A novel and convenient bacterial platform for production of encapsidated double‐stranded RNA targeting white spot syndrome virus in shrimp

Abstract

White spot syndrome virus (WSSV) is a highly infectious virus that can cause 100% mortality in farmed shrimp in the matter of days, leading to significant economic losses to shrimp aquaculture worldwide. To mitigate the adverse impact of WSSV, effective antiviral strategies are necessary. Currently, double‐stranded RNA (dsRNA), which can silence viral gene expression through an RNA interference (RNAi) pathway, is among the most promising therapeutic tools for WSSV, but its farm‐scale utilization is held back by high costs and the lack of delivery approach. Recently, virus‐like particles (VLPs) have been applied as nanocarriers to deliver dsRNA into shrimp tissues, resulting in prolonged half‐life of the encapsidated dsRNA and stimulation of shrimp innate immunity. However, recombinant VLPs and dsRNA are traditionally expressed in two different E. coli strains: a protease‐deficient BL21(DE3) strain and an RNase III‐deficient HT115(DE3) strain, respectively. The ability to produce both VLPs and dsRNA simultaneously in a cell will reduce the costs and steps associated with the production, but attempts at VLP‐dsRNA coexpression in each of these strains resulted in degradation of either VLP or dsRNA due to the presence of proteases or RNaseIII, respectively. Here, to streamline VLP‐dsRNA production and allow simultaneous expression of VLP and dsRNA in the same cell, P1 transduction was employed to generate a novel E. coli strain which is both protease‐ and RNase III‐deficient. The newly engineered E. coli strain is able to express both MrNV‐VLP and VP28 dsRNA efficiently. Therefore, this new expression platform will pave the way for development of effective and low‐cost production of VLP‐encapsulated dsRNA for protection against viral infection in farmed shrimp. Support or Funding Information The authors would like to thank the following institutions for supporting research and scholarship to graduate student: Thailand Graduate Institute of Science and Technology (TGIST), National Science and Technology Development Agency (NSTDA) and Mahidol University.