Spongiform Encephalopathies In Animals Research Articles

Chronic wasting disease as a part of animal spongiform encephalopathies

Chronic wasting disease as a part of animal spongiform encephalopathies

Public health aspects of human and animal spongiform encephalopathies

This group of re-emerging human and animal diseases has recently attracted much attention, as well as concern, both in the scientific world and among the general public. In this paper the various public health aspects of these diseases are discussed. The epidemiology, both in human beings and animals, has been reviewed and the causative agents described. Diagnosis, pathology, prevention and control are addressed, showing how the risk to animals and human beings could be minimized

N-Terminal Regions of Prion Protein: Functions and Roles in Prion Diseases.

The normal cellular isoform of prion protein, designated PrPC, is constitutively converted to the abnormally folded, amyloidogenic isoform, PrPSc, in prion diseases, which include Creutzfeldt-Jakob disease in humans and scrapie and bovine spongiform encephalopathy in animals. PrPC is a membrane glycoprotein consisting of the non-structural N-terminal domain and the globular C-terminal domain. During conversion of PrPC to PrPSc, its 2/3 C-terminal region undergoes marked structural changes, forming a protease-resistant structure. In contrast, the N-terminal region remains protease-sensitive in PrPSc. Reverse genetic studies using reconstituted PrPC-knockout mice with various mutant PrP molecules have revealed that the N-terminal domain has an important role in the normal function of PrPC and the conversion of PrPC to PrPSc. The N-terminal domain includes various characteristic regions, such as the positively charged residue-rich polybasic region, the octapeptide repeat (OR) region consisting of five repeats of an octapeptide sequence, and the post-OR region with another positively charged residue-rich polybasic region followed by a stretch of hydrophobic residues. We discuss the normal functions of PrPC, the conversion of PrPC to PrPSc, and the neurotoxicity of PrPSc by focusing on the roles of the N-terminal regions in these topics.

Prion protein signaling induces M2 macrophage polarization and protects from lethal influenza infection in mice.

The cellular prion protein, PrPC, is a glycosylphosphatidylinositol anchored-membrane glycoprotein expressed most abundantly in neuronal and to a lesser extent in non-neuronal cells. Its conformational conversion into the amyloidogenic isoform in neurons is a key pathogenic event in prion diseases, including Creutzfeldt-Jakob disease in humans and scrapie and bovine spongiform encephalopathy in animals. However, the normal functions of PrPC remain largely unknown, particularly in non-neuronal cells. Here we show that stimulation of PrPC with anti-PrP monoclonal antibodies (mAbs) protected mice from lethal infection with influenza A viruses (IAVs), with abundant accumulation of anti-inflammatory M2 macrophages with activated Src family kinases (SFKs) in infected lungs. A SFK inhibitor dasatinib inhibited M2 macrophage accumulation in IAV-infected lungs after treatment with anti-PrP mAbs and abolished the anti-PrP mAb-induced protective activity against lethal influenza infection in mice. We also show that stimulation of PrPC with anti-PrP mAbs induced M2 polarization in peritoneal macrophages through SFK activation in vitro and in vivo. These results indicate that PrPC could activate SFK in macrophages and induce macrophage polarization to an anti-inflammatory M2 phenotype after stimulation with anti-PrP mAbs, thereby eliciting protective activity against lethal infection with IAVs in mice after treatment with anti-PrP mAbs. These results also highlight PrPC as a novel therapeutic target for IAV infection.

Absence of Evidence for a Causal Link between Bovine Spongiform Encephalopathy Strain Variant L-BSE and Known Forms of Sporadic Creutzfeldt-Jakob Disease in Human PrP Transgenic Mice.

Since the quasi-extinction of classical BSE, atypical BSE forms are the sole BSE variants circulating in cattle worldwide. They are observed in rare cases of old cattle, making them difficult to detect. Extrapolation of our results suggests that L-BSE may propagate in humans as an unrecognized form of CJD, and we urge both the continued utilization of precautionary measures to eliminate these agents from the human food chain and active surveillance for CJD phenotypes in the general population.

