Experimental Infection of Cattle With a Novel Prion Derived From Atypical H-Type Bovine Spongiform Encephalopathy

Abstract

H-type bovine spongiform encephalopathy (H-BSE) is an atypical form of BSE in cattle. During passaging of H-BSE in transgenic bovinized (TgBoPrP) mice, a novel phenotype of BSE, termed BSE-SW emerged and was characterized by a short incubation time and host weight loss. To investigate the biological and biochemical properties of the BSE-SW prion, a transmission study was conducted in cattle, which were inoculated intracerebrally with brain homogenate from BSE-SW-infected TgBoPrP mice. The disease incubation period was approximately 15 months. The animals showed characteristic neurological signs of dullness, and severe spongiform changes and a widespread, uniform distribution of disease-associated prion protein (PrP) were observed throughout the brain of infected cattle. Immunohistochemical PrP staining of the brain revealed the presence of intraglial accumulations and plaque-like deposits. No remarkable differences were identified in vacuolar lesion scores, topographical distribution patterns, and staining types of PrP in the brains of BSE-SW- vs H-BSE-infected cattle. PrP deposition was detected in the ganglia, vagus nerve, spinal nerve, cauda equina, adrenal medulla, and ocular muscle. Western blot analysis revealed that the specific biochemical properties of the BSE-SW prion, with an additional 10- to 12-kDa fragment, were well maintained after transmission. These findings indicated that the BSE-SW prion has biochemical properties distinct from those of H-BSE in cattle, although clinical and pathologic features of BSW-SW in cattle are indistinguishable from those of H-BSE. The results suggest that the 2 infectious agents, BSE-SW and H-BSE, are closely related strains.

Animal prion diseases: the risks to human health

“…Following oral challenge of cattle with a range of doses of L‐BSE‐infected cattle brain homogenate, only one animal that received the highest dose (50 g) developed neurological clinical signs. This animal showed a similar tissue distribution of PrP Sc to that observed in IC‐challenged animals (central and peripheral nervous systems), although there were subtle differences in the distribution of PrP Sc within the brain regions .…”

Bovine Spongiform Encephalopathy – A Review from the Perspective of Food Safety

“…The brain of all the BSE-SW inoculated calves had severe spongiform changes, and a widespread and uniform distribution of PrP Sc . The transmitted BSE-SW had the biological properties distinct from those of H-BSE, but clinical and pathologic features in the transmitted cattle were indistinguishable from those of H-BSE cattle 105,106) .…”