Control of White Spot Syndrome Virus (WSSV) of Shrimp Using Genome Editing

No drugs or treatmentsare available to combat viral diseases in shrimp such as the white spot syndrome disease (WSD) caused by white spot syndrome virus (WSSV). Viral diseases can rapidly spread in shrimp stocks and threaten the viability of the US and global shrimp aquaculture industry. While management and good biosecurity are part of the solution, having a direct method to respond to an outbreak or to assure incoming shrimp are clear of virus would be a strong additional tool for the industry.The use of genome editing technology (such as CRISPR/Cas)to attack the invading organism rather than to modify the genome of the host contrasts with most current applications of this new technology (i.e., targeting the genome of the host organism). Success of this project would allow more rapid response to viral outbreaks, more rapid introduction of wild shrimp that can be certified virus free, and provide a needed tool for the industry to improve biosecurity. During Phase I the project will design constructs to target WSV, test the efficacy of CRISPR/Cas vectors to cure and/or prevent WSD in primary cell culture and whole shrimp through injection as a feasibility study for this approach to cure WSD. Phase I will develop genome editing-based productsthat target early and late genes of the white spot syndrome virus (WSSV). These vectors will be evaluated for their ability to inhibit replication of WSSV in primary shrimp cell culture. Additionally, purified genome editing-based products will be injected into shrimp to show that control of WSSV is possible in live shrimp. Formulations will be made to stabilize these genome editing-based productsand target them to cellular membranes; stability and release will be evaluated.Shrimp farming in the USA is relatively sophisticated and is capable of maintaining clean stocks through careful management and biosecurity protocols. However, introduction of new stock from other farms or the wild poses the risk of introduced diseases. Additionally, open culturing systems are attractive in certain regions and would benefit from additional tools to combat viral outbreaks. The approach to be developed in this program will allow more rapid introduction of new diversity in the breeding stocksafely and ensure that if viral diseaseoutbreaks occur economic losses are minimized.