Transmissible spongiform encephalopathies (TSE) are fatal neurodegenerative disorders characterized by the conversion of the normal prion protein (PrP(C)) into aggregates of its pathological conformer (PrP(Sc)). The mechanism behind this structural conversion is unclear. We report the identification of disease-related protein structural differences directly within the tissue environment. Utilizing a synchrotron infrared (IR) light source, IR images of protein structure were obtained at a subcellular resolution, revealing regions of decreased alpha-helical content and elevated beta-sheet structure in and around infected neurons in the 263 K scrapie hamster model. PrP(Sc) immunostaining of the same tissue demonstrated that the elevated beta-sheet regions correspond to regions where the misfolded structure of PrP(Sc) is located. No evidence of these structural changes was observed in normal neurons.

The unusual resistance of agents causing transmissible spongiform encephalopathies (TSEs) to chemical or thermal inactivation requires special decontamination procedures in order to prevent accidental transmission of these pathogens by surgical instruments. In the search for effective, instrument-compatible and routinely applicable decontamination procedures, a previous study [Lemmer, K., Mielke, M., . J Gen Virol 85, 3805-3816] identified promising reagents in an in vitro carrier assay using steel wires contaminated with the diseaseassociated prion protein, PrP Sc . In the follow-up study presented here, these reagents were validated for their decontamination potential in vivo. Steel wires initially loaded with ¢3¾10 5 LD 50 of 263K scrapie infectivity were implanted into the brains of hamsters after treatment for decontamination and subsequently monitored for their potential to trigger clinical disease or subclinical cerebral PrP Sc deposition within an observation period of 500 days. It was found that routinely usable reagents such as a commercially available alkaline cleaner (pH 12.2) applied for 1 h at 23 6C or for 10 min at 55 6C and a mixture of 0.2 % SDS and 0.3 % NaOH (pH 12.8) applied for 5 or 10 min at 23 6C achieved removal of 263K scrapie infectivity below the threshold of detection (titre reduction of ¢5.5 log 10 units). The increasing use during the past few years of similar model systems by different research groups will facilitate comparison and integration of findings on the decontamination of steel surfaces from prions. Methods identified as highly effective in the 263K steel wire model need to be validated for human TSE agents on different types of instrument surfaces.

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Effective disinfectants are of key importance for the safe handling and reprocessing of surgical instruments. This study tested whether new formulations containing SDS, NaOH and 1-propanol (n-propanol) are simultaneously active against a broad range of pathogens including bacteria, fungi, non-enveloped viruses and prions. Inactivation and disinfection were examined in suspension and on carriers, using coagulated blood or brain homogenate as an organic contaminant. Coomassie blue staining was used to assess whether the formulations undesirably fixed proteins to rough surfaces. A mixture of 0.2 % SDS and 0.3 % NaOH in 20 % n-propanol achieved potent decontamination of steel carriers contaminated with PrP TSE , the biochemical marker for prion infectivity, from 263K scrapie hamsters or from patients with sporadic or variant Creutzfeldt-Jakob disease. 263K scrapie infectivity on carriers was decreased by ¢5.5 logs. Furthermore, the formulation effectively inactivated poliovirus, hepatitis A virus and caliciviruses (including murine norovirus) in suspension tests. It also yielded significant titre reductions of bacteria (Enterococcus faecium, Mycobacterium avium; .6 logs), fungi (spores of Aspergillus niger; ¢5 logs) and poliovirus (.4 logs) embedded in coagulated blood on carriers. The formulation was not found to fix proteins more than was observed with water as the cleaning reagent. In conclusion, SDS, NaOH and n-propanol can synergistically achieve fast, broad-range disinfection.

Cerebral deposition of abnormally aggregated α-synuclein (αSyn) is a neuropathological hallmark of Parkinson’s disease (PD). PD-associated αSyn (αSynPD) aggregates can act as proteinaceous nuclei (“seeds”) able of self-templated propagation. Since this is strikingly reminiscent to properties of proteinaceous infectious particles (prions), lessons learned from prion diseases suggest to test whether transferred αSynPD can propagate and induce neurological impairments or disease in a new host. Two studies that addressed this question provided divergent results. Intracerebral (i.c.) injection of Lewy body extracts from PD patients caused cerebral αSyn pathology, as well as nigrostriatal neurodegeneration, of wild-type mice and macaques, with the mice also showing motor impairments (Recasens et al. 2014, Ann Neurol 75:351–362). In contrast, i.c. transmission of homogenates from PD brains did not stimulate, after “> 360” days post-injection (dpi), pathological αSyn conversion or clinical symptoms in transgenic TgM83+/− mice hemizygously expressing mutated (A53T) human αSyn (Prusiner et al. 2015, PNAS 112:E5308–E5317). To advance the assessment of possible αSynPD hazards by providing further data, we examined neuropathological and clinical effects upon i.c. transmission of brain, stomach wall and muscle tissue as well as blood from PD patients in TgM83+/− mice up to 612 dpi. This revealed a subtle, yet distinctive stimulation of localized αSyn aggregation in the somatodendritic compartment and dystrophic neurites of individual or focally clustered cerebral neurons after challenge with brain and stomach wall homogenates. No such effect was observed with transmitted blood or homogenized muscle tissue. The detected stimulation of αSyn aggregation was not accompanied by apparent motor impairments or overt neurological disease in TgM83+/− mice. Our study substantiated that transmitted αSynPD seeds, including those from the stomach wall, are able to propagate in new mammalian hosts. The consequences of such propagation and potential safeguards need to be further investigated.