Location: Virus and Prion Research
Project Number: 5030-32000-228-008-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Sep 1, 2019
End Date: Aug 31, 2024
Objective:
Determine the relationship of a genetic polymorphism in the prion protein gene of an Alabama beef cattle herd to atypical L-type BSE.
Approach:
The research effort being proposed will involve two specific objectives, and include: 1) an evaluation of the genotype of older cattle with this potential phenotype; and, 2) development of a cohort of calves that are homozygous wild-type (R/R), heterozygous (R/T) and homozygous affected (T/T).
Specific Objective #2 will be accomplished through selective breeding of R/T genotype cattle at the farm of origin and utilization of advanced reproductive technologies developed by Cooperator. First, estrus synchronization/timed artificial insemination (TAI) techniques on R/T cattle will be performed. Starting in January 2020, between 40-50 cattle with the R/T genotype will be separated from the other members of the herd into distinct breeding groups, and setup for estrus synchronization-TAI using semen from bulls who we already have confirmed have the genetic polymorphism. Following TAI, two clean-up bulls who have been confirmed to possess the R/T genotype will be used to breed 20-25 cows each for a 60-day breeding season. Second, superovulation-embryo transfer or superovulation-in vitro fertilization of select R/T cattle will be performed at Cooperator's facility. One of the cattle to be utilized in the advanced reproductive technologies program is the sole-surviving offspring of the original 2017 Alabama BSE cow.Three (3) cows known to have the R/T genotype will be setup for embryo transfer (ET) or in vitro fertilization (IVF). We anticipate performing ET once monthly or IVF twice monthly on these 3 cows and freezing the resulting high quality grade embryos. Once calves are born either to dams (farm of origin breedings) or recipients (ET or IVF), they will be tested for the PRNP polymorphism and raised with their dams until weaning at approximately 8 months of age when 30 calves (10 each with R/R, R/T, and T/T genotype) will be transferred to USDA-ARS for susceptibility studies.
