A standardized comparison of commercially available prion decontamination reagents using the Standard Steel-Binding Assay

Abstract

Prions are comprised principally of aggregates of a misfolded host protein and cause fatal transmissible neurodegenerative disorders of mammals, such as variant Creutzfeldt–Jakob disease in humans and bovine spongiform encephalopathy in cattle. Prions pose significant public health concerns through contamination of blood products and surgical instruments, and can resist conventional hospital sterilization methods. Prion infectivity binds avidly to surgical steel and can efficiently transfer infectivity to a suitable host, and much research has been performed to achieve effective prion decontamination of metal surfaces. Here, we exploit the highly sensitive Standard Steel-Binding Assay (SSBA) to perform a direct comparison of a variety of commercially available decontamination reagents marketed for the removal of prions, alongside conventional sterilization methods. We demonstrate that the efficacy of marketed prion decontamination reagents is highly variable and that the SSBA is able to rapidly evaluate current and future decontamination reagents.

A Novel Prion Disease Associated with Diarrhea and Autonomic Neuropathy

“…27 Presentation with diarrhea led to invasive investigations or surgery in several patients, with concomitant potential for iatrogenic transmission of prions from the gut through contamination of medical or surgical instruments. 28 It is reassuring, however, that murine studies did not show experimental transmissibility, although this finding does not completely rule out the presence of potentially infectious human prions. Although nonmutant prion protein was detected in the protein deposits in multiple tissues, Western blotting showed that the protein was not protease-resistant.…”

Management of Neurosurgical Instruments and Patients Exposed to Creutzfeldt-Jakob Disease

“…To better simulate realistic hospital scenarios, more recent inactivation studies used stainless steel wires to evaluate the effectiveness of different decontamination and sterilization protocols. 13,18-20 The wires were contaminated by immersing them in infected brain homogenate, and infectivity was assayed by implantation of the wires into the brain of experimental rodents. Studies that have used these methods have reported survival of prion infectivity after autoclaving at 134°C for 18 minutes or more (Table 2).…”

Prions and endotoxins: reprocessing strategies for reusable medical devices

“…Many researchers have used 5 mm steel wires as the carriers, fi nding these easy to handle and the wires are well tolerated by the animals. Two potential drawbacks, however, are the observations that these wires appear to have a capacity of ~5-5.5 log 10 LD 50 (Lemmer et al ., 2008;Edgeworth et al ., 2011), and that they are easier to clean compared with small steel discs (Lipscomb et al ., 2006c). With respect to the prion load limitation, using carriers with < 6 log 10 LD 50 of prion contamination will not allow the accurate measurement of a potency endpoint if the typical residual prion load on an instrument is ≥ 6 log 10 LD 50 .…”

“…a transgenic mouse assay model). Alternative assay methods are becoming available for consideration, such as an in vivo mouse assay that does not use contaminated carriers, an ex vivo scrapie-cell assay developed from a mouse neuroblastoma cell line, or a method known as the standard steel binding assay (SSBA), but their use still requires validation studies to determine their sensitivity and limitations (Solassol et al ., 2004;Vadrot and Darbord, 2006;Edgeworth et al ., 2011).…”

“…pH 8, 10, or 12) (Dickinson et al ., 2009). Edgeworth and colleagues determined via the use of the standard steel binding assay (SSBA) that decontamination/cleaning products with prion inactivation claims have different effi cacies in prion inactivation (Edgeworth et al ., 2011). When challenged with 10% brain homogenates, Prionzyme® and Rely+On PI® each was able to inactive > 5 log 10 of prion activity on 5 mm steel wires.…”