Scrapie infectivity

Lansbury PT Jr, Caughey B. The chemistry of scrapie infection implications of the ice 9 metaphor. Chem Biol 1995 2 1-5. 

Seeger, H., Heikenwalder, M., Zeller, N., Kranich, J., Schwarz, P., Gaspert, A., Seifert, B., Miele, G., and Aguzzi, A. (2005). Coincident scrapie infection and nephritis lead to urinary prion excretion. Science 310, 324-326. 

Wille, H., Baldwin, M. A., Cohen, F. E., DeArmond, S. J., and Prusiner, S. B. (1996). Prion protein amyloid Separation of scrapie infectivity from PrP polymers. Ciba Found. Symp. 199, 181-199 discussion 199-201. 

Schmerr and Jenny established a CE-based immunoassay for the detection of prion protein (24). In this competitive assay, peptides derived from the prion protein and labeled with fluorescein were used. This allowed them to distinguish scrapie-infected brain preparations from noninfected. For identification, the ratio between the peaks resulting from the free and the com-plexed peptide with a specific antibody was used. The results were in agreement with other data on the brain preparations achieved by Western blot analysis. The CE-based assay provides the advantage of direct detection of the scrapie protein in blood and tissue preparations with high sensitivity. Furthermore, due to the small sample amount needed for analysis, the CE-based assay is applicable to the putative diagnostics of prion protein in body fluids. 

MJ Schmerr, A Jenny. A diagnostic test for scrapie-infected sheep using capillary electrophoresis immunoassays with fluorescent-labeled peptides. Electrophoresis 19 409-414, 1998. 

In sheep wdth mastitis, a chronic inflammation of the mammary gland, and concurrent scrapie, prion infection is present in FDCs and macrophages in lymphoid follicles that develop adjacent to mammary ducts (Ligios et ah, 2005). Although, there are no accounts of prion shedding from colostrum in scrapie-infected sheep without mastitis, macrophages can be shed into the milk of sheep with mastitis. Secretion of the scrapie-infected macrophages in colostrum of sheep with mastitis could potentially play a role in vertical transmission of scrapie since the route of spread from ewe to lamb has not been determined. 

However, the emergence of variant Creutzfeldt-Jakob disease (vCJD) in the UK and France has raised concern about a new theoretical risk of infection in patients treated with blood and blood products (198). Animal experiments in which blood from sheep infected with bovine spongiform encephalopathy and natural scrapie-infected sheep into scrapie-free recipient animals have suggested disease transmission by the blood transfusion route in 2 of 24 sheep with bovine spongiform encephalopathy and in 4 of 21 sheep with scrapie (199). Many European countries have incorporated leukodepletion of all blood products, as leukocytes are believed to play a key role in the pathogenesis of variant Creutzfeldt-Jakob disease (198). In some countries, people who have lived in the UK for a period longer than 6 months between 1980 and 1996 are excluded from blood donation (13). Furthermore, it has been shown that various steps used in the manufacture of plasma-derived products also contribute to reduced infectivity by bovine spongiform encephalopathy (198). 

Duguid, J.R. and M.C. Dinauer. Library subtraction of in vitro cDNA libraries to identify differentially expressed genes in scrapie infection. Nucleic Acids Res. 18 2789—2792, 1990. 

With the high spatial resolution of the synchrotron, individual cells within a tissue can be probed with subcellular resoluhon. For example, the structures of misfolded protein aggregates in neurological protein folding diseases have been identified in the brain tissue of Alzheimer s disease patients [31-33], while infectious prion proteins have been characterized in scrapie [34-37]. Additional biochemical changes have also been observed in the fingerprint regions of Alzheimer s [38], Parkinson s [39] and scrapie-infected tissues [40]. 

Scott M, Foster D, Mirenda C, Serban D, Coufal F, Walchli M, Torchia M, Groth D, Carlson G, DeArmond SJ, Westaway D, Prusiner SB (1989) Transgenic mice expressing hamster prion protein produce species-specific scrapie infectivity and amyloid plaques. Cell 59 847-857... 

On the experimental front, the structure of PrPSc derived from brain tissue of scrapie-infected transgenic mice expressing GPI-free prion protein was recently examined by the hydrogen/deuterium exchange method [105], In contrast to the models described above, these data indicate that the PrPc >PrPSc conversion involves major refolding of the entire region C-terminal to residue 80-90, and that this region in PrPSc consists of a network of (3-strands and relatively short turns, with no native a-helices present. 

Riesner D, Kellings K, Post K et al (1996) Disruption of prion rods generates 10-nm spherical particles having high alpha-helical content and lacking scrapie infectivity. J Virol 70 1714-1722... 

Arnold JE, Tipler C, Laszlo L, Hope J, Landon M, Mayer RJ (1995) The abnormal isoform of the prion protein accumulates in late-endosome-like organelles in scrapie-infected mouse-brain. J Pathol 176 403... 

Caughey B, Race RE, Ernst D, Buchmeier MJ, Chesebro B (1989) Prion protein biosynthesis in scrapie-infected and uninfected neuroblastoma cells. J Virol 63 175... 

Winklhofer KF, Tatzelt J (2000) Cationic lipopolyamines induce degradation of PrPSc in scrapie-infected mouse neuroblastoma cells. Biol Chem 381 463 169... 

A library of fe(6-chloro-2-methoxyacridin-9-yl) and fe(7-chloro-2-met-hoxybenzo[Z>][l,5]naphthyridin-10-yl) analogs was synthesized to explore the effect of structurally diverse linkers on PrPSe replication in scrapie-infected neuroblastoma cells (2003MI4). 

Barletta, J.M., Edelman, D.C., Highsmith, W.E., and Constantine, N.T. (2005) Detec tion of ultra low levels of pathologic prion protein in scrapie infected hamster brain homogenates using real time immuno PCR. Journal of Virological Methods, 127, 154 164. 

The biosyntJiesis of PrP-sen and PrP-res has been studied using normal mouse neuroblastoma (MNB) cells, which only express PrP-sen, and mouse scrapie-infected neuroblastoma (Sc+-MNB) cells, which are persistendy infected with mouse scrapie and express both PrP-sen and PrP-res (Fig. 1C). The synthesis of PrP-sen in uninfected and scrapie-infected MNB cells appears to be the same, but in Sc+-MNB, where PrP-sen is the precursor to PrP-res (Borchelt et al, 1990 Caughey and Raymond, 1991), the biosynthesis of PrP-res differs dramatically from that of PrP-sen (Caughey et al, 1989 Borchelt et al, 1990 Caughey and Raymond, 1991 Caughey et al., 1991a Taraboulos etal., 1992). 

Both PrP-sen and PrP-res contain a single intramolecular disulfide bond (Fig. 2) (Turk et al, 1988). The importance of disulfide bonds in TSE disease was first suggested by early experiments demonstrating that treatment of mouse scrapie-infected brain fractions with SDS and 2-mercaptoethanol significantly reduced scrapie infectivity (Somerville et al, 1980). Consistent with these in vivo results, the presence of the disulfide bond appears to affect PrP folding and PrP-res formation. Removal of the disulfide bond in PrP-sen leads to a protease-resistant form of PrP (Jackson et al, 1999 Ma and Lindquist, 1999) and prevents its conversion to protease resistance in an in vitro conversion assay (Herrmann and Caugbey, 1998). 

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