Reproduction Abstracts

Introduction: In 1986, typical borine spongiform encephalopathy (BSE) was found in UK. Cattle were orally given abnormal prion protein in the brain of sheep with Scrapie. Orally administered abnormal prion protein causes variant type Creutzfeldt-Jakob disease infection in human. In 2003, spontaneous BSE was found in many countries. Spontaneous BSE is transmissible from cattle to monkey. In 2012, United States Department of Agriculture reported that spontaneous BSE cow was found in California. To make prion gene homo knockout (KO) cattle is only solution against BSE problem.

Materials and methods: We made 11 prion gene homo KO Japanese Black cow and revealed her characteristics as follows: firstly, prion gene was knockouted in fibroblast cells prepared from embryo. The somatic cell nucleus of prion gene hetero KO fibroblast was transferred into oocyte with removal of nucleus (somatic cell nuclear cloning: SCNC). After activation and in vitro culture, the blastocysts were transplanted into the uterus. Secondary, prion gene was knockouted in the embryo fibroblast cells, and then the 2nd SCNC was performed. Prion gene homo KO calves were born.

Results and discussion: No obvious difference was observed between KO cows and controls (SCNC cows) at the 0, 3, 6, 12 or 18 months of age. In the brain tissue of KO cows, anti-oxidative function was decreased at 24 months of age. To produce the prion gene homo KO cattle is useful and the only way to ensure the safety of bovine derived products.