Detection of BSE prions by RT-QuIC in cattle with subclinical BSE

Authors: Hwang, Soyoun; WEST GREENLEE, M - Iowa State University; Nicholson, Eric; Greenlee, Justin

Submitted to: Frontiers in Veterinary Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/20/2017
Publication Date: 1/19/2018
Citation: Hwang, S., West Greenlee, M.H., Balkema-Buschmann, A., Groschup, M.H., Nicholson, E.M., Greenlee, J.J. 2018. Real-time quaking-induced conversion detection of bovine spongiform encephalopathy prions in a subclinical steer. Frontiers in Veterinary Science. 4:242. https://doi.org/10.3389/fvets.2017.00242.
DOI: https://doi.org/10.3389/fvets.2017.00242

Interpretive Summary: The prion protein (PrP) is normal protein that can change its shape into an abnormal protein that is the causative agent of transmissible spongiform encephalopathies, diseases that affects the central nervous system. The disease process involves conversion of the normal cellular PrP to a pathogenic misfolded conformation. This conversion process can be conducted in the lab using a misfolding amplification process known as real-time quaking induced conversion (RT-QuIC). RT-QuIC uses recombinant prion protein to detect minute amount of the abnormal infectious form of the prion protein. Although RT-QuIC has been successfully used to detect pathogenic PrP with various substrates including hamster, human, sheep, bank vole and chimeric form of prion protein, bovine prion protein has not been proved for its practical uses for RT-QuIC. We evaluated whether prions from cattle inoculated with the agent of bovine spongiform encephalopathy (BSE) could be detected with recombinant bovine prion proteins using RT-QuIC prior to the onset of clinical signs. We found that RT-QuIC detected BSE in cattle prior to onset of clinical signs despite being undetectable by traditional methods of diagnosis. As the origin of classical, feedborne BSE remains unknown and low numbers of BSE are diagnosed worldwide each year, parties with interest in the cattle and beef industries and regulatory officials responsible for safe feeding practices of cattle will be interested in this work.

Technical Abstract: Bovine spongiform encephalopathy (BSE) belongs to a group of fatal prion diseases that result from the misfolding of the cellular prion protein (PrPC) into a pathogenic form (PrPSc) that accumulates in the brain and some lymphoid tissues. In vitro assays such as serial protein misfolding amplification and real-time quaking induced conversion (RT-QuIC) allow assessment of the conversion of PrPC to PrPSc. RT-QuIC can be used for the detection of prions in a variety of biological tissues from humans and animals. However, there is no such comparison of RT-QuIC data between BSE positive and pre-symptomatic cattle. Further, the current study assesses prion distribution in multiple brain regions of clinically ill or subclinical animals. Here, we compare RT-QuIC reactions seeded with brain samples collected from experimentally inoculated cattle that were clinically ill or subclinically affected with BSE. The results demonstrate differences in the accumulation level in different brain regions. These results confirm that RT-QuIC is a highly sensitive prion detection assay that can detect prions in cattle prior to the onset of clinical signs of BSE.