Using double-stranded RNA for the control of Laem-Singh Virus (LSNV) in Thai P. monodon.

Viral inhibition by double-stranded (ds)RNA is a potential therapeutic approach for controlling shrimp viral diseases. Here, we describe the successful oral application of dsRNA targeting Laem-Singh Virus (LSNV) to diminish monodon slow growth syndrome (MSGS) in Thai Penaeus monodon. Shrimp feed formulated with bacterially expressed LSNV-dsRNA was given to shrimp for 9 weeks. RT-PCR results revealed that all control shrimp were LSNV-positive at the end of experiment, while the shrimp that received dsRNA-feed exhibited 20-60% LSNV reduction. The average body weight of treated shrimp (number of shrimp=100) was significantly higher than that of the control group. Such increase is likely due to the elimination of MSGS caused by LSNV, as size variation of the treated group is much lower than that in the control group. This study demonstrates for the first time that feed with LSNV-specific dsRNA promotes the overall growth of P. monodon and relieves MSGS condition in LSNV-infected shrimp. The work reaffirms the potential of dsRNA application for controlling viral disease in shrimp farming.