Dynamics and genetics of PrPSc placental accumulation in sheep

J Gen Virol. 2007 Mar;88(Pt 3):1056-1061. doi: 10.1099/vir.0.82218-0.

Abstract

Placentae from scrapie-affected ewes are an important source of contamination. This study confirmed that scrapie-incubating ewes bearing susceptible genotypes could produce both abnormal prion protein (PrPSc)-positive and -negative placentae, depending only on the PRP genotype of the fetus. The results also provided evidence indicating that scrapie-incubating ARR/VRQ ewes may be unable to accumulate prions in the placenta, whatever the genotype of their progeny. Multinucleated trophoblast cells appeared to play a key role in placental PrPSc accumulation. PrPSc accumulation began in syncytiotrophoblasts before disseminating to uninucleated trophoblasts. As these result from trophoblast/uterine epithelial cell fusion, syncytiotrophoblast cells expressed maternal and fetal PrPC, whilst uninucleated trophoblast cells only expressed fetal PrPC. In ARR/VRQ scrapie-infected ewes, expression of the ARR allele by syncytiotrophoblasts appeared to prevent initiation of PrPSc placental deposition. The absence of prions in affected ARR/VRQ sheep placentae reinforces strongly the interest in ARR selection for scrapie control.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alleles
  • Animals
  • Female
  • Fetus
  • Genotype
  • Immunohistochemistry
  • Placenta / chemistry*
  • Placenta / pathology
  • PrPSc Proteins / analysis*
  • Pregnancy
  • Pregnancy Complications / metabolism
  • Pregnancy Complications / pathology
  • Pregnancy Complications / veterinary*
  • Scrapie / metabolism*
  • Scrapie / pathology
  • Sheep
  • Trophoblasts / chemistry

Substances

  • PrPSc Proteins