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Transmissible spongiform encephalopathy (TSE) surveillance in goats relies on tests initially approved for cattle, subsequently assessed for sheep, and approval extrapolated for use in “small ruminants.” The current EU-approved immunodetection tests employ antibodies against various epitopes of the prion protein PrPSc, which is encoded by the host PRNPgene. The caprine PRNPgene is polymorphic, mostly at codons different from the ovine PRNP. The EU goat population is much more heterogeneous than the sheep population, with more PRNP-related polymorphisms, and with marked breed-related differences. The ability of the current tests to detect disease-specific PrPScgenerated against these different genetic backgrounds is currently assumed, rather than proven. We examined whether common polymorphisms within the goat PRNPgene might have any adverse effect on the relative performance of EU-approved rapid tests. The sample panel comprised goats from the UK, Cyprus, France, and Italy, with either experimental or naturally acquired scrapie at both the preclinical and/or unknown and clinical stages of disease. Test sensitivity was significantly lower and more variable when compared using samples from animals that were preclinical or of unknown status. However, all of the rapid tests included in our study were able to correctly identify all samples from animals in the clinical stages of disease, apart from samples from animals polymorphic for serine or aspartic acid at codon 146, in which the performance of the Bio-Rad tests was profoundly affected. Our data show that some polymorphisms may adversely affect one test and not another, as well as underline the dangers of extrapolating from other species.

ABSTRACTBovine spongiform encephalopathy (BSE) created a global European crisis in the 1980s and 90s, with very serious health and economic implications. Classical BSE now appears to be under control, to a great extent as a result of a global research effort that identified the sources of prions in meat and bone meal (MBM) and developed new animal-testing tools that guided policy. Priority (www.prionpriority.eu) was a European Union (EU) Framework Program 7 (FP7)-funded project through which 21 European research institutions and small and medium enterprises (SMEs) joined efforts between 2009 and 2014, to conduct coordinated basic and applied research on prions and prion diseases. At the end of the project, the Priority consortium drafted a position paper (www.prionpriority.eu/Priorityposition paper) with its main conclusions. In the present opinion paper, we summarize these conclusions.With respect to the issue of re-introducing ruminant protein into the feed-chain, our opinion is that sustaining an absolute ban on feeding ruminant protein to ruminants is essential. In particular, the spread and impact of non-classical forms of scrapie and BSE in ruminants is not fully understood and the risks cannot be estimated. Atypical prion agents will probably continue to represent the dominant form of prion diseases in the near future in Europe. Atypical L-type BSE has clear zoonotic potential, as demonstrated in experimental models. Similarly, there are now data indicating that the atypical scrapie agent can cross various species barriers. More epidemiological data from large cohorts are necessary to reach any conclusion on the impact of its transmissibility on public health. Re-evaluations of safety precautions may become necessary depending on the outcome of these studies.Intensified searching for molecular determinants of the species barrier is recommended, since this barrier is key for important policy areas and risk assessment. Understanding the structural basis for strains and the basis for adaptation of a strain to a new host will require continued fundamental research, also needed to understand mechanisms of prion transmission, replication and how they cause nervous system dysfunction and death. Early detection of prion infection, ideally at a preclinical stage, also remains crucial for development of effective treatment strategies.

The authors, who are life members of the Australian Plants Society Tasmania (APST), describe their wildflower garden in Legana, Tasmania. They relate how the 0.5 hectare garden has evolved into an informal native plant garden. They grown a wide range of plants with over 50 species including 20 acacias which are native to Tasmania, bulbines and several species of diplarrena, Black Peppermint, Black Wattle, Prickly Box , and Native Cherry.

The paraffin-embedded tissue (PET) blot was modified for use as a tool to differentiate between classical scrapie and experimental bovine spongiform encephalopathy (BSE) in sheep. Medulla (obex) from 21 cases of classical scrapie and 6 cases of experimental ovine BSE were used to develop the method such that it can be used as a tool to differentiate between BSE and scrapie in the same way that differential immunohistochemistry (IHC) has been used previously. The differential PET blot successfully differentiated between all of the scrapie and ovine BSE cases. Differentiation was permitted more easily with PET blot than by differential IHC, with accurate observations possible at the macroscopic level. At the microscopic level, sensitivity was such that discrimination by the differential PET blot could be made with more confidence than with differential IHC in cases where the immunohistochemical differences were subtle. The differential PET blot makes use of harsh epitope demasking conditions, and, because of the differences in the way prion protein is processed in different prion diseases, it can serve as a new, highly sensitive method to discriminate between classical scrapie and experimental BSE in sheep.

In a consignment of sheep brains from New Zealand, to be used in Europe as negative control material in scrapie rapid screening test evaluations, brain samples from 1 sheep (no. 1512) gave the following initially confusing results in various screening tests: the brainstem repeatedly produced negative results in 2 very similar screening kits (enzyme-linked immunosorbent assay [ELISA]-1, ELISA-2), a macerate made from brainstem and cerebellum returned a clearly positive result in ELISA-2, and the macerate and a brainstem sample gave negative results in a third screening test (ELISA-3). In subsequent testing, cerebellum tissue alone tested strongly positive in ELISA-1 and produced a banding pattern very similar to atypical scrapie/Nor98 in a confirmatory Western blot (WB). The macerate showed weak staining in the confirmatory WB but presented a staining pattern identical to atypical scrapie/Nor98 in the scrapie-associated fibril WB. The latter test confirmed conclusively the first case of atypical scrapie/Nor98 in a sheep from New Zealand. Other parts of the brain either tested negative or very weak positive in ELISA-2 and in WBs, or tested with negative results by histopathology and immunohistochemistry. It appears that sheep no. 1512 is a case of atypical scrapie/Nor98 in which the abnormal prion protein was detected mainly in the cerebellum. This case emphasizes the need to retain brainstem, and cerebral and cerebellar tissues, as frozen and fixed materials, for conclusive confirmatory testing. Furthermore, consideration should be given to which screening method to use.

