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Dm Taylor - One of the best experts on this subject based on the ideXlab platform.
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Papers and Articles Effect of rendering procedures on the Scrapie Agent
2016Co-Authors: Dm Taylor, S L Woodgate, A J Fleetwood, R J G CawthorneAbstract:A pool of Scrapie-infected sheep brains was used to spike mix-tures of porcine bone and intestine. These were processed in pilot-scale facsimiles of 12 rendering procedures that were in use within the European Union in 1991, and three that were not. Meat and bone meal, and tallow, were produced from the rendered tissues. Suspensions of all the meat and bone meal samples, and two of the tallow samples were assayed in mice for Scrapie infectivity. Neither of the tallow samples had any detectable infectivity but the meat and bone meal samples were positive, except for those produced by processes involv-ing exposure to hyperbaric steam. In addition, greaves were produced from the Scrapie-spiked raw materials by an atypi-cal low-temperature process and subjected to solvent extrac-tion with hot heptane. The treated greaves were then exposed to steam to drive off residual solvent. Although the starting titre of infectivity in these greaves was low, there appeared to be no reduction in infectivity as a result of the treatments with hot heptane and steam. However, there was no detectable infectivity in the meat and bone meal prepared from the greaves produced by the atypical low-temperature process after it had been exposed to hyperbaric steam. Scrapie is a fatal neurological disease that affects sheep and goats (and occasionally moufflon) in many parts of the world, and it has been endemic for at least two centuries among sheep in Great Britain and some of the countries of western Europe (Parry 1983). The disease is caused by an unconventional transmissible Agent that is uncharacterised but has unusual properties, including a high resistance to inactivation (Taylor and others 1994). Bovine spongiform encephalopathy (BSE) is a Scrapie-like disease of cat-tle, the first sporadic cases of which are suspected to have occurred in England in 1985 (Wells and others 1987). The disease has now affected more than 166,000 cattle in the United Kingdom, and smaller numbers of indigenous cattle in France, th
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closely similar values obtained when the me7 strain of Scrapie Agent was titrated in parallel by two individuals in separate laboratories using two sublines of c57bl mice
Journal of Virological Methods, 2000Co-Authors: Dm Taylor, I Mcconnell, C E FergusonAbstract:A single C57BL mouse-brain infected with the ME7 strain of mouse-passaged Scrapie Agent was used to carry out four parallel infectivity titrations in mice. These were carried out by two individuals in two laboratories using two sublines of C57BL mice. The titre values obtained by the four assays were very similar, and showed no significant differences between the two different operatives, the two different laboratories or the two different sublines of C57BL mice. The data confirm the validity of comparing these types of transmission data generated in different laboratories when a common methodology is used.
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survival of Scrapie Agent after exposure to sodium dodecyl sulphate and heat
Veterinary Microbiology, 1999Co-Authors: Dm Taylor, I Mcconnell, Karen Fernie, Philip SteeleAbstract:Abstract Fifty mg aliquots of macerated mouse-brain infected with the 22A strain of Scrapie Agent were treated by exposing them without mechanical mixing to (a) distilled water for 2 h, (b) 5% sodium dodecyl sulphate (SDS) for 2 h, (c) autoclaving at 121°C for 15 min in distilled water, (d) autoclaving at 121°C for 15 min in 5% SDS, or (e) boiling in 5% SDS for 15 min. Prior to injection into mice, all samples were washed by a procedure that is described and was shown not to reduce infectivity titres. Although the infectivity titre of the sample that was autoclaved in SDS was reduced considerably, infectivity was present in all of the samples exposed to cold or hot SDS.
