Variable patterns of distribution of PrP(CWD) in the obex and cranial lymphoid tissues of Rocky Mountain elk (Cervus elaphus nelsoni) with subclinical chronic wasting disease

Sections of medulla oblongata, taken at the level of the obex, palatine tonsil and medial retropharyngeal lymph node from 10,269 captive Rocky Mountain elk (Cervus elaphus nelsoni), were examined by immunohistochemical staining with monoclonal antibody for the prion protein associated with the transmissible spongiform encephalopathy of cervids, chronic wasting disease (PrP(CWD)). The protein was detected in 226 of them. On the basis of the anatomical location of the deposits in the brainstem of 183 elk, four distinct patterns of distribution of PrP(CWD) within the parasympathetic region of the dorsal motor nucleus of the vagus nerve and the adjacent nuclei were observed. Mild gross lesions of chronic wasting disease (serous atrophy of fat) were observed in only three elk, all with spongiform degeneration; the other elk were considered to be in the preclinical stage of the disease. In contrast with the relatively predictable distribution of prion protein (PrP) in the brain and cranial nodes of sheep and mule deer, the distribution of PrP(CWD) in the brain and nodes of the elk was more variable and unrelated to their PrP genotype. One hundred and fifty-five of the 226 positive elk had deposits of PrP(CWD) in the brainstem and lymphoid tissues, 43 had deposits only in the lymphoid tissue and 28 had deposits only in the brainstem.     

Chronic wasting disease in a Wisconsin white-tailed deer farm

In September 2002, chronic wasting disease (CWD), a prion disorder of captive and wild cervids, was diagnosed in a white-tailed deer (Odocoileus virginianus) from a captive farm in Wisconsin. The facility was subsequently quarantined, and in January 2006 the remaining 76 deer were depopulated. Sixty animals (79%) were found to be positive by immunohistochemical staining for the abnormal prion protein (PrP(CWD)) in at least one tissue; the prevalence of positive staining was high even in young deer. Although none of the deer displayed clinical signs suggestive of CWD at depopulation, 49 deer had considerable accumulation of the abnormal prion in the medulla at the level of the obex. Extraneural accumulation of the abnormal protein was observed in 59 deer, with accumulation in the retropharyngeal lymph node in 58 of 59 (98%), in the tonsil in 56 of 59 (95%), and in the rectal mucosal lymphoid tissue in 48 of 58 (83%). The retina was positive in 4 deer, all with marked accumulation of prion in the obex. One deer was considered positive for PrP(CWD) in the brain but not in the extraneural tissue, a novel observation in white-tailed deer. The infection rate in captive deer was 20-fold higher than in wild deer. Although weakly related to infection rates in extraneural tissues, prion genotype was strongly linked to progression of prion accumulation in the obex. Antemortem testing by biopsy of recto-anal mucosal-associated lymphoid tissue (or other peripheral lymphoid tissue) may be a useful adjunct to tonsil biopsy for surveillance in captive herds at risk for CWD infection.     

Comparison of retropharyngeal lymph node and obex region of the brainstem in detection of chronic wasting disease in white-tailed deer (Odocoileus virginianus).

Chronic wasting disease (CWD) in Wisconsin was first identified in February 2002. By April 2005, medial retropharyngeal lymph node (RLN) tissues had been examined from over 75,000 white-tailed deer for the presence of CWD by either immunohistochemical (IHC) staining for the prion protein associated with CWD (PrP(res)) or by using enzyme-linked immunosorbent assays with confirmation of positives by IHC staining and had been detected in 469 animals. Obex tissue was also available from 438 of the CWD-positive animals and was CWD positive by IHC staining in 355 (81%). To verify whether false-negative results were possible examining only RLN, both obex and RLN samples were examined for CWD by IHC staining from 4,430 of the white-tailed deer harvested from an area in Wisconsin where the overall deer CWD prevalence was approximately 6.2%. Two hundred and fourteen of the 269 positive deer (79.6%) had deposits of PrP(res) in both obex and lymphoid tissues, 55 (20.4%) had deposits only in lymphoid tissue, and there were no deer that had deposits only in obex.     

