The Experts below are selected from a list of 306 Experts worldwide ranked by ideXlab platform
Juan Maria Torres - One of the best experts on this subject based on the ideXlab platform.
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Thermostability as a highly dependent prion strain feature
Scientific Reports, 2019Co-Authors: Alba Marín-moreno, Juan Carlos Espinosa, Patricia Aguilar-calvo, Mohammed Moudjou, Vincent Béringue, Juan Maria TorresAbstract:Prion diseases are caused by the conversion of physiological PrP^C into the pathogenic misfolded protein PrP^Sc, conferring new properties to PrP^Sc that vary upon prion strains. In this work, we analyze the thermostability of three prion strains (BSE, RML and 22L) that were heated at 98 °C for 2 hours. PrP^Sc resistance to proteinase K (PrP^res), residual infectivity by mouse bioassay and in vitro templating activity by protein misfolding cyclic amplification (PMCA) were studied. Heated strains showed a huge loss of PrP^res and a radically different infectivity loss: RML was the most thermolabile strain (6 to 7 log10 infectivity loss), followed by 22L (5 log10) while BSE was the most thermostable strain with low or null infectivity reduction showing a clear dissociation between PrP^res and infectivity. These results indicate that thermostability is a strain-specific feature, measurable by PMCA and mouse bioassay, and a great tool to distinguish prion strains.
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progression of prion infectivity in asymptomatic cattle after oral bovine spongiform encephalopathy challenge
Journal of General Virology, 2007Co-Authors: Juan Carlos Espinosa, Monica Morales, Joaquin Castilla, Mark Rogers, Juan Maria TorresAbstract:The presence of BSE prion infectivity in asymptomatic cattle and its tissue distribution are important concerns for both human and veterinary health and food safety. In this work, a collection of tissues from asymptomatic cattle challenged orally with BSE and culled at 20, 24, 27, 30 and 33 months have been used to inoculate intracerebrally BoPrP-Tg110 mice expressing bovine PrP to assess their infectivity. Results demonstrate that BSE infectivity in asymptomatic cattle is essentially restricted to the nervous system, Peyer's patches and tonsils, as reported previously for terminally BSE-diseased cattle. BSE infectivity was detectable in Peyer's patches and tonsils at all time points analysed, but infectivity in nervous tissues (brainstem and sciatic nerve) was only detectable after 27 months from inoculation. Infectivity in brainstem increased markedly at 33 months after inoculation. All other investigated tissues or fluids (spleen, skeletal muscle, blood and urine) revealed no detectable infectivity throughout the time course studied.
Robert G Rohwer - One of the best experts on this subject based on the ideXlab platform.
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reduction in infectivity of endogenous transmissible spongiform encephalopathies present in blood by adsorption to selective affinity resins
The Lancet, 2006Co-Authors: Luisa Gregori, Julia Tait Lathrop, Peter A D Edwardson, Brian C Lambert, Steven J Burton, David J Hammond, Patrick V Gurgel, Ruben G Carbonell, Robert G RohwerAbstract:Summary Background Transmissible spongiform encephalopathies (TSE) can be contracted through blood transfusion. Selective adsorption of the causative agent from donated blood might be one of the best ways of managing this risk. In our study, affinity resin L13, which reduces brain-derived infectivity spiked into human red blood cell concentrate by around 4 log 10 ID 50 , and its equivalent, L13A, produced on a manufacturing scale, were assessed for their ability to remove TSE infectivity endogenously present in blood. Methods 500 mL of scrapie-infected hamster whole blood was leucoreduced at full scale before passage through the affinity resins. Infectivity of whole blood, leucoreduced whole blood (challenge), and the recovered blood from each flow-through was measured by limiting dilution titration. Findings Leucoreduction removed 72% of input infectivity. 15 of 99 animals were infected by the challenge, whereas none of the 96 or 100 animals inoculated with the final flow-throughs from either resin developed the disease after 540 days. The limit of detection of the bioassay was 0·2 infectious doses per mL. The overall reduction of the challenge infectivity was more than 1·22 log 10 ID. The results showed removal of endogenous TSE infectivity from leucoreduced whole blood by affinity ligands. The same resins adsorb normal and abnormal prion protein from human infections with variant, sporadic, and familial Creutzfeldt-Jakob disease, in the presence of blood components. Interpretation TSE affinity ligands, when incorporated into appropriate devices, can be used to mitigate the risks from TSE-infected blood, blood products, and other materials exposed to TSE infectivity.
