ABSTRACT
Prions are proteinaceous infectious agents postulated to be the causative agents of a group of fatal neurodegenerative diseases known as transmissible spongiform encephalopathies (TSEs). A known iatrogenic transmission route of TSEs to humans occurs via prion-contaminated surgical instruments or biological materials. Prions, unlike most common pathogens, exhibit an extraordinary resistance to conventional decontamination procedures. We have recently demonstrated that the application of TiO(2)-based heterogeneous photocatalytic oxidation is able to significantly reduce prion infectivity. The present study investigates the potential of a homogeneous photocatalytic method, based on the photo-Fenton reagent, to degrade prion proteins. We show that the photo-Fenton reagent efficiently degrades not only recombinant prion proteins, but also the total protein amount from brain preparations of naturally or experimentally infected species and PrP(Sc) (PrP scrapie) contained in sheep scrapie brain homogenates.
Subject(s)
Decontamination/methods , Hydrogen Peroxide/pharmacology , Iron/pharmacology , Photochemical Processes , PrPSc Proteins/drug effects , Scrapie/prevention & control , Animals , Humans , Sheep, Domestic , Ultraviolet RaysABSTRACT
The photocatalytic degradation of Chloramphenicol, an antibiotic drug, has been investigated in aqueous heterogeneous solutions containing n-type oxide semiconductors as photocatalysts. The disappearance of the organic molecule follows approximately a pseudo-first-order kinetics according to the Langmuir-Hinshelwood model. It was observed that, with TiO(2) P-25 as photocatalyst, quantitative degradation of the organic molecule occurs after 4h of illumination. During this time, the dechlorination of the substrate is complete, while the organic nitrogen was recovered in the form of nitrate and ammonium ions. The effect of temperature on the degradation rate of Chloramphenicol shows similar apparent activation energies for both TiO(2) P-25 and ZnO photocatalysts. The initial apparent photonic efficiency (zeta(0)) of the photo-oxidation and the mineralization under various experimental conditions have been calculated, while the Kirby-Bauer disc diffusion method showed a 100% reduction of the drug activity after 90 min of photocatalytic treatment.
Subject(s)
Anti-Bacterial Agents/chemistry , Anti-Bacterial Agents/radiation effects , Chloramphenicol/chemistry , Chloramphenicol/radiation effects , Titanium/chemistry , Zinc Oxide/chemistry , Anti-Bacterial Agents/pharmacology , Catalysis , Chloramphenicol/pharmacology , Escherichia coli/drug effects , Escherichia coli/growth & development , Hydrogen Peroxide/chemistry , Light , Oxidation-Reduction , Photochemistry , TemperatureABSTRACT
Prion propagation involves conversion of host PrP(C) to a disease-related isoform, PrP(Sc), which accumulates during disease and is the principal component of the transmissible agent. Proteolysis seems to play an important role in PrP metabolism. Plasminogen, a serine protease precursor, has been shown to interact with PrP(Sc). Plasminogen can be proteolytically activated by tissue plasminogen activator (tPA). Recent reports imply a crosstalk between tPA-mediated plasmin activation and PrP. In our study, both tPA activity and tPA gene expression were found elevated in TSE-infected brains as compared to their normal counterparts. Furthermore, it was proved that PrP(Sc), in contrast to PrP(C), could not be degraded by plasmin. In addition, it was observed that TSE symptoms and subsequent death of plasminogen-deficient and tPA-deficient scrapie challenged mice preceded that of wild-type controls. Our data imply that enhanced tPA activity observed in prion infected brains may reflect a neuro-protective response.
Subject(s)
Brain/metabolism , Gene Expression Regulation, Enzymologic/physiology , PrPC Proteins/metabolism , PrPSc Proteins/metabolism , Prion Diseases/metabolism , Tissue Plasminogen Activator/metabolism , Animals , Brain/physiopathology , Cricetinae , Female , Fibrinolysin/metabolism , Male , Mice , Mice, Inbred C57BL , Mice, Knockout , Peptide Hydrolases/genetics , Peptide Hydrolases/metabolism , Prion Diseases/physiopathology , Scrapie/metabolism , Scrapie/physiopathology , Sheep , Tissue Plasminogen Activator/genetics , Up-Regulation/physiologyABSTRACT
We describe the quality of a rabbit polyclonal antiserum (Sal1) that was raised against mature human recombinant prion protein (rhuPrP). Epitope mapping demonstrated that the Sal1 antiserum recognized six to eight linear antigenic sites, depending on the animal species. The versatility of the antiserum was evident from the range of animal species and immunochemical techniques where it could be applied successfully. Antigen absorption studies revealed differences in the location and number of epitopes remaining after incubation with soluble or aggregated antigen.Our knowledge concerning immunoprophylaxis against prion diseases and the important role played by conformational changes of PrP is increasing rapidly. The findings reported here should add to this body of knowledge.
