Marx P A, Munn R J, Joy K I
California Primate Research Center, Department of Medical Pathology, University of California, Davis.
Lab Invest. 1988 Jan;58(1):112-8.
Electron microscopy of human immunodeficiency virus (HIV) has provided evidence for a virion model which when sectioned, consists of a circular envelope surrounding an inner conical core. When sections are perpendicular to the core axis, the envelope is still circular, but the tapered core appears as a dot near the center of the envelope. An observation inconsistent with the present model is the frequent finding of an electron-lucent "polygonal window" associated with the virion envelope. Here, we provide evidence for a new model of HIV. This model, which accounts for the polygonal windows and the shape of the envelope, places the conical core inside a regular polyhedron that lies just under the envelope. We tested the validity of various polyhedrons with three-dimensional computer graphics which emulate thin section electron microscopy. With this technique, about 2000 computer-generated "thin sections" of HIV-models were compared with electron micrographs of HIV. A structure consistent with the computer-generated data reveals a detailed model for HIV with the following features; (a) the conical core is inside an envelope-associated capsid having icosadeltahedral symmetry. This envelope-associated capsid is 60-sided and contains 32 vertices, 20 of which have hexagonal symmetry and 12 of which have pentagonal symmetry, (b) the inner rodlike core abuts the inside of any 2 opposing hexagonal vertices, (c) the pentagonal vertices do not support the inner core. A comparison of these results with that of Gelderblom et al. (Gelderblom HR, Hausmann EHS, Ozel M, Pauli G, Koch MA: Fine structure of HIV and immunolocalization of structural proteins. Virology 156: 171, 1987), suggests that the p17 polypeptide is a component of the envelope-associated icosadeltahedral capsid. This computer emulation technique provides a thorough test of this model of HIV, but does not constitute proof. Additional testing methods such as bidirectional metal shadowing and freeze etching will be needed to confirm this new virion structure. Additionally, this computer technique may be useful for testing the proposed morphology for cell organelles.
对人类免疫缺陷病毒（HIV）的电子显微镜观察为一种病毒体模型提供了证据，该模型在切片时，由围绕内部锥形核心的圆形包膜组成。当切片垂直于核心轴时，包膜仍然是圆形的，但逐渐变细的核心在包膜中心附近呈现为一个点。一个与当前模型不一致的观察结果是，经常发现与病毒体包膜相关的电子透明“多边形窗口”。在此，我们为HIV提出了一种新模型。该模型解释了多边形窗口和包膜的形状，将锥形核心置于恰好在包膜下方的正多面体内。我们使用模拟薄切片电子显微镜的三维计算机图形技术测试了各种多面体的有效性。通过这项技术，将约2000个计算机生成的HIV模型“薄切片”与HIV的电子显微照片进行了比较。与计算机生成数据一致的结构揭示了具有以下特征的HIV详细模型：（a）锥形核心位于具有二十面体对称性的包膜相关衣壳内。这个包膜相关衣壳有60个面，包含32个顶点，其中20个具有六边形对称性，12个具有五边形对称性；（b）内部棒状核心紧靠任意两个相对的六边形顶点内部；（c）五边形顶点不支撑内部核心。将这些结果与盖尔德布洛姆等人（Gelderblom HR，Hausmann EHS，Ozel M，Pauli G，Koch MA：HIV的精细结构和结构蛋白的免疫定位。病毒学156：171，1987）的结果进行比较，表明p17多肽是包膜相关二十面体衣壳的一个组成部分。这种计算机模拟技术对该HIV模型进行了全面测试，但并不构成证据。还需要双向金属阴影和冷冻蚀刻等额外测试方法来确认这种新的病毒体结构。此外，这种计算机技术可能有助于测试所提出的细胞器形态。
