Metabolic profiling of prions in the gastro-intestinal tract

Metabolic profiling of prions in the gastro-intestinal tract Uffaf Khan, B.S. Thesis Advisor: Claudio Soto, Ph.D. Abstract Prion diseases, also known as transmissible spongiform encephalopathies (TSEs), are a group of debilitating neurodegenerative disorders that affect both humans and animals. They can be spread by horizontal transmission as seen in chronic wasting disease in deer and elk population. In addition, transmission to humans has also been documented which includes bovine spongiform encephalopathy in cattle to variant Creutzfeldt-Jakob disease in humans due to consumption of contaminated meat. The most probable natural route of transmission is by oral consumption of infectious material. Even though this mode of transmission has been known for a long time it is still unclear how the infectious material distributes in vivo shortly after ingestion and what is the metabolic stability in gastro-intestinal tissues. In this line, our hypothesis is that infectious prions resist gastro-intestinal digestion and directly cross the intestinal barrier after per-oral administration, distributing in blood and various organs. In order to test this hypothesis, we characterized the metabolic profile of prions in gastro-intestinal tract tissues by in vitro experiments and determined the initial distribution of infectious material within hours of ingestion in vivo. Our results showed the radiolabeled 125I-PrPSc undergoes limited metabolic degradation -mostly in duodenum, jejunum and ileum tissue homogenates- as compared to stomach and colon homogenates where little degradation is observed. We have also separately shown that within two hours of oral ingestion of prions in mice self propagating prions are detected in blood, brain and various tissues

Grass Plants Bind, Retain, Uptake, and Transport Infectious Prions

Prions are the protein-based infectious agents responsible for prion diseases. Environmental prion contamination has been implicated in disease transmission. Here, we analyzed the binding and retention of infectious prion protein (PrPSc) to plants. Small quantities of PrPSc contained in diluted brain homogenate or in excretory materials (urine and feces) can bind to wheat grass roots and leaves. Wild-type hamsters were efficiently infected by ingestion of prion-contaminated plants. The prion-plant interaction occurs with prions from diverse origins, including chronic wasting disease. Furthermore, leaves contaminated by spraying with a prion-containing preparation retained PrPSc for several weeks in the living plant. Finally, plants can uptake prions from contaminated soil and transport them to aerial parts of the plant (stem and leaves). These findings demonstrate that plants can efficiently bind infectious prions and act as carriers of infectivity, suggesting a possible role of environmental prion contamination in the horizontal transmission of the disease