Deletion of Cellular Prion Protein (PrPC) Results in Peripheral Lymphocytosis and Larger Platelets

Cellular prion protein (PrPC) is a GPI-anchored cell surface glycoprotein that is expressed in the brain, blood, bone marrow (BM), and lymphoid tissue. PrPC can be converted post-translationally into scrapie-PrP (PrPSc), which is involved in the pathogenesis of neurodegenerative diseases including Creutzfeldt-Jakob disease, Kuru disease in humans, and scrapie and bovine spongiform encephalopathy in animals. However, the biological function of PrPSc has yet to be conclusively elucidated.In order to understand the role of PrPC in the hematopoietic system, we compared bone marrow, lymphoid organs and peripheral blood of PrPC knockout mice (KO) to age and sex-matched transgenic mice used as background controls (WT) expressing human PrPC under the control of a mouse PrPC promoter with a slightly augmented expression (2-fold) of PrPC. Complete blood count (CBC) showed a significant increase of WBC in KO mice (KO 9.03 ± 5.16 x109/L vs. WT 4.13 ± 1.87 x109/L, p = 0.0405; Table 1 and Figure 1). Further analysis of WBC differential revealed that the elevated number of WBC in KO mice was due to lymphocytosis. Specifically, KO mice had a 3-fold increase in the absolute lymphocyte count (KO 7.59 ± 4.63 x109/L vs. WT 2.90 ± 1.32 x109/L, p = 0.0303), as well as a higher lymphocyte percentage (KO 82.47 ± 4.20% vs. WT 70.19 ± 4.44%, p = 0.0011) compared to controls. KO mice also had a trend toward higher hemoglobin (KO 12.00 ± 4.40 g/dL vs. WT 9.84 ± 4.83 g/dL), RBC (KO 8.01 ± 2.87 x1012/L vs. WT 6.25 ± 3.11 x1012/L), and hematocrit (KO 43.94 ± 17.00 % vs. WT 36.04 ± 18.07 %) compared to WT mice. Additionally, platelet count in KO mice was higher than control mice (KO 762.20 ± 138.61 x 109/L vs. WT 661.80 ± 230.20 x 109/L). Of interest, the mean platelet volume (platelet size) was significantly increased in KO mice compared to controls (KO 6.00 ± 0.29 fL vs. WT 5.24 ± 0.56 fL, p =0.0140). Thus, absence of PrPC resulted in significant leukocytosis and specifically higher absolute count and percentage of lymphocytes, as well as larger platelets in peripheral blood.To further analyze if the observed lymphocytosis is due to abnormalities in hematopoiesis or lymphopoiesis, bone marrow (BM), thymus, spleen and lymph nodes from WT and KO mice were isolated and examined by flow cytometry using a comprehensive panel of fluorochrome-conjugated antibodies specific for all hematologic cell precursors/lineages. Analysis of all cell populations in each of these organs revealed no significant differences in the numbers of RBC and megakaryocyte in BM, and of lymphocytes in the thymus, spleen and lymph nodes (data no shown). Additionally, histological analysis of BM, thymus, spleen and lymph nodes tissue from KO and WT animals failed to show morphological differences between the two groups (data not shown). Therefore, lack of PrPC does not appear to affect hematopoiesis and lymphopoiesis.In summary, our findings indicate that PrPC deficiency translates into a significant increase in the number of lymphocytes in peripheral blood; however, development and maturation of lymphocytes in KO mice appeared normal. Therefore, PrPC might be critical in the survival and trafficking of lymphocytes in peripheral blood. The molecular mechanisms underlying the observed changes in lymphocytes and platelets, and whether there are any related changes in the functions of lymphocytes and platelets will be subject of future studies.Table 1Complete blood count (CBC) of PrPC WT and KO miceWTKOp valueMean ± SDMean ± SDWBC (109/L)4.13 ± 1.879.03 ± 5.160.0405Absolute lymphocyte count (109/L)2.90 ± 1.327.59 ± 4.630.0303Lymphocyte (%)70.19 ± 4.4482.47 ± 4.200.0011RBC (1012/L)6.25 ± 3.118.01 ± 2.870.1898HB (g/dL)9.84 ± 4.8312.00 ± 4.400.2404HCT (%)36.04 ± 18.0743.94 ± 17.000.2618PLT (109/L)661.80 ± 230.20762.20 ± 138.610.2138MPV (fL)5.24 ± 0.566.00 ± 0.290.0140SD: Standard deviation; WBC: White blood cell; RBC: Red blood cell; HB: Hemoglobin; HCT: Hematocrit; RDW: Red cell distribution width; PLT: Platelet; MPV: Mean platelet volume [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Small-Molecule Theranostic Probes: A Promising Future in Neurodegenerative Diseases