Distribution of protease-resistant prion protein and spongiform encephalopathy in free-ranging mule deer (Odocoileus hemionus) with chronic wasting disease

Serial sections of brain and palatine tonsil were examined by immunohistochemical staining (IHC) using monoclonal antibody F89/160.1.5 for detecting protease-resistant prion protein (PrP(res)) in 35 hunter-killed mule deer (Odocoileus hemionus) with chronic wasting disease. Serial sections of brain were stained with hematoxylin and eosin and examined for spongiform encephalopathy (SE). Clinical signs of disease were not observed in any of these deer. On the basis of the location and abundance of IHC and the location and severity of SE, deer were placed into four categories. Category 1 (n = 8) was characterized by IHC in the palatine tonsil with no evidence of IHC or SE in the brain. Category 2 (n = 13) was characterized by IHC in the palatine tonsil and IHC with or without SE in the dorsal motor nucleus of the vagus nerve (DMNV). Category 3 (n = 2) was characterized by IHC in the palatine tonsil, IHC with SE in the myelencephalon, and IHC without SE in the hypothalamus. Category 4 (n = 12) was characterized by IHC in the palatine tonsil and IHC with SE throughout the brain. Category I may represent early lymphoid tissue localization of PrP(res). The DMNV appears to be the most consistent single neuroanatomic site of detectable PrP(res). Categories 2-4 may represent a progression of spread of PrP(res) and SE throughout the brain. IHC in tonsil and brain and SE in brain were not detected in 208 control deer.     

Abundant PrP(CWD) in tonsil from mule deer with preclinical chronic wasting disease.

A monoclonal antibody dot-blot assay was used to evaluate detergent lysates of tonsil tissue from mule deer to detect PrP(CWD), the marker for the cervid transmissible spongiform encephalopathy chronic wasting disease (CWD). Samples of formalin-fixed brain and tonsil tissues from mule deer were examined for PrP(CWD) using immunohistochemistry (IHC) with Mab F99/97.6.1, the gold standard for diagnosis of preclinical CWD. The contralateral tonsil from each of the 143 deer was prepared for confirmatory IHC and as a 10% (wt/vol) detergent lysate without purification or enrichment steps for monoclonal antibody dot-blot assay. PrP(CWD) was detected by dot-blot assay in 49 of 50 samples considered positive by IHC. Forty-eight of the positive samples were evaluated with a quantitative dot-blot assay calibrated with recombinant PrP. Tonsillar PrP(CWD) concentrations ranged from 34 to 1,188 ng per 0.5 mg starting wet weight of tissue. The abundant PrP(CWD) in mule deer tonsil will facilitate development and validation of high-throughput screening tests for CWD in large populations of free-ranging deer.     

Quantitation and localization of immunoglobulin E containing cells in bovine lymphoid tissues

Although recent studies have begun to describe and quantify IgE responses in bovine serum and secretions, little is known about the distribution and quantity of IgE containing cells in cattle. In the present study, cells with cytoplasmic IgE were quantitated in bovine lymphoid tissues, using immunoperoxidase staining and evaluation by an image analysing computer (Quantimet). Frozen sections from retropharyngeal, bronchial and mesenteric lymph nodes, tonsil and spleen were stained from 11 calves, some of which had been exposed to antigen by aerosol or injection. Although individual variability was considerable, bronchial and mesenteric lymph nodes generally contained the greatest percentage of IgE containing cells, while retropharyngeal lymph node, tonsil, and spleen had less. Parenteral immunization with ovalbumin appeared to increase the splenic percentage, while aerosol exposure to ovalbumin was associated with a greater percentage of IgE containing cells in bronchial lymph nodes. Comparison of the present results with those reported for other species shows some similar trends in IgE localization.     

Validation of monoclonal antibody F99/97.6.1 for immunohistochemical staining of brain and tonsil in mule deer (Odocoileus hemionus) with chronic wasting disease.