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effect of rendering procedures on the Scrapie Agent
Veterinary Record, 1997Co-Authors: Dm Taylor, S L Woodgate, A J Fleetwood, R J G CawthorneAbstract:A pool of Scrapie-infected sheep brains was used to spike mixtures of porcine bone and intestine. These were processed in pilot-scale facsimiles of 12 rendering procedures that were in use within the European Union in 1991, and three that were not. Meat and bone meal, and tallow, were produced from the rendered tissues. Suspensions of all the meat and bone meal samples, and two of the tallow samples were assayed in mice for Scrapie infectivity. Neither of the tallow samples had any detectable infectivity but the meat and bone meal samples were positive, except for those produced by processes involving exposure to hyperbaric steam. In addition, greaves were produced from the Scrapie-spiked raw materials by an atypical low-temperature process and subjected to solvent extraction with hot heptane. The treated greaves were then exposed to steam to drive off residual solvent. Although the starting titre of infectivity in these greaves was low, there appeared to be no reduction in infectivity as a result of the treatments with hot heptane and steam. However, there was no detectable infectivity in the meat and bone meal prepared from the greaves produced by the atypical low-temperature process after it had been exposed to hyperbaric steam.
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inactivation of the 22a strain of Scrapie Agent by autoclaving in sodium hydroxide
Veterinary Microbiology, 1997Co-Authors: Dm Taylor, Karen Fernie, I McconnellAbstract:Samples of macerated mouse-brain infected with the 22A strain of Scrapie Agent were subjected to gravity-displacement autoclaving at 121°C for 30 minutes in the presence of 2 M sodium hydroxide. No infectivity was detectable by mouse bioassay in samples which were either held for an hour at room temperature before autoclaving, or autoclaved immediately after adding the hydroxide. In contrast, all of the mice injected with a control sample, held for an hour in distilled water before autoclaving, developed Scrapie. If adopted as a routine decontamination procedure it is recommended that hydroxide-treated waste should be autoclaved in sealed heat-resistant containers which can withstand the pressures involved. This would make the procedure safer for the operator, and avoid autoclave damage through exposure to sodium hydroxide.
Richard E. Race - One of the best experts on this subject based on the ideXlab platform.
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characteristics of 263k Scrapie Agent in multiple hamster species
Emerging Infectious Diseases, 2009Co-Authors: Kimberly Meadewhite, Kent D Barbian, Brent Race, Cynthia Favara, Don Gardner, Lara Taubner, Stephen F Porcella, Richard E. RaceAbstract:Transmissible spongiform encephalopathy (TSE) diseases are known to cross species barriers, but the pathologic and biochemical changes that occur during transmission are not well understood. To better understand these changes, we infected 6 hamster species with 263K hamster Scrapie strain and, after each of 3 successive passages in the new species, analyzed abnormal proteinase K (PK)–resistant prion protein (PrPres) glycoform ratios, PrPres PK sensitivity, incubation periods, and lesion profiles. Unique 263K molecular and biochemical profiles evolved in each of the infected hamster species. Characteristics of 263K in the new hamster species seemed to correlate best with host factors rather than Agent strain. Furthermore, 2 polymorphic regions of the prion protein amino acid sequence correlated with profile differences in these TSE-infected hamster species.
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transgenic mice with neuron specific expression of a hamster prion protein minigene are susceptible to hamster Scrapie Agent
1998Co-Authors: Bruce Chesebro, Suzette A Priola, Richard E. RaceAbstract:The degenerative brain diseases known as transmissible spongiform encephalopathies (TSE) occur naturally in primates and ruminants, and include Scrapie of sheep, bovine spongiform encephalopathy, and several human diseases such as Creutzfeldt-Jakob disease, Kuru, and Gerstmann-Straussler-Scheinker syndrome. During the course of TSE diseases brain tissue accumulates a proteinase K-resistant protein, known as PrP-res or PrPSc, which is associated with the pathogenic process [1–3]. PrP-res is post-translationally derived from a normal host proteinase K-sensitive PrP molecule (PrP-sen) [4–6] by an as yet undefined mechanism. PrP may play a critical role in interspecies transmission of TSE diseases. Many species show resistance to disease induction by TSE Agents derived from other species. This resistance or “species barrier” is manifested either by total lack of disease induction or by a prolonged incubation period prior to onset of clinical disease. Genetic studies have indicated that the PrP genotype strongly influences the host susceptibility to TSE Agents [7–9]. Transgenic mice with a 40 kb transgene expressing high levels of hamster PrP (HPrP)-sen are susceptible to disease when inoculated with the hamster Scrapie Agent while normal mice are resistant [10,11]. This suggests that transmission of Scrapie may be dependent on interactions between the host PrP-sen and the PrP-res derived from the donor of the inoculated Agent. Interactions between PrP molecules from different species have been found to inhibit generation of PrP-res in both Scrapie-infected cells [12] and in cell-free systems [13,14], and such inhibitory interactions may provide a biochemical explanation for the species barrier.
