Caesarean derivation and hand-rearing does not prevent scrapie in the offspring of infected ewes.

Jim Foster, Wilfred Goldmann, Nora Hunter

Research output: Contribution to journalMeeting abstract


Natural transmission of scrapie between sheep is not fully understood. Although scrapie has been demonstrated to transmit between adult sheep, the available evidence suggests the very young lamb is at high risk of picking up infection from their scrapie affected mothers. Early literature claimed evidence of in utero transmission but the studies were compromised by lack of knowledge of the control of disease susceptibility by the PRNP gene. More recently it has been thought likely that lambs become infected after birth by ingestion of contaminated birth fluids, including blood, or from contact with voided placental tissues. It is likely that multiple infection routes function in transmission of sheep scrapie so it is difficult to conduct clean experiments to differentiate pre- and post-natal factors. However as highly sensitive methods have now shown that PrPSc is present in infected ewe amniotic fluid (which is ingested repeatedly by developing fetuses) this should be seriously considered as a possible route by which oral infection could be achieved.
In this complex study we experimentally infected pregnant ewes of known PRNP genotype with a distinctive scrapie strain (SSBP/1) and looked for evidence of transmission of SSBP/1 to the offspring. The sheep were from the NPU Cheviot flock which has endemic natural scrapie from which SSBP/1 can be differentiated on the basis of histology, genetics of disease incidence and strain typing bioassay in mice. This presentation describes one segment of the study in which, for a proportion of the infected ewes, lambs were removed by midline laparotomy just prior to the estimated birth date and then hand reared in complete isolation from the adult sheep. The lambs were fed by human handlers and given colostrum and reconstituted milk powder from sources in New Zealand prior to weaning. This treatment however did not prevent scrapie appearing in some of the offspring of fully susceptible mothers. Following mouse strain typing, in tg338 mice, we demonstrate clear evidence of the appearance of SSBP/1 scrapie in the lambs. Taking into account all the stringent disease security measures that we had in place it is difficult for us to understand how this strain could have infected the lambs in any other way than pre-natally from their SSBP/1 infected mothers. Our results strongly suggest that in utero transmission of scrapie may have occurred in these sheep.
Original languageEnglish
Pages (from-to)63
Number of pages1
Issue numberSuppt.
Publication statusPublished - May 2014
EventPrion 2014 - Trieste, Italy, United Kingdom
Duration: 24 May 201430 Jun 2014


  • scrapie
  • prion
  • sheep


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