Using phytoglycogen to deliver long dsRNA molecules as an antiviral drug in shrimp

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Shrimp is the largest single seafood commodity by value in the world, estimated at $40 billion in 2017. Aquaculture shrimp production is dominated by two species, the black tiger shrimp (Penaeus monodon) and the pacific white shrimp (Penaeus vannamei). Both of these species are exquisitely susceptible to outbreaks of viral disease, generally with catastrophic mass mortalities ranging from 80-100%. The antiviral immune response in shrimp is not fully understood; however, we do know that double-stranded (ds)RNA, whether coding for virus sequences specific to the infection or not can lend protection against virus replication. The present study will use a novel phytoglycogen (PhG) nanoparticle, developed by our industrial partner (Glysantis Inc; Guelph, ON) as a carrier for dsRNA to be used as a shrimp feed additive. PhG is attractive as a nanoparticle in this application because it is non-toxic, food-grade, biodegradable, non-immunogenic, and highly amenable to chemical modifications. In preliminary studies we have demonstrated that aquatic animal cells treated with dsRNA-PhG mounted a more robust (>10 fold) induction of innate antiviral genes when compared to dsRNA alone. Thus using dsRNA-PhG would reduce the amount of dsRNA needed to protect shrimp, thus reducing cost. In addition to the marketability of these findings, this research will also broaden our understanding of dsRNA-mediated antiviral pathways in shrimp and generate a continuous shrimp cell line for the development of diagnostic tools, and basic research on shrimp immunity. Combined this knowledge will significantly progress our understanding of shrimp innate antiviral immunity, for the betterment of this economically important animal, as well as positively impact a Canadian company, producing novel revenue streams and employment opportunities.