Prion diseases are fatal neurodegenerative illnesses, which include Creutzfeldt-Jakob disease in humans and scrapie, chronic wasting disease, and bovine spongiform encephalopathy in animals. They are caused by unconventional infectious agents consisting primarily of misfolded, aggregated, β-sheet-rich isoforms, denoted prions, of the physiological cellular prion protein (PrPC). Many lines of evidence suggest that prions (PrPSc) act both as a template for this conversion and as a neurotoxic agent causing neuronal dysfunction and cell death. As such, PrPSc may be considered as both a neuropathological hallmark of the disease and a therapeutic target. Several diagnostic imaging probes have been developed to monitor cerebral amyloid lesions in patients with neurodegenerative disorders (such as Alzheimer's disease, Parkinson's disease, and prion disease). Examples of these probes are Congo red, thioflavin T, and their derivatives. We synthesized a series of styryl derivatives, denoted theranostics, and studied their therapeutic and/or diagnostic potentials. Here we review the salient traits of these small molecules that are able to detect and modulate aggregated forms of several proteins involved in protein misfolding diseases. We then highlight the importance of further studies for their practical implications in therapy and diagnostics.

Biological Effects and Use of PrP Sc - and PrP-Specific Antibodies Generated by Immunization with Purified Full-Length Native Mouse Prions

The prion agent is the infectious particle causing spongiform encephalopathies in animals and humans and is thought to consist of an altered conformation (PrP(Sc)) of the normal and ubiquitous prion protein PrP(C). The interaction of the prion agent with the immune system, particularly the humoral immune response, has remained unresolved. Here we investigated the immunogenicity of full-length native and infectious prions, as well as the specific biological effects of the resulting monoclonal antibodies (MAbs) on the binding and clearance of prions in cell culture and in in vivo therapy. Immunization of prion knockout (Prnp(0/0)) mice with phosphotungstic acid-purified mouse prions resulted in PrP-specific monoclonal antibodies with binding specificities selective for PrP(Sc) or for both PrP(C) and PrP(Sc). PrP(Sc)-specific MAb W261, of the IgG1 isotype, reacted with prions from mice, sheep with scrapie, deer with chronic wasting disease (CWD), and humans with sporadic and variant Creutzfeldt-Jakob disease (CJD) in assays including a capture enzyme-linked immunosorbent assay (ELISA) system. This PrP(Sc)-specific antibody was unable to clear prions from mouse neuroblastoma cells (ScN2a) permanently infected with scrapie, whereas the high-affinity MAb W226, recognizing both isoforms, PrP(Sc) and PrP(C), did clear prions from ScN2a cells, as determined by a bioassay. However, an attempt to treat intraperitoneally prion infected mice with full-length W226 or with a recombinant variable-chain fragment (scFv) from W226 could only slightly delay the incubation time. We conclude that (i) native, full-length PrP(Sc) elicits a prion-specific antibody response in PrP knockout mice, (ii) a PrP(Sc)-specific antibody had no prion-clearing effect, and (iii) even a high-affinity MAb that clears prions in vitro (W226) may not necessarily protect against prion infection, contrary to previous reports using different antibodies.

Prion propagation and toxicity in vivo occur in two distinct mechanistic phases

Mammalian prions cause fatal neurodegenerative conditions including Creutzfeldt-Jakob disease in humans and scrapie and bovine spongiform encephalopathy in animals. Prion infections are typically associated with remarkably prolonged but highly consistent incubation periods followed by a rapid clinical phase. The relationship between prion propagation, generation of neurotoxic species and clinical onset has remained obscure. Prion incubation periods in experimental animals are known to vary inversely with expression level of cellular prion protein. Here we demonstrate that prion propagation in brain proceeds via two distinct phases: a clinically silent exponential phase not rate-limited by prion protein concentration which rapidly reaches a maximal prion titre, followed by a distinct switch to a plateau phase. The latter determines time to clinical onset in a manner inversely proportional to prion protein concentration. These findings demonstrate an uncoupling of infectivity and toxicity. We suggest that prions themselves are not neurotoxic but catalyse the formation of such species from PrP(C). Production of neurotoxic species is triggered when prion propagation saturates, leading to a switch from autocatalytic production of infectivity (phase 1) to a toxic (phase 2) pathway.

