Viral suppressors of RNA silencing hinder exogenous and endogenous small RNA pathways in Drosophila.
BACKGROUND
In plants and insects, RNA interference (RNAi) is the main responder against viruses and shapes the basis of antiviral immunity. Viruses counter this defense by expressing viral suppressors of RNAi (VSRs). While VSRs in Drosophila melanogaster were shown to inhibit RNAi through different modes of action, whether they act on other silencing pathways remained unexplored.


RESULTS
Here we show that expression of various plant and insect VSRs in transgenic flies does not perturb the Drosophila microRNA (miRNA) pathway; but in contrast, inhibits antiviral RNAi and the RNA silencing response triggered by inverted repeat transcripts, and injection of dsRNA or siRNA. Strikingly, these VSRs also suppressed transposon silencing by endogenous siRNAs (endo-siRNAs).


CONCLUSIONS
Our findings identify VSRs as tools to unravel small RNA pathways in insects and suggest a cosuppression of antiviral RNAi and endo-siRNA silencing by viruses during fly infections.
Berry
Bassam
B
Institut Pasteur, Drosophila Genetics and Epigenetics, CNRS-URA2578, Paris, France.
Deddouche
Safia
S
Kirschner
Doris
D
Imler
Jean-Luc
JL
Antoniewski
Christophe
C
D000818:Animals; D030801:Animals, Genetically Modified; D003433:Crosses, Genetic; D004331:Drosophila melanogaster / Q000821:virology*; D020868:Gene Silencing; D006579:Heterozygote; D017956:Photoreceptor Cells, Invertebrate; D034622:RNA Interference; D012330:RNA, Double-Stranded / Q000737:chemistry; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019076:Transgenes
D012330:RNA, Double-Stranded