Centro Nacional de Biotecnologia (CNB-CSIC) , Darwin, 3 , 28049 Madrid , Spain.
Departament de Física de la Matèria Condensada, Facultat de Física , Universitat de Barcelona , Martí i Franquès 1 , 08028 Barcelona , Spain.
ACS Nano. 2019 Jul 23;13(7):7842-7849. doi: 10.1021/acsnano.9b02133. Epub 2019 Jun 26.
Viruses undergo mesoscopic morphological changes as they interact with host interfaces and in response to chemical cues. The dynamics of these changes, over the entire temporal range relevant to virus processes, are unclear. Here, we report on creep compliance experiments on a small icosahedral virus under uniaxial constant stress. We find that even at small stresses, well below the yielding point and generally thought to induce a Hookean response, strain continues to develop in time sparse, randomly distributed, relatively rapid plastic events. The intermittent character of mechanical compliance only appears above a loading threshold, similar to situations encountered in granular flows and the plastic deformation of crystalline solids. The threshold load is much smaller for the empty capsids of the brome mosaic virus than for the wild-type virions. The difference highlights the involvement of RNA in stabilizing the assembly interface. Numerical simulations of spherical crystal deformation suggest intermittency is mediated by lattice defect dynamics and identify the type of compression-induced defect that nucleates the transition to plasticity.
病毒在与宿主界面相互作用以及响应化学信号时会发生介观形态变化。这些变化的动力学在与病毒过程相关的整个时间范围内尚不清楚。在这里，我们报告了在单轴恒应力下对一种小型二十面体病毒进行的蠕变实验。我们发现，即使在远远低于屈服点且通常被认为会产生胡克响应的较小应力下，应变也会随着时间的推移而持续发展，表现为稀疏、随机分布、相对较快的塑性事件。力学顺应性的间歇性仅在加载阈值以上出现，类似于在颗粒流和晶体固体的塑性变形中遇到的情况。空衣壳的布鲁氏菌病毒的空载阈值比野生型病毒粒子小得多。这种差异突出了 RNA 参与稳定组装界面的作用。球形晶体变形的数值模拟表明，不连续性是由晶格缺陷动力学介导的，并确定了引发向塑性转变的压缩诱导缺陷的类型。
