Although icosahedral viruses have obvious and highly symmetrical features, asymmetric structural elements are also present. Asymmetric features may be inherent since the genome and location of minor capsid proteins are typically incorporated without adhering to icosahedral symmetry. Asymmetry also develops during the virus life cycle in order to accomplish key functions such as genome packaging, release, and organization. However, resolving asymmetric features complicates image processing during single-particle cryoEM analysis. This review summarizes the current state of knowledge regarding asymmetric structural features with specific examples drawn from members of picornaviridae, parvoviradae, microviradae, and leviviridae.

虽然二十面体病毒具有明显和高度对称的特征，但也存在不对称结构元素。不对称特征可能是固有的，因为次要衣壳蛋白的基因组和位置通常在不遵守二十面体对称性的情况下并入。为了完成基因组包装、释放和组织等关键功能，病毒生命周期中也会出现不对称性。然而，解决不对称特征会使单粒子冷冻电镜分析过程中的图像处理复杂化。这篇综述总结了关于不对称结构特征的知识现状，并给出了来自小核糖核酸病毒科、细小病毒科、微病毒科和小病毒科成员的具体例子。