A unifying structural and functional model of the coronavirus replication organelle: Tracking down RNA synthesis

by Eric J. Snijder, Ronald W. A. L. Limpens, Adriaan H. de Wilde, Anja W. M. de Jong, Jessika C. Zevenhoven-Dobbe, Helena J. Maier, Frank F. G. A. Faas, Abraham J. Koster, Montserrat B árcena Zoonotic coronavirus (CoV) infections, such as those responsible for the current severe acute respiratory syndrome-CoV 2 (SARS-CoV-2) pandemic, cause grave international public health concern. In infected cells, the CoV RNA-synthesizing machinery associates with modified endoplasmic reticulum memb ranes that are transformed into the viral replication organelle (RO). Although double-membrane vesicles (DMVs) appear to be a pan-CoV RO element, studies to date describe an assortment of additional CoV-induced membrane structures. Despite much speculation, it remains unclear which RO element(s) acc ommodate viral RNA synthesis. Here we provide detailed 2D and 3D analyses of CoV ROs and show that diverse CoVs essentially induce the same membrane modifications, including the small open double-membrane spherules (DMSs) previously thought to be restricted to gamma- and delta-CoV infections and pro posed as sites of replication. Metabolic labeling of newly synthesized viral RNA followed by quantitative electron microscopy (EM) autoradiography revealed abundant viral RNA synthesis associated with DMVs in cells infected with the beta-CoVs Middle East respiratory syndrome-CoV (MERS-CoV) and SARS- CoV and the gamma-CoV infectious bronchitis virus. RNA synthesis could not be linked to DMSs or any othe...
Source: PLoS Biology: Archived Table of Contents - Category: Biology Authors: Source Type: research