Application of YHV-protease dsRNA for protection and therapeutic treatment against yellow head virus infection in Litopenaeus vannamei.

While farming of the Pacific white shrimp Litopenaeus vannamei is well established in North and South America, the industry has more recently been introduced to Asia, and the Pacific white shrimp is now the most commonly farmed species in Thailand. However, outbreaks of yellow head virus (YHV) disease in the Pacific white shrimp have caused severe economic losses and currently there is no effective prevention or treatment of YHV infections. The YHV-protease double-stranded RNA (YHV-Pro dsRNA) can act as both a prophylactic agent and as a treatment to inhibit YHV replication in infected black tiger shrimp Penaeus monodon. The utility of this methodology to other shrimp species has not, however, been established. The purpose of this study was to determine whether YHV-Pro dsRNA can be applied to the Pacific white shrimp. To assess prophylactic efficiency, YHV-Pro dsRNA was injected into juvenile shrimp 24 h prior to challenge with YHV. Subsequent YHV replication was inhibited by YHV-Pro dsRNA as compared with injection of an unrelated dsRNA. For therapeutic treatment of YHV-infected shrimp, shrimp were challenged with YHV before dsRNA injection. Injection of YHV-Pro dsRNA up to 6 h post-infection resulted in the almost complete elimination of YHV replication. These results suggest that YHV-Pro dsRNA can also be broadly applied as a prophylactic agent to inhibit YHV replication and therapeutic treatment of YHV-infected Pacific white shrimp.