title: Cytorhabdovirus phosphoprotein shows RNA silencing suppressor activity in plants, but not in insect cells.
abstract: RNA silencing in plants and insects provides an antiviral defense and as a countermeasure most viruses encode RNA silencing suppressors (RSS). For the family Rhabdoviridae, no detailed functional RSS studies have been reported in plant hosts and insect vectors. In agroinfiltrated Nicotiana benthamiana leaves we show for the first time for a cytorhabdovirus, lettuce necrotic yellows virus (LNYV), that one of the nucleocapsid core proteins, phosphoprotein (P) has relatively weak local RSS activity and delays systemic silencing of a GFP reporter. Analysis of GFP small RNAs indicated that the P protein did not prevent siRNA accumulation. To explore RSS activity in insects, we used a Flock House virus replicon system in Drosophila S2 cells. In contrast to the plant host, LNYV P protein did not exhibit RSS activity in the insect cells. Taken together our results suggest that P protein may target plant-specific components of RNA silencing post siRNA biogenesis.
authors.affiliation: Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, St Lucia, Qld 4072, Australia.
authors.forename: Krin S
authors.initials: KS
authors.lastname: Mann
authors.affiliation: School of Biological Sciences, The University of Queensland, St Lucia, Qld 4072, Australia.
authors.forename: Karyn N
authors.initials: KN
authors.lastname: Johnson
authors.affiliation: Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, St Lucia, Qld 4072, Australia. Electronic address: r.dietzgen@uq.edu.au.
authors.forename: Ralf G
authors.initials: RG
authors.lastname: Dietzgen
mesh_terms: D000818:Animals; D004330:Drosophila / Q000235:genetics* / Q000821:virology*; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D012209:Rhabdoviridae / Q000235:genetics / Q000378:metabolism*; D014026:Nicotiana / Q000235:genetics* / Q000821:virology*; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D010750:Phosphoproteins; D014764:Viral Proteins
keywords: Agroinfiltration; Drosophila S2 cells; Flock House virus; Green fluorescent protein; Lettuce necrotic yellows virus; RNA silencing suppression; Viral protein expression