Infection of chicken coronavirus infectious bronchitis virus (IBV) is initiated by binding of the viral heavily N-glycosylated attachment protein spike to the alpha-2,3-linked sialic acid receptor Neu5Ac. Previously, we have shown that N-glycosylation of recombinantly expressed receptor binding domain (RBD) of the spike of IBV-M41 is of critical importance for binding to chicken trachea tissue. Here we investigated the role of N-glycosylation of the RBD on receptor specificity and virus replication in the context of the virus particle. Using our reverse genetics system we were able to generate recombinant IBVs for nine-out-of-ten individual N-glycosylation mutants. In vitro growth kinetics of these viruses were comparable to the virus containing the wild-type M41-S1. Furthermore, Neu5Ac binding by the recombinant viruses containing single N-glycosylation site knock-out mutations matched the Neu5Ac binding observed with the recombinant RBDs. Five N-glycosylation mutants lost the ability to bind Neu5Ac and gained binding to a different, yet unknown, sialylated glycan receptor on host cells. These results demonstrate that N-glycosylation of IBV is a determinant for receptor specificity.

中文翻译：

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传染性支气管炎病毒 M41 刺突的 N-糖基化决定了受体特异性。


鸡冠状病毒传染性支气管炎病毒 (IBV) 的感染是通过病毒高度 N-糖基化的附着蛋白刺突与 α-2,3 连接的唾液酸受体 Neu5Ac 的结合来启动的。此前，我们已经证明，IBV-M41 刺突重组表达的受体结合域 (RBD) 的 N-糖基化对于与鸡气管组织的结合至关重要。在这里，我们研究了 RBD N-糖基化对病毒颗粒背景下受体特异性和病毒复制的作用。使用我们的反向遗传学系统，我们能够为十分之九的个体 N-糖基化突变体生成重组 IBV。这些病毒的体外生长动力学与含有野生型 M41-S1 的病毒相当。此外，含有单个 N-糖基化位点敲除突变的重组病毒的 Neu5Ac 结合与重组 RBD 观察到的 Neu5Ac 结合相匹配。五个 N-糖基化突变体失去了结合 Neu5Ac 的能力，并获得了与宿主细胞上不同但未知的唾液酸化聚糖受体的结合。这些结果证明 IBV 的 N-糖基化是受体特异性的决定因素。