Highly Sensitive Detection of Small Ruminant Bovine Spongiform Encephalopathy within Transmissible Spongiform Encephalopathy Mixes by Serial Protein Misfolding Cyclic Amplification

Gough, Kevin C.; Bishop, Keith; Maddison, Ben C.

doi:10.1128/jcm.01693-14

Cited by 11 publications

(17 citation statements)

References 19 publications

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“…Furthermore, PMCA can selectively detect C-BSE in mixtures of brain homogenates (BHs) from C-BSE-and scrapie-infected sheep with 100% specificity and 97% sensitivity (25). Still, it remains important to develop highly sensitive methods that can discriminate C-BSE from other prion strains in cattle.…”

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confidence: 99%

Detection and Discrimination of Classical and Atypical L-Type Bovine Spongiform Encephalopathy by Real-Time Quaking-Induced Conversion

et al. 2015

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Statutory surveillance of bovine spongiform encephalopathy (BSE) indicates that cattle are susceptible to both classical BSE (C-BSE) and atypical forms of BSE. Atypical forms of BSE appear to be sporadic and thus may never be eradicated. A major challenge for prion surveillance is the lack of sufficiently practical and sensitive tests for routine BSE detection and strain discrimination. The real-time quaking-induced conversion (RT-QuIC) test, which is based on prion-seeded fibrillization of recombinant prion protein (rPrP Sen ), is known to be highly specific and sensitive for the detection of multiple human and animal prion diseases but not BSE. Here, we tested brain tissue from cattle affected by C-BSE and atypical L-type bovine spongiform encephalopathy (L-type BSE or L-BSE) with the RT-QuIC assay and found that both BSE forms can be detected and distinguished using particular rPrP Sen substrates. Specifically, L-BSE was detected using multiple rPrP Sen substrates, while C-BSE was much more selective. This substrate-based approach suggests a diagnostic strategy for specific, sensitive, and rapid detection and discrimination of at least some BSE forms.T ransmissible spongiform encephalopathies (TSEs), or prion diseases, such as Creutzfeldt-Jakob disease (CJD) in humans and bovine spongiform encephalopathy (BSE) in cattle, are fatal neurodegenerative disorders characterized by spongiosis, neuronal loss, gliosis, and abnormal deposition of host-encoded prion protein (PrP) in the brain. The infectious agent responsible for TSEs appears to be largely composed of a misfolded and multimeric form of prion protein (PrP Sc ), which is able to induce polymerization and conformational conversion of normal proteasesensitive prion protein (PrP Sen ) into PrP Sc and its partially protease-resistant forms (PrP Res ) (1). BSE and its link to variant Creutzfeldt-Jakob disease (vCJD) in humans have raised important food safety issues. The incidence of classical BSE (C-BSE) has decreased as a result of disease-control programs, such as the ruminant feed ban (2). However, atypical forms of bovine prion disease have been identified in several countries (3). These emerging bovine prion strains can be categorized as H-type BSE (H-BSE) or L-type BSE (L-BSE or bovine amyloidotic spongiform encephalopathy [BASE] when amyloid plaques are present in the brain). These atypical BSE strains are differentiated biochemically by the electrophoretic mobility and glycoform pattern of PrP Res after proteinase K (PK) digestion (4-7). Currently, both of these atypical bovine prion strains, which mainly affect older animals (8), are thought to be sporadic forms of bovine prion diseases (9) and are still rare (less than 100 cases identified worldwide to date).It is suspected that one of these atypical L-BSE or H-BSE strains may have instigated the C-BSE epidemic, as suggested, for example, by the fact that the L-BSE strain can convert to C-BSE following serial passage in mice (5,6,10). Further concerns about the atypical BSE strains have arisen from...

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Detection and Discrimination of Classical and Atypical L-Type Bovine Spongiform Encephalopathy by Real-Time Quaking-Induced Conversion

et al. 2015

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“…Recently, a serial protein misfolding cyclic amplification assay (sPMCA) has been developed to specifically detect classic BSE even within the presence of scrapie prions. It has been reported that in a blind trial, this sPMCA-based assay specifically amplified BSE PrP Sc within brain mixes with 100% specificity and 97% sensitivity when BSE agent was diluted into scrapie-infected brain homogenates at 1% (vol/vol) [ 47 ]. Compared to mouse bioassay this in vitro technique may offer a quick, reliable and more cost effective method in detecting BSE in the presence of scrapie.…”

Section: Discussionmentioning

confidence: 99%

Ability of wild type mouse bioassay to detect bovine spongiform encephalopathy (BSE) in the presence of excess scrapie

