Flock House virus B2 protein is a suppressor of RNA silencing
RNA silencing is a powerful eukaryotic antiviral response that targets viral transcripts for degradation using short interfering RNAs (siRNAs). siRNAs are 21-25 nt segments generated by Dicer cleavage of viral dsRNAs, resulting from secondary structure or replicative intermediates. Incorporation of these siRNAs into RNA-induced silencing complexes (RISC) targets the RISC to specifically degrade the complementary viral RNAs.
The Flock House virus (FHV) B2 protein, translated from subgenomic RNA3, has been identified as a suppressor of RNA silencing in a variety of hosts. B2 binds dsRNA independent of sequence length or identity. Biochemical results suggest that B2 inhibits cleavage of the FHV genome by Dicer and the incorporation of FHV siRNAs into RISC by binding long dsRNAs and viral siRNAs respectively. Current work focuses on characterizing the mechanism of B2 suppression during the FHV infection cycle.
