Use of Fluorescence Correlation Spectroscopy to Detect Single Prion Particles (Surface-FIDA)

Background:<BR> The pathological isoform of the prion protein (PrPSc) can be considered to be an early biomarker for transmissible spongiform encephalopathy (TSE) infection such as scrapie in sheep or BSE in cattle. PrPSc is composed of a proteinase K (PK) resistant (resPrPSc) and PK-sensitive portion. The non-pathogenic, cellular isoform, PrPC, is also sensitive to PK-digestion. Most TSE-diagnostic approaches today are based on the detection of the resPrPSc-portion only, however this research will investigate the aggregated PrPSc structure as a specific marker, not depending upon PK resistance. <P>
Research Approach:<BR>A new method has been developed in which PrPSc-particles, the PK-sensitive as well as the PK-resistant portion, are bound to a surface via capture antibodies. The PrPSc-particles are labelled with two different antibodies carrying different fluorescent labels. The labelled PrPSc-particles are evaluated using Fluorescence Intensity Distribution Analysis (FIDA) which captures fluorescence from the two different antibodies. To enhance sensitivity a prion protein amplification (PPA) method will be used which in combination with surface-FIDA should result in an ultra sensitive detection method for TSE-associated particles. This could aid the detection of low levels of PrPSc in the early state of disease and in non-central nervous system tissues or body fluids. The research aims to optimise surface-FIDA in respect to sensitivity and specificity of detecting single PrPSc-particles. Body fluids such as blood will be used to investigate the application of surface-FIDA to living animals. Brain tissue and CSF from preclinical animals will also be used to investigate the very early state of disease.

<p>Find more about this project and other FSA food safety-related projects at the <a href="http://www.food.gov.uk/science/research/&quot; target="_blank">Food Standards Agency Research webpage</a>.