title: A virus-encoded inhibitor that blocks RNA interference in mammalian cells.
abstract: Nodamura virus (NoV) is a small RNA virus that is infectious for insect and mammalian hosts. We have developed a highly sensitive assay of RNA interference (RNAi) in mammalian cells that shows that the NoV B2 protein functions as an inhibitor of RNAi triggered by either short hairpin RNAs or small interfering RNAs. In the cell, NoV B2 binds to pre-Dicer substrate RNA and RNA-induced silencing complex (RISC)-processed RNAs and inhibits the Dicer cleavage reaction and, potentially, one or more post-Dicer activities. In vitro, NoV B2 inhibits Dicer-mediated RNA cleavage in the absence of any other host factors and specifically binds double-stranded RNAs corresponding in structure to Dicer substrates and products. Its abilities to bind to Dicer precursor and post-Dicer RISC-processed RNAs suggest a mechanism of inhibition that is unique among known viral inhibitors of RNAi.
authors.affiliation: G. W. Hooper Research Foundation, University of California, San Francisco, 513 Parnassus Ave., HSW 1501, Box 0552, San Francisco, CA 94143-0552, USA. csulliv1@itsa.ucsf.edu
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Sullivan
authors.forename: Don
authors.initials: D
authors.lastname: Ganem
mesh_terms: D002460:Cell Line; D053487:DEAD-box RNA Helicases; D004722:Endoribonucleases / Q000378:metabolism; D005821:Genetic Techniques; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D030381:Nodaviridae / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity; D020365:RNA Helicases / Q000378:metabolism; D034622:RNA Interference; D012330:RNA, Double-Stranded / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D034743:RNA-Induced Silencing Complex / Q000378:metabolism; D043244:Ribonuclease III; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
chemical_list: D012330:RNA, Double-Stranded; D034741:RNA, Small Interfering; D034743:RNA-Induced Silencing Complex; D014764:Viral Proteins; D049452:Green Fluorescent Proteins; D004722:Endoribonucleases; C408087:DICER1 protein, human; D043244:Ribonuclease III; D053487:DEAD-box RNA Helicases; D020365:RNA Helicases