Oysters are globally important aquaculture species, but sustainable production is hampered by mortality due to outbreaks of Oyster Herpes Virus. Genetic selection for improved resistance is a major goal, as is understanding the mechanisms underlying genetic resistance. Recent work by Roslin and Cefas has resulted in development and production of a medium density SNP-array for genome-wide association studies of oyster herpes-virus resistance in pacific oyster. The study combined Cefas disease challenge data and Roslin animal genetics expertise to identify parts of the oyster genome that can provide resistance to oyster herpes virus. It is now crucial to understand more about the biology of these resistance QTLs, and to develop ways of incorporating them in commercial production. To do this a joint Roslin-Cefas PhD student will undertake an experimental approach to identify, challenge and characterise resistance phenotypes. The process will initially involve further development of larval challenge protocols, genetic characterisation of viral strains and genetic and phenotypic characterisation of resistance profiles in UK oysters before performing challenges against each other. Following on from this, a gene-editing approach via CRISPR/Cas to fully characterise the individual effect of each resistance QTL against various forms of the virus. The primary outcomes from this work will be completing development of a larval disease challenge system as a model for resistance in later life, development of a gene-editing technique for one of the most important bivalve species in the world, and developing an understanding of the interaction between host genetic resistance and different strains of the virus. In addition to generating new fundamental knowledge, the outcomes of this project will have direct impact on the oyster industry in Europe by facilitating the development of new breeding strategies for improving oyster production.