Aberrant ERK 1/2 complex activation and localization in scrapie-infected GT1-1 cells

BackgroundFatal neurodegenerative disorders such as Creutzfeldt-Jakob and Gerstmann-Sträussler-Scheinker diseases in humans, scrapie and bovine spongiform encephalopathy in animals, are characterized by the accumulation in the brain of a pathological form of the prion protein (PrP) denominated PrPSc. The latter derives from the host cellular form, PrPC, through a process whereby portions of its α-helical and coil structures are refolded into β-sheet structures.ResultsIn this work, the widely known in vitro model of prion replication, hypothalamic GT1-1 cell line, was used to investigate cellular and molecular responses to prion infection. The MAP kinase cascade was dissected to assess the phosphorylation levels of src, MEK 1/2 and ERK 1/2 signaling molecules, both before and after prion infection. Our findings suggest that prion replication leads to a hyper-activation of this pathway. Biochemical analysis was complemented with immunofluorescence studies to map the localization of the ERK complex within the different cellular compartments. We showed how the ERK complex relocates in the cytosol upon prion infection. We correlated these findings with an impairment of cell growth in prion-infected GT1-1 cells as probed by MTT assay. Furthermore, given the persistent urgency in finding compounds able to cure prion infected cells, we tested the effects on the ERK cascade of two molecules known to block prion replication in vitro, quinacrine and Fab D18. We were able to show that while these two compounds possess similar effects in curing prion infection, they affect the MAP kinase cascade differently.ConclusionsTaken together, our results help shed light on the molecular events involved in neurodegeneration and neuronal loss in prion infection and replication. In particular, the combination of chronic activation and aberrant localization of the ERK complex may lead to a lack of essential neuroprotective and survival factors. Interestingly, these data seem to define some common traits with other neurodegenerative disorders such as, for example, Alzheimer's disease.

Bilateral Vestibular Failure as an Early Sign in Creutzfeldt-Jakob Disease

Bilateral vestibular failure causes dysfunction of the vestibulo-ocular reflex with consecutive symptoms like apparent movements of the visual environment during head movements (oscillopsia) and unsteady gait in darkness or on uneven ground. A definite case of Creutzfeldt-Jakob disease in which bilateral vestibular loss was one of the first clinical signs is reported. Further, in a series of 9 consecutive patients with Creutzfeldt-Jakob disease (6 probable, 3 definite), 3 had bilateral vestibular loss at initial presentation. The vestibular nuclei are known to be severely affected in animal spongiform encephalopathies. They might also be a vulnerable target in human prion diseases.

Fibrillization of recombinant bovine prion protein (rec-PrP) in vitro

112 Conversion of normal prion protein ( PrP c ) from the conformation with predominantly α -helical structure into the conformation rich in β -structures ( PrP sc , β -PrP, and PrP res ) underlies the pathogenesis of prion diseases, a special class of degenerative diseases of the nervous system of humans and animals. Prion diseases, or transmissible spongiform encephalopathies (TSEs) of humans, include the Creutzfeldt–Jakob disease (CJD), the Gerstmann–Straussler–Scheinker syndrome, new variant of CJD, kuru, as well as the fatal familial insomnia. The most well-known transmissible spongiform encephalopathies of animals are scrapie of sheep, chronic wasting disease of deer and moose, and bovine spongiform encephalopathy (mad cow disease) [1]. In the course of development of transmissible spongiform encephalopathies, amyloid fibrils (the so-called scrapie-associated fibrils) are formed in brain tissue of both animals and humans. These fibrils consist of β -PrP and are partially resistant to proteolysis. Transmissible spongiform encephalopathies differ in clinical symptoms, neuropathology, neuroanatomical distribution of PrP sc in tissues, and incubation period. It is believed that this heterogeneity of transmissible spongiform encephalopathies is determined by distinctions in the trimeric structure of pathological isoforms of PrP sc [1]. To understand the molecular mechanisms of conversion, the causes of strain differences of causative agents of transmissible spongiform encephalopathies, and interspecies transmission of prion diseases, transformation of recombinant PrP (rec-PrP) of human and different animal species into amyloid fibrils has been performed in vitro in the past years in several laboratories [3–6]. It was shown that the amino acid sequence of PrP markedly affects the formation and morphology of fibrils.

Risk analysis of Transmissible Spongiform Encephalopathies in animals: state-of-the-art

The Bovine Spongiform Encephalopathy (BSE) crisis of the last two decades has shown that proper interaction of risk assessment, risk management and risk communication is essential. Mathematical models and risk assessments have been used as a basis for BSE risk management options and much of the legislation regarding the control and eradication of BSE. Much uncertainty regarding important input parameters remains a major constraint in risk assessment. Uncertainty is one of the most critical and most difficult aspects of communication of risks about Transmissible Spongiform Encephalopathies (TSEs). Nevertheless, the decline in the BSE epidemic in the UK and most European countries demonstrates that management has been, for the most part, successful. Literature pertaining to the three inter-related facets of risk analysis: risk assessment, risk management and risk communication of TSEs of animal origin was reviewed and used to describe the state-of-the-art of risk analysis for TSEs.

