MDA5 Detects the Double-Stranded RNA Replicative Form in Picornavirus-Infected Cells

• DOI: 10.1016/j.celrep.2012.10.005
• Publication Date: 2012-11-08T19:16:52Z
• Authors: Qian Feng; Stanleyson V. Hato; Martijn A. Langereis; Jan Zoll; Richard Virgen-Slane; Alys Peisley; Sun Hur; Bert L. Semler; Ronald P. van Rij; Frank J.M. van Ku...
• Keywords: 0301 basic medicine; Interferon-Induced Helicase, IFIH1; QH301-705.5; Messenger; Picornaviridae; Transfection; Article; Cell Line; DEAD-box RNA Helicases; Double-Stranded; Mice; 03 medical and health sciences; self; Animals; Humans; Viral; Horses; RNA, Messenger; Biology (General); RNA, Double-Stranded; NCMLS 2: Immune Regulation; Interferon-alpha; Interferon-beta; initiation; Up-Regulation; Poly I-C; RNA; RNA, Viral; acid; recognition; protein; N4i 1: Pathogenesis and modulation of inflammation NCMLS 1: Infection and autoimmunity; N4i 2: Invasive mycoses and compromised host NCMLS 1: Infection and autoimmunity; HeLa Cells

RIG-I and MDA5 are cytosolic RNA sensors that play a critical role in innate antiviral responses. Major advances have been made in identifying RIG-I ligands, but our knowledge of the ligands for MDA5 remains restricted to data from transfection experiments mostly using poly(I:C), a synthetic dsRNA mimic. Here, we dissected the IFN-α/β-stimulatory activity of different viral RNA species produced during picornavirus infection, both by RNA transfection and in infected cells in which specific steps of viral RNA replication were inhibited. Our results show that the incoming genomic plus-strand RNA does not activate MDA5, but minus-strand RNA synthesis and production of the 7.5 kbp replicative form trigger a strong IFN-α/β response. IFN-α/β production does not rely on plus-strand RNA synthesis and thus generation of the partially double-stranded replicative intermediate. This study reports MDA5 activation by a natural RNA ligand under physiological conditions.