Department of Molecular Biology and Biochemistry, University of California, Irvine, 560 Steinhaus Hall, Irvine, CA 92697-3900, USA.
Microbiol Mol Biol Rev. 2011 Jun;75(2):268-85. doi: 10.1128/MMBR.00041-10.
Atomic force microscopy (AFM) can visualize almost everything pertinent to structural virology and at resolutions that approach those for electron microscopy (EM). Membranes have been identified, RNA and DNA have been visualized, and large protein assemblies have been resolved into component substructures. Capsids of icosahedral viruses and the icosahedral capsids of enveloped viruses have been seen at high resolution, in some cases sufficiently high to deduce the arrangement of proteins in the capsomeres as well as the triangulation number (T). Viruses have been recorded budding from infected cells and suffering the consequences of a variety of stresses. Mutant viruses have been examined and phenotypes described. Unusual structural features have appeared, and the unexpectedly great amount of structural nonconformity within populations of particles has been documented. Samples may be imaged in air or in fluids (including culture medium or buffer), in situ on cell surfaces, or after histological procedures. AFM is nonintrusive and nondestructive, and it can be applied to soft biological samples, particularly when the tapping mode is employed. In principle, only a single cell or virion need be imaged to learn of its structure, though normally images of as many as is practical are collected. While lateral resolution, limited by the width of the cantilever tip, is a few nanometers, height resolution is exceptional, at approximately 0.5 nm. AFM produces three-dimensional, topological images that accurately depict the surface features of the virus or cell under study. The images resemble common light photographic images and require little interpretation. The structures of viruses observed by AFM are consistent with models derived by X-ray crystallography and cryo-EM.
原子力显微镜（AFM）可以观察到几乎所有与结构病毒学相关的内容，其分辨率可接近电子显微镜（EM）的分辨率。已经识别出了膜，已经观察到了 RNA 和 DNA，并且已经将大型蛋白质组装体解析为组成亚结构。已经以高分辨率观察到了二十面体病毒的衣壳和包膜病毒的二十面体衣壳，在某些情况下，分辨率足够高，可以推断出衣壳粒中的蛋白质排列以及三角数（T）。已经记录了病毒从受感染的细胞中出芽，并遭受各种压力的后果。已经检查了突变病毒并描述了表型。出现了异常的结构特征，并且已经记录了颗粒群体中出乎意料的大量结构不一致性。可以在空气中或液体中（包括培养基或缓冲液）、在细胞表面原位或在组织学程序之后对样品进行成像。AFM 是非侵入性和非破坏性的，可以应用于软生物样品，特别是在采用轻敲模式时。原则上，只需对单个细胞或病毒粒子进行成像即可了解其结构，尽管通常会收集尽可能多的图像。虽然横向分辨率受悬臂尖端的宽度限制，只有几个纳米，但高度分辨率却异常出色，约为 0.5nm。AFM 产生的三维、拓扑图像准确地描绘了研究中的病毒或细胞的表面特征。这些图像类似于常见的光照片图像，几乎不需要解释。通过 AFM 观察到的病毒结构与通过 X 射线晶体学和 cryo-EM 得出的模型一致。