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neuron specific expression of a hamster prion protein minigene in transgenic mice induces susceptibility to hamster Scrapie Agent
Neuron, 1995Co-Authors: Richard E. Race, Bruce Chesebro, Darwin Ernst, Suzette A Priola, Richard A Bessen, J Dockter, Glenn F Rall, Lennart Mucke, Michael B A OldstoneAbstract:Abstract To study the effect of cell type-restricted hamster PrP expression on susceptibility to the hamster Scrapie Agent, we generated transgenic mice using a 1 kb hamster cDNA clone containing the 0.76 kb HPrP open reading frame under control of the neuron-specific enolase promoter. In these mice, expression of HPrP was detected only in brain tissue, with highest levels found in neurons of the cerebellu, hippocampus, thalamus, and cerebral cortex. These transgenic mice were susceptible to infection by the 263K strain of hamster Scrapie with an average incubation period of 93 days, compared to 72 days in normal hamsters. In contrast, nontransgenic mice were not susceptible to this Agent. These results indicate that neuron-specific expression of the 1 kb HPrP minigene including the HPrP open-reading frame is sufficient to mediate susceptibility to hamster scraple, and that HPrP expression in nonneuronal brain cells is not necessary to overcome the TSE species barrier.
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comparative analysis of Scrapie Agent inactivation methods
Journal of Virological Methods, 1993Co-Authors: Darwin R Ernst, Richard E. RaceAbstract:A Scrapie-infected hamster brain homogenate was subjected to several different potential inactivation methods. Methods included autoclaving for various lengths of time, either alone or in combination with different concentrations of sodium hydroxide or LpH, an aqueous acid phenolic derivative (Calgon Vestal Laboratories in St. Louis, MO). Inactivation treatments utilizing either NaOH or LpH alone were also evaluated. It was determined that several of the treatments inactivated all of the detectable infectivity.
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Congo red inhibition of Scrapie Agent replication.
Journal of Virology, 1993Co-Authors: Byron Caughey, D Ernst, Richard E. RaceAbstract:Congo red inhibits the accumulation of protease-resistant PrP in Scrapie-infected mouse neuroblastoma cells. Here we show that Congo red also inhibits the replication of Scrapie infectivity in these cells. This observation is consistent with the idea that protease-resistant PrP is a vital component of the Scrapie Agent or that Agent replication depends on the presence of protease-resistant PrP in the cell.
Justin J Greenlee - One of the best experts on this subject based on the ideXlab platform.
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transmission of the atypical nor98 Scrapie Agent to suffolk sheep with vrq arq arq arq and arq arr genotypes
PLOS ONE, 2021Co-Authors: Eric D Cassmann, Najiba Mammadova, Jo S Moore, Sylvie L Benestad, Justin J GreenleeAbstract:Scrapie is a transmissible spongiform encephalopathy that occurs in sheep. Atypical/Nor98 Scrapie occurs in sheep that tend to be resistant to classical Scrapie and it is thought to occur spontaneously. The purpose of this study was to test the transmission of the Atypical/Nor98 Scrapie Agent in three genotypes of Suffolk sheep and characterize the distribution of misfolded prion protein (PrPSc). Ten sheep were intracranially inoculated with brain homogenate from a sheep with Atypical/Nor98 Scrapie. All sheep with the ARQ/ARQ and ARQ/ARR genotypes developed Atypical/Nor98 Scrapie confirmed by immunohistochemistry, and one sheep with the VRQ/ARQ genotype had detectable PrPSc consistent with Atypical/Nor98 Scrapie at the experimental endpoint of 8 years. Sheep with mild early accumulations of PrPSc in the cerebellum had concomitant retinal PrPSc. Accordingly, large amounts of retinal PrPSc were identified in clinically affected sheep and sheep with dense accumulations of PrPSc in the cerebellum.
