Measuring Site-specific Glycosylation Similarity between Influenza a Virus Variants with Statistical Certainty.
Measuring Site-specific Glycosylation Similarity between Influenza a Virus Variants with Statistical Certainty.
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DOI：
10.1074/mcp.ra120.002031
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发表时间：
2020-09
期刊：
影响因子：
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通讯作者：
Zaia J
中科院分区：
文献类型：
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作者：
Chang D;Hackett WE;Zhong L;Wan XF;Zaia J
甲型流感病毒的抗原漂移导致疫苗效果不佳。包膜蛋白血凝素上积累的 N 连接糖基化位点可以保护抗原区域免受适应性免疫反应的影响。定量了解糖基化相似性如何与蛋白质序列变异或病毒表达平台的变化相关，对于改进疫苗设计是必要的。这些结果表明，与野生型对应物相比，流感突变株具有明显不同的糖基化。甲型流感病毒中 N 连接糖基化的变化会影响病毒的抗原性。即使在异源糖基化蛋白质中，也可以量化糖基化相似性。流感病毒中的糖基化与相关毒株具有可测量的、位点特异性的不同。甲型流感病毒 (IAV) 突变迅速，导致抗原漂移和疫苗逐年效果不佳。设计有效疫苗的一大挑战是基因突变经常导致 IAV 包膜蛋白血凝素 (HA) 的氨基酸发生变化，从而产生新的 N-糖基化序列。由此产生的 N-聚糖会引起抗原屏蔽，使病毒能够逃避适应性免疫反应。目前，候选疫苗菌株的选择涉及将流行菌株中的抗原性与 HA 蛋白序列相关联，但位点特异性糖基化信息的定量比较可能会提高设计针对进化菌株的更广泛有效性的疫苗的能力。然而，人们对糖基化对HA的免疫优势、抗原性和免疫原性的影响了解甚少，并且没有经过充分测试的方法来比较病毒样本之间的糖基化相似性。在这里，我们提出了一种对两种相关病毒株之间的相似性进行统计严格量化的方法，该方法考虑了糖肽糖型的存在和丰度。我们通过确定来自 A/Switzerland/9715293/2013 (SWZ13) 的 WT IAV HA 和 SWZ13 突变株之间在蛋白质水平上的糖基化存在可量化的差异来证明我们方法的优势，即使 N-糖基化序列没有改变。我们确定了位点特异性，WT 和突变体 HA 在头部结构域的糖基化位点上具有不同的相似性，反映了在保持病毒适应性的同时逃避宿主免疫反应的竞争压力。据我们所知，我们的结果首次量化了具有相当大聚糖异质性的相关蛋白质中发生的糖基化状态的变化。我们的结果提供了一种了解糖基化状态的变化如何与蛋白质序列的变化相关的方法，这对于改进 IAV 疫苗株的选择是必要的。当我们找到用于疫苗生产的新表达载体时，了解糖基化尤其重要，因为糖基化状态很大程度上取决于宿主物种。
Antigenic drift in influenza A virus results in poor vaccine effectiveness. Accumulating N-linked glycosylation sites on the envelope protein hemagglutinin shield antigenic regions from adaptive immune responses. Quantitatively understanding how glycosylation similarity correlates with changes in protein sequence variation or viral expression platforms is necessary for improving vaccine design. These results presented demonstrate that a mutant strain of influenza has measurably distinct glycosylation compared to its wild-type counterpart. Highlights Changes in N-linked glycosylation in influenza A virus affect antigenicity of the virus. Glycosylation similarity can be quantified, even in heterogeneously glycosylated proteins. Glycosylation is measurably and site-specifically distinct in influenza from related strains. Influenza A virus (IAV) mutates rapidly, resulting in antigenic drift and poor year-to-year vaccine effectiveness. One challenge in designing effective vaccines is that genetic mutations frequently cause amino acid variations in IAV envelope protein hemagglutinin (HA) that create new N-glycosylation sequons; resulting N-glycans cause antigenic shielding, allowing viral escape from adaptive immune responses. Vaccine candidate strain selection currently involves correlating antigenicity with HA protein sequence among circulating strains, but quantitative comparison of site-specific glycosylation information may likely improve the ability to design vaccines with broader effectiveness against evolving strains. However, there is poor understanding of the influence of glycosylation on immunodominance, antigenicity, and immunogenicity of HA, and there are no well-tested methods for comparing glycosylation similarity among virus samples. Here, we present a method for statistically rigorous quantification of similarity between two related virus strains that considers the presence and abundance of glycopeptide glycoforms. We demonstrate the strength of our approach by determining that there was a quantifiable difference in glycosylation at the protein level between WT IAV HA from A/Switzerland/9715293/2013 (SWZ13) and a mutant strain of SWZ13, even though no N-glycosylation sequons were changed. We determined site-specifically that WT and mutant HA have varying similarity at the glycosylation sites of the head domain, reflecting competing pressures to evade host immune response while retaining viral fitness. To our knowledge, our results are the first to quantify changes in glycosylation state that occur in related proteins of considerable glycan heterogeneity. Our results provide a method for understanding how changes in glycosylation state are correlated with variations in protein sequence, which is necessary for improving IAV vaccine strain selection. Understanding glycosylation will be especially important as we find new expression vectors for vaccine production, as glycosylation state depends greatly on the host species.