DAO prepress abstract   -  DOI: https://doi.org/10.3354/dao03805

ABSTRACT: Many studies have demonstrated that long double-stranded RNAs (dsRNAs) targeting essential genes of white spot syndrome virus (WSSV) can induce a sequence-specific antiviral RNA interference (RNAi) response in shrimp, thereby offering protection against WSSV infection. However, further experimental data on the required dose of dsRNAs and the duration of protection from a single administration are necessary to establish RNAi-mediated methods as effective and practical antiviral measures. In this study, we evaluated the protective efficacy and the duration of protection provided by a single administration of various doses of WSSV’s ribonucleotide reductase 2 (rr2)-targeting long dsRNA in white-leg shrimp (Litopenaeus vannamei). The protective efficacy of long dsRNA targeting WSSV rr2 was not diminished by the reduction of a dose of dsRNA to 100 ng/g of body weight, suggesting that a relatively low amount of long dsRNA can effectively induce an RNAi response in shrimp. Furthermore, shrimp were well-protected against WSSV challenges for up to 4 weeks post-administration of the rr2-targeting long dsRNA, although the protective effect almost disappeared at 6 weeks post-administration. These results suggest that long dsRNAs can provide protection against WSSV for at least one month, and monthly administration of long dsRNAs could serve as a long-term protective strategy for shrimp against WSSV.