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effectiveness of leucoreduction for removal of infectivity of transmissible spongiform encephalopathies from blood
The Lancet, 2004Co-Authors: Luisa Gregori, Nancy Mccombie, D S Palmer, Paul Birch, Samuel O Sowemimocoker, Antonio Giulivi, Robert G RohwerAbstract:In 1999, the UK implemented universal leucoreduction as a precaution against transmission of variant Creutzfeldt-Jakob disease by transfusion of domestic blood or red blood cells. We aimed to assess how effectively leucoreduction reduced infectivity of transmissible spongiform encephalopathies (TSEs) in blood. 450 mL of whole blood collected and pooled from scrapie-infected hamsters was leucoreduced with a commercial filter. Blood cell concentrations were quantified, and infectivity titres measured. Blood cell recovery and white blood cell removal complied with American Association of Blood Banks standards. Leucofiltration removed 42% (SD 12) of the total TSE infectivity in endogenously infected blood. Leucoreduction is necessary for the removal of white-cell-associated TSE infectivity from blood; however, it is not, by itself, sufficient to remove all blood-borne TSE infectivity.
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the distribution of infectivity in blood components and plasma derivatives in experimental models of transmissible spongiform encephalopathy
Transfusion, 1998Co-Authors: Paul Brown, Robert G Rohwer, B C Dunstan, C Macauley, D C Gajdusek, William N. DrohanAbstract:BACKGROUND: The administration of blood components from donors who subsequently develop Creutzfeldt-Jakob disease has raised the issue of blood as a possible vehicle for iatrogenic disease. STUDY DESIGN AND METHODS: We examined infectivity in blood components and Cohn plasma fractions in normal human blood that had been “spiked” with trypsinized cells from a scrapie-infected hamster brain, and in blood of clinically ill mice that had been inoculated with a mouse-adapted strain of human transmissible spongiform encephalopathy. Infectivity was assayed by intracerebral inoculation of the blood specimens into healthy animals. RESULTS: Most of the infectivity in spiked human blood was associated with cellular blood components; the smaller amount present in plasma, when fractionated, was found mainly in cryoprecipitate (the source of factor VIII) and fraction I+II+III (the source of fibrinogen and immunoglobulin); almost none was recovered in fraction IV (the source of vitamin-K-dependent proteins) and fraction V (the source of albumin). Mice infected with the human strain of spongiform encephalopathy had very low levels of endogenous infectivity in buffy coat, plasma, cryoprecipitate, and fraction I+II+III, and no detectable infectivity in fractions IV or V. CONCLUSION: Convergent results from exogenous spiking and endogenous infectivity experiments, in which decreasing levels of infectivity occurred in cellular blood components, plasma, and plasma fractions, suggest a potential but minimal risk of acquiring Creutzfeldt-Jakob disease from the administration of human plasma protein concentrates.
James W. Ironside - One of the best experts on this subject based on the ideXlab platform.
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detection of variant creutzfeldt jakob disease infectivity in extraneural tissues
The Lancet, 2001Co-Authors: Moira E Bruce, I Mcconnell, R G Will, James W. IronsideAbstract:Summary Abnormal accumulations of prion protein (PrP) can be detected in the spleen, lymph nodes, and tonsils of patients with variant Creutzfeldt-Jakob disease (vCJD). Therefore, it has been assumed, but not shown, that these tissues harbour infectivity, which in turn presents the potential for iatrogenic spread through surgery. Here, we show and measure levels of infectivity in spleen and tonsil from two patients with vCJD, by bioassay in intracerebrally inoculated RIII mice. Similar bioassays failed to detect infectivity in buffy coat and plasma.
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Oral infection by the bovine spongiform encephalopathy prion
Proceedings of the National Academy of Sciences of the United States of America, 1999Co-Authors: Robert G. Will, James W. IronsideAbstract:There is, however, variation in pathogenesis that is determined by factors including the interaction between host genome and agent strain. Some breeds of sheep affected by natural scrapie, for example, Montadales, have no detectable infectivity in peripheral tissues, and the distribution of infectivity in the brain may vary according to the breed of sheep (5). In bovine spongiform encephalopathy (BSE) infectivity has not been detected in peripheral tissues in natural disease, except for dorsal root ganglia and possibly bone marrow, although infectivity has been found in terminal ileum after experimental oral challenge with BSE brain (6). An important implication of this data is that, accepting the limits of the sensitivity of bioassay …
Juan S Bonifacino - One of the best experts on this subject based on the ideXlab platform.
