Delivery of double stranded RNA by Macrobrachium rosenbergii nodavirus-like particles to protect shrimp from white spot syndrome virus

We tested the use of Macrobrachium rosenbergii nodavirus-like particles (MrNv-VLPs) as a delivery mechanism to carry therapeutic agents against white spot syndrome in shrimp. We used constructed double-stranded RNA called VP28 (VP28 dsRNA) against WSSV envelope genes to confer protection against the pathogen. Results showed that MrNv-VLP was able to encapsulate VP28 dsRNA. Using enhanced green fluorescent protein (EGFP) as a reporter, we found that VLP penetrated various shrimp tissues including the muscle, hepatopancreas, and gill. A statistically significant relative survival rate of 44.5% was obtained in the group of shrimp receiving encapsulated VP28 dsRNA-VLP after WSSV challenge as compared to 100% mortality in the control shrimp at 7 days post-infection. Shrimp treated with EGFP dsRNA loaded into MrNv-VLPs showed relatively similar motility rates as those of controls. Moreover, MrNv-VLP encapsulation improved VP28 dsRNA efficiency against WSSV. A higher survival rate of 16.7% was observed in the group of shrimp receiving encapsulated VP28 dsRNA-VLP when compared to those receiving naked VP28 dsRNA. These results indicate that MrNv-VLP is a good candidate for use as a therapeutic delivery system against shrimp diseases due to its self-reassembly property, broad target of various shrimp tissues and immune enhancement.