键残基之间的上位性，包括130环、150环和190螺旋。有趣的是，与不对称N-聚糖的结合与人及雪貂呼吸道组织的结合之间存在正相关。这些结果阐明了甲型H3N2流感病毒进化过程中受体结合特异性的上位性本质。
