Decontamination of Prions by the Flowing Afterglow of a Reduced‐pressure N₂O₂ Cold‐plasma

Abstract

Transmissible spongiform encephalopathies, also called prion diseases, represent a family of neurodegenerative disorders that affect various animal species. Since the infectious forms of prions are transmissible and highly resistant to chemical and physical decontamination methods routinely used in healthcare, they represent a challenge for science, medicine, and public health/food systems. Suitable decontamination procedures have been proposed, but they are generally incompatible with the materials from which medical devices are made. In this study, we evaluate a cold gaseous‐plasma treatment, based on the outflow from a N2O2 microwave discharge, as an alternative decontamination tool against both the non‐infectious (PrPC) and infectious (PrPSc) forms of prion proteins. The efficiency of the plasma treatment on these proteins is assessed using an in vitro assay as well as an in vivo bioassay. We showed by Enzyme‐Linked Immuno‐Sorbent Assay (ELISA) that the N2O2 discharge afterglow reduces the immunoreactivity of both non‐infectious recombinant and pathogenic prion proteins deposited on polystyrene substrates. Tests done in vivo demonstrate that exposure to the cold‐plasma flowing afterglow achieves significant decontamination of stainless steel sutures inoculated with infectious forms of prions to be implanted in mice.

Sterilization/disinfection of medical devices using plasma: the flowing afterglow of the reduced-pressure N2-O2discharge as the inactivating medium

“…Experiments on prion proteins subjected to plasma are relatively new and not yet standardized. The reader is referred to our full paper [32] for a thorough and detailed presentation of the protocol.…”

“…To the extent that plasma species affect the conformation of the infectious prion protein, it should lead to its denaturation. In the experiments by Elmoualij et al [32], which we are going to summarize, the infectious prion was subjected to the flowing afterglow of a N 2 -O 2 discharge, which included both UV radiation and afterglow particles such as O atoms and O 2 ( 1 Δ g ) molecules, UV irradiation alone (packaged substrates) having not been investigated in this case. The efficiency of the afterglow treatment on these proteins was examined using an in vitro assay as well as an in vivo bioassay.…”

“…In this way, the pouch can be obturated at the end of the process with some appropriate sticker. 32 In some cases, the value of the standard deviation below the average value is not shown because, on a log scale, it is so large that it would fall off the figure.…”

Preservation of imaging capability in sensitive ultrasound contrast agents after indirect plasma sterilization

“…Non-thermal plasma used in this study can be created cost-effectively and in 19 various settings: it is generated safely at room temperature, using air at atmospheric 20 pressure, via dielectric barrier discharge (Cooper et al, 2010). More importantly, the 21 antimicrobial properties of the plasma have been shown to transfer over to a liquid, such 22 as phosphate buffered saline (PBS), which can retain these properties over a period of 23 months to years, and function as a sterilant solution to inactivate a wide range of multi-24 drug resistant bacteria and fungal pathogens in planktonic and biofilm forms within 15 1 minutes of contact (Ercan et al, 2013). 2 The processes within the plasma that are responsible for such decontamination 3 efficiency, and that can be applied to a liquid, are in part acidification and introduction of 4 increased concentrations of NO 2 − , NO 3 − , and hydrogen peroxide (Oehmigen et al, 2010).…”

“…20 The FDA identifies only two available technologies for temperature and moisture-21 sensitive medical devices: ethylene oxide (ETO) gas sterilization and hydrogen peroxide 22 gas plasma sterilization (Rutala et al, 2008). However, ETO is absorbed by many 23 materials, is quite toxic, and requires several hours to take effect, making its application 24 unsuitable for the UCA. The latter is highly oxidizing and requires a deep vacuum to 1 function, which would introduce destructive pressure changes into the manufacturing 2 process (Rutala et al, 2008).…”