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Sturm R, Kreitinger G, Booth C, Smith L, Pedersen J, Li L. Absolute quantification of prion protein (90-231) using stable isotope-labeled chymotryptic peptide standards in a LC-MRM AQUA workflow. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2012; 23:1522-33. [PMID: 22714949 PMCID: PMC3579656 DOI: 10.1007/s13361-012-0411-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2012] [Revised: 05/08/2012] [Accepted: 05/10/2012] [Indexed: 05/12/2023]
Abstract
Substantial evidence indicates that the disease-associated conformer of the prion protein (PrP(TSE)) constitutes the etiologic agent in prion diseases. These diseases affect multiple mammalian species. PrP(TSE) has the ability to convert the conformation of the normal prion protein (PrP(C)) into a β-sheet rich form resistant to proteinase K digestion. Common immunological techniques lack the sensitivity to detect PrP(TSE) at subfemtomole levels, whereas animal bioassays, cell culture, and in vitro conversion assays offer higher sensitivity but lack the high-throughput the immunological assays offer. Mass spectrometry is an attractive alternative to the above assays as it offers high-throughput, direct measurement of a protein's signature peptide, often with subfemtomole sensitivities. Although a liquid chromatography-multiple reaction monitoring (LC-MRM) method has been reported for PrP(TSE), the chemical composition and lack of amino acid sequence conservation of the signature peptide may compromise its accuracy and make it difficult to apply to multiple species. Here, we demonstrate that an alternative protease (chymotrypsin) can produce signature peptides suitable for a LC-MRM absolute quantification (AQUA) experiment. The new method offers several advantages, including: (1) a chymotryptic signature peptide lacking chemically active residues (Cys, Met) that can confound assay accuracy; (2) low attomole limits of detection and quantitation (LOD and LOQ); and (3) a signature peptide retaining the same amino acid sequence across most mammals naturally susceptible to prion infection as well as important laboratory models. To the authors' knowledge, this is the first report on the use of a non-tryptic peptide in a LC-MRM AQUA workflow.
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Affiliation(s)
- Robert Sturm
- School of Pharmacy and Department of Chemistry, University of Wisconsin-Madison
| | - Gloria Kreitinger
- School of Pharmacy and Department of Chemistry, University of Wisconsin-Madison
| | - Clarissa Booth
- Molecular and Environmental Toxicology Center, University of Wisconsin-Madison
| | - Lloyd Smith
- School of Pharmacy and Department of Chemistry, University of Wisconsin-Madison
| | - Joel Pedersen
- Molecular and Environmental Toxicology Center, University of Wisconsin-Madison
- Department of Soil Science, University of Wisconsin-Madison
| | - Lingjun Li
- School of Pharmacy and Department of Chemistry, University of Wisconsin-Madison
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Tamgüney G, Richt JA, Hamir AN, Greenlee JJ, Miller MW, Wolfe LL, Sirochman TM, Young AJ, Glidden DV, Johnson NL, Giles K, DeArmond SJ, Prusiner SB. Salivary prions in sheep and deer. Prion 2012; 6:52-61. [PMID: 22453179 DOI: 10.4161/pri.6.1.16984] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Scrapie of sheep and chronic wasting disease (CWD) of cervids are transmissible prion diseases. Milk and placenta have been identified as sources of scrapie prions but do not explain horizontal transmission. In contrast, CWD prions have been reported in saliva, urine and feces, which are thought to be responsible for horizontal transmission. While the titers of CWD prions have been measured in feces, levels in saliva or urine are unknown. Because sheep produce ~17 L/day of saliva, and scrapie prions are present in tongue and salivary glands of infected sheep, we asked if scrapie prions are shed in saliva. We inoculated transgenic (Tg) mice expressing ovine prion protein, Tg(OvPrP) mice, with saliva from seven Cheviot sheep with scrapie. Six of seven samples transmitted prions to Tg(OvPrP) mice with titers of -0.5 to 1.7 log ID₅₀ U/ml. Similarly, inoculation of saliva samples from two mule deer with CWD transmitted prions to Tg(ElkPrP) mice with titers of -1.1 to -0.4 log ID₅₀ U/ml. Assuming similar shedding kinetics for salivary prions as those for fecal prions of deer, we estimated the secreted salivary prion dose over a 10-mo period to be as high as 8.4 log ID₅₀ units for sheep and 7.0 log ID₅₀ units for deer. These estimates are similar to 7.9 log ID₅₀ units of fecal CWD prions for deer. Because saliva is mostly swallowed, salivary prions may reinfect tissues of the gastrointestinal tract and contribute to fecal prion shedding. Salivary prions shed into the environment provide an additional mechanism for horizontal prion transmission.
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Affiliation(s)
- Gültekin Tamgüney
- Institute for Neurodegenerative Diseases, Department of Neurology, University of California, San Francisco, CA, USA
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Saunders SE, Bartelt-Hunt SL, Bartz JC. Occurrence, transmission, and zoonotic potential of chronic wasting disease. Emerg Infect Dis 2012; 18:369-76. [PMID: 22377159 PMCID: PMC3309570 DOI: 10.3201/eid1803.110685] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Chronic wasting disease (CWD) is a fatal, transmissible prion disease that affects captive and free-ranging deer, elk, and moose. Although the zoonotic potential of CWD is considered low, identification of multiple CWD strains and the potential for agent evolution upon serial passage hinders a definitive conclusion. Surveillance for CWD in free-ranging populations has documented a continual geographic spread of the disease throughout North America. CWD prions are shed from clinically and preclinically affected hosts, and CWD transmission is mediated at least in part by the environment, perhaps by soil. Much remains unknown, including the sites and mechanisms of prion uptake in the naive host. There are no therapeutics or effective eradication measures for CWD-endemic populations. Continued surveillance and research of CWD and its effects on cervid ecosystems is vital for controlling the long-term consequences of this emerging disease.
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Kim HJ, Tark DS, Lee YH, Kim MJ, Lee WY, Cho IS, Sohn HJ, Yokoyama T. Establishment of a cell line persistently infected with chronic wasting disease prions. J Vet Med Sci 2012; 74:1377-80. [PMID: 22673102 DOI: 10.1292/jvms.12-0061] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Elk prion protein (PrP(C)) has been confirmed to be capable of rendering rabbit epithelial RK13 cells permissive to temporal infection by chronic wasting disease (CWD) prions. The present study satisfactorily generated persistently CWD prion-affected RK13 cells (RKC1-11) using elk PrP(C) expressing cells (elkRK13) that were generated via the lentiviral expression system with high efficiency. The elkRK13 cells have been shown to be permissive to accumulation of abnormal isoforms of prion protein (PrP(Sc)) resulting from CWD prions up to 97 serial passages thus far. This novel prion-affected cell line will help facilitate investigation of the molecular basis of CWD prion pathogenesis and confirmation of CWD prion infectivity in vitro.
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Affiliation(s)
- Hyo-Jin Kim
- Foreign Animal Disease Division, Animal Plant and Fisheries Quarantine and Inspection Agency, Anyang, Gyeonggi-do, Korea
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Highly efficient amplification of chronic wasting disease agent by protein misfolding cyclic amplification with beads (PMCAb). PLoS One 2012; 7:e35383. [PMID: 22514738 PMCID: PMC3325955 DOI: 10.1371/journal.pone.0035383] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2011] [Accepted: 03/15/2012] [Indexed: 11/19/2022] Open
Abstract
Protein misfolding cyclic amplification (PMCA) has emerged as an important technique for detecting low levels of pathogenic prion protein in biological samples. The method exploits the ability of the pathogenic prion protein to convert the normal prion protein to a proteinase K-resistant conformation. Inclusion of Teflon® beads in the PMCA reaction (PMCAb) has been previously shown to increase the sensitivity and robustness of detection for the 263 K and SSLOW strains of hamster-adapted prions. Here, we demonstrate that PMCAb with saponin dramatically increases the sensitivity of detection for chronic wasting disease (CWD) agent without compromising the specificity of the assay (i.e., no false positive results). Addition of Teflon® beads increased the robustness of the PMCA reaction, resulting in a decrease in the variability of PMCA results. Three rounds of serial PMCAb allowed detection of CWD agent from a 6.7 × 10(-13) dilution of 10% brain homogenate (1.3 fg of source brain). Titration of the same brain homogenate in transgenic mice expressing cervid prion protein (Tg(CerPrP)1536(+/-) mice) allowed detection of CWD agent from the 10(-6) dilution of 10% brain homogenate. PMCAb is, thus, more sensitive than bioassay in transgenic mice by a factor exceeding 10(5). Additionally, we are able to amplify CWD agent from brain tissue and lymph nodes of CWD-positive white-tailed deer having Prnp alleles associated with reduced disease susceptibility.
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Greenwood AD, Vincendeau M, Schmädicke AC, Montag J, Seifarth W, Motzkus D. Bovine spongiform encephalopathy infection alters endogenous retrovirus expression in distinct brain regions of cynomolgus macaques (Macaca fascicularis). Mol Neurodegener 2011; 6:44. [PMID: 21699683 PMCID: PMC3152937 DOI: 10.1186/1750-1326-6-44] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2011] [Accepted: 06/23/2011] [Indexed: 01/10/2023] Open
Abstract
Background Prion diseases such as bovine spongiform encephalopathies (BSE) are transmissible neurodegenerative diseases which are presumably caused by an infectious conformational isoform of the cellular prion protein. Previous work has provided evidence that in murine prion disease the endogenous retrovirus (ERV) expression is altered in the brain. To determine if prion-induced changes in ERV expression are a general phenomenon we used a non-human primate model for prion disease. Results Cynomolgus macaques (Macaca fasicularis) were infected intracerebrally with BSE-positive brain stem material from cattle and allowed to develop prion disease. Brain tissue from the basis pontis and vermis cerebelli of the six animals and the same regions from four healthy controls were subjected to ERV expression profiling using a retrovirus-specific microarray and quantitative real-time PCR. We could show that Class I gammaretroviruses HERV-E4-1, ERV-9, and MacERV-4 increase expression in BSE-infected macaques. In a second approach, we analysed ERV-K-(HML-2) RNA and protein expression in extracts from the same cynomolgus macaques. Here we found a significant downregulation of both, the macaque ERV-K-(HML-2) Gag protein and RNA in the frontal/parietal cortex of BSE-infected macaques. Conclusions We provide evidence that dysregulation of ERVs in response to BSE-infection can be detected on both, the RNA and the protein level. To our knowledge, this is the first report on the differential expression of ERV-derived structural proteins in prion disorders. Our findings suggest that endogenous retroviruses may induce or exacerbate the pathological consequences of prion-associated neurodegeneration.
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Affiliation(s)
- Alex D Greenwood
- German Primate Center, Leibniz-Institute for Primate Research, Unit of Infection Models, D-37077 Göttingen, Germany.
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A simple, versatile and sensitive cell-based assay for prions from various species. PLoS One 2011; 6:e20563. [PMID: 21655184 PMCID: PMC3105100 DOI: 10.1371/journal.pone.0020563] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2011] [Accepted: 05/03/2011] [Indexed: 12/03/2022] Open
Abstract
Detection and quantification of prion infectivity is a crucial step for various fundamental and applied aspects of prion research. Identification of cell lines highly sensitive to prion infection led to the development of cell-based titration procedures aiming at replacing animal bioassays, usually performed in mice or hamsters. However, most of these cell lines are only permissive to mouse-adapted prions strains and do not allow titration of prions from other species. In this study, we show that epithelial RK13, a cell line permissive to mouse and bank vole prion strains and to natural prion agents from sheep and cervids, enables a robust and sensitive detection of mouse and ovine-derived prions. Importantly, the cell culture work is strongly reduced as the RK13 cell assay procedure designed here does not require subcultivation of the inoculated cultures. We also show that prions effectively bind to culture plastic vessel and are quantitatively detected by the cell assay. The possibility to easily quantify a wider range of prions, including rodent experimental strains but also natural agents from sheep and cervids, should prompt the spread of cell assays for routine prion titration and lead to valuable information in fundamental and applied studies.
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In vitro amplification of misfolded prion protein using lysate of cultured cells. PLoS One 2011; 6:e18047. [PMID: 21464935 PMCID: PMC3065467 DOI: 10.1371/journal.pone.0018047] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2010] [Accepted: 02/18/2011] [Indexed: 11/19/2022] Open
Abstract
Protein misfolding cyclic amplification (PMCA) recapitulates the prion protein (PrP) conversion process under cell-free conditions. PMCA was initially established with brain material and then with further simplified constituents such as partially purified and recombinant PrP. However, availability of brain material from some species or brain material from animals with certain mutations or polymorphisms within the PrP gene is often limited. Moreover, preparation of native PrP from mammalian cells and tissues, as well as recombinant PrP from bacterial cells, involves time-consuming purification steps. To establish a convenient and versatile PMCA procedure unrestricted to the availability of substrate sources, we attempted to conduct PMCA with the lysate of cells that express cellular PrP (PrPC). PrPSc was efficiently amplified with lysate of rabbit kidney epithelial RK13 cells stably transfected with the mouse or Syrian hamster PrP gene. Furthermore, PMCA was also successful with lysate of other established cell lines of neuronal or non-neuronal origins. Together with the data showing that the abundance of PrPC in cell lysate was a critical factor to drive efficient PrPSc amplification, our results demonstrate that cell lysate in which PrPC is present abundantly serves as an excellent substrate source for PMCA.
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59
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Joint Scientific Opinion on any possible epidemiological or molecular association between TSEs in animals and humans. EFSA J 2011. [DOI: 10.2903/j.efsa.2011.1945] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
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Manuelidis L. Nuclease resistant circular DNAs copurify with infectivity in scrapie and CJD. J Neurovirol 2010; 17:131-45. [PMID: 21165784 DOI: 10.1007/s13365-010-0007-0] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2010] [Revised: 10/19/2010] [Accepted: 10/22/2010] [Indexed: 11/29/2022]
Abstract
In transmissible encephalopathies (TSEs), it is commonly believed that the host prion protein transforms itself into an infectious form that encodes the many distinct TSE agent strains without any nucleic acid. Using a Ф29 polymerase and chromatography strategy, highly infectious culture and brain preparations of three different geographic TSE agents all contained novel circular DNAs. Two circular "Sphinx" sequences, of 1.8 and 2.4 kb, copurified with infectious particles in sucrose gradients and, as many protected viruses, resisted nuclease digestion. Each contained a replicase ORF related to microviridae that infect commensal Acinetobacter. Infectious gradient fractions also contained nuclease-resistant 16 kb mitochondrial DNAs and analysis of >4,000 nt demonstrated a 100% identity with their species-specific sequences. This confirmed the fidelity of the newly identified sequences detailed here. Conserved replicase regions within the two Sphinx DNAs were ultimately detected by PCR in cytoplasmic preparations from normal cells and brain but were 2,500-fold less than in parallel-infected samples. No trace of the two Sphinx replicases was found in enzymes, detergents, or other preparative materials using exhaustive PCR cycles. The Sphinx sequences uncovered here could have a role in TSE infections despite their apparently symbiotic, low-level persistence in normal cells and tissues. These, as well as other cryptic circular DNAs, may cause or contribute to neurodegeneration and infection-associated tumor transformation. The current results also raise the intriguing possibility that mammals may incorporate more of the prokaryotic world in their cytoplasm than previously recognized.
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Affiliation(s)
- Laura Manuelidis
- Yale University Medical School, 333 Cedar Street, New Haven, CT 06510, USA.
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61
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Mays CE, Ryou C. Plasminogen stimulates propagation of protease‐resistant prion protein
in vitro. FASEB J 2010. [DOI: 10.1096/fj.10.163600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Charles E. Mays
- Sanders‐Brown Center on AgingDepartment of MicrobiologyImmunology and Molecular GeneticsUniversity of Kentucky College of Medicine Lexington Kentucky USA
| | - Chongsuk Ryou
- Sanders‐Brown Center on AgingDepartment of MicrobiologyImmunology and Molecular GeneticsUniversity of Kentucky College of Medicine Lexington Kentucky USA
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Abstract
While prions share the ability to propagate strain information with nucleic acid-based pathogens, it is unclear how they mutate and acquire fitness in the absence of this informational component. Because prion diseases occur as epidemics, understanding this mechanism is of paramount importance for implementing control strategies to limit their spread and for evaluating their zoonotic potential. Here we review emerging evidence indicating how prion protein primary structures, in concert with PrP(Sc) conformational compatibility, determine prion strain mutation.
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Affiliation(s)
- Glenn C Telling
- Department of Microbiology, Immunology and Molecular Genetics, Sanders Brown Center on Aging, Department of Neurology, University of Kentucky Medical Center, Lexington, KY, USA.
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63
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Mays CE, Ryou C. Plasminogen stimulates propagation of protease-resistant prion protein in vitro. FASEB J 2010; 24:5102-12. [PMID: 20732953 DOI: 10.1096/fj.10-163600] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
To clarify the role of plasminogen as a cofactor for prion propagation, we conducted functional assays using a cell-free prion protein (PrP) conversion assay termed protein misfolding cyclic amplification (PMCA) and prion-infected cell lines. Here, we report that plasminogen stimulates propagation of the protease-resistant scrapie PrP (PrP(Sc)). Compared to control PMCA conducted without plasminogen, addition of plasminogen in PMCA using wild-type brain material significantly increased PrP conversion, with an EC(50) = ∼56 nM. PrP conversion in PMCA was substantially less efficient with plasminogen-deficient brain material than with wild-type material. The activity stimulating PrP conversion was specific for plasminogen and conserved in its kringle domains. Such activity was abrogated by modification of plasminogen structure and interference of PrP-plasminogen interaction. Kinetic analysis of PrP(Sc) generation demonstrated that the presence of plasminogen in PMCA enhanced the PrP(Sc) production rate to ∼0.97 U/μl/h and reduced turnover time to ∼1 h compared to those (∼0.4 U/μl/h and ∼2.5 h) obtained without supplementation. Furthermore, as observed in PMCA, plasminogen and kringles promoted PrP(Sc) propagation in ScN2a and Elk 21(+) cells. Our results demonstrate that plasminogen functions in stimulating conversion processes and represents the first cellular protein cofactor that enhances the hypothetical mechanism of prion propagation.
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Affiliation(s)
- Charles E Mays
- Sanders-Brown Center on Aging and Department of Microbiology, Immunology and Molecular Genetics, University of Kentucky College of Medicine, Lexington, Kentucky, USA
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