A new monoclonal antibody (MAb), F99/97.6.1, that has been used to demonstrate scrapie-associated prion protein PrP(Sc) in brain and lymphoid tissues of domestic sheep with scrapie was used in an immunohistochemistry assay for diagnosis of chronic wasting disease (CWD) in mule deer (Odocoileus hemionus). The MAb F99/97.6.1 immunohistochemistry assay was evaluated in brain and tonsil tissue from 100 mule deer that had spongiform encephalopathy compatible with CWD and from 1,050 mule deer outside the CWD-endemic area. This MAb demonstrated abnormal protease-resistant prion protein (PrP(res)) in brains of all of the 100 mule deer and in 99 of the 100 tonsil samples. No immunostaining was seen in samples collected from deer outside the endemic area. MAb F99/97.6.1 demonstrated excellent properties for detection of PrP(res) in fresh, frozen, or mildly to moderately autolytic samples of brain and tonsil. This immunohistochemistry assay is a sensitive, specific, readily standardized diagnostic test for CWD in deer.     

Detection by real-time quaking-induced conversion (RT-QuIC), ELISA,and IHC of chronic wasting disease prion in lymph nodes from Pennsylvania white-tailed deer with specific PRNP genotypes

Chronic wasting disease (CWD) is a prion-mediated, transmissible disease of cervids, including deer (Odocoileus spp.), which is characterized by spongiform encephalopathy and death of the prion-infected animals. Official surveillance in the United States using immunohistochemistry (IHC) and ELISA entails the laborious collection of lymphoid and/or brainstem tissue after death. New, highly sensitive prion detection methods, such as real-time quaking-induced conversion (RT-QuIC), have shown promise in detecting abnormal prions from both antemortem and postmortem specimens. We compared RT-QuIC with ELISA and IHC for CWD detection utilizing deer retropharyngeal lymph node (RLN) tissues in a diagnostic laboratory setting. The RLNs were collected postmortem from hunter-harvested animals. RT-QuIC showed 100% sensitivity and specificity for 50 deer RLN (35 positive by both IHC and ELISA, 15 negative) included in our study. All deer were also genotyped for PRNP polymorphism. Most deer were homozygous at codons 95, 96, 116, and 226 (QQ/GG/AA/QQ genotype, with frequency 0.86), which are the codons implicated in disease susceptibility. Heterozygosity was noticed in Pennsylvania deer, albeit at a very low frequency, for codons 95GS (0.06) and 96QH (0.08), but deer with these genotypes were still found to be CWD prion-infected.     

Comparison of two automated immunohistochemical procedures for the diagnosis of scrapie in domestic sheep and chronic wasting disease in North American white-tailed deer (Odocoileus virginianus) and mule deer (Odocoileus hemionus).

Two commercially available automated immunohistochemistry platforms, Ventana NexES and DakoCytomation Autostainer Universal Staining System, were compared for diagnosing sheep scrapie and cervid chronic wasting disease. Both automated platforms used the same antiprion protein monoclonal primary antibodies, but different platform-specific linker and amplification reagents and procedures. Duplicate sections of brainstem (at the level of the obex) and lymphoid tissue (retropharyngeal lymph node or tonsil) from the same tissue block were immunostained for the comparison. Examination of 1,020 tissues from 796 sheep revealed 100% concordance of results between the Ventana NexES and DakoCytomation platforms for diagnosing sheep scrapie from lymphoid tissue (103/103 positive; 405/405 negative) and brainstem (120/120 positive; 392/392 negative). Similarly, examination of 1,008 tissues from 504 white-tailed deer revealed 100% concordance between the Ventana NexES and DakoCytomation platforms for diagnosing chronic wasting disease from lymphoid tissue (104/104 positive; 400/400 negative) and brainstem (104/104 positive; 400/400 negative). Examination of 1,152 tissues from 482 mule deer revealed a concordance of 98.6% in lymphoid tissue and 99.9% in brainstem between the Ventana NexES and DakoCytomation platforms for diagnosing chronic wasting disease. The results indicate equivalence or near equivalence between the DakoCytomation and Ventana NexES autostainer platforms for identification of the disease-associated prion protein (PrPd)-positive and PrPd-negative brain and lymphoid tissues in sheep, white-tailed deer, and mule deer.     