Corda

Thorne

Beck

et al. 2015

acta neuropathol commun

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IntroductionScrapie and bovine spongiform encephalopathy (BSE) are transmissible spongiform encephalopathies (TSEs) which naturally affect small and large ruminants respectively. However, small ruminants, which are susceptible to BSE under experimental conditions, have been exposed to the same or similar contaminated food additives as cattle. To date two natural cases of BSE in small ruminants have been reported. As a result surveillance projects, combined with appropriate control measures, have been established throughout the European Union (EU) to minimize the overall incidence of small ruminant TSEs. Although BSE can be differentiated from classical scrapie (subsequently referred to as scrapie) if appropriate discriminatory tests are applied, the value of these tests in BSE/scrapie co-infection scenarios has not been evaluated fully. Mouse bioassay is regarded as the gold standard regarding differentiation of distinct TSE strains and has been used as to resolve TSE cases were laboratory tests produced equivocal results. However, the ability of this method to discriminate TSE strains when they co-exist has not been examined systematically. To address this issue we prepared in vitro mixtures of ovine BSE and scrapie and used them to challenge RIII, C57BL/6 and VM mice.ResultsDisease phenotype analysis in all three mouse lines indicated that most phenotypic parameters (attack rates, incubation periods, lesion profiles and Western blots) were compatible with scrapie phenotypes as were immunohistochemistry (IHC) data from RIII and C57BL/6 mice. However, in VM mice that were challenged with BSE/scrapie mixtures a single BSE-associated IHC feature was identified, indicating the existence of BSE in animals where the scrapie phenotype was dominant.ConclusionsWe conclude that wild type mouse bioassay is of limited value in detecting BSE in the presence of scrapie particularly if the latter is in relative excess.Electronic supplementary materialThe online version of this article (doi:10.1186/s40478-015-0194-2) contains supplementary material, which is available to authorized users.

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“…In addition, the use of AHQ/AHQ substrate did not support the amplification of any classical or atypical/Nor98 scrapie isolates from sheep with a range of PRNP genotypes. These observations have been developed into a sensitive assay using a combination of the VRQ/VRQ and AHQ/AHQ brain homogenate substrates [ 113 ]. These two substrates encourage the amplification of BSE over scrapie and when used in sequential rounds of PMCA have demonstrated amplification specificity to BSE, even when BSE is present with a vast excess of different scrapie isolates [ 113 , 114 ].…”

Section: In Vitro Replication Of Prion Typesmentioning

confidence: 99%

“…These observations have been developed into a sensitive assay using a combination of the VRQ/VRQ and AHQ/AHQ brain homogenate substrates [ 113 ]. These two substrates encourage the amplification of BSE over scrapie and when used in sequential rounds of PMCA have demonstrated amplification specificity to BSE, even when BSE is present with a vast excess of different scrapie isolates [ 113 , 114 ]. The assay was shown to be far superior to ELISA and western blot tests for detecting ovine BSE in the presence of a large excess of scrapie agent [ 114 ].…”

Section: In Vitro Replication Of Prion Typesmentioning

confidence: 99%

Methods for Differentiating Prion Types in Food-Producing Animals

Gough

Rees

Ives

et al. 2015

Biology

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Prions are an enigma amongst infectious disease agents as they lack a genome yet confer specific pathologies thought to be dictated mainly, if not solely, by the conformation of the disease form of the prion protein (PrPSc). Prion diseases affect humans and animals, the latter including the food-producing ruminant species cattle, sheep, goats and deer. Importantly, it has been shown that the disease agent of bovine spongiform encephalopathy (BSE) is zoonotic, causing variant Creutzfeldt Jakob disease (vCJD) in humans. Current diagnostic tests can distinguish different prion types and in food-producing animals these focus on the differentiation of BSE from the non-zoonotic agents. Whilst BSE cases are now rare, atypical forms of both scrapie and BSE have been reported, as well as two types of chronic wasting disease (CWD) in cervids. Typing of animal prion isolates remains an important aspect of prion diagnosis and is now becoming more focused on identifying the range of prion types that are present in food-producing animals and also developing tests that can screen for emerging, novel prion diseases. Here, we review prion typing methodologies in light of current and emerging prion types in food-producing animals.

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Highly Sensitive Detection of Small Ruminant Bovine Spongiform Encephalopathy within Transmissible Spongiform Encephalopathy Mixes by Serial Protein Misfolding Cyclic Amplification

Cited by 11 publications

References 19 publications

Detection and Discrimination of Classical and Atypical L-Type Bovine Spongiform Encephalopathy by Real-Time Quaking-Induced Conversion

Detection and Discrimination of Classical and Atypical L-Type Bovine Spongiform Encephalopathy by Real-Time Quaking-Induced Conversion

Ability of wild type mouse bioassay to detect bovine spongiform encephalopathy (BSE) in the presence of excess scrapie

Methods for Differentiating Prion Types in Food-Producing Animals

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