Drosophila X virus-like particles as efficient dsRNA carriers for improved RNAi against the invasive species, Drosophila suzukii

RNA interference (RNAi) has been exploited as a promising strategy for pest control and also has great potential against the spotted wing drosophila (SWD) Drosophila suzukii . However, since RNAi is poorly induced in D. suzukii through the oral intake of unprotected double-stranded RNA (dsRNA), establishing a potent strategy for dsRNA delivery remains essential. In this study, we developed novel virus-like particles (VLPs) derived from the Drosophila X virus (DXV) and investigated their capability to deliver dsRNA in vitro in cultured insect cells and in vivo in live insects. First, the polyproteins of DXV fused at the C-terminus with eGFP or Myc-tag were able to self-assemble into VLPs, in a spherical shape similar to authentic virions. Then, dsRNA molecules were loaded into the DXV-VLPs by a dis-/reassembly strategy and were demonstrated to be partly sheltered from degradation in body fluids from D. suzukii . Furthermore, DXV-VLPs were able to carry the dsRNA efficiently into Drosophila S2 cells and D. suzukii adults. By targeting the essential vha26 gene in D. suzukii adult, DXV-VLP∷dsvha26 complexes could induce higher mortality (46%) and gene silencing (36%) compared with the DXV-VLP∷dsGFP, and unprotected dsvha26 (less than 17% mortality and no silencing). Taken together, as a proof-of-concept, this study suggests that insect virus-based VLPs can function as nano-vehicles for dsRNA delivery into insects and provide a tool to improve RNAi for fundamental studies and pest control.