title: Broad bean wilt virus 2 encoded VP53, VP37 and large capsid protein orchestrate suppression of RNA silencing in plant.
abstract: Viruses encode RNA silencing suppressors to counteract host RNA silencing-mediated defense responses. In this study, we demonstrate that VP53, VP37 and LCP encoded by RNA2 of broad bean wilt virus 2 (BBWV-2), a member of the genus Fabavirus, are strong suppressors of RNA silencing triggered by single-stranded sense RNA. They, however, had no effect on suppression of RNA silencing induced by double-stranded RNA. We provide evidence that these three suppressors can significantly limit the accumulation of small interfering RNAs (siRNAs) in tissues where the GFP gene has been silenced, and prevent the long distance spread of the induced silencing signal. Gel mobility shift assays showed that all three suppressors could bind ssRNA in a size-specific manner. Interestingly, VP37 and LCP, but not VP53, could reverse the silencing of a GFP gene in leaf tissue. Furthermore, these three proteins are capable of enhancing pathogenicity of potato virus X. Collectively, our findings indicate that viruses employ a more sophisticated strategy to overcome the host defense response mediated through suppression of RNA silencing during virus infection. As far as we are aware, this is the first report of RNA silencing suppressors encoded by a virus in the genus Fabavirus.
authors.affiliation: State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou 310029, People's Republic of China.
authors.forename: Lingfang
authors.initials: L
authors.lastname: Kong
authors.affiliation: State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou 310029, People's Republic of China.
authors.forename: Yaqin
authors.initials: Y
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou 310029, People's Republic of China.
authors.forename: Xiuling
authors.initials: X
authors.lastname: Yang
authors.affiliation: Department of Biology, University of Texas at San Antonio, San Antonio, TX 78249, USA.
authors.forename: Garry
authors.initials: G
authors.lastname: Sunter
authors.affiliation: State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou 310029, People's Republic of China. Electronic address: zzhou@zju.edu.cn.
authors.forename: Xueping
authors.initials: X
authors.lastname: Zhou
mesh_terms: D024202:Electrophoretic Mobility Shift Assay; D019181:Fabavirus / Q000276:immunology* / Q000502:physiology*; D054884:Host-Pathogen Interactions; D057131:Immune Evasion; D011485:Protein Binding; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D014026:Nicotiana / Q000276:immunology* / Q000821:virology*; D014764:Viral Proteins / Q000378:metabolism*
chemical_list: D034741:RNA, Small Interfering; D014764:Viral Proteins
keywords: Broad bean wilt virus 2; Large capsid protein; RNA silencing; Suppressor; VP37; VP53