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efficient transmission of classical Scrapie Agent x124 by intralingual route to genetically susceptible sheep with a low dose inoculum
Research in Veterinary Science, 2020Co-Authors: Najiba Mammadova, Eric D Cassmann, Justin J GreenleeAbstract:Abstract Scrapie is a naturally occurring prion disease of sheep and goats that results in accumulation of the misfolded prion protein (PrPSc) and progressive neurodegeneration. After inoculation with classical Scrapie isolate x124, susceptibility and incubation period are associated with valine at codon 136 (V136) of the prion protein: VRQ/VRQ had the shortest incubation periods, followed by VRQ/ARQ sheep, while ARQ/ARQ sheep only developed disease after inoculation via the intracerebral route. Intralingual inoculation of TSE Agents effectively transmits disease similar to intracranial inoculation; therefore, it is possible that oral lesions may facilitate susceptibility to Scrapie transmission. In this study, investigated the infectivity of decreasing doses of the x124 Scrapie Agent (100 mg, 50 mg, 20 mg, and 10 mg) on incubation time and attack rate after experimental intralingual inoculation into VRQ/ARQ sheep. The lowest inoculum dose tested in this study effectively transmitted the x124 Scrapie Agent in VRQ/ARQ sheep with a 100% attack rate and no significant difference in incubation times among sheep inoculated with varying doses. Moreover, immunohistochemistry and western blot analysis revealed similar biochemical and immunohistochemical features among the four cohorts of sheep irrespective of inoculum dose. This study provides a starting point for further investigation to determine the minimum infectious dose of x124 Scrapie in sheep and its effect on attack rate and incubation time, central for assessing the potential risk of Scrapie occurrence in sheep flock.
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source genotype influence on cross species transmission of transmissible spongiform encephalopathies evaluated by rt quic
PLOS ONE, 2018Co-Authors: Soyoun Hwang, Justin J Greenlee, Natalie M Vance, Eric M NicholsonAbstract:Scrapie is a naturally occurring transmissible spongiform encephalopathy of sheep and goats. This fatal neurodegenerative disease is caused by misfolding of the cellular prion protein to pathogenic β-rich conformers (PrPSc) that accumulate in higher order structures of the brain and other tissues. This conversion has been used for in vitro assays including serial protein misfolding amplification and real-time quaking induced conversion (RT-QuIC). RT-QuIC can be used for the detection of prions and for strain discrimination in a variety of biological tissues from humans and animals. In this study, we evaluated how PrPSc isolated from sheep of different genotypes after inoculation with the Scrapie Agent influence the fibril formation in vitro using RT-QuIC. We found that reaction mixtures seeded with PrPSc from genotype VRQ/VRQ sheep brains have better conversion efficiency with 132M elk substrate compared to reactions seeded with PrPSc from the brains of sheep with the ARQ/ARQ genotype no matter which strain of Scrapie was used to seed the reactions. We also inoculated transgenic mice expressing 132M elk PRNP (Tg12) with the Scrapie Agent from different genotypes of sheep to compare with our RT-QuIC results. The bioassays support the data showing a significantly shorter incubation period for inoculum from VRQ/VRQ sheep when compared to inoculum from ARQ/ARQ sheep. Thus, we conclude that the genotype of both source and recipient can strongly influence transmission.
