Scrapie resistance in ARQ sheep.

Area of Science:

• Veterinary Genetics
• Prion Disease Research
• Sheep Health

Background:

• Scrapie is a fatal neurodegenerative disease in sheep.
• Ovine prion protein (PrP) gene variations influence scrapie susceptibility.
• Sheep homozygous for A(136)R(154)Q(171) are typically susceptible to scrapie.

Purpose of the Study:

• To investigate the association of ovine prion protein gene variation with scrapie survival time.
• To identify specific single nucleotide polymorphism (SNP) alleles that prolong survival in scrapie-exposed sheep.

Main Methods:

• Analysis of scrapie-exposed sheep with known A(136)R(154)Q(171) genotype.
• Identification and association analysis of four SNP alleles within the ovine prion gene.
• Comparison of survival times based on different allelic variations, including T112 and M112.

Main Results:

• Four SNP alleles were significantly associated with prolonged survival in scrapie-exposed sheep.
• The T112 allele was linked to an additional 687 days of survival compared to M112 (OR=42.5, P=0.00014).
• Sheep homozygous for the T112 allele (TARQ genotype) did not develop scrapie, indicating potential additive effects.

Conclusions:

• Specific variations in the ovine prion protein gene, particularly the T112 allele, are associated with extended survival from scrapie.
• The TARQ genotype confers genetic resistance to the development of classical scrapie in sheep.
• These findings have implications for breeding programs aimed at enhancing scrapie resistance in sheep populations.