Department of Chemistry and Biochemistry, Emmy-Noether Group "Bionanointerfaces" , Freie Universität Berlin , Takustrasse 3 , 14195 Berlin , Germany.
Department of Biology, Molecular Biophysics , Humboldt-Universität zu Berlin, IRI Life Sciences , Invalidenstr. 42 , 10115 Berlin , Germany.
Nano Lett. 2019 Mar 13;19(3):1875-1882. doi: 10.1021/acs.nanolett.8b04969. Epub 2019 Feb 13.
Viruses, such as influenza A, typically bind to the plasma membrane of their host by engaging multiple membrane receptors in parallel, thereby forming so-called multivalent interactions that are created by the collective action of multiple weak ligand-receptor bonds. The overall interaction strength can be modulated by changing the number of engaged receptors. This feature is used by viruses to achieve a sufficiently firm attachment to the host's plasma membrane but also allows progeny viruses to leave the plasma membrane after completing the virus replication cycle. Design of strategies to prevent infection, for example, by disturbing these attachment and detachment processes upon application of antivirals, requires quantification of the underlying multivalent interaction in absence and presence of antivirals. This is still an unresolved problem, as there is currently no approach available that allows for determining the valency (i.e., of the number of receptors bound to a particular virus) on the level of single viruses under equilibrium conditions. Herein, we track the motion of single influenza A/X31 viruses (IAVs; interacting with the ganglioside GD1a incorporated in a supported lipid bilayer) using total internal reflection fluorescence microscopy and show that IAV residence time distributions can be deconvoluted from valency effects by taking the IAV mobility into account. The so-derived off-rate distributions, expressed in dependence of an average, apparent valency, show the expected decrease in off-rate with increasing valency but also show an unexpected peak structure, which can be linked to a competition in the opposing functionalities of the two influenza A virus spike proteins, hemagglutinin (HA), and neuraminidase (NA). By application of the antiviral zanamivir that inhibits the activity of NA, we provide direct evidence, how the HA/NA balance modulates this virus-receptor interaction, allowing us to assess the inhibition concentration of zanamivir based on its effect on the multivalent interaction.
病毒，如甲型流感病毒，通常通过并行结合多个膜受体来与宿主的质膜结合，从而形成所谓的多价相互作用，这种相互作用是由多个弱配体-受体键的集体作用产生的。通过改变结合的受体数量，可以调节整体相互作用强度。这种特性被病毒用于实现与宿主质膜的足够牢固附着，但也允许子代病毒在完成病毒复制周期后离开质膜。设计预防感染的策略，例如通过在应用抗病毒药物时干扰这些附着和脱离过程，需要在没有和存在抗病毒药物的情况下量化潜在的多价相互作用。这仍然是一个未解决的问题，因为目前没有可用的方法可以在平衡条件下确定单个病毒上的价数（即结合到特定病毒的受体数量）。在此，我们使用全内反射荧光显微镜跟踪单个甲型流感病毒（IAV；与整合在支撑脂质双层中的神经节苷脂 GD1a 相互作用）的运动，并表明可以通过考虑 IAV 的迁移率来从价数效应中解卷积 IAV 停留时间分布。以平均表观价数为条件表示的由此得出的离解速率分布显示，离解速率随价数的增加而降低，但也显示出出乎意料的峰结构，这可以与两种流感病毒刺突蛋白血凝素（HA）和神经氨酸酶（NA）的相反功能之间的竞争相关。通过应用抑制 NA 活性的抗病毒药物扎那米韦，我们提供了直接证据，证明 HA/NA 平衡如何调节这种病毒-受体相互作用，使我们能够基于其对多价相互作用的影响来评估扎那米韦的抑制浓度。