Immunohistochemical detection and distribution of prion protein in a goat with natural scrapie.

Formalin-fixed, paraffin-embedded tissue sections from a 3-year-old female Angora goat suffering from clinical scrapie were immunostained after hydrated autoclaving using a monoclonal antibody (mAb, F99/97.6.1; IgG1) specific for a conserved epitope on the prion protein. Widespread and prominent deposition of the scrapie isoform of the prion protein (PrPSc) was observed in the brain, brainstem, spinal cord, retina, postganglionic neurons associated with parasympathetic ganglia of myenteric and submucosal plexuses, Peyer's patches, peripheral lymph nodes, and pharyngeal and palatine tonsils. The goat was homozygous for PrP alleles encoding 5 octapeptide repeat sequences in the N-terminal region of the prion protein and isoleucine at codon 142, a genotype associated with high susceptibility and short incubation times in goats. The results of this study indicate that mAb F99/97.6.1 is useful for detection of PrPSc deposition, and this is a specific and reliable immunohistochemical adjunct to histopathology for diagnosis of natural caprine scrapie, although precise determination of the diagnostic sensitivity and specificity of the assay as a diagnostic test for scrapie in goats will require examination of a sufficiently large sample size. As with ovine scrapie, prion protein is widely distributed in the central and peripheral nervous systems, gastrointestinal tract, and lymphoid tissues in natural caprine scrapie.     

Adaptation and evaluation of a rapid test for the diagnosis of sheep scrapie in samples of rectal mucosa.

In recent publications, it was shown that disease-associated prion protein (PrP(d)) accumulates in the lymphoid tissue of the rectal mucosa of a high proportion of scrapie-infected sheep at clinical and preclinical stages, regardless of several host factors; PrP(d) can also be detected in biopsy specimens of rectal mucosa, with an increased probability proportional to age or incubation period and with an efficiency almost identical to that of tonsil biopsies. Rectal biopsies have the advantages of providing higher numbers of lymphoid follicles and of being simpler to perform, which makes them suitable for scrapie screening in the field. In biopsy samples, PrP(d) could be demonstrated by immunohistochemical (IHC) and Western immunoblotting methods, and the purpose of the present study was to optimize and evaluate a "rapid test" for the diagnosis of scrapie in rectal biopsy samples. The HerdChek CWD (chronic wasting disease) antigen EIA (enzyme immunoassay) test was chosen and, once optimized, provided specificity and sensitivity figures of 99.2% and 93.5%, respectively, compared with IHC results in the same samples obtained at a postmortem. The sensitivity of the assay increased from 82.1%, when a single rectal mucosa sample was tested to 99.4% for those sheep in which 3 or more samples were analyzed. Similarly, sensitivity values of the HerdChek CWD antigen EIA test on biopsy samples increased from 95% to 100% for sheep subjected to 1 or 2 sequential biopsies 4 months apart, respectively. Thus, a preclinical diagnosis of scrapie in live sheep can be achieved by a combination of a simple sampling procedure, which can be repeated several times with no detrimental effect for the animals, and a rapid and efficient laboratory method.     

Development of monoclonal antibodies against the abnormal prion protein isoform (PrPres) associated with chronic wasting disease (CWD)

Monoclonal antibodies (mAbs) specific for the abnormal prion protein isoform (PrP^res) are indispensable for diagnosing chronic wasting disease (CWD). In this study, eight mAbs were developed by immunizing PrP knockout mice with recombinant elk PrP and an immunogenic PrP peptide. The reactivity of the mAbs to recombinant PrP and the PrP peptide was measured, and their isotypes were subsequently determined. Among them, four mAbs (B85-05, B85-08, B85-12, and B77-75) were shown by Western blotting to recognize proteinase K-treated brain homogenate derived from an elk suffering from CWD.     