Insoluble Aggregates and Protease-resistant Conformers of Prion Protein in Uninfected Human Brains

Aggregated prion protein (PrPSc), which is detergent-insoluble and partially proteinase K (PK)-resistant, constitutes the major component of infectious prions that cause a group of transmissible spongiform encephalopathies in animals and humans. PrPSc derives from a detergent-soluble and PK-sensitive cellular prion protein (PrPC) through an alpha-helix to beta-sheet transition. This transition confers on the PrPSc molecule unique physicochemical and biological properties, including insolubility in nondenaturing detergents, an enhanced tendency to form aggregates, resistance to PK digestion, and infectivity, which together are regarded as the basis for distinguishing PrPSc from PrPC. Here we demonstrate, using sedimentation and size exclusion chromatography, that small amounts of detergent-insoluble PrP aggregates are present in uninfected human brains. Moreover, PK-resistant PrP core fragments are detectable following PK treatment. This is the first study that provides experimental evidence supporting the hypothesis that there might be silent prions lying dormant in normal human brains.

Diagnosis of Transmissible Spongiform Encephalopathies in Animals: A Review

Transmissible spongiform encephalopathies (TSEs) in animals include, among others, bovine spongiform encephalopathy (BSE), scrapie, chronic wasting disease, and atypical forms of prion diseases. Diagnosis of TSEs is based on identification of characteristic lesions or on detection of the abnormal prion proteins in tissues, often by use of their partial proteinase K resistance property. Correctly sampling of target tissues is of utmost importance as this has a considerable effect on test sensitivity. Most of the rapid or screening tests are based on ELISA or Western immunoblot (WB) analysis, and many are officially approved. Confirmatory testing is normally performed by use of histologic examination, immunohistochemical analysis, certain WB protocols, or detection of prion fibrils by use of electron microscopy (scrapie-associated fibril). The discriminatory methods for diagnostic use are mostly based on WB technology and provide initial identification of the prion strain, particularly for differentiation of BSE from scrapie in small ruminants. Definitive prion strain characterization is performed by use of bioassays, usually in mice. A burgeoning number of transgenic mice have been developed for TSE studies. Development of new tests with higher sensitivity and of more reliable diagnostic applications for live animals tested for food safety reasons is a rapidly developing field. Ultimately, the choice of a test for TSE diagnosis depends on the rationale for the testing.

Human and animal spongiform encephalopathies are the result of chronic autoimmune attack in the CNS: a novel medical theory supported by overwhelming experimental evidence.

Spongiform encephalopathies, also called "prion diseases", are fatal degenerative diseases of the central nervous system which can occur in animals (such as the "mad cow disease" in cattle) and also in humans. This paper presents a novel medical theory concerning the pathogenic mechanisms for various human and animal spongiform encephalopathies. It is hypothesized that various forms of prion diseases are essentially autoimmune diseases, resulting from chronic autoimmune attack of the central nervous system. A key step in the pathogenic process leading towards the development of spongiform encephalopathies involves the production of specific autoimmune antibodies against the disease-causing prion protein (PrPsc) and possibly other immunogenic macromolecules present in the brain. As precisely explained in this paper, the autoimmune antibodies produced against PrPsc are responsible for the conversion of the normal cellular prion protein (PrPc) to PrPsc, for the accumulation of PrPsc in the brain and other peripheral tissues, and also for the initiation of an antibody-mediated chronic autoimmune attack of the central nervous system neurons, which would contribute to the development of characteristic pathological changes and clinical symptoms associated with spongiform encephalopathies. The validity and correctness of the proposed theory is supported by an overwhelming body of experimental observations that are scattered in the biomedical literature. In addition, the theory also offers practical new strategies for early diagnosis, treatment, and prevention of various human and animal prion diseases.