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Evaluation of a combinatorial approach to prion inactivation using an oxidizing Agent, SDS, and proteinase K
BMC Veterinary Research, 2013Co-Authors: Jodi D Smith, Eric M Nicholson, Justin J GreenleeAbstract:Background Prions demonstrate an unusual resistance to methods effective at inactivating conventional microorganisms. This has resulted in a very tangible and difficult infection control challenge to the medical and veterinary communities, as well as animal agriculture and related industries. Currently accepted practices of harsh chemical treatments such as prolonged exposure to sodium hydroxide or sodium hypochlorite, or autoclaving are not suitable in many situations. Less caustic and more readily applicable treatments to contaminated environments are therefore desirable. We recently demonstrated that exposure of the RML Scrapie Agent to a commercial product containing sodium percarbonate (SPC-P) with or without sodium dodecyl sulfate (SDS) rendered PrP^Sc sensitive to proteinase K (PK), but did not eliminate infectivity. The current study was designed to evaluate the efficacy of a combinatorial approach to inactivating prions by exposing RML-positive brain homogenate to SPC-P and SDS followed by PK. Treated samples were evaluated for PrP^Sc-immunoreactivity by western blot, and residual infectivity by mouse bioassay. Results Treatment of infected brain homogenate with SPC-P and SDS followed by PK exposure resulted in a 4–5 log_10 reduction in infectivity when bioassayed in tg a 20 mice. Conclusions This study demonstrates that exposure of the RML Scrapie Agent to SPC-P and SDS followed by PK markedly reduces, but does not eliminate infectivity. The results of this study encourage further investigation into whether consecutive or concomitant exposure to sodium percarbonate, SDS, and a protease may serve as a viable and non-caustic option for prion inactivation.
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exposure of rml Scrapie Agent to a sodium percarbonate based product and sodium dodecyl sulfate renders prp sc protease sensitive but does not eliminate infectivity
BMC Veterinary Research, 2013Co-Authors: Jodi D Smith, Eric M Nicholson, Gregory H Foster, Justin J GreenleeAbstract:Prions, the causative Agents of the transmissible spongiform encephalopathies, are notoriously difficult to inactivate. Current decontamination recommendations by the World Health Organization include prolonged exposure to 1 N sodium hydroxide or > 20,000 ppm sodium hypochlorite, or autoclaving. For decontamination of large stainless steel surfaces and equipment as in abattoirs, for example, these methods are harsh or unsuitable. The current study was designed to evaluate the effectiveness of a commercial product containing sodium percarbonate to inactivate prions. Samples of mouse brain infected with a mouse-adapted strain of the Scrapie Agent (RML) were exposed to a sodium percarbonate-based product (SPC-P). Treated samples were evaluated for abnormal prion protein (PrPSc)-immunoreactivity by western blot analysis, and residual infectivity by mouse bioassay. Exposure to a 21% solution of SPC-P or a solution containing either 2.1% or 21% SPC-P in combination with sodium dodecyl sulfate (SDS) resulted in increased proteinase K sensitivity of PrPSc. Limited reductions in infectivity were observed depending on treatment condition. A marginal effect on infectivity was observed with SPC-P alone, but an approximate 2–3 log10 reduction was observed with the addition of SDS, though exposure to SDS alone resulted in an approximate 2 log10 reduction. This study demonstrates that exposure of a mouse-adapted Scrapie strain to SPC-P does not eliminate infectivity, but does render PrPSc protease sensitive.
I Mcconnell - One of the best experts on this subject based on the ideXlab platform.
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closely similar values obtained when the me7 strain of Scrapie Agent was titrated in parallel by two individuals in separate laboratories using two sublines of c57bl mice
Journal of Virological Methods, 2000Co-Authors: Dm Taylor, I Mcconnell, C E FergusonAbstract:A single C57BL mouse-brain infected with the ME7 strain of mouse-passaged Scrapie Agent was used to carry out four parallel infectivity titrations in mice. These were carried out by two individuals in two laboratories using two sublines of C57BL mice. The titre values obtained by the four assays were very similar, and showed no significant differences between the two different operatives, the two different laboratories or the two different sublines of C57BL mice. The data confirm the validity of comparing these types of transmission data generated in different laboratories when a common methodology is used.
