No abstract available.
Prions*

No abstract available.
Prions*

Animals ; PrPSc Proteins ; metabolism ; pathogenicity ; Prion Diseases ; transmission ; Prions ; physiology

OBJECTIVETo expatiate dynamic changes in hamsters infected with scrapie strain 263K, to observe the presence and aggravation of various forms of PrP and PrP(Sc) during incubation period, and to probe primarily the relationship between the onset of clinic manifestations and the presence of different PrP(Sc) forms.

METHODSHamster-adapted scrapie strain 263K was intracerebrally inoculated into hamsters. Different forms of PrP and PrP(Sc) were monitored dynamically by Western blot and immuno-histochemical assays. The presence of scrapie-associated fibril (SAF) was assayed by electron microscopy analysis (EM) and immuno-golden EM.

RESULTSPrP(Sc) was initially detected in the brain tissues of the animals in 20 days post-inoculation by immunohistochemistry and 40 days with Western blot. Quantitative evaluations revealed that the amounts of PrP and PrP(Sc) in brain tissues increased along with the incubation. Several high and low molecular masses of PrP were seen in the brains of the long-life span infected animals. Deglycosylation assays identified that the truncated PrP in the infected brains showed similar glycosylation patterns as the full-length PrP. The presence of short fragments was seemed to relate with the onset of clinical conditions.

CONCLUSIONThese results indicate that infectious agents exist and accumulate in central nerve system prior to the onset of the illness. Various molecular patterns of PrP(Sc) may indwell in brain tissues during the infection.

Animals ; Blotting, Western ; Brain ; metabolism ; ultrastructure ; Cricetinae ; Disease Models, Animal ; Female ; Glycosylation ; Immunohistochemistry ; Mesocricetus ; Microscopy, Electron ; PrP 27-30 Protein ; analysis ; metabolism ; PrPC Proteins ; analysis ; metabolism ; PrPSc Proteins ; analysis ; metabolism ; Scrapie ; metabolism ; pathology

Misfolded isoform of prion protein (PrP), termed scrapie PrP (PrP(Sc)), tends to aggregate into various fibril forms. Previously, we reported various conditions that affect aggregation of recombinant PrP into amyloids. Because amyloidogenesis of PrP is closely associated with transmissible spongiform encephalopathies such as Creutzfeldt-Jakob disease in humans, we investigated infectivity of recombinant PrP amyloids generated in vitro. Using cultured cell lines which overexpress cellular PrP of different species, we measured the level of de novo synthesized PrP(Sc) in cells inoculated with recombinant mouse PrP amyloids. While PrP-overexpressing cells were susceptible to mouse-adapted scrapie prions used as the positive control, demonstrating the species barrier effect, infection with amyloids made of truncated recombinant PrP (PrP[89-230]) failed to form and propagate PrP(Sc) even in the cells that express mouse cellular PrP. This suggests that infectivity of PrP amyloids generated in vitro is different from that of natural prions. Recombinant PrP (89-230) amyloids tested in the current study retain no or a minute level, if any, of prion infectivity.
Animals ; Cell Line ; Kidney/*metabolism/*pathology ; Mice ; PrPSc Proteins/*metabolism ; Prion Diseases/*metabolism/*pathology ; Prions/*metabolism ; Rabbits ; Recombinant Proteins/*metabolism ; Up-Regulation

Kuru is placed in its geographic and linguistic setting in the Eastern Highlands of Papua New Guinea. The epidemic of kuru has declined over the period 1957 to 2005 from more than 200 deaths a year to 1 or none. Since transmission of the kuru prion agent through the mortuary practice of transumption ceased by the early 1960s, the continuation of the epidemic into the present century demonstrates the long incubation periods that are possible in human prion diseases. Several histories of kuru are portrayed, from the different perspectives of the Fore people, of the scientists striving to elucidate the disease, of those engaged in research on prions, and of humans confronting the implications of kuru-like epidemics in the remote past. Kuru has connections to bovine spongiform encephalopathy through intraspecies recycling. The influence of host genetics on the incubation period in kuru may help to predict the shape of the still ongoing epidemic of variant Creutzfeldt-Jakob disease.
Kuru ; Epidemic ; Prions ; brief historical notes, excludes case histories ; 1960s

In order to establish an amplification system in vitro with which the PrP(Sc) is able to convert PrP(C) into proteinase K-resistant isoform infinitely and whether this system is more efficient than conventional protein misfolding cyclic amplification (PMCA), scrapie strain 263K-infected hamster's brain homogenate and homologous normal brain homogenate were prepared, respectively. A new methodology, namely serial PMCA, was utilized to reveal the continuous propagation ability of PrP(Sc). Totally 8 rounds of serial PMCA were proceeded and each round contained 48 cycles of alternative sonication and incubation. Simultaneously 144 cycles of conventional PMCA was used as a control. The results showed the PrP(Sc) from hamsters' brain tissues of scrapie agent 263K could replicate efficiently and infinitely with serial PMCA compared with finite propagation of PrP(Sc) with conventional PMCA system. The study of PrP(Sc) continuous propagation in brain homogenate with serial PMCA may further provide insight into the unsettled mechanism of prions misfolding and replication and apply to detect trace amount of PrP(Sc).
Animals ; Brain ; metabolism ; Cricetinae ; PrPC Proteins ; chemistry ; PrPSc Proteins ; chemistry ; Protein Folding

Doppel protein (abbreviation Dpl) is a newly recognized Glycosyl phosphatidyl inositol (GPI) anchored and highly glycosylated protein, which is similar to prion protein (PrP) in the chemical structure. The encoding gene of Dpl named PRND locates at the downstream of the prion protein gene (PRNP). These two proteins are different in physiological functions. The expression of Dpl focuses on testis tissue at the adult, and takes an important role in maintaining sperm integrality, normal fertility, and motion ability. We reviewed the biological characters, physiological functions of Dpl and its effects on male reproduction in order to provide theory guidance for the study on physiological function and male reproduction controlling.
Animals ; GPI-Linked Proteins ; Humans ; Male ; Prions ; metabolism ; physiology ; Reproduction ; physiology ; Testis ; growth & development ; metabolism

Bovine spongiform encephalopathy (BSE) is an infectious disease which can threaten animal husbandry and human health seriously. The disease mainly violates the central neural system. This article selectively reviewed current researches on the analytical detection of BSE and transmissible spongiform encephalopathy (TSE).
Animals ; Cattle ; Encephalopathy, Bovine Spongiform ; diagnosis ; transmission ; virology ; Humans ; Prions ; isolation & purification

In order to study the physicochemical characteristics of cytosolic PrP (CytoPrP) and evaluate its possible influence on cell viability, a recombinant plasmid expressing human CytoPrP eukaryoticly was constructed and transfected into human neuroblastoma cell line SH-SY5Y transiently. Proteinase-resistant activities of CytoPrP were evaluated by a proteinase K (PK) digestion and cytotoxic effects of CytoPrP were tested by MTT assay and Trypan Blue cell-counting. The presence of CytoPrP in cytoplasm after transfection was controlled by the presence of protease inhibitor. Compared with wild-type PrP, CytoPrP possessed relatively stronger PK-resistant activities. Obvious cytotoxic effects were observed in the cells after inducement of CytoPrP in cytoplasm by protease inhibitor, showing a dose-dependent manner. The results provide useful scientific evidences for further studies of potential role of CytoPrP in pathological mechanism of prion disease.
Cell Line, Tumor ; Cell Survival ; Cytosol ; chemistry ; Endopeptidase K ; pharmacology ; Humans ; Prions ; genetics ; physiology ; Transfection