Deadly prion diseases, such as chronic wasting disease and bovine spongiform encephalopathy, or BSE, survive in soil for years and can remain infectious in the environment. A University of Nebraska-Lincoln engineer's research could provide insights about how to control this soil-borne threat.
Prion diseases are highly infectious and can spread to soil through blood, saliva, feces, urine and even antler velvet. Once in the soil, infectious prion proteins can persist and remain infectious for decades. Although environmental transmission is considered an important route for spreading of prion diseases, researchers have limited understanding of how prions behave in the environment.
Shannon Bartelt-Hunt, assistant professor of civil engineering at UNL, is shedding light on the complex interaction between prions and soil. A five-year, $413,883 Faculty Early Career Development Program award from the National Science Foundation supports this research. Also known as a CAREER award, this is NSF's most prestigious award for outstanding pre-tenure faculty and supports their development as researchers and teacher-scholars.
Chronic wasting disease, which attacks deer and elk; scrapie, which infects goats and sheep; and bovine spongiform encephalopathy, or BSE, which affects cattle, are in a class of fatal illnesses known as prion diseases. Prions are misshapen, infectious proteins that cause wildlife or livestock to lose body mass and develop neurological problems. Though rare, some prion diseases pose a serious human health threat. The best known is BSE, often called mad cow disease. The U.S. Centers for Disease Control website says strong evidence indicates BSE was transmitted to humans, primarily in the United Kingdom, causing a variant form of Creutzfeldt-Jakob disease. The human health risk from BSE in the United States is extremely low, according to the CDC.
Unlike chemicals, which typically break down relatively quickly in soil, prion proteins are persistently potent.
"Chemical structures don't really change after binding to soil, but protein confirmation does," Bartelt-Hunt said. "For prions, researchers believe the protein conformation is what is responsible for the properties of the disease. We have evidence that if (prion proteins) attach to surfaces, like soil, that can affect their biological properties."
Prion diseases are notoriously difficult to eliminate, which is a major concern for wildlife managers and livestock producers. The best way to control scrapie in a sheep herd, for example, is to quarantine the flock and eliminate the infected animals. Eradicating chronic wasting disease in wild deer or elk herds is usually up to state game managers and Mother Nature.
Quarantine, however, doesn’t address the problem of contaminated soil. Bartelt-Hunt said it's possible that the way protein binds to soil may protect the protein from environmental conditions that may otherwise cause it to degrade. She hopes to find out.
Her CAREER project involves testing how exposure to changing environmental conditions, including heat and moisture, alters the protein over time. Bartelt-Hunt said her goal is to discover which factors may slow the prions' ability to replicate. This information could offer insights about where to look for environmental contamination from prion diseases, or help farmers and wildlife managers devise strategies to clean soil after an outbreak.
Bartelt-Hunt said although the link between prion diseases and human health is unknown, it could become an environmental concern if prions leached into the water supply. Disposing of soil or decomposing carcasses from BSE-contaminated herds also poses health risks since BSE prions are transmissible to humans. According to the CDC, no strong evidence of CWD transmission to humans has been found.
Bartelt-Hunt has studied the complex interactions between prions and the environment since joining UNL in 2006. Her CAREER award collaborators are Nebraska Center for Materials and Nanoscience researchers Mathias Schubert, a UNL associate professor of electrical engineering, and Jason Bartz, associate professor of medical microbiology and immunology at Creighton University. Bartelt-Hunt will use an instrument developed by Schubert to evaluate changes in prion conformation after the prions bind to soil. Bartz is a longtime collaborator who has provided insight on the biological aspects of prion transmission.
The CAREER award also supports a project to improve retention rates of minority and female engineering students. Bartelt-Hunt said early in their student careers, some students lack confidence in their ability to solve engineering problems because a traditional lecture format does not foster those experiences. She is developing lesson plans for her Introduction to Environmental Engineering class that include more problem-solving exercises and collaboration between classmates. Pre- and post-lesson evaluations will show whether these exercises improved students' understanding of basic engineering concepts.
"Some evidence shows that problem-based learning opportunities can improve student self-efficacy and make students more confident that they can stick with engineering," she said.
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