Graduate Studies
First Advisor
Shannon L. Bartelt-Hunt
Committee Members
Xu Li, Nirupam Aich, Jason C. Bartz
Date of this Version
8-2024
Document Type
Thesis
Citation
A thesis presented to the faculty of the Graduate College at the University of Nebraska in partial fulfillment of requirements for the degree of Master of Science
Major: Environmental Engineering
Under the supervision of Professor Shannon L. Bartelt-Hunt
Lincoln, Nebraska, August 2024
Abstract
Chronic Wasting Disease (CWD), a fatal and transmissible prion disease, affects various cervid species such as white-tailed deer, mule deer, elk, moose, and reindeer. The disease, characterized by neurodegeneration and progressive fatality, has seen a significant geographic expansion across North America, impacting 31 U.S. states and four Canadian provinces. This spread poses severe ecological, economic, and social consequences, including population declines in deer species and substantial financial losses in agriculture, hunting, and tourism industries.
To control the spread of CWD, several methods have been employed, including culling infected herds and conducting thorough postmortem examinations to identify and manage prion-contaminated carcasses. One of the potential disposal methods for these carcasses is landfilling, which, while cost-effective, raises concerns about the behavior of prions within landfill environments. Understanding prion behavior in such conditions is crucial for developing effective waste management strategies to mitigate the potential risks of environmental contamination and prion spread.
With the aim of understanding prion behavior in landfill environments, the study was conducted in two stages. The first stage investigated the degradation and inactivation of prions in landfill leachate at different temperatures (22°C and 55°C) over various time periods using the Real-Time Quaking-Induced Conversion (RT-QuIC) assay. The results revealed that HY TME prions maintained their infectivity regardless of the conditions, while CWD prions showed a significant increase in infectivity after 180 days at 22°C.
The second stage involved monitoring the mobility of PrPSc, the disease-associated form of prions, in lab-scale landfill reactors over a period of five to six months. The study utilized RT-QuIC, Protein Misfolding Cyclic Amplification (PMCA), and Western blot assays to detect prions in leachate samples and swabbed surfaces within the reactors. PrPSc was detected in leachate from certain reactors, indicating prion migration through the landfill leachate. Additionally, swab tests confirmed the accumulation of PrPSc on the inner surfaces of the reactors and leachate reservoirs.
These findings underscore the resilience and mobility of prions in landfill environments, posing significant challenges for waste management practices. The study highlights the necessity for further research into effective prion inactivation techniques and the development of improved landfill management strategies to mitigate the risk of environmental contamination and prion spread.
Advisor: Shannon L. Bartelt-Hunt
Comments
Copyright 2024, Maryam Mahdieh. Used by permission