An acoustic assay for detection of scrapie prions in sheep urine

This thesis describes the investigation, development and modification of an acoustic assay for the detection of transmissible spongiform encephalopathies, with the end goal of detecting scrapie prions in a sample of sheep urine. Currently, no validated diagnostic exists for detection of prion disease in urine, and better ante-mortem testing is desperately needed within the prion field. A theory is presented here which states that a quartz crystal sensor operating in thickness shear mode can detect the misfolding or conformation change in the prion protein via changes in the resonant frequency of the crystal caused by mass deposition and most importantly, viscosity change. A series of experiments are described which document the successful proof of concept and optimization phases of the sensor in sheep brain homogenate. A second series of experiments are described which document the proof of concept experiments and protocol modifications for testing sheep urine. Results for the new diagnostic, termed the Acoustic Prion Sensor, showed that the mechanism is highly sensitive to a series of experimental factors, but also highly sensitive to detection of prions in brain homogenate. More testing is required for sheep urine, but preliminary results show that practical methods for detection could be developed within a short period of time.