The article provides information on Acacias that can be found in Tasmania. There are about 21 species and about 25 varieties and subspecies of Acacias from shrubs to trees all over Tasmania except in alpine regions. Some species common in these areas which have commercial value are Acacia melanoxylon or Blackwood, Acacia dealbata or silver wattle, and the Acacia mearnsii or black wattle.

Scrapie, a transmissible spongiform encephalopathy of sheep and goats, exists in most small ruminant-producing countries of the world. A novel form of this disease was recently recognized and is known by various names, including Nor98, Nor98-like, and atypical scrapie. Differing from classic scrapie in epidemiology, histopathology, and biochemical characteristics, atypical scrapie cases have been identified throughout Europe and in the United States. Enhanced scrapie surveillance efforts recently identified 3 cases of atypical scrapie in Canada.

Transmissible spongiform encephalopathies (TSEs) in animals include, among others, bovine spongiform encephalopathy (BSE), scrapie, chronic wasting disease, and atypical forms of prion diseases. Diagnosis of TSEs is based on identification of characteristic lesions or on detection of the abnormal prion proteins in tissues, often by use of their partial proteinase K resistance property. Correctly sampling of target tissues is of utmost importance as this has a considerable effect on test sensitivity. Most of the rapid or screening tests are based on ELISA or Western immunoblot (WB) analysis, and many are officially approved. Confirmatory testing is normally performed by use of histologic examination, immunohistochemical analysis, certain WB protocols, or detection of prion fibrils by use of electron microscopy (scrapie-associated fibril). The discriminatory methods for diagnostic use are mostly based on WB technology and provide initial identification of the prion strain, particularly for differentiation of BSE from scrapie in small ruminants. Definitive prion strain characterization is performed by use of bioassays, usually in mice. A burgeoning number of transgenic mice have been developed for TSE studies. Development of new tests with higher sensitivity and of more reliable diagnostic applications for live animals tested for food safety reasons is a rapidly developing field. Ultimately, the choice of a test for TSE diagnosis depends on the rationale for the testing.

ObjectivesTo carry out a further survey of archived appendix samples to understand better the differences between existing estimates of the prevalence of subclinical infection with prions after the bovine spongiform encephalopathy epizootic and to see whether a broader birth cohort was affected, and to understand better the implications for the management of blood and blood products and for the handling of surgical instruments. DesignIrreversibly unlinked and anonymised large scale survey of archived appendix samples.SettingArchived appendix samples from the pathology departments of 41 UK hospitals participating in the earlier survey, and additional hospitals in regions with lower levels of participation in that survey.Sample32 441 archived appendix samples fixed in formalin and embedded in paraffin and tested for the presence of abnormal prion protein (PrP).ResultsOf the 32 441 appendix samples 16 were positive for abnormal PrP, indicating an overall prevalence of 493 per million population (95% confidence interval 282 to 801 per million). The prevalence in those born in 1941-60 (733 per million, 269 to 1596 per million) did not differ significantly from those born between 1961 and 1985 (412 per million, 198 to 758 per million) and was similar in both sexes and across the three broad geographical areas sampled. Genetic testing of the positive specimens for the genotype at PRNPcodon 129 revealed a high proportion that were valine homozygous compared with the frequency in the normal population, and in stark contrast with confirmed clinical cases of vCJD, all of which were methionine homozygous at PRNPcodon 129.ConclusionsThis study corroborates previous studies and suggests a high prevalence of infection with abnormal PrP, indicating vCJD carrier status in the population compared with the 177 vCJD cases to date. These findings have important implications for the management of blood and blood products and for the handling of surgical instruments.

It is currently believed that primary transmission of classical scrapie to wild-type mice is inefficient and characterized by low attack rates and variable incubation periods and lesion profiles. Consequently, strain characterization of classical scrapie in these mice relies on subpassage. The aim of this study was to perform a retrospective analysis of lesion profiles and immunohistochemistry patterns after transmission of a large number of classical scrapie sources to wild-type mice and to investigate trends that might be used to characterize the agent without subpassaging. Scrapie field cases (n = 31) collected from individual farms between 1996 and 1999 were inoculated into RIII, C57BL, and VM mice and profiled using standard methodology and analyzed by immunohistochemistry. Using cluster analysis to resultant lesion profiles produced groups of similar lesion profiles in RIII and C57BL mice. We observed correlations between lesion profile clusters and the ovine prion protein (PrP) genotype. Immunohistochemistry indicated donor-mediated trends in the PrPSc pattern. These results indicate that ovine PrP genotype is a factor that is linked to both the lesion profile and the pattern of PrPSc deposition on primary transmission of classical scrapie to wild-type mice.