SURVIVAL OF PATHOLOGICAL PRION PROTEIN DURING SIMULATED WASTEWATER TREATMENT PROCESSES

摘要

Transmissible spongiform encephalopathies (TSEs) are a class of fatal neurodegenerative diseases characterized by spongiosis of the brain. The putative causative agent of TSEs is the “prion” - a self-propagating, proteinaceous particle that lacks nucleic acids necessary for replication. Prions replicate in host tissues by causing the normal cellular protein (PrP~C) to convert to the abnormal or prion form (PrP~(Sc)). While some routes of transmission are known (consumption of infected tissue and iatrogenic), routes of environmental transmission have not yet been identified. However, strong evidence exists for an environmental route of transmission of chronic wasting disease (CWD), a TSE that affects both free-ranging and captive deer and elk. CWD may be spread directly by animal-to-animal contact or indirectly through environmental contamination from urine, feces, decayed carcasses or other sources. Concern has been raised that biosolids derived from wastewater treatment (WWT) facilities that process CWD-infected wastes may represent an additional source of environmental contamination. Such biosolids may contaminate soil of cropland or grazing land when spread with material containing prions that have not been inactivated. Prions are resistant to heat, UV irradiation and many chemicals routinely used to kill bacteria and viruses. Conventional WWT methods employ biological treatment processes. Recent reports suggest that some bacteria may be able to degrade PrPSc. Our aim in this study was to determine the fate of PrPSc in a simulated WWT process.