White-tailed deer are susceptible to the agent of sheep scrapie by intracerebral inoculation

ABSTRACT: Interspecies transmission studies afford the opportunity to better understand the potential host range and origins of prion diseases. The purpose of this experiment was to determine susceptibility of white-tailed deer to the agent of scrapie after intracerebral inoculation and to compare clinical signs and lesions to those reported for chronic wasting disease (CWD). Deer (n = 5) were inoculated with 1 mL of a 10% (wt/vol) brain homogenate derived from a sheep clinically affected with scrapie. A non-inoculated deer was maintained as a negative control. Deer were observed daily for clinical signs of disease and euthanized and necropsied when unequivocal signs of scrapie were noted. One animal died 7 months post inoculation (pi) due to intercurrent disease. Examinations of brain tissue for the presence of the disease-associated abnormal prion protein (PrPSc) by western blot (WB) and immunohistochemistry (IHC) were negative whereas IHC of lymphoid tissues was positive. Deer necropsied at 15-22 months pi were positive for scrapie by IHC and WB. Deer necropsied after 20 months pi had clinical signs of depression and progressive weight loss. Tissues with PrPSc immunoreactivity included brain (at levels of cerebrum, hippocampus, colliculus, cerebellum, and brainstem), trigeminal ganglion, neurohypophysis, retina, spinal cord, and various lymphoid tissues including tonsil, retropharyngeal and mesenteric lymph nodes, Peyer's patches, and spleen. This work demonstrates for the first time that white-tailed deer are susceptible to sheep scrapie by intracerebral inoculation. To further test the susceptibility of white-tailed deer to scrapie these experiments will be repeated with a more natural route of inoculation.     

Experimental transmission of chronic wasting disease (CWD) of elk (Cervus elaphus nelsoni), white-tailed deer (Odocoileus virginianus), and mule deer (Odocoileus hemionus hemionus) to white-tailed deer by intracerebral route

To compare clinical and pathologic findings of chronic wasting disease (CWD) in a natural host, 3 groups (n = 5) of white-tailed deer (WTD) fawns were intracerebrally inoculated with a CWD prion of WTD, mule deer, or elk origin. Three other uninoculated fawns served as controls. Approximately 10 months postinoculation (MPI), 1 deer from each of the 3 inoculated groups was necropsied and their tissues were examined for lesions of spongiform encephalopathy (SE) and for the presence of abnormal prion protein (PrP(d)) by immunohistochemistry (IHC) and Western blot (WB). The remaining deer were allowed to live until they developed clinical signs of the disease which began approximately 18 MPI. By 26 MPI, all deer were euthanatized on humane grounds. Obvious differences in clinical signs or the incubation periods were not observed between the 3 groups of deer given CWD. In 1 of 3 nonclinical deer euthanatized at 10 MPI, minimal microscopic lesions of SE were seen in the central nervous system (CNS) tissues, and PrP(d) was observed by IHC in tissues of all 3 deer. In the clinical deer, CNS lesions of SE and PrP(d) accumulations were more severe and extensive. It is concluded that the 3 sources of CWD prion did not induce significant differences in time to clinical disease or qualitative differences in signs or lesions in WTD. However, this observation does not imply that these CWD agents would necessarily behave similarly in other recipient species.     

Field validation and assessment of an enzyme-linked immunosorbent assay for detecting chronic wasting disease in mule deer (Odocoileus hemionus), white-tailed deer (Odocoileus virginianus), and Rocky Mountain elk (Cervus elaphus nelsoni).

