A new mechanism of antiviral immunity has been discovered by the research group of Hu Yuanyang and Zhou Xi at Wuhan University College of Life Science. Their research was published as the spotlight article in the Journal of Virology, an internationally renowned journal in microbiology.

The article, Targeting of Dicer-2 and RNA by a Viral RNA silencing Suppressor in Drosophila Cells, was authored by Qi Nan, a doctor candidate at WHU and Associate Professor Zhou Xi. The research group discovered a new mechanism in which viruses can suppress antiviral immunity in protein by directly suppressing Dicer in RNA interference (RNAi) access. This breakthrough by the group follows their two articles on Wuhan nodavirus (WhNV) published in Journal of Virology in May and September, 2011.

RNAi is a eukaryotic gene-silencing mechanism that functions as a type of antiviral immunity in diverse organisms. To combat RNAi-mediated immunity, viruses encode viral suppressors of RNA silencing (VSRs) that target RNA and protein components in the RNAi machinery. Although the endonuclease Dicer plays key roles in RNA immunity, little is known about how VSRs target Dicer and it was previously unknown whether viruses can suppress Dicer.

Hu Yuanyang and Zhou Xi’s research group found that by directly interacting with different regions of Drosophila Dicer-2 (Dcr-2), the B2 protein from Wuhan nodavirus (WhNV), the counterpart of Flock House virus (FHV), can block the activities of Dicer-2 in processing double-stranded RNA (dsRNA) and incorporating small interfering RNA (siRNA) into the RNA-induced silencing complex (RISC). The research further explains the molecular mechanism of the interaction. 

This is the first time researchers have demonstrated that a host’s Dicer can be directly suppressed by virus, a new chapter in studying how viruses antagonize RNAi.