Evidence of scrapie transmission to sheep via goat milk

BMC Veterinary Research

Research Article

Hugh A. Simmons¹  Timm Konold¹  Lorenzo González²  Marion M. Simmons³  Steve A. C. Hawkins³  Leigh Thorne⁴ 

[1] Animal Sciences Unit, Animal and Plant Health Agency Weybridge, New Haw, Addlestone, KT15 3NB, Surrey, UK;Pathology Department, Animal and Plant Health Agency Lasswade, Pentlands Science Park, Bush Loan, Penicuik, EH26 0PZ, Midlothian, UK;Pathology Department, Animal and Plant Health Agency Weybridge, New Haw, Addlestone, KT15 3NB, Surrey, UK;Virology Department, Animal and Plant Health Agency Weybridge, New Haw, Addlestone, KT15 3NB, Surrey, UK;

关键词: Transmissible spongiform encephalopathy;    Scrapie;    Goat;    Sheep;    Milk;    Colostrum;    Transmission;    Protein misfolding cyclic amplification;    Prion protein;    Genotype;   

DOI  :  10.1186/s12917-016-0807-4

 received in 2016-04-29, accepted in 2016-08-19,  发布年份 2016

来源: Springer

【 摘 要 】

BackgroundPrevious studies confirmed that classical scrapie can be transmitted via milk in sheep. The current study aimed to investigate whether scrapie can also be transmitted via goat milk using in vivo (new-born lambs fed milk from scrapie-affected goats due to the unavailability of goat kids from guaranteed scrapie-free herds) and in vitro methods (serial protein misfolding cyclic amplification [sPMCA] on milk samples).ResultsIn an initial pilot study, new-born lambs of two different prion protein gene (PRNP) genotypes (six VRQ/VRQ and five ARQ/ARQ) were orally challenged with 5 g brain homogenate from two scrapie-affected goats to determine susceptibility of sheep to goat scrapie. All sheep challenged with goat scrapie brain became infected based on the immunohistochemical detection of disease-associated PrP (PrPsc) in lymphoid tissue, with an ARQ/ARQ sheep being the first to succumb. Subsequent feeding of milk to eight pairs of new-born ARQ/ARQ lambs, with each pair receiving milk from a different scrapie-affected goat, resulted in scrapie in the six pairs that received the largest volume of milk (38–87 litres per lamb), whereas two pairs fed 8–9 litres per lamb, and an environmental control group raised on sheep milk from healthy ewes, did not show evidence of infection when culled at up to 1882 days of age. Infection in those 12 milk recipients occurred regardless of the clinical status, PrPsc distribution, caprine arthritis-encephalitis virus infection status and PRNP polymorphisms at codon 142 (II or IM) of the donor goats, but survival time was influenced by PRNP polymorphisms at codon 141. Serial PMCA applied to a total of 32 milk samples (four each from the eight donor goats collected throughout lactation) detected PrPsc in one sample each from two goats.ConclusionsThe scrapie agent was present in the milk from infected goats and was able to transmit to susceptible species even at early preclinical stage of infection, when PrPsc was undetectable in the brain of the donor goats. Serial PMCA as a PrPsc detection method to assess the risk of scrapie transmission via milk in goats proved inefficient compared to the bioassay.

【 授权许可】

CC BY   
© Crown copyright; licensee BioMed Central Ltd. 2016