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survival of Scrapie Agent after exposure to sodium dodecyl sulphate and heat
Veterinary Microbiology, 1999Co-Authors: Dm Taylor, I Mcconnell, Karen Fernie, Philip SteeleAbstract:Abstract Fifty mg aliquots of macerated mouse-brain infected with the 22A strain of Scrapie Agent were treated by exposing them without mechanical mixing to (a) distilled water for 2 h, (b) 5% sodium dodecyl sulphate (SDS) for 2 h, (c) autoclaving at 121°C for 15 min in distilled water, (d) autoclaving at 121°C for 15 min in 5% SDS, or (e) boiling in 5% SDS for 15 min. Prior to injection into mice, all samples were washed by a procedure that is described and was shown not to reduce infectivity titres. Although the infectivity titre of the sample that was autoclaved in SDS was reduced considerably, infectivity was present in all of the samples exposed to cold or hot SDS.
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inactivation of the 22a strain of Scrapie Agent by autoclaving in sodium hydroxide
Veterinary Microbiology, 1997Co-Authors: Dm Taylor, Karen Fernie, I McconnellAbstract:Samples of macerated mouse-brain infected with the 22A strain of Scrapie Agent were subjected to gravity-displacement autoclaving at 121°C for 30 minutes in the presence of 2 M sodium hydroxide. No infectivity was detectable by mouse bioassay in samples which were either held for an hour at room temperature before autoclaving, or autoclaved immediately after adding the hydroxide. In contrast, all of the mice injected with a control sample, held for an hour in distilled water before autoclaving, developed Scrapie. If adopted as a routine decontamination procedure it is recommended that hydroxide-treated waste should be autoclaved in sealed heat-resistant containers which can withstand the pressures involved. This would make the procedure safer for the operator, and avoid autoclave damage through exposure to sodium hydroxide.
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the effect of dry heat on the me7 strain of mouse passaged Scrapie Agent
Journal of General Virology, 1996Co-Authors: Dm Taylor, I Mcconnell, Karen FernieAbstract:Partial survival of lyophilized Scrapie Agent has been reported previously following exposure to dry heat at 360 °C for 1 h, and led to speculation that Scrapie-like Agents might not be completely inactivated by incineration. However, it is known that dried infectivity is more difficult to inactivate by heat than that in hydrated samples. In this present study it was shown that the infectivity in macerates of mouse-brain infected with the ME7 strain of Scrapie Agent was not completely inactivated by exposure to dry heat at temperatures up to 180 °C for 1 h but the titre of surviving infectivity reduced progressively as the temperature was increased. No infectivity was recovered after a 1 h exposure at 200 °C. These data suggest that Scrapie-like Agents are unlikely to survive incineration.
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replication of Scrapie in spleens of scid mice follows reconstitution with wild type mouse bone marrow
Journal of General Virology, 1996Co-Authors: H Fraser, Karen Brown, Karen Stewart, I Mcconnell, Patricia A Mcbride, A WilliamsAbstract:SCID mice are resistant to intraperitoneal infection with 103 and 104 intracerebral ID50 units of ME7 Scrapie Agent whereas they develop disease after intracerebral challenge. However, higher doses introduced, by intraperitoneal or subcutaneous routes, produce disease. Immunocompetent mice of the same strain (CB20) developed Scrapie following either intracerebral or intraperitoneal infection. Bioassay of spleens from SCID mice infected with 10-1 dilutions of ME7 Scrapie by intraperitoneal, intracerebral or abdominal subcutaneous injection showed traces or low levels of infectivity in spleen. However, subcutaneous injection beneath the skin of the neck failed to infect the spleen. CB20 bone marrow reconstitution of SCID mice resulted in the regeneration of a normal lymphoid architecture in the spleen. Spleens from these reconstituted mice, infected intracerebrally with a 10-1 dilution of ME7 contained high levels of infectivity. These results suggest that the ability to replicate Scrapie Agent in spleen or lymphoid tissue depends on the restoration of normal lymphoid structure and in particular the presence of differentiated follicular dendritic cells. The possibility that SCID mice can select minor strains of Scrapie which are normally unrecognized in cloned ME7 is discussed.