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The autophagy protein ATG9A promotes HIV-1 infectivity
Retrovirology, 2019Co-Authors: Elodie Mailler, Eric O. Freed, Abdul A. Waheed, David C. Gershlick, Sang Yoon Park, Juan S BonifacinoAbstract:Background Nef is a multifunctional accessory protein encoded by HIV-1, HIV-2 and SIV that plays critical roles in viral pathogenesis, contributing to viral replication, assembly, budding, infectivity and immune evasion, through engagement of various host cell pathways. Results To gain a better understanding of the role of host proteins in the functions of Nef, we carried out tandem affinity purification-mass spectrometry analysis, and identified over 70 HIV-1 Nef-interacting proteins, including the autophagy-related 9A (ATG9A) protein. ATG9A is a transmembrane component of the machinery for autophagy, a catabolic process in which cytoplasmic components are degraded in lysosomal compartments. Pulldown experiments demonstrated that ATG9A interacts with Nef from not only HIV-1 and but also SIV (cpz, smm and mac). However, expression of HIV-1 Nef had no effect on the levels and localization of ATG9A, and on autophagy, in the host cells. To investigate a possible role for ATG9A in virus replication, we knocked out ATG9A in HeLa cervical carcinoma and Jurkat T cells, and analyzed virus release and infectivity. We observed that ATG9A knockout (KO) had no effect on the release of wild-type (WT) or Nef-defective HIV-1 in these cells. However, the infectivity of WT virus produced from ATG9A-KO HeLa and Jurkat cells was reduced by ~ fourfold and eightfold, respectively, relative to virus produced from WT cells. This reduction in infectivity was independent of the interaction of Nef with ATG9A, and was not due to reduced incorporation of the viral envelope (Env) glycoprotein into the virus. The loss of HIV-1 infectivity was rescued by pseudotyping HIV-1 virions with the vesicular stomatitis virus G glycoprotein. Conclusions These studies indicate that ATG9A promotes HIV-1 infectivity in an Env-dependent manner. The interaction of Nef with ATG9A, however, is not required for Nef to enhance HIV-1 infectivity. We speculate that ATG9A could promote infectivity by participating in either the removal of a factor that inhibits infectivity or the incorporation of a factor that enhances infectivity of the viral particles. These studies thus identify a novel host cell factor implicated in HIV-1 infectivity, which may be amenable to pharmacologic manipulation for treatment of HIV-1 infection.
David Harrich - One of the best experts on this subject based on the ideXlab platform.
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Protein methylation is required to maintain optimal HIV-1 infectivity
Retrovirology, 2006Co-Authors: Nicole M Willemsen, Eleanor M Hitchen, Tracey J Bodetti, Ann Apolloni, David Warrilow, Sabine C Piller, David HarrichAbstract:Background: Protein methylation is recognized as a major protein modification pathway regulating diverse cellular events such as protein trafficking, transcription, and signal transduction. More recently, protein arginine methyltransferase activity has been shown to regulate HIV-1 transcription via Tat. In this study, adenosine periodate (AdOx) was used to globally inhibit protein methyltransferase activity so that the effect of protein methylation on HIV-1 infectivity could be assessed. Results: Two cell culture models were used: HIV-1-infected CEM T-cells and HEK293T cells transfected with a proviral DNA plasmid. In both models, AdOx treatment of cells increased the levels of virion in culture supernatant. However, these viruses had increased levels of unprocessed or partially processed Gag-Pol, significantly increased diameter, and displayed reduced infectivity in a MAGI X4 assay. AdOx reduced infectivity equally in both dividing and non-dividing cells. However, infectivity was further reduced if Vpr was deleted suggesting virion proteins, other than Vpr, were affected by protein methylation. Endogenous reverse transcription was not inhibited in AdOx-treated HIV-1, and infectivity could be restored by pseudotyping HIV with VSV-G envelope protein. These experiments suggest that AdOx affects an early event between receptor binding and uncoating, but not reverse transcription. Conclusion: Overall, we have shown for the first time that protein methylation contributes towards maximal virus infectivity. Furthermore, our results also indicate that protein methylation regulates HIV-1 infectivity in a complex manner most likely involving the methylation of multiple viral or cellular proteins and/or multiple steps of replication.
