title: La Crosse virus nonstructural protein NSs counteracts the effects of short interfering RNA.
abstract: Through a process known as RNA interference (RNAi), double-stranded short interfering RNAs (siRNAs) silence gene expression in a sequence-specific manner. Recently, several viral proteins, including the nonstructural protein NSs of tomato spotted wilt virus (a plant-infecting bunyavirus), the interferon antagonist protein NS1 of influenza virus, and the E3L protein of vaccinia virus, have been shown to function as suppressors of RNAi, presumably as a counterdefense against cellular mechanisms that decrease viral production. La Crosse virus (LACV), a member of the California serogroup of orthobunyaviruses, has a trisegmented negative-stranded genome comprised of large (L), medium (M), and small (S) segments. To develop a strategy for segment-specific inhibition of transcription, we designed 13 synthetic siRNAs targeting specific RNA segments of the LACV genome that decreased LACV replication and antigen expression in mammalian (293T) and insect (C6/36) cells. Furthermore, NSs, a LACV nonstructural protein, markedly inhibited RNAi directed both against an LACV M segment construct and against a host gene (glyeraldehyde-3-phosphate dehydrogenase), suggesting a possible role for this viral protein in the suppression of RNA silencing. Segment-specific siRNAs will be useful as a tool to analyze LACV transcription and replication and to obtain recombinant viruses. Additionally, NSs will help us to identify molecular pathways involved in RNAi and further define its role in the innate immune system.
authors.affiliation: Department of Neurology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-4283, USA.
authors.forename: Samantha S
authors.initials: SS
authors.lastname: Soldan
authors.forename: Matthew L
authors.initials: ML
authors.lastname: Plassmeyer
authors.forename: Meghan K
authors.initials: MK
authors.lastname: Matukonis
authors.forename: Francisco
authors.initials: F
authors.lastname: González-Scarano
mesh_terms: D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D002522:Chlorocebus aethiops; D015967:Gene Expression Regulation, Viral; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000235:genetics / Q000378:metabolism; D006801:Humans; D018062:La Crosse virus / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity*; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D034622:RNA Interference; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D014709:Vero Cells; D017361:Viral Nonstructural Proteins / Q000235:genetics / Q000378:metabolism*; D010948:Viral Plaque Assay; D014779:Virus Replication
chemical_list: D035683:MicroRNAs; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D017361:Viral Nonstructural Proteins; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases