| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
1 Department of Veterinary Sciences, University of Wyoming, Wyoming State Veterinary Laboratory (WSVL), 1174 Snowy Range Road, Laramie, WY 82070, USA
2 Veterinary Services Branch, Wyoming Game and Fish Department (WGFD), Wheatland, WY 82201, USA
Correspondence
Jean E. Jewell
jjewell{at}uwyo.edu
 |
ABSTRACT |
|---|
 TOP ABSTRACT INTRODUCTIONMETHODSRESULTSDISCUSSIONREFERENCES |
|---|
|
INTRODUCTION |
|---|
|
TOPABSTRACTINTRODUCTIONMETHODSRESULTSDISCUSSIONREFERENCES |
|---|
; Williams, 2005; Kreeger et al., 2006). In common with other TSEs, such as scrapie of sheep and goats, bovine spongiform encephalopathy, transmissible mink encephalopathy and the human TSEs, a diagnostic hallmark of CWD infection is accumulation of a disease-associated prion protein, PrPd, in the central nervous system (CNS). PrPd, which is an aberrantly refolded conformational isoform of a normal cellular glycoprotein, PrPC (Prusiner, 2004), replicates during infection by inducing the conversion of PrPC to the PrPd conformation. PrPd is partially protease-resistant, unlike PrPC, and this difference is the basis of many molecular detection protocols currently used; it may also account for extracellular accumulation of PrPd in vivo and survival through the digestive tract of exposed cervids.
The widespread involvement of both lymphoid and nervous-system tissues as sites of accumulation of PrPd during scrapie and CWD infection has been described extensively (Hadlow et al., 1982; van Keulen et al., 1995, 1996; Sigurdson et al., 1999, 2001; Miller & Williams, 2002; Spraker et al., 2002b), but recent investigations have also demonstrated the presence of PrPd in skeletal muscles of TSE-infected laboratory mice and hamsters, of sheep, deer and humans (Bosque et al., 2002; Bartz et al., 2003; Glatzel et al., 2003; Thomzig et al., 2003; Andréoletti et al., 2004; Mulcahy et al., 2004; Ashwath et al., 2005; Casalone et al., 2005; Angers et al., 2006; Thomzig et al., 2006). The levels of PrPd that accumulated in muscles were lower than those found in CNS or lymphoid tissue; however, in rodents, muscle-derived PrPd was shown to be infectious (Bosque et al., 2002; Angers et al., 2006). The detection of PrPd (designated PrPSc in scrapie) in skeletal muscles of scrapie-infected sheep (Andréoletti et al., 2004) and of infectivity in skeletal muscle of CWD-infected mule deer (Angers et al., 2006) has raised the level of concern on the issue of potential human health risks that might be encountered by consuming prion-containing meat.
Based on epidemiological evidence and transgenic mouse bioassays, CWD seems not to be transmitted to humans (Belay et al., 2004; Kong et al., 2005). However, because deer and elk are food sources, hunters in areas where CWD is known to occur are advised not to consume brain, spinal cord or lymph nodes, not to kill and eat any animals that are obviously unwell and to submit samples to state game agencies for testing (for example, http://www.wildlife.utah.gov/news/05-10/cwd.php; http://wildlife.state.co.us/CWD/index.asp; http://www.dnr.state.wi.us/org/land/wildlife/whealth/issues/CWD/index.htm; http://gf.state.wy.us/services/education/cwd/index.asp; http://www.ngpc.state.ne.us/wildlife/guides/cwd/faq.asp; http://www.sdgfp.info/Wildlife/hunting/BigGame/CWD.htm). Information on PrPd in muscle tissue of cervids is therefore of interest to hunters, as well as pertinent to research questions on the pathogenesis of CWD in its natural hosts. An extensive immunohistochemical analysis of tissue samples from naturally infected mule deer (Spraker et al., 2002a) and a report of two elk inoculated intracerebrally (i.c.) with scrapie (Hamir et al., 2004) both failed to detect PrPd in muscle tissues. However, Angers et al. (2006) recently reported successful TSE transmission to transgenic mice inoculated i.c. with extracts of skeletal muscle from CWD-infected mule deer. We report here the detection of PrPd in cardiac muscle of two species of cervid as a result of our investigation of striated muscle samples from CWD-infected and uninfected mule deer, white-tailed deer, elk and moose by using ELISA, Western blots and immunohistochemistry (IHC).
|
METHODS |
|---|
|
TOPABSTRACTINTRODUCTIONMETHODSRESULTSDISCUSSIONREFERENCES |
|---|
Sample preparation, gel electrophoresis, Western blot transfer and development.
To prepare samples for gel electrophoresis and subsequent Western blot analysis, tissue homogenates (10 %, w/v) from frozen tissues were prepared in 0.1 M Tris/HCl (pH 8.0), 0.1 M NaCl (TBS100). Frozen tissue was allowed to thaw partially at room temperature in a biological safety cabinet and samples (approx. 150–200 mg) were cut from the interior of the muscle mass as described above for ELISA samples. Homogenates were prepared in 1.5 ml TBS100 by processing in FastPrep vials (Q-Biogene) containing about 0.25 ml 1.0 mm zirconia/silica beads (BioSpec) and one 0.25 inch ceramic bead (Q-Biogene) in a FastPrep FP120 bead mill homogenizer (ThermoSavant) for two cycles of 30 s each on high speed (setting 6.5), with 5 min room temperature cooling between cycles. Homogenates were stored in the bead vials at –20 °C and reprocessed for 10 s at speed 4 in a FastPrep to resuspend tissue particles aggregated by freezing. Tissue slurries were removed from large remaining particles of connective tissue with the aid of a fine-tip transfer pipette (Samco Scientific). Aliquots (0.1 ml) were treated with 100 µg PK ml–1 (Invitrogen) and 2 units DNase (Benzonase Nuclease; Novagen) in TBS100, 0.5 % each of Nonidet P-40 (Pierce) and sodium deoxycholate, 1 % sodium N-lauroylsarcosine (SLS), 1 mM each of CaCl2 and MgCl2, for 30 min at 45 °C. Digestion was terminated by addition of protease inhibitor (Pefabloc; Fisher Scientific) to 4 mM. Samples were centrifuged at 1200 g for 3 min and supernatants, after transfer to clean 1.7 ml microfuge tubes, were made up to 2 % in SLS and prewarmed to 37 °C. Methods for sodium phosphotungstic acid (NaPTA) precipitation were adapted from published protocols (Safar et al., 1998; Wadsworth et al., 2001; McCutcheon et al., 2005). A 1/12 volume of 4 % (w/v) NaPTA, 0.17 M MgCl2, adjusted to pH 7.4 with NaOH, was added at 37 °C and samples were incubated for 30 min with shaking at 37 °C, followed by centrifugation at room temperature for 30 min at 16 100 g. Supernatants were discarded and pellets were resuspended in 1x NuPAGE LDS denaturing sample buffer (Invitrogen) with 3 % SDS added and heated to 100 °C for 8 min before gel electrophoresis. Samples were loaded on preformed 1 mm 4–12 % Bis/Tris SDS-PAGE denaturing, reducing, polyacrylamide gradient gels in MOPS/SDS running buffer (NuPAGE gel system; Invitrogen) and electrophoresed for 1 h at 200 V. Molecular mass markers were MagicMark XP Western protein standard (Invitrogen).
Samples from gels were transferred electrophoretically to Immobilon-P PVDF membrane (Millipore) in 25 mM Tris, 192 mM glycine, 10 % methanol by using a Hoefer TE22 Mightly Small Transphor tank (Amersham Biosciences) at 400 mA for 1 h with stirring and cooling of transfer buffer. Following transfer, membranes (blots) were rinsed briefly in 100 % methanol and air-dried. Preceding Western immunoblot development, dried blots were rinsed for 15 s in 100 % methanol and for 2 min in distilled water and placed in 30 ml blocking buffer [50 mM Tris/HCl (pH 7.5), 150 mM NaCl, 0.1 % Tween 20 (Bio-Rad) (TBS-T)], containing 4 % non-fat dry milk (NFDM) (Carnation) and 2 mg normal goat serum ml–1 (Jackson ImmunoResearch Laboratories) for 30 min at room temperature. Blots were subsequently incubated for 1 h with anti-PrP antibody (mouse monoclonal F99/97.6.1; VMRD Inc.) diluted 1 : 200 in TBS-T/NFDM, followed by three 10 min washes in 50 ml TBS-T per wash and a second incubation in blocking buffer for 5 min, before incubating for 30 min with horseradish peroxidase-conjugated F(ab')2 fragment of goat anti-mouse IgG (Jackson ImmunoResearch Laboratories) diluted 1 : 30 000 in TBS-T/NFDM. Secondary antibody incubation was followed by five 10 min washes in TBS-T, chemiluminescent detection by using ECL Western blotting reagents (Amersham Biosciences) according to the manufacturer's directions and exposure of Kodak BioMax ML film for times ranging from 1 min to overnight, followed by manual film development. Digitized images for figures were obtained by scanning developed films and photoediting with HP Director software; photoediting was limited to cropping and labelling images and adjustments in brightness and contrast.
IHC.
Striated muscle tissues collected at necropsy were preserved in 10 % neutral-buffered formalin. Samples were trimmed into sections, treated in formic acid, rinsed, dehydrated, paraffin-embedded, prepared for immunohistochemical staining and stained, all as described previously (Miller & Williams, 2002), with the following modifications: immersion in 98 % formic acid of sections on slides to enhance epitope exposure was for 5 min, followed by a rinse in 50 mM Tris/HCl (pH 7.6), 0.15 M NaCl, then deionized water; cooling after autoclaving was for 40 min. Primary antibody was mAb F99/97.6.1 [Anti-Prion (99); Ventana Medical Systems]. Digitized images for figures were obtained by using an Olympus BX51 light microscope equipped with a MicroFire digital camera and PictureFrame for Windows software to view and photograph slides. Photoediting (Microsoft Office Picture Manager) was limited to cropping and labelling images and adjustments in brightness, contrast or colour balance.
Animals and tissues.
Samples were of muscle tissues that had been collected at necropsy at the WSVL and frozen. Animals included free-ranging deer collected for CWD surveillance and submitted by WGFD to the WSVL for necropsy and testing, and captive or free-ranging animals that were subjects in other CWD research projects carried out in collaboration with WGFD and/or the Colorado Division of Wildlife. All elk and moose were experimental animals from WGFD research.
|
RESULTS |
|---|
|
TOPABSTRACTINTRODUCTIONMETHODSRESULTSDISCUSSIONREFERENCES |
|---|
).
|
). For samples tested only in lv, PK-resistant PrP was found in five of seven elk, two of eight white-tailed deer and none of three mule deer. Results are summarized in Table 1. The relative concentration of PrPd in lv was estimated visually from band intensity and comparison of tissue weights per sample lane to be roughly 10- to 100-fold lower than that demonstrated in brain tissue of the same animals (Fig. 3). Because both brain and heart samples can exhibit locational sampling variation as shown, more detailed estimates of concentrations were not made. We did not detect PrPd by Western blot in any of the other muscles tested in any of the animals, including uninfected controls (data not shown).
|
|
|
|
). If PrPd were associated primarily with cells of the cardiac conduction system or with intramural cardiac ganglia, we reasoned that such arrangements could produce ‘hit-or-miss' sampling and might account for results that showed both lv-positive and lv-negative specimens among the CWD-positive animals. We observed variable intensity of the PK-resistant PrPd bands from lv-positive animals (Fig. 4
), particularly some of the elk samples, indicating uneven but dispersed distributions of PrPd within the ventricular tissue. However, we were unable to demonstrate the presence of PrPd in the lv tissue of any mule deer, moose or three white-tailed deer and three elk that had previously been negative.
IHC
Inspection of sections of fixed lv tissue by IHC revealed anti-PrP-labelled groups of laterally adjacent muscle cells within the ordinary myocardium, often surrounded by cells with no detectable stain (Fig. 5a, b). Labelled antigen was more readily visible in longitudinal than in transverse cross-sections of cardiac myocytes. Staining generally consisted of punctate granules of chromagen scattered in an apparently cell-associated fashion (Fig. 5c), sometimes in linear patterns along the edge of a muscle cell (Fig. 5d), but not consistently so. Subcellular structures or nerve fibres with which PrPd might have been associated were not identified. Epicardial nerves and ganglia and subendocardial and myocardial Purkinje fibres lacked detectable PrPd staining. Staining of PrPd in elk myocardium was similar to that of white-tailed deer (Fig. 5e).
|
Distribution of PrPd in heart
By using complete hearts collected and frozen at necropsy from two captive CWD-affected white-tailed deer (the generous gift of Dr L. L. Wolfe, Colorado Division of Wildlife, Denver, CO, USA) and from a CWD-affected free-ranging white-tailed deer (the generous gift of D. Edmunds, University of Wyoming, Laramie, WY, USA), we tested other areas of the heart by Western blot to investigate how restricted or widespread PrPd accumulation might be. One specimen (WTD21) was positive for PrPd throughout the right atrium and strongly so in the free wall of both ventricles (Fig. 6a); another (WTD22) was weakly positive only in atrial tissue taken from the terminal crest between the right auricle and atrium, and in the interatrial septum adjacent and cranial to the opening of the coronary sinus in the area of the atrioventricular node (Fig. 6b). Heart of the free-ranging white-tailed deer (WTD20) was positive in all atrial areas sampled, strongly so in the region of the sinoatrial node, but negative in the free wall of the lv (Fig. 6c). These results indicated that PrPd could be present in atrial tissue without being detected in ventricular muscle. Our results with lv tissues probably underestimated the frequency of PrPd deposition in cardiac tissues of CWD-affected white-tailed deer. By using the complete heart from a mule deer that died in a late stage of CWD (MD18), we assayed 16 sites in atria and ventricles by Western blot for PrPd. All samples were negative (Fig. 6d, e). No complete hearts were available from CWD-affected elk.
|
|
DISCUSSION |
|---|
|
TOPABSTRACTINTRODUCTIONMETHODSRESULTSDISCUSSIONREFERENCES |
|---|
reported the observation of TSE in transgenic mice following i.c. inoculation with extracts of semitendinosus muscle from CWD-infected mule deer. Similar tests of skeletal muscles from CWD-infected white-tailed deer or elk have not yet been reported.
The negative evidence in the case of mule deer heart is somewhat more convincing, because positive heart samples from white-tailed deer and elk are essentially positive controls by which the lack of PrPd in mule deer heart can be validated for each assay. In addition, our negative results for mule deer heart are in agreement with an earlier investigation using IHC (Spraker et al., 2002a). Results of experiments to demonstrate the infectivity of cardiac-associated PrPd by bioassays, as well as to test for infectivity in mule deer heart, are not yet completed.
It was not known previously that PrPd accumulated in cardiac muscle of any TSE-infected animals and several questions are raised by these findings. One question is whether impairment of cardiac function is associated with prion deposition in myocardium. For the human spongiform encephalopathies, one case has been reported of PrPd detected by IHC in an endomyocardial biopsy sample from a Creutzfeld–Jakob disease patient with dilated cardiomyopathy (DCM) (Ashwath et al., 2005). The authors of that report suggested the possibility of prion-induced DCM on the basis of finding no other causes for the condition after an exhaustive search. Neither DCM nor other gross lesions in heart of CWD-infected deer and elk have been commonly observed at necropsy (E. S. Williams, unpublished observations; T. E. Cornish, personal communication). Disturbances in heart rate have been identified in BSE-infected cattle (Austin et al., 1997; Pomfrett et al., 2004), but were attributed possibly to associated neuropathology in the parasympathetic centres of cardiac innervation; neither infectivity nor PrPSc has been detected in heart of BSE-infected cattle (Wells et al., 1996; European Commission Scientific Steering Committee, 2002; Buschmann & Groschup, 2005; Wells et al., 2005). Similar data from cardiac monitoring of CWD-infected cervids are not available, but could be informative.
It remains to be determined whether the prions that we detected in cardiac tissue were localized to nerve fibres or subcellular structures within myocytes. For this study, our IHC examination of cardiac tissues from CWD-infected animals was restricted to lv. The grouped arrangement of PrP-labelled myocytes that we found in ventricular muscle might be the result of prion movement along nerve fibres that correspond to a particular subpopulation of neurons innervating the heart. Further investigation, such as co-labelling studies, will be required for a better understanding of the structural arrangements underlying our observations.
It will also be necessary to examine by IHC sites throughout the heart such as were analysed in frozen tissues by Western blot, in order to find out what the distribution of PrPd is and, possibly, where it appears first. Many of the heart-positive animals were in clinical stages of disease, but the time during infection at which PrPd appears in heart tissue has not been determined. Although discussions of routes by which PrPd reaches the heart are speculative in nature at this time, if it appears only after having progressed to the brain and spinal cord, this would suggest secondary dissemination from CNS to the heart, possibly via efferent parasympathetic and sympathetic neurons that innervate the heart from parasympathetic nuclei of the ventrolateral medulla of the brainstem (nucleus ambiguus primarily) (Loewy & Spyer, 1990; Standish et al., 1994) and from sympathetic preganglionic neurons that arise in the intermediolateral cell column of rostral sections of the thoracic spinal cord (McKibben & Getty, 1969a, b, 1970; Cabot, 1990). Both autonomic cardiac-control centres are among neural sites that accumulate PrPd during CWD infection following initial deposition and propagation in the dorsal motor nucleus of the vagus and in the spinal cord (Sigurdson et al., 1999, 2001; Peters et al., 2000; Spraker et al., 2002b).
Finally, determining what differential factors in these closely related species are responsible for the appearance of PrPd in heart of elk and white-tailed deer, but not of mule deer, may provide important insights into variables that promote or inhibit prion trafficking along neural conduits during a TSE infection.
|
ACKNOWLEDGEMENTS |
|---|
|
REFERENCES |
|---|
|
TOPABSTRACTINTRODUCTIONMETHODSRESULTSDISCUSSIONREFERENCES |
|---|
Angers, R. C., Browning, S. R., Seward, T. S., Sigurdson, C. J., Miller, M. W., Hoover, E. A. & Telling, G. C. (2006). Prions in skeletal muscles of deer with chronic wasting disease. Science 311, 1117.
Ashwath, M. L., DeArmond, S. J. & Culclasure, T. (2005). Prion-associated dilated cardiomyopathy. Arch Intern Med 165, 338–340.
Austin, A. R., Pawson, L., Meek, S. & Webster, S. (1997). Abnormalities of heart rate and rhythm in bovine spongiform encephalopathy. Vet Rec 141, 352–357.
Bartz, J. C., Kincaid, A. E. & Bessen, R. A. (2003). Rapid prion neuroinvasion following tongue infection. J Virol 77, 583–591.[CrossRef][Medline]
Belay, E. D., Maddox, R. A., Williams, E. S., Miller, M. W., Gambetti, P. & Schonberger, L. B. (2004). Chronic wasting disease and potential transmission to humans. Emerg Infect Dis 10, 977–984.[Medline]
Bosque, P. J., Ryou, C., Telling, G., Peretz, D., Legname, G., DeArmond, S. J. & Prusiner, S. B. (2002). Prions in skeletal muscle. Proc Natl Acad Sci U S A 99, 3812–3817.
Buschmann, A. & Groschup, M. (2005). Highly bovine spongiform encephalopathy-sensitive transgenic mice confirm essential restriction of infectivity to the nervous system in clinically diseased cattle. J Infect Dis 192, 934–942.[CrossRef][Medline]
Cabot, J. B. (1990). Sympathetic preganglionic neurons: cytoarchitecture, ultrastructure, and biophysical properties. In Central Regulation of Autonomic Functions, pp. 44–67. Edited by A. D. Loewy & K. M. Spyer. New York: Oxford University Press.
Casalone, C., Corona, C., Crescio, M. I., Martucci, F., Mazza, M., Ru, G., Bozzetta, E., Acutis, P. L. & Caramelli, M. (2005). Pathological prion protein in the tongues of sheep infected with naturally occurring scrapie. J Virol 79, 5847–5849.
European Commission Scientific Steering Committee (2002). Update of the opinion on TSE infectivity distribution in ruminant tissues. http://europa.eu.int/comm/food/fs/sc/ssc/out296_en.pdf
Glatzel, M., Abela, E., Maissen, M. & Aguzzi, A. (2003). Extraneural pathologic prion protein in sporadic Creutzfeldt–Jakob disease. N Engl J Med 349, 1812–1820.
Hadlow, W. J., Kennedy, R. C. & Race, R. E. (1982). Natural infection of Suffolk sheep with scrapie virus. J Infect Dis 146, 657–664.[Medline]
Hamir, A. N., Miller, J. L. & Cutlip, R. C. (2004). Failure to detect prion protein (PrPres) by immunohistochemistry in striated muscle tissues of animals experimentally inoculated with agents of transmissible spongiform encephalopathy. Vet Pathol 41, 78–81.
Kong, Q., Huang, S., Zou, W. & 16 other authors (2005). Chronic wasting disease of elk: transmissibility to humans examined by transgenic mouse models. J Neurosci 25, 7944–7949.
Kreeger, T. J., Montgomery, D. L., Jewell, J. E., Schultz, W. & Williams, E. S. (2006). Oral transmission of chronic wasting disease in captive Shira's moose. J Wildl Dis (in press).
Loewy, A. D. & Spyer, K. M. (1990). Vagal preganglionic neurons. In Central Regulation of Autonomic Function, pp. 68–87. Edited by A. D. Loewy & K. M. Spyer. New York: Oxford University Press.
McCutcheon, S., Hunter, N. & Houston, F. (2005). Use of a new immunoassay to measure PrPSc levels in scrapie-infected sheep brains reveals PrP genotype-specific differences. J Immunol Methods 298, 119–128.[CrossRef][Medline]
McKibben, J. S. & Getty, R. (1969a). A comparative study of the cardiac innervation in domestic animals: sheep. Acta Anat (Basel) 74, 228–242.[Medline]
McKibben, J. S. & Getty, R. (1969b). A study of the cardiac innervation in domestic animals: cattle. Anat Rec 165, 141–152.[CrossRef][Medline]
McKibben, J. S. & Getty, R. (1970). A comparative study of the cardiac innervation in domestic animals: the goat. Anat Anz 126, 161–171.[Medline]
Miller, M. W. & Williams, E. S. (2002). Detection of PrPCWD in mule deer by immunohistochemistry of lymphoid tissues. Vet Rec 151, 610–612.
Mulcahy, E. R., Bartz, J. C., Kincaid, A. E. & Bessen, R. A. (2004). Prion infection of skeletal muscle cells and papillae in the tongue. J Virol 78, 6792–6798.
Peters, J., Miller, J. M., Jenny, A. L., Peterson, T. L. & Carmichael, K. P. (2000). Immunohistochemical diagnosis of chronic wasting disease in preclinically affected elk from a captive herd. J Vet Diagn Invest 12, 579–582.
Pomfrett, C. J. D., Glover, D. G., Bollen, B. G. & Pollard, B. J. (2004). Perturbation of heart rate variability in cattle fed BSE-infected material. Vet Rec 154, 687–691.
Prusiner, S. (2004). An introduction to prion biology and diseases. In Prion Biology and Diseases, 2nd edn, pp. 1–87. Edited by S. Prusiner. Cold Spring Harbor, NY: Cold Spring Harbor Laboratory.
Safar, J., Wille, H., Itri, V., Groth, D., Serban, H., Torchia, M., Cohen, F. E. & Prusiner, S. B. (1998). Eight prion strains have PrPSc molecules with different conformations. Nat Med 4, 1157–1165.[CrossRef][Medline]
Sigurdson, C. J., Williams, E. S., Miller, M. W., Spraker, T. R., O'Rourke, K. I. & Hoover, E. A. (1999). Oral transmission and early lymphoid tropism of chronic wasting disease PrPres in mule deer fawns (Odocoileus hemionus). J Gen Virol 80, 2757–2764.
Sigurdson, C. J., Spraker, T. R., Miller, M. W., Oesch, B. & Hoover, E. A. (2001). PrPCWD in the myenteric plexus, vagosympathetic trunk and endocrine glands of deer with chronic wasting disease. J Gen Virol 82, 2327–2334.
Spraker, T. R., Zink, R. R., Cummings, B. A., Sigurdson, C. J., Miller, M. W. & O'Rourke, K. I. (2002a). Distribution of protease-resistant prion protein and spongiform encephalopathy in free-ranging mule deer (Odocoileus hemionus) with chronic wasting disease. Vet Pathol 39, 546–556.
Spraker, T. R., Zink, R. R., Cummings, B. A., Wild, M. A., Miller, M. W. & O'Rourke, K. I. (2002b). Comparison of histological lesions and immunohistochemical staining of proteinase-resistant prion protein in a naturally occurring spongiform encephalopathy of free-ranging mule deer (Odocoileus hemionus) with those of chronic wasting disease of captive mule deer. Vet Pathol 39, 110–119.
Standish, A., Enquist, L. W. & Schwaber, J. S. (1994). Innervation of the heart and its central medullary origin defined by viral tracing. Science 263, 232–234.
Thomzig, A., Kratzel, C., Lenz, G., Krüger, D. & Beekes, M. (2003). Widespread PrPSc accumulation in muscles of hamsters orally infected with scrapie. EMBO Rep 4, 530–533.[CrossRef][Medline]
Thomzig, A., Cardone, F., Krüger, D., Pocchiari, M., Brown, P. & Beekes, M. (2006). Pathological prion protein in muscles of hamsters and mice infected with rodent-adapted BSE or vCJD. J Gen Virol 87, 251–254.
van Keulen, L. J. M., Schreuder, B. E. C., Meloen, R. H., Poelen-van den Berg, M., Mooij-Harkes, G., Vromans, M. E. W. & Langeveld, J. P. M. (1995). Immunohistochemical detection and localization of prion protein in brain tissue of sheep with natural scrapie. Vet Pathol 32, 299–308.[Abstract]
van Keulen, L. J. M., Schreuder, B. E. C., Meloen, R. H., Mooij-Harkes, G., Vromans, M. E. W. & Langeveld, J. P. M. (1996). Immunohistochemical detection of prion protein in lymphoid tissues of sheep with natural scrapie. J Clin Microbiol 34, 1228–1231.[Abstract]
Wadsworth, J. D. F., Joiner, S., Hill, A. F., Campbell, T. A., Desbruslais, M., Luthert, P. J. & Collinge, J. (2001). Tissue distribution of protease resistant prion protein in variant Creutzfeldt-Jakob disease using a highly sensitive immunoblotting assay. Lancet 358, 171–180.[CrossRef][Medline]
Wells, G. A. H., Dawson, M., Hawkins, S. A. C., Austin, A. R., Green, R. B., Dexter, I., Horigan, M. W. & Simmons, M. M. (1996). Preliminary observations on the pathogenesis of experimental bovine spongiform encephalopathy. In Bovine Spongiform Encephalopathy: The BSE Dilemma, pp. 28–44. Edited by C. J. Gibbs, Jr. New York: Springer.
Wells, G. A. H., Spiropoulos, J., Hawkins, S. A. C. & Ryder, S. J. (2005). Pathogenesis of experimental bovine spongiform encephalopathy: preclinical infectivity in tonsil and observations on the distribution of lingual tonsil in slaughtered cattle. Vet Rec 156, 401–407.
Williams, E. S. (2005). Chronic wasting disease. Vet Pathol 42, 530–549.
Williams, E. S. & Young, S. (1992). Spongiform encephalopathies in Cervidae. Rev Sci Tech 11, 551–567.[Medline]
Received 19 December 2005;
accepted 6 July 2006.
This article has been cited by other articles:
|
|
 |
|
  R. Linden, V. R. Martins, M. A. M. Prado, M. Cammarota, I. Izquierdo, and R. R. Brentani Physiology of the Prion Protein Physiol Rev, April 1, 2008; 88(2): 673 - 728. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 W. M. Dlakic, E. Grigg, and R. A. Bessen Prion Infection of Muscle Cells In Vitro J. Virol., May 1, 2007; 81(9): 4615 - 4624. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. Meade-White, B. Race, M. Trifilo, A. Bossers, C. Favara, R. Lacasse, M. Miller, E. Williams, M. Oldstone, R. Race, et al. Resistance to Chronic Wasting Disease in Transgenic Mice Expressing a Naturally Occurring Allelic Variant of Deer Prion Protein J. Virol., May 1, 2007; 81(9): 4533 - 4539. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 K. A. Fox, J. E. Jewell, E. S. Williams, and M. W. Miller Patterns of PrPCWD accumulation during the course of chronic wasting disease infection in orally inoculated mule deer (Odocoileus hemionus). J. Gen. Virol., November 1, 2006; 87(Pt 11): 3451 - 3461. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| INT J SYST EVOL MICROBIOL | MICROBIOLOGY | J GEN VIROL |
| J MED MICROBIOL | ALL SGM JOURNALS | |
Deceased 29 December 2004. 