Mammalian Prion Protein Suppresses Bax-induced Cell Death in Yeast

Several lines of evidence suggest that PrP(C), the non-infectious form of the prion protein, may function to protect neurons and other cells from stress or toxicity. In this paper, we report on the use of the yeast Saccharomyces cerevisiae as a model system to assay the cytoprotective activity of PrP(C). The mammalian pro-apoptotic protein, Bax, confers a lethal phenotype when expressed in yeast. Since overexpression of PrP(C) has been found to prevent Bax-mediated cell death in cultured human neurons, we explored whether PrP could also suppress Bax-induced cell death in yeast. We utilized a form of mouse PrP containing a modified signal peptide that we had previously shown is efficiently targeted to the secretory pathway in yeast. We found that this PrP potently suppressed the death of yeast cells expressing mammalian Bax under control of a galactose-inducible promoter. In contrast, cytosolic PrP-(23-231) failed to rescue growth of Bax-expressing yeast, indicating that protective activity requires targeting of PrP to the secretory pathway. Deletion of the octapeptide repeat region did not affect the rescuing activity of PrP, but deletion of a charged region encompassing residues 23-31 partially eliminated activity. We also tested several PrP mutants associated with human familial prion diseases and found that only a mutant containing nine extra octapeptide repeats failed to suppress Bax-induced cell death. These findings establish a simple and genetically tractable system for assaying a putative biological activity of PrP(C).

La protéine du prion et le cuivre : un lien mystérieux

Prion diseases form a group of fatal neurodegenerative disorders including Creutzfeldt–Jakob disease in humans and bovine spongiform encephalopathy in animals. All of which are characterized by the accumulation of abnormally folded isoform of the cellular prion protein (PrP C), denoted PrP Sc, which is the major component of infectious prion diseases. The function of PrP C remains elusive. Its amino-terminal region contains a repeated five octapeptide domain that binds copper. The protein is believed to display a superoxide dismutase like activity, and hence a possible protective function against oxidative stress. In this review, relationship between PrP, copper and oxidative stress was analysed. Thus, metal ions and oxidative stress would play an essential role in the pathogenesis of prion diseases and represent important targets for future therapeutic targets or a novel diagnostic marker.

Failure to demonstrate involvement of antibodies to Acinetobacter calcoaceticus in transmissible spongiform encephalopathies of animals

Acinetobacter calcoaceticus, a soil microbe, contains molecular sequences which resemble those found in neurofilaments of the brain tissue. It was hypothesized that if cattle ingest large amounts of feedstuff containing A. calcoaceticus, they may develop an autoimmune reaction, with consequences of pathological changes associated with transmissible spongiform encephalopathies (TSEs). The hypothesis was tested using a small number of serum samples collected from cattle and it was found that affected individuals had elevated serum antibody levels to this organism. If this finding was substantiated, it would provide a possible means of diagnosing TSEs in vivo. In the present communication, a larger number of cattle, elk and sheep with or without TSEs were tested using A. calcoaceticus whole cell and lipopolysaccharide antigens as well as myelin basic protein (MBP). It was found that antibody levels in normal and affected animals overlapped considerably, thus casting doubt on the usefulness of these antigens as diagnostic tools for TSEs and on the hypothesis of A. calcoaceticus being a cause of TSEs.

PrPC is sorted to the basolateral membrane of epithelial cells independently of its association with rafts.

PrP(C) is a glycosylphosphatidylinositol-anchored protein expressed in neurons as well as in the cells of several peripheral tissues. Although the normal function of PrP(C) remains unknown, a conformational isoform called PrP(Sc) (scrapie) has been proposed to be the infectious agent of transmissible spongiform encephalopathies in animals and humans. Where and how the PrP(C) to PrP(Sc) conversion occurs in the cells is not yet known. Therefore, dissecting the intracellular trafficking of the wild-type prion protein, as well as of the scrapie isoform, can be of major relevance to the pathogenesis of the diseases. In this report we have analyzed the exocytic pathway of transfected mouse PrP(C) in thyroid and kidney polarized epithelial cells. In contrast to the majority of glycosylphosphatidylinositol-anchored proteins, we found that PrP(C) is localized mainly on the basolateral domain of the plasma membrane of both cell lines. This is reminiscent of the predominant somatodendritic localization found in neurons. However, similarly to apical glycosylphosphatidylinositol-proteins, PrP(C) associates with detergent-resistant microdomains, which have been suggested to have a role in apical sorting of glycosylphosphatidylinositol-proteins, as well as in the conversion process of PrP(C) to PrP(Sc). In order to discriminate whether detergent-resistant microdomains have a direct role in PrP(Sc) conversion, or whether they are involved in the transport of the protein to the site of its conversion, we have examined the effect of disruption of detergent-resistant microdomain association on PrP(C) intracellular traffic. Consistent with the unusual basolateral localization of this glycosylphosphatidylinositol-linked protein, our data exclude a classical role for detergent-resistant microdomains in the post-trans-Golgi network sorting and transport of PrP(C) to the plasma membrane.