PrP^Sc accumulation in fetal cotyledons of scrapieresistant lambs is influenced by fetus location in the uterus

Authors

Janet Alverson, U.S. Department of Agriculture
Katherine I. O'Rourke, U.S. Department of AgricultureFollow
Timothy V. Baszler, Washington Animal Disease Diagnotic Laboratory

Document Type

Article

Date of this Version

2006

Comments

Published in Journal of General Virology (2006), 87, 1035–1041

Abstract

Placentae from scrapie-infected ewes have been shown to accumulate PrP^Sc when the genotype of the fetus is of a susceptible genotype (VRQ/VRQ, ARQ/VRQ or ARQ/ARQ). Cotyledons from fetuses of genotypes ARR/ARR, ARQ/ARR and ARQ/VRR have previously been shown to be resistant to PrP^Sc accumulation. By using ewes from a naturally infected scrapie flock, cotyledons from fetuses of multiple births of different genotypes were examined. PrP^Sc was detected in fetal cotyledons of genotype ARQ/ARQ, but not in cotyledons from their dizygotic twin of genotype ARQ/ARR. This confirms earlier reports of single fetuses of these genotypes, but is the first description of such a finding in twin fetuses, one of each genotype. It is also demonstrated that cotyledons from sibling fetuses of genotypes ARQ/VRQ and ARQ/ARQ have different patterns of PrP^Sc accumulation depending on whether the dam is of genotype ARQ/ARQ or ARQ/VRQ. Lastly, it is shown that cotyledons from fetuses with resistant genotypes are weakly positive for PrP^Sc when they have shared the same pregnant uterine horn with a fetus of a susceptible genotype with cotyledons positive for the detection of PrP^Sc. Additionally, a PCR product for the Sry gene, a product specific to males, was found in cotyledons from female fetuses that had shared a uterine horn with a male fetus. This indicates that some sharing of fetal blood occurs between placentomes and fetuses residing in the same uterine horn, which can result in PrP^Sc accumulation in cotyledons with resistant genotypes.