Development of a Bacillus thuringiensis based dsRNA production platform to control sacbrood virus in Apis cerana

BACKGROUND Sacbrood virus (SBV) is a fatal viruses that infects the Asian honey bee, Apis cerana in Korea. Recently, RNA interference (RNAi) has been suggested as a promising strategy for the suppression of honey bee viruses. For the efficient control of SBV infection using RNAi, simple and cost-effective methods to produce double-stranded RNA (dsRNA) are needed. RESULTS To develop a dsRNA production platform using Bacillus thuringiensis (Bt), pBTdsSBV-VP1 vector was constructed in which the SBV vp1 gene was located between two oppositely oriented cyt promoters. Both strands of the vp1 gene were bidirectionally transcribed under the control of the sporulation-dependent cyt promoter in Bt cells transformed with pBTdsSBV-VP1, and the resulting dsRNA was easily extracted from the Bt transformant, Bt 4Q7/pBTdsSBV-VP1, by inducing its autolysis. The replication of SBV was dramatically suppressed in A. cerana workers who ingested the dsRNA produced from the Bt 4Q7/pBTdsSBV-VP1. CONCLUSION In this study, we successfully silenced SBV in its host, A. cerana, by the application of exogenous dsRNA produced from an entomopathogenic bacteria, Bt. These results suggested that Bt could be a useful dsRNA production platform to control viral pathogens in their host insects. (c) 2019 Society of Chemical Industry