Role of hemagglutinin surface density in the initial stages of influenza virus fusion:: Lack of evidence for cooperativity
Role of hemagglutinin surface density in the initial stages of influenza virus fusion:: Lack of evidence for cooperativity
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DOI：
10.1128/jvi.74.6.2714-2720.2000
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发表时间：
2000-03-01
影响因子：
5.4
通讯作者：
Stegmann, T
中科院分区：
文献类型：
--
作者：
G端nther-Ausborn, S;Schoen, P;Stegmann, T
流感病毒血凝素（HA）介导的膜融合被认为是通过多个HA三聚体的协同作用进行的。为了确定触发融合所需的HA三聚体的最小数量，并评估这些HA三聚体之间协同作用的重要性，我们生成了含有源自两种不同pH依赖性病毒株的核心重组HA的病毒体，X-47（最佳融合pH为5.1，阈值pH为5.6）和A/Shangdong(最佳融合pH为5.6；阈值为pn 6.0)，并通过荧光脂质混合试验测量这些病毒体与红细胞鬼的融合。在一定的HA /脂质比下，不同X-47- a /山东HA比的病毒体表现出相似的鬼影结合活性，低ph诱导的a /山东HA的构象变化不影响X-47 HA的融合活性。当pH为5.7时，这些病毒体的初始融合率与A/山东HA的表面密度成正比，每个病毒体一个A/山东三聚体似乎足以诱导融合。融合开始前延迟时间的倒数与融合能HA的表面密度成正比。这些结果支持了HA三聚体在流感病毒融合过程中没有协同作用的观点。
Membrane fusion mediated by influenza virus hemagglutinin (HA) is believed to proceed via the cooperative action of multiple HA trimers. To determine the minimal number of HA trimers required to trigger fusion, and to assess the importance of cooperativity between these HA trimers, we have generated virosomes containing coreconstituted HAs derived from two strains of virus with different pH dependencies for fusion, X-47 (optimal fusion at pH 5.1; threshold at pH 5.6) and A/Shangdong (optimal fusion at pH 5.6; threshold at pn 6.0), and measured fusion of these virosomes with erythrocyte ghosts by a fluorescence lipid mixing assay. Virosomes with different X-47-to-A/Shangdong HA ratios, at a constant HA-to-lipid ratio, showed comparable ghost-binding activities, and the low-pH-induced conformational change of A/Shangdong HA did not affect the fusion activity of X-47 HA. The initial rate of fusion of these virosomes at pH 5.7 increased directly proportional to the surface density of A/Shangdong HA, and a single A/Shangdong trimer per virosome appeared to suffice to induce fusion. The reciprocal of the lag time before the onset of fusion was directly proportional to the surface density of fusion-competent HA. These results support the notion that there is no cooperativity between HA trimers during influenza virus fusion.