Natural scrapie and PrP genotype: case‐control studies in British sheep

Abstract

Natural scrapie in sheep is associated with polymorphisms of the PrP gene, particularly at amino acid codons 136, 154 and 171. This paper reports the results of nine scrapie case-control studies in Bleu du Maine, Herdwick, Merino x Shetland, Poll Dorset, Scottish Halfbred, Shetland, Soay, Suffolk and Swaledale sheep from British flocks affected by scrapie. In some outbreaks, scrapie was found to occur only in animals with at least one PrP allele encoding valine at codon 136 (V136), usually a relatively rare allele in healthy controls. In other outbreaks, the V136, PrP allele was either not found or was not an absolute prerequisite for scrapie to develop. Although scrapie had a strong tendency to affect sheep with PrP genotypes homozygous for glutamine at codon 171 (QQ171), these genotypes (QQ171 but varying at other codon positions) were relatively common in healthy controls. The reliable prediction of scrapie susceptibility in previously uninvestigated sheep flocks will therefore require information at least about PrP genotypes at codons 136 and 171.

Scrapie transmission in Britain: a recipe for a mathematical model

“…However, one popular breed is signi¢cantly overrepresented amongst the scrapie farms whilst others are signi¢cantly underrepresented. It is known that there is a strong association between clinical scrapie and certain polymorphisms of the sheep PrP gene (Hunter et al 1997 ). It will be interesting to see if the risks of clinical scrapie revealed by this study predict the prevalence of susceptible genotypes in the relevant breeds.…”

Seleção de ovinos geneticamente resistentes ao scrapie

“…Polimorfismos no gene da proteína priônica celular (PRNP) estão associados a diferenças de susceptibilidade ao agente infeccioso (GOLDMANN et al, 1990;HUNTER et al, 1997a;1997b;DAWSON et al, 1998). A suscetibilidade do genótipo ARR/ARR aos agentes causadores do scrapie clássico é extremamente baixa, porém não mais considerada nula desde os primeiros casos comprovados de animais ARR/ARR infectados (GROSCHUP et al, 2007).…”

Comparison of the ovine prion protein genotype profiles of breeds Tigaie with Black Head and Merino

“…These codons were investigated in several countries to develop sheep breeding programs (6,(9)(10)(11)(12). Combinations of polymorphisms at these 3 codons give rise to 5 commonly seen haplotypes (alleles): ARR, AHQ, ARH, VRQ, and ARQ.…”