Goat Scrapie Susceptibility

Quick Summary

Scrapie is a fatal, infectious neurodegenerative prion disease that affects sheep and goats. Natural mutations in the prion protein gene of sheep and goats have been identified which confer susceptibility or resistance to scrapie.

Phenotype: Goats with certain natural mutations (variants) in the prion protein gene have increased resistance to classical scrapie compared to goats lacking the mutations.

Alleles:

N = asparagine at position 146
S = serine at position 146 (confers genetic resistance against classical scrapie)
Q = glutamine at position 222
K = lysine at position 222 (confers genetic resistance against classical scrapie)

Breeds appropriate for testing: All breeds

Explanation of Results:

  • Goats with N/N, Q/Q genotype have no copies of the protective variants and are susceptible to classical scrapie.
  • Goats with N/N, Q/K genotype have one copy of the K222 protective variant (lysine at position 222) and have increased resistance to classical scrapie.
  • Goats with N/N, K/K genotype have two copies of the K222 protective variant (lysine at position 222) and have increased resistance to classical scrapie.
  • Goats with N/S, Q/Q genotype have one copy of the S146 protective variant (serine at position 146) and have increased resistance to classical scrapie.
  • Goats with S/S, Q/Q genotype have two copies of the S146 protective variant (serine at position 146) and have increased resistance to classical scrapie.
  • Goats with N/S, Q/K genotype have one copy of both the S146 protective variant (serine at position 146) and K222 protective variant (lysine at position 222) and have increased resistance to classical scrapie.
Price

$30 one test per animal

Additional Details

Scrapie prion protein visible stained in red in mouse neural tissue
Photomicrograph showing scrapie prion proteins (stained red) in neurons in a mouse neural tissue sample. Image credit: National Institute of Allergy and Infectious Diseases (NIAID)

Scrapie is a fatal, infectious neurodegenerative disease that affects sheep and goats. The disease results from infection with pathogenic agents known as “prions” which change the normal prion protein (PrPC) to the improperly folded, disease-associated form (PrPSc). The abnormal PrPSc is resistant to the protein turnover process and forms deposits in the central nervous system and some peripheral tissues that lead to progressive neurodegeneration. Goat scrapie is similar to a group of prion diseases that includes Creutzfeldt-Jakob disease in humans, bovine spongiform encephalopathy (BSE) in cattle, sheep scrapie and chronic wasting disease in cervids. The disease impacts animal health and welfare, animal movement, and trade.

Natural mutations (also called variants or alleles) in the prion protein gene (PRNP) of sheep and goats have been identified which confer susceptibility or resistance to scrapie. In the goat, S146 and K222 variants have been confirmed, experimentally and in the field, to confer genetic resistance against classical scrapie. These variants are named for the amino acid changes in the PRNP protein. S146 indicates serine (S) at position 146 instead of normal asparagine (N) and K222 indicates lysine (K) instead of normal glutamine (Q) at position 222. Serine-146 or Lysine-222 forms of PrPC are more resistant to conversion to the abnormal PrPSc.

This test for classical scrapie in goats screens for presence/absence of the protective alleles S146 and K222. Information from the test can be used by breeders to select breeding stock to increase frequency of beneficial alleles in their herds. The latest research shows that even a single copy of S146 or K222 alleles confers resistance to classical scrapie beyond the productive lifetimes of goats. Breeding for resistance is an effective means to control classical scrapie at the herd and population levels. This test is applicable to goats of all types and breeds, including those raised in the U.S.

Turnaround Time
6 - 10 business days
Type of Sample

Species

Type of Test

Results Reported As
146 222 Interpretation of Results
NN QQ No copies of protective variants. Susceptible to classical scrapie.
NN QK One copy of K222 protective variant. Increased resistance to classical scrapie.
NN KK Two copies of K222 protective variant. Increased resistance to classical scrapie.
NS QQ One copy of S146 protective variant. Increased resistance to classical scrapie.
NS QK One copy each of S146 and K222 protective variants. Increased resistance to classical scrapie.
SS QQ Two copies of S146 protective variant. Increased resistance to classical scrapie.
References

White, S., Herrmann-Hoesing, L., O’Rourke, K., Waldron, D., Rowe, J., & Alverson, J. (2008). Prion gene (PRNP) haplotype variation in United States goat breeds. Genetics Selection Evolution, 40(5), 553-561. doi: 10.1051/gse:2008021

White, S.N., Reynolds, J.O., Waldron, D.F., Schneider, D.A., & O'Rourke, K.I. (2012). Extended scrapie incubation time in goats singly heterozygous for PRNP S146 or K222. Gene, 501(1), 49-51. doi: 10.1016/j.gene.2012.03.068

Cinar, M.U., Schneider, D.A., Waldron, D.F., O’Rourke, K.I., & White, S.N. (2018). Goats singly heterozygous for PRNP S146 or K222 orally inoculated with classical scrapie at birth show no disease at ages well beyond 6 years. The Veterinary Journal, 233, 19-24. doi: 10.1016/j.tvjl.2017.12.019