Characterization of Primary Bovine Cells for Genome-Editing at the PrP Locus

Problem: With the recent development of BSE or mad cow disease, markets around the world are crying out for a safer beef product. Given that the incidence of BSE is actually quite low, why has it had such a profound impact on the public? The answer relates to the discovery in the UK during 1994 of an outbreak in young people of the fatal neurodegenerative disease Creutzfeld-Jakob Disease (CJD) that previously had been seen only in individuals in their 6th and 7th decades. BSE and sporadic CJD are both prion-mediated diseases and the brain pathology of patients dying with this new variant CJD (nvCJD) confirmed that it is also prion-mediated and of BSE origin. To date there have been approximately 130 fatal human cases of nvCJD. However since over 1 million contaminated cattle may have entered the human food chain, there is great concern that the eventual total number of CJD cases stemming from the BSE source could be much higher. Purpose: As no vaccine, antemortem diagnostic test or therapy exists for either nvCJD or BSE, protection depends on preventative measures. The development of cattle that are genetically resistant to acquiring or transmitting BSE would be a major step in this direction. We will use the genome editing technology GenEdit to: 1) Disable the bovine PrP gene so there is no target for BSE infection, or 2) introduce a single amino acid change to render the animal resistant to infection. GenEdit does not introduce foreign DNA into the genome of the cell (non-GMO) and the modified cells are indistinguishable from cells carrying a naturally occurring mutation.