Experimental H-type bovine spongiform encephalopathy characterized by plaques and glial- and stellate-type prion protein deposits

Atypical bovine spongiform encephalopathy (BSE) has recently been identified in Europe, North America, and Japan. It is classified as H-type and L-type BSE according to the molecular mass of the disease-associated prion protein (PrPSc). To investigate the topographical distribution and deposition patterns of immunolabeled PrPSc, H-type BSE isolate was inoculated intracerebrally into cattle. H-type BSE was successfully transmitted to 3 calves, with incubation periods between 500 and 600 days. Moderate to severe spongiform changes were detected in the cerebral and cerebellar cortices, basal ganglia, thalamus, and brainstem. H-type BSE was characterized by the presence of PrP-immunopositive amyloid plaques in the white matter of the cerebrum, basal ganglia, and thalamus. Moreover, intraglial-type immunolabeled PrPSc was prominent throughout the brain. Stellate-type immunolabeled PrPSc was conspicuous in the gray matter of the cerebral cortex, basal ganglia, and thalamus, but not in the brainstem. In addition, PrPSc accumulation was detected in the peripheral nervous tissues, such as trigeminal ganglia, dorsal root ganglia, optic nerve, retina, and neurohypophysis. Cattle are susceptible to H-type BSE with a shorter incubation period, showing distinct and distinguishable phenotypes of PrPSc accumulation

Intraspecies Prion Transmission Results in Selection of Sheep Scrapie Strains

Background: Sheep scrapie is caused by multiple prion strains, which have been classified on the basis of their biological characteristics in inbred mice. The heterogeneity of natural scrapie prions in individual sheep and in sheep flocks has not been clearly defined. Methodology/Principal Findings: In this study, we intravenously injected 2 sheep (Suffolk and Corriedale) with material from a natural case of sheep scrapie (Suffolk breed). These 3 sheep had identical prion protein (PrP) genotypes. The protease-resistant core of PrP (PrPres) in the experimental Suffolk sheep was similar to that in the original Suffolk sheep. In contrast, PrPres in the Corriedale sheep differed from the original PrPres but resembled the unusual scrapie isolate, CH1641. This unusual PrPres was not detected in the original sheep. The PrPres distributions in the brain and peripheral tissues differed between the 2 breeds of challenged sheep. A transmission study in wild-type and TgBoPrP mice, which overexpressing bovine PrP, led to the selection of different prion strains. The pathological features of prion diseases are thought to depend on the dominantly propagated strain. Conclusions/Significance: Our results indicate that prion strain selection occurs after both inter- and intraspecie

Sulfated Dextrans Enhance In Vitro Amplification of Bovine Spongiform Encephalopathy PrPSc and Enable Ultrasensitive Detection of Bovine PrPSc

Prions, infectious agents associated with prion diseases such as Creutzfeldt-Jakob disease in humans, bovine spongiform encephalopathy (BSE) in cattle, and scrapie in sheep and goats, are primarily comprised of PrP(Sc), a protease-resistant misfolded isoform of the cellular prion protein PrP(C). Protein misfolding cyclic amplification (PMCA) is a highly sensitive technique used to detect minute amounts of scrapie PrP(Sc). However, the current PMCA technique has been unsuccessful in achieving good amplification in cattle. The detailed distribution of PrP(Sc) in BSE-affected cattle therefore remains unknown.We report here that PrP(Sc) derived from BSE-affected cattle can be amplified ultra-efficiently by PMCA in the presence of sulfated dextran compounds. This method is capable of amplifying very small amounts of PrP(Sc) from the saliva, palatine tonsils, lymph nodes, ileocecal region, and muscular tissues of BSE-affected cattle. Individual differences in the distribution of PrP(Sc) in spleen and cerebrospinal fluid samples were observed in terminal-stage animals. However, the presence of PrP(Sc) in blood was not substantiated in the BSE-affected cattle examined.The distribution of PrP(Sc) is not restricted to the nervous system and can spread to peripheral tissues in the terminal disease stage. The finding that PrP(Sc) could be amplified in the saliva of an asymptomatic animal suggests a potential usefulness of this technique for BSE diagnosis. This highly sensitive method also has other practical applications, including safety evaluation or safety assurance of products and byproducts manufactured from bovine source materials

Isolation of two distinct prion strains from a scrapie-affected sheep

We performed a transmission study using mice to clarify the characteristics of the most recent case of scrapie in Japan. The mice that were inoculated with the brain homogenate from a scrapie-affected sheep developed progressive neurological disease, and one of the scrapie-affected mice showed unique clinical signs during primary transmission. This mouse developed obesity, polydipsia, and polyuria. In contrast, the other affected mice exhibited weight loss and hypokinesia. In subsequent passages, the mice showed distinct characteristic scrapie phenotypes. This finding may prove that different prion strains coexist in a naturally affected sheep with scrapie

Serotyping of 800 Strains of Erysipelothrix Isolated from Pigs Affected with Erysipelas and Discrimination of Attenuated Live Vaccine Strain by Genotyping

Eight hundred Erysipelothrix strains isolated between 1992 and 2002 from swine with erysipelas in Japan were serotyped. Thirty-seven, 47, 73, and 643 strains were isolated from animals with acute septicemia, urticaria, chronic endocarditis, and chronic arthritis, respectively, of which 381, 146, 254, and 19 isolates belonged to serotypes 1a, 1b, and 2b and other serotypes, respectively. All serotype 1a isolates were further examined for acriflavine resistance and their genotypes to discriminate them from the attenuated live vaccine strain, defined as serotype 1a, which is resistant to 0.02% acriflavine and which shows low levels of pathogenicity in mice. Of the serotype 1a isolates, 64.6% were acriflavine resistant, with 98.4% of these acriflavine-resistant strains having been isolated from animals with chronic arthritis. By randomly amplified polymorphic DNA (RAPD) analysis, almost all the acriflavine-resistant serotype 1a strains showed the 253-bp band characteristic of vaccine strains and were easily discriminated from all 113 strains of acriflavine-sensitive serotype 1a strains from animals with acute and subacute swine erysipelas. The incidence of acriflavine-resistant strains of the distinctive RAPD type 1-2 was markedly higher than that of the other RAPD types and serotypes. RAPD type 1-2 strains also included a specific group identifiable by restriction fragment length polymorphism DNA analysis. Furthermore, the pathogenicities of 29 isolates of RAPD type 1-2 for mice were lower than those of the 21 isolates of other RAPD types. Our results indicate that RAPD type 1-2 strains are live vaccine strains and that 37% of the cases of chronic swine erysipelas detected in the past 11 years in Japan have occurred as a side effect of live vaccine use

Heterogeneity of the Abnormal Prion Protein (PrPSc) of the Chandler Scrapie Strain

The pathological prion protein, PrPSc, displays various sizes of aggregates. In this study, we investigated the conformation, aggregation stability and proteinase K (PK)-sensitivity of small and large PrPSc aggregates of mouse-adapted prion strains. We showed that small PrPSc aggregates, previously thought to be PK-sensitive, are resistant to PK digestion. Furthermore, we showed that small PrPSc aggregates of the Chandler scrapie strain have greater resistance to PK digestion and aggregation-denaturation than large PrPSc aggregates of this strain. We conclude that this strain consists of heterogeneous PrPSc