Karen Fernie - One of the best experts on this subject based on the ideXlab platform.
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survival of Scrapie Agent after exposure to sodium dodecyl sulphate and heat
Veterinary Microbiology, 1999Co-Authors: Dm Taylor, I Mcconnell, Karen Fernie, Philip SteeleAbstract:Abstract Fifty mg aliquots of macerated mouse-brain infected with the 22A strain of Scrapie Agent were treated by exposing them without mechanical mixing to (a) distilled water for 2 h, (b) 5% sodium dodecyl sulphate (SDS) for 2 h, (c) autoclaving at 121°C for 15 min in distilled water, (d) autoclaving at 121°C for 15 min in 5% SDS, or (e) boiling in 5% SDS for 15 min. Prior to injection into mice, all samples were washed by a procedure that is described and was shown not to reduce infectivity titres. Although the infectivity titre of the sample that was autoclaved in SDS was reduced considerably, infectivity was present in all of the samples exposed to cold or hot SDS.
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inactivation of the 22a strain of Scrapie Agent by autoclaving in sodium hydroxide
Veterinary Microbiology, 1997Co-Authors: Dm Taylor, Karen Fernie, I McconnellAbstract:Samples of macerated mouse-brain infected with the 22A strain of Scrapie Agent were subjected to gravity-displacement autoclaving at 121°C for 30 minutes in the presence of 2 M sodium hydroxide. No infectivity was detectable by mouse bioassay in samples which were either held for an hour at room temperature before autoclaving, or autoclaved immediately after adding the hydroxide. In contrast, all of the mice injected with a control sample, held for an hour in distilled water before autoclaving, developed Scrapie. If adopted as a routine decontamination procedure it is recommended that hydroxide-treated waste should be autoclaved in sealed heat-resistant containers which can withstand the pressures involved. This would make the procedure safer for the operator, and avoid autoclave damage through exposure to sodium hydroxide.
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the effect of dry heat on the me7 strain of mouse passaged Scrapie Agent
Journal of General Virology, 1996Co-Authors: Dm Taylor, I Mcconnell, Karen FernieAbstract:Partial survival of lyophilized Scrapie Agent has been reported previously following exposure to dry heat at 360 °C for 1 h, and led to speculation that Scrapie-like Agents might not be completely inactivated by incineration. However, it is known that dried infectivity is more difficult to inactivate by heat than that in hydrated samples. In this present study it was shown that the infectivity in macerates of mouse-brain infected with the ME7 strain of Scrapie Agent was not completely inactivated by exposure to dry heat at temperatures up to 180 °C for 1 h but the titre of surviving infectivity reduced progressively as the temperature was increased. No infectivity was recovered after a 1 h exposure at 200 °C. These data suggest that Scrapie-like Agents are unlikely to survive incineration.
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exposure to autoclaving or sodium hydroxide extends the dose response curve of the 263k strain of Scrapie Agent in hamsters
Journal of General Virology, 1996Co-Authors: David M Taylor, Karen FernieAbstract:An analysis was made of incubation period data from experiments in which samples of brain-tissue infected with the 263K strain of Scrapie Agent were injected intracerebrally into hamsters following exposure of the tissue to autoclaving or sodium hydroxide. Where there was survival of infectivity, this often produced extended mean incubation periods compared with the maximal incubation periods in controls injected with untreated Agent. These results confirmed that, after chemical or physical treatment, infectivity titre should not be calculated by comparing the incubation period from a single dilution-group against a standard dose-response curve for untreated Agent.