Protection of yellow head virus infection in shrimp by feeding of bacteria expressing dsRNAs.

Although prevention of shrimp mortality from yellow head virus (YHV) infection via dsRNA injection has been well demonstrated for many years, it has not yet been applied in a farm culture because of its impracticality. Hence, oral administration of dsRNA becomes an alternative and desirable approach. This study is the first to demonstrate that oral feeding of Escherichia coli expressing shrimp Rab7 gene (dsRab7) or YHV protease gene (dsYHV) could inhibit YHV replication and lowered shrimp mortality. E. coli HT115 expressing dsRab7 or dsYHV or a combination of these dsRNAs were embedded in agar and used to feed vannamei shrimp at early juvenile stage before YHV challenge. After 4 days of continuous feeding of dsRNAs, strong inhibitory effect on shrimp mortality was observed in which dsRab7 gave the highest effect (70% reduction from the control) whereas dsYHV showed a 40% reduction. Our results reveal the potential of anti-YHV strategy via orally delivered dsRNA for application in the shrimp farm industry.