University of Lübeck, Institute of Virology and Cell Biology,Ratzeburger Allee 160, 23562 Lübeck, Germany.
University of Lübeck, Institute of Chemistry,Ratzeburger Allee 160, 23562 Lübeck, Germany.
Glycobiology. 2017 Nov 1;27(11):1027-1037. doi: 10.1093/glycob/cwx078.
Human noroviruses (HuNoV), members of the family Caliciviridae, are the major cause of acute viral gastroenteritis worldwide. Successful infection is linked to the ability of the protruding (P) domain of the viral capsid to bind histo-blood group antigens (HBGA). Binding to gangliosides plays a major role for many nonhuman calici- and noroviruses. Increasing evidence points to a broader role of sialylated carbohydrates such as gangliosides in norovirus infection. Here, we compare HBGA and ganglioside binding of a GII.4 HuNoV variant (MI001), previously shown to be infectious in a HuNoV mouse model. Saturation transfer difference nuclear magnetic resonance spectroscopy, native mass spectrometry (MS) and surface plasmon resonance spectroscopy were used to characterize binding epitopes, affinities, stoichiometry and dynamics, focusing on 3'-sialyllactose, the GM3 ganglioside saccharide and B antigen. Binding was observed for 3'-sialyllactose and various HBGAs following a multistep binding process. Intrinsic affinities (Kd) of fucose, 3'-sialyllactose and B antigen were determined for the individual binding steps. Stronger affinities were observed for B antigen over 3'-sialyllactose and fucose, which bound in the mM range. Binding stoichiometry was analyzed by native MS showing the presence of four B antigens or two 3'-sialyllactose in the complex. Epitope mapping of 3'-sialyllactose revealed direct interaction of α2,3-linked sialic acid with the P domain. The ability of HuNoV to engage multiple carbohydrates emphasizes the multivalent nature of norovirus glycan-specificity. Our findings reveal direct binding of a GII.4 HuNoV P dimer to α2,3-linked sialic acid and support a broader role of ganglioside binding in norovirus infection.
人类诺如病毒（HuNoV）属于杯状病毒科，是全世界急性病毒性胃肠炎的主要病原体。病毒衣壳的突出（P）结构域与特定的组织血型抗原（HBGA）结合是成功感染的关键。许多非人类杯状病毒和诺如病毒主要通过与神经节苷脂结合来实现感染。越来越多的证据表明，唾液酸化碳水化合物（如神经节苷脂）在诺如病毒感染中发挥着更广泛的作用。在这里，我们比较了先前在 HuNoV 小鼠模型中显示具有感染性的 GII.4 HuNoV 变体（MI001）与 HBGA 和神经节苷脂的结合。我们使用饱和转移差核磁共振波谱、天然质谱（MS）和表面等离子体共振光谱来表征结合表位、亲和力、计量和动力学，重点研究 3'-唾液酸乳糖、GM3 神经节苷脂糖和 B 抗原。观察到 3'-唾液酸乳糖和各种 HBGA 在后多步结合过程中发生结合。确定了每个结合步骤中果糖、3'-唾液酸乳糖和 B 抗原的固有亲和力（Kd）。B 抗原与 3'-唾液酸乳糖和果糖相比具有更强的亲和力，其结合在 mM 范围内。通过天然 MS 分析得出结合计量，结果显示复合物中存在四个 B 抗原或两个 3'-唾液酸乳糖。3'-唾液酸乳糖的表位作图揭示了α2,3 连接的唾液酸与 P 结构域的直接相互作用。HuNoV 能够结合多种碳水化合物，这强调了诺如病毒糖基特异性的多价性质。我们的研究结果揭示了 GII.4 HuNoV P 二聚体与α2,3 连接的唾液酸的直接结合，并支持神经节苷脂结合在诺如病毒感染中的更广泛作用。
