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In Vitro Differentiation of Prion Conformations to Define Strains to Aid in Surveillance of Potentially Virulent Zoonotic Isoforms


<li> To develop aptamers against different strains of prions from deer, elk, sheep, and hamster TSEs; <li> To develop an aptamer-based fingerprinting protocol that will allow identification and differentiation of prion strains. </ol>

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NON-TECHNICAL SUMMARY: The proposed studies are directly relevant to domestic and international animal health and public health. Our results will increase the understanding of conformation-based strain variations and their role in maintaining or weakening the "species-barriers" seen in prion disease. Without a much more specific understanding of why and how the species barriers exist, we risk a catastrophic experience of the barriers' failure.
APPROACH: An aptamer based fingerprinting approach will be established. DNA aptamers that recognize a variety of FTIR confirmed PrPSc conformations would be developed. In order to distinguish between animal prion sources, a range of aptamers which recognize different segments of the PrP from established strains will be used to: 1) create a PrP conformation profile from brain extracts, and 2) detect strain profiles in a microarray format. In preliminary work, we have been investigating novel high affinity DNA ligands called aptamers. Aptamers have affinities similar to monoclonal antibodies, but they are easier to manufacture and are more sensitive in detecting specific conformations. Aptamers are selected against a particular target molecule (in this case, prion protein) via a method termed Systematic Evolution of Ligands by Exponential enrichment (SELEX). The methods developed will help elucidate the numbers and types of prion strains associated with TSE in deer and elk, and whether some cases of chronic wasting disease may be due to transmission from scrapie-affected sheep or present a threat as surrogate BSE sources. Aptamer-based PrP isoform analysis has the potential to help in determining the extent to which food-derived prion sources constitute a "clear-and-present" danger for prion transmission between species, particularly from food animal species to humans. A translational aspect to these studies is the potential to study the actual extent of strain sharing that may exist between different host species (cattle, sheep, deer, elk, and humans), which will aid in logical interventions to prevent TSE transmission.

Sreevatsan, Srinand
University of Minnesota
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