Improved preventive and curative effects of YHV infection in Penaeus monodon by a combination of two double stranded RNAs

YHV causes a severe mortality in Penaeus monodon resulting in a high economic loss of shrimp culture industry. Presently, there is no effective means to prevent or cure YHV infection in shrimp. Double stranded RNA (dsRNA) targeting viral genes exhibited a good protection of the YHV infection. DsRNA targeting a shrimp gene PmRab7 similarly gave a good preventive effect. In this study, a combination of dsRNA targeting viral and host genes showed improved prevention and cure of the YHV infection. For a one gram shrimp, dsRNA-YHV at 1.25 μg/g shrimp plus dsRNA-PmRab7 at 0.63 μg/g shrimp showed a significantly improved prevention of shrimp mortality over 2.50 μg dsRNA-YHV alone. In a curative mode, a combination gave a complete cure when the shrimp was infected 3 h prior to the dsRNAs treatment, while the single dsRNA resulted in approximately 40% shrimp mortality. At 12 h YHV infection prior to the dsRNA treatment, a significantly lower level of shrimp mortality was observed in the combined dsRNAs than the single one. Therefore, the combination of dsRNA demonstrated higher efficacy than the single dsRNA injection in both prevention and cure of YHV infection in P. monodon. This result further demonstrated a more effective means to combat a viral disease in shrimp by a combination of dsRNA targeting the virus gene and the host gene.