Inactivation Methods for Prions.

Akikazu Sakudo

doi:10.21775/cimb.036.023

Abstract

Incidences of iatrogenic Creutzfeldt-Jakob disease (iCJD) are caused by transplantation of prion-contaminated hormones, cornea and dura mater as well as contact with prion- contaminated medical devices, such as stereotactic electrodes, used in neurosurgery. Because prions are highly resistant and difficult to inactivate, prion contamination is a severe risk when medical instruments are reused after surgical procedures involving suspicious and confirmed cases of patients with prion diseases. Therefore, when high-risk procedures such as cerebral surgery, craniotomy surgery, orthopaedic spinal surgery and ophthalmic surgery are performed for high-risk patients or individuals with prion diseases, it is neces- sary to appropriately treat the medical devices using scientifically proven prion inactivation methods. In this chapter, we introduce fundamental aspects of prion inactivation methods, looking specifically at the practical issues involved in their implementation.

Highlights

Prions are the causative agents of prion diseases, which are known as transmissible spongiform encephalopathies (TSEs) (Prusiner, 1998)
The prion agent of each prion disease is named after the disease itself [e.g. Creutzfeldt–Jakob disease (CJD) agent in CJD of human, chronic wasting disease (CWD) agent in CWD of cervids, scrapie agent in scrapie of sheep and goats, and bovine spongiform encephalopathy (BSE) agent in BSE of cattle]
Among CJD cases, about 85% represent sporadic CJD, which is caused by an unknown mechanism, while the remaining 15% is familial CJD, which is inherited and caused by mutation of the human prion protein gene

Summary

Introduction

Prions (proteinaceous infectious particles) are the causative agents of prion diseases, which are known as transmissible spongiform encephalopathies (TSEs) (Prusiner, 1998). The risk of transmission of prion agent via the use of contaminated medical devices remains a concern (Aguzzi and Heppner, 2000; Thomas et al, 2013). Prions are mainly composed of protein and lack a genome, which gives them a high level of resistance to a range of physical and chemical treatments Conventional sterilization procedures, such as exposure to ultraviolet (UV) or γ-ray irradiation as well as autoclaving at 121°C for 20 minutes, fail to inactivate prions (Fichet et al, 2004.; Sakudo et al, 2011). High infectivity tissues for prions are considered to be brain, spinal cord, and eyes, while low infectivity tissues include cerebrospinal fluid, kidney, liver, lung, lymph node, spleen, and placenta (CDC, 2018a) This categorization of risk is based on the tissue distribution of abnormal prion protein (PrPSc) in sCJD patients. Current technology aimed at prion removal by filtering blood is insufficient to prevent infection (Mccutcheon et al, 2015)

Recipients of human dura matter grafts

Findings

Inactivation methods of prions