RNA interference (RNAi) is a major antiviral pathway that shapes evolution of RNA viruses. We show here that Nora virus, a natural Drosophila pathogen, is both a target and suppressor of RNAi. We detected viral small RNAs with a signature of Dicer-2 dependent small interfering RNAs in Nora virus infected Drosophila. Furthermore, we demonstrate that the Nora virus VP1 protein contains RNAi suppr...

RNA3 and RNA4 of beet necrotic yellow vein virus (BNYVV) are not essential for virus multiplication, but are associated with vector-mediated infection and disease development in sugar beet roots. Here, a unique role for RNA4 in virus transmission, virulence and RNA silencing suppression was demonstrated. Mutagenic analysis revealed that the RNA4-encoded p31 open reading frame (ORF) was involved...

A broad range of parasites rely on the functions of effector proteins to subvert host immune response and facilitate disease development. The notorious Phytophthora pathogens evolved effectors with RNA silencing suppression activity to promote infection in plant hosts. Here we report that the Phytophthora Suppressor of RNA Silencing 1 (PSR1) can bind to an evolutionarily conserved nuclear prote...

RNA silencing functions as an antiviral defense through the action of DICER-like (DCL) and ARGONAUTE (AGO) proteins. In turn, plant viruses have evolved strategies to counteract this defense mechanism, including the expression of suppressors of RNA silencing. Potato virus X (PVX) does not systemically infect Arabidopsis thaliana Columbia-0, but is able to do so effectively in mutants lacking at...

ARGONAUTE 1 (AGO1) slices endogenous messenger RNAs (mRNAs) during both microRNA (miRNA)- and short interfering RNA (siRNA)-guided post-transcriptional silencing. We have previously reported that AGO1 homeostasis is maintained through the repressive action of miR168 on AGO1 mRNA and the stabilizing effect of AGO1 protein on miR168, but siRNA-mediated AGO1 regulation has not been reported. Here,...

Mosquito-borne flaviviruses, including yellow fever virus (YFV), Zika virus (ZIKV), and West Nile virus (WNV), profoundly affect human health. The successful transmission of these viruses to a human host depends on the pathogen's ability to overcome a potentially sterilizing immune response in the vector mosquito. Similar to other invertebrate animals and plants, the mosquito's RNA silencing pa...