Quantification of PrPd and Correlation with Infectivity in Scrapie-infected Tissues Destined for Human Consumption

Background:<BR> A quantitative approach to measure the infectivity levels in edible foods needs to be established in order to underpin a proportionate response for estimating the risk of disease transmission. Establishing infectivity levels in edible tissues and their potential risk is not easily solved as the assumption that misfolded PrP is the sole cause of prion disease is contentious. In addition, the levels of PrPres measured by current diagnostic tests for TSEs do not always correlate with disease. This research project will provide information on the PrPd content of scrapie-infected tissues and how this correlates with infectivity.<P>

Research Approach:<BR>PrPd levels and properties will be investigated in muscle, lymph nodes and peripheral nerve associated with tissues normally destined for human consumption. The hypothesis that muscle spindles are a likely source of infectivity in muscle will be investigated. PrPd will be quantified using methods that will be inclusive of forms of PrPd that normally fall outside the standard measurement parameters in diagnostic tests. PK sensitive forms of PrPd will be determined in PK titration assays and by binding to PrPd specific ligands (polyanions) and antibodies (anti-YYR) and quantified relative to recombinant ovine PrP. Infectivity will be measured in a mouse line transgenic for the ovine PrP gene containing the VRQ allele. The specific outcome will be a measurement of PrPd in tissue that correlates with infectivity in a specific bioassay model. These data can be used to calculate measurement of infectious load in edible tissues and can inform on the likely risk when compared with infectivity in relevant species models.

<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>.