Tissue samples (n = 25,050 total) from 23,256 mule deer (Odocoileus hemionus), Rocky Mountain elk (Cervus elaphus nelsoni), and white-tailed deer (Odocoileus virginianus) collected statewide in Colorado were examined for chronic wasting disease (CWD) using an enzyme-linked immunosorbent assay developed by Bio-Rad Laboratories, Inc. (brELISA), in a 2-phase study. In the validation phase of this study, a total of 4,175 retropharyngeal lymph nodes (RLN) or obex (OB) tissue samples were examined independently by brELISA and immunohistochemistry (IHC). There were 137 IHC-positive samples and 4,038 IHC-negative samples. Optical density (OD) values from brELISA were classified as "not detected" or "suspect" based on recommended cutoff values during the validation phase. Using IHC-positive cases as known CWD-infected individuals and assuming IHC-negative cases as uninfected, the relative sensitivity of brELISA depending on species ranged from 98.3% to 100% for RLN samples and 92.1% to 93.3% for OB samples; the relative specificity of brELISA depending on species ranged from 99.9% to 100% for RLN samples and was 100% for OB samples. Overall agreement between brELISA and IHC was > or = 97.6% in RLN samples and > or = 95.7% in OB samples of all species where values could be calculated; moreover, mean brELISA OD values were > or = 46X higher in IHC-positive samples than in IHC-negative samples. Discrepancies were observed only in early-stage cases of CWD. Based on the validation phase data, only RLN samples were collected for the field application phase of this study and only samples with brELISA OD values > 0.1 were examined by IHC. Among 20,875 RLN samples screened with brELISA during this second testing phase, 155 of 8,877 mule deer, 33 of 11,731 elk, and 9 of 267 white-tailed deer samples (197 total) had OD values > 0.1 and were further evaluated by IHC to confirm evidence of CWD infection. Of cases flagged for IHC follow-up, 143 of 155 mule deer, 29 of 33 elk, and all 9 white-tailed deer were confirmed positive. Mean (+/- SE) OD values for IHC-positive cases detected during the field application phase were comparable with those measured in RLN tissues during the validation phase. Based on these data, brELISA was determined to be an excellent rapid test for screening large numbers of samples in surveys designed to detect CWD infections in deer and elk populations.     

A case of chronic wasting disease in an elk imported to Korea from Canada

A seven-year-old male elk (Cervus elaphus nelsoni) was euthanized and necropsied after having a 3-week history of body weight loss, emaciation, excessive salivation, teeth grinding, fever, anorexia, and respiratory distress. The elk was imported into Korea from Canada on March 9, 1997. Gross pathologic findings were restricted to a diffuse fibrinous pneumonia. Microscopic lesions included mild neuronal vacuolation and spongiform change in the neuropil of selected brain stem nuclei and generalized astrocytosis. Immunohistochemistry for protease-resistant prion protein (PrP(res)) was positive in all brain sections but more pronounced in the section of the obex of the medulla. And the PrP(res) was also detected by western immunoblotting in the brain and spinal cord. All the remaining elk and deer that had been in contact with this elk were destroyed and negative for chronic wasting disease (CWD). To our knowledge, this is the first case of CWD occurring outside of the U.S.A. and Canada.     

Evaluation of Western blotting methods using samples with or without sodium phosphotungstic acid precipitation for diagnosis of scrapie and chronic wasting disease

The purpose of this study was to enhance the sensitivity of the Western blot (WB) test for use as an alternative and confirmatory method for the diagnosis of scrapie and chronic wasting disease (CWD) in Canada by comparing 2 sample preparation procedures: an abnormal prion protein (PrPSc) concentration procedure using sodium phosphotungstic acid (PTA) precipitation and a procedure using crude sample without precipitation. A total of 100 cerebrum samples (52 sheep and 48 elk), including 66 negative (31 sheep, 35 elk) and 34 positive (21 scrapie and 13 CWD positive) samples diagnosed by using immunohistochemistry (IHC) on retropharyngeal lymph node (RPLN) and medulla oblongata at obex, were tested by using WB with the 2 sample preparation procedures. The WB using non-PTA enriched sample (crude extract) detected, on average, only 71.7% (9 of 15, 60.0% for scrapie, 5 of 6, 83.3% for CWD) of the samples that tested positive by using WB with PTA enriched samples. No case was positive by WB using crude extract but negative by WB using PTA enriched sample. No false positive was found. Serial dilution of PTA precipitated samples demonstrated that the technique increases the detection limit approximately 100 fold. Additionally, the comparison of the WB and IHC on cerebrum from all the positive cases demonstrated that WB following PTA precipitation and IHC had 100% agreement by detecting 6 positive for CWD on cerebrum; while IHC detected scrapie in only 14 out of 15 positive cerebrum samples by using WB following PTA precipitation. Phosphotungstic acid precipitation is therefore a useful adjunct to WB analysis of scrapie and CWD and tissues.     

