The placenta shed from goats with classical scrapie is infectious to goat kids and lambs

David A Schneider,Katherine I O'Rourke,Sally A Madsen-Bouterse,Dongyue Zhuang,Rohana P Dassanayake,Thomas C Truscott

doi:10.1099/vir.0.000151

Abstract

The placenta of domestic sheep plays a key role in horizontal transmission of classical scrapie. Domestic goats are frequently raised with sheep and are susceptible to classical scrapie, yet potential routes of transmission from goats to sheep are not fully defined. Sparse accumulation of disease-associated prion protein in cotyledons casts doubt about the role of the goat's placenta. Thus, relevant to mixed-herd management and scrapie-eradication efforts worldwide, we determined if the goat's placenta contains prions orally infectious to goat kids and lambs. A pooled cotyledon homogenate, prepared from the shed placenta of a goat with naturally acquired classical scrapie disease, was used to orally inoculate scrapie-naı¨ve prion genotype-matched goat kids and scrapie-susceptible lambs raised separately in a scrapie-free environment. Transmission was detected in all four goats and in two of four sheep, which importantly identifies the goat's placenta as a risk for horizontal transmission to sheep and other goats.

Highlights

The placenta of domestic sheep plays a key role in horizontal transmission of classical scrapie
The transmissible spongiform encephalopathies (TSE) are a heterogeneous group of disorders differing in aetiology, pathology, host range, strain repertoire and efficient transmission routes
Scrapie eradication programmes are largely based on the observation that classical scrapie is efficiently transmitted through contact with the placenta shed by infected ewes (Pattison et al, 1972) and that susceptibility is limited by polymorphisms in the prion protein gene, PRNP (Goldmann, 2008)

Summary

Short Communication

The placenta shed from goats with classical scrapie is infectious to goat kids and lambs. Relevant to mixed-herd management and scrapie-eradication efforts worldwide, we determined if the goat’s placenta contains prions orally infectious to goat kids and lambs. The shed placenta contains abundant accumulation of diseaseassociated misfolded prion protein (PrPSc) (Andreoletti et al, 2002; Lacroux et al, 2007; Tuo et al, 2001, 2002), is infectious (Onodera et al, 1993; Pattison et al, 1972; 1974; Race et al, 1998), plays a key role in horizontal transmission (Hoinville et al, 2010; Touzeau et al, 2006) and contributes to environmental contamination (Andreoletti et al, 2002; Gough & Maddison, 2010). Donor goat 3950 and all three kids associated with this placenta were heterozygous for the central caprine PRNP haplotypes 1 and 2 (White et al, 2008), which only differ at codon 240 [respectively, proline (P) and serine (S)] Both haplotypes are associated with susceptibility to classical scrapie disease (Vaccari et al, 2009)

Prions are shed in goat placenta

Sheep Goat Negative biopsy Positive biopsy Begin clinical signs Moved locations

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