The bovine spongiform encephalopathy (BSE) crisis clearly demonstrated the need to keep animal transmissible spongiform encephalopathies (TSE) under control in order to protect animal and human health. Scrapie is the most widespread TSE of livestock in the world. For this reason, health authorities in different countries have elaborated plans that aim towards scrapie eradication. The unusual na...

How susceptible pigs are to infection with sheep prions is unknown. We show, through transmission experiments in transgenic mice expressing porcine prion protein (PrP), that the susceptibility of this mouse model to bovine spongiform encephalopathy (BSE) can be enhanced after its passage in ARQ sheep, indicating that the pathogenicity of the BSE agent is modified after passage in sheep. Transge...

Classical bovine spongiform encephalopathy (c-BSE) is the only animal prion disease reputed to be zoonotic, causing variant Creutzfeldt-Jakob disease (vCJD) in humans and having guided protective measures for animal and human health against animal prion diseases. Recently, partial transmissions to humanized mice showed that the zoonotic potential of scrapie might be similar to c-BSE. We here re...

A cellular form of the prion protein (PrPC) is thought to be a substrate for an abnormal isoform of th eprion protein (PrPSc) in scrapie. PrPC is abundant in tissues of the central nervous system, but little is known about the distribution of PrPC in non-neuronal tissues of sheep, the natural host of scrapie. This study investigated the tissue distribution of PrPC in sheep. Although PrPC was ab...

Transmissible spongiform encephalopathies are fatal neurodegenerative diseases that include variant Creutzfeldt-Jakob disease in humans, scrapie in small ruminants, and bovine spongiform encephalopathy (BSE) in cattle. Scrapie is not considered a public health risk, but BSE has been linked to variant Creutzfeldt-Jakob disease. Small ruminants are susceptible to BSE, and in 2005 BSE was identifi...

Creutzfeldt-Jakob disease is a rare progressive neurological disorder which is eventually fatal. Attention has recently been focused upon the iatrogenic transmission of this disease by four published reports of patients developing Creutzfeldt-Jakob disease associated with the administration of human growth hormone preparations originally prepared from human cadaver pituitaries. Characterized cl...

Although scrapie has been studied for many years, the nature of the scrapie agent remains obscure (14). In spite of a number of unusual properties, this agent has been generally considered to be a virus (9, 13). In a previous study, repeated daily injections of 6,000 units of interferon failed to protect mice challenged intracerebrally (ic) with about 5,000 median lethal dose (LD50) of the scra...

Public and animal health controls to limit human exposure to animal prions are focused on bovine spongiform encephalopathy (BSE), but other prion strains in ruminants may also have zoonotic potential. One example is atypical/Nor98 scrapie, which evaded statutory diagnostic methods worldwide until the early 2000s. To investigate whether sheep infected with scrapie prions could be another source ...

The study of the biology of scrapie in sheep is irretrievably associated with the genetics of the PrP gene in sheep. Control of susceptibility and resistance is so closely linked to certain alleles of the sheep PrP gene that no review on scrapie can avoid PrP genetics. Before the importance of PrP protein was discovered and before the influence of the gene itself on disease incidence was unders...

Mice devoid of PrPC (Prnp%) are resistant to scrapie and do not allow propagation of the infectious agent (prion). PrPC-expressing neuroectodermal tissue grafted into Prnp% brains but not the surrounding tissue consistently exhibits scrapie-specific pathology and allows prion replication after inoculation. Scrapie prions administered intraocularly into wild-type mice spread efficiently to the c...