Preliminary observations on the experimental transmission of scrapie to elk (Cervus elaphus nelsoni) by intracerebral inoculation

To determine the transmissibility of scrapie to Rocky Mountain elk (Cervus elaphus nelsoni), six elk calves were inoculated intracerebrally with brain suspension from sheep naturally affected with scrapie. One elk developed a brain abscess and was euthanatized at 7 weeks postinoculation (PI), and two others died at 6 and 15 months PI because of physical injuries. At 25 and 35 months PI, two other elk died after brief terminal neurologic episodes. Necropsy of these revealed moderate weight loss but no other gross lesions. Microscopically, characteristic lesions of spongiform encephalopathy were seen throughout the brains and the spinal cords, and in both cases these tissues were positive for PrP(res) by immunohistochemistry. Brains of both animals were positive for PrP(res) by western blot and for scrapie-associated fibrils (SAFs) by negative stain electron microscopy. PrP(res) and SAFs were not detected in the three elk that died or were euthanatized because of coincidental causes. Over 3.5 years after initiation of this experiment, the one remaining inoculated elk and two uninoculated (control) elk are alive and apparently healthy. These preliminary findings demonstrate that 1) sheep scrapie agent can be transmitted to elk by intracerebral inoculation; 2) the infection can result in severe, widely distributed spongiform change and accumulations of PrP(res) in the central nervous system (CNS); and 3) based on the examination of a limited number of CNS sections from two cases, this condition cannot be distinguished from chronic wasting disease with currently available diagnostic techniques.     

The first Canadian indigenous case of bovine spongiform encephalopathy (BSE) has molecular characteristics for prion protein that are similar to those of BSE in the United Kingdom but differ from those of chronic wasting disease in captive elk and deer

Brain tissue from a case of bovine spongiform encephalopathy (BSE) from Alberta was subjected to a Western immunoblotting technique to ascertain the molecular profile of any disease-specific, abnormal prion protein, that is, prion protein that is protease-resistant (PrP(res)). This technique can discriminate between isolates from BSE, ovine scrapie, and sheep experimentally infected with BSE. Isolates of brain tissue from the BSE case in Alberta, 3 farmed elk with chronic wasting disease (CWD) from different parts of Saskatchewan, and 1 farmed white-tailed deer with CWD from Edmonton, Alberta, were examined alongside isolates of brain tissue from BSE, ovine scrapie, and sheep experimentally infected with BSE from the United Kingdom (UK). The molecular weights of PrP(res) and the cross reactions to 2 specific monoclonal antibodies (mAbs) were determined for each sample. The BSE isolates from Canada and the UK had very similar PrP(res) molecular weights and reacted with only 1 of the 2 mAbs. The PrP(res) isolated from both elk and white-tailed deer with CWD had a higher molecular weight profile than did the corresponding PrP(res) from the scrapie and BSE isolates. The PrP(res) from CWD cases cross reacted with both mAbs, a property shared with PrP(res) in isolates from scrapie but not with PrP(res) isolates from BSE or sheep experimentally infected with BSE. The results from this study seem to confirm that the PrP(res) isolated from the BSE case in Alberta has similar molecular properties to the PrP(res) isolated from a BSE case in the UK, and that it differs in its molecular and immunological characteristics from the CWD and scrapie cases studied.