科学家发现了一种冠状病毒的三维结构。冠状病毒会造成上呼吸道和胃肠道的炎症，而且可能导致从SARS到感冒在内的疾病。Abraham Koster及其同事利用一种电子显微镜技术获得了鼠肝炎冠状病毒（MHV）及其核糖核蛋白核心的完整图像。此前，科学家只有它们的二维图像，这妨碍了对该病毒的发病机制的详细研究。
冠状病毒是一种“包膜”病毒，这意味着它们的病毒载荷被蛋白质覆盖，这些蛋白质帮助病毒与其宿主融合。这组科学家证明了鼠冠状病毒有一个明显的球形外形，以及一个厚的异乎寻常的包膜，几乎是典型生物膜的厚度的两倍。他们报告说，这种额外的厚度是由一种广泛折叠的蛋白质核心而非一个有壳核心构成的一个额外的内层造成的。这组作者提出，破解鼠肝炎冠状病毒的结构可以让科学家更好地为该病毒基因组建模，并提供对哺乳动物病毒结构的更完整的理解。（生物谷Bioon.com）
生物谷推荐原始出处：
PNAS January 5, 2009, doi: 10.1073/pnas.0805270106
Cryo-electron tomography of mouse hepatitis virus: Insights into the structure of the coronavirion
Montserrat Bárcenaa, Gert T. Oostergetelb, Willem Bartelinkc, Frank G. A. Faasa, Arie Verkleijd, Peter J. M. Rottierc, Abraham J. Kostera,1, and Berend Jan Boschc
aDepartment of Molecular Cell Biology, Electron Microscopy Section, Leiden University Medical Center, 2300 RC, Leiden, The Netherlands
bBiophysical Chemistry, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9497 AG, Groningen, The Netherlands
cDepartment of Infectious Diseases and Immunology, Virology Division, Faculty of Veterinary Medicine, Utrecht University, 3584 CL, Utrecht, The Netherlands; and
dDepartment of Molecular Cell Biology, Utrecht University, 3584 CH, Utrecht, The Netherlands
Edited by Stanley Perlman, University of Iowa, Iowa City, IA, and accepted by the Editorial Board November 20, 2008 (received for review June 3, 2008)
Abstract
Coronaviruses are enveloped viruses containing the largest reported RNA genomes. As a result of their pleomorphic nature, our structural insight into the coronavirion is still rudimentary, and it is based mainly on 2D electron microscopy. Here we report the 3D virion structure of coronaviruses obtained by cryo-electron tomography. Our study focused primarily on the coronavirus prototype murine hepatitis virus (MHV). MHV particles have a distinctly spherical shape and a relatively homogenous size (≈85 nm envelope diameter). The viral envelope exhibits an unusual thickness (7.8 ± 0.7 nm), almost twice that of a typical biological membrane. Focal pairs revealed the existence of an extra internal layer, most likely formed by the C-terminal domains of the major envelope protein M. In the interior of the particles, coiled structures and tubular shapes are observed, consistent with a helical nucleocapsid model. Our reconstructions provide no evidence of a shelled core. Instead, the ribonucleoprotein seems to be extensively folded onto itself, assuming a compact structure that tends to closely follow the envelope at a distance of ≈4 nm. Focal contact points and thread-like densities connecting the envelope and the ribonucleoprotein are revealed in the tomograms. Transmissible gastroenteritis coronavirion tomograms confirm all the general features and global architecture observed for MHV. We propose a general model for the structure of the coronavirion in which our own and published observations are combined.
