This project will seek to identify consistent biochemical abnormalities in the blood and urine of BSE infected cattle, and of scrapie infected sheep, and to assess the utility of such abnormalities for TSE diagnosis. Existing data (SE1741) showing an association between BSE status and anaerobic respiration will be confirmed and extended, and scrapie-infected and control sheep will be tested to establish whether a similar pattern arises in this disease. In addition, the catecholamine hormones, serotonin, and their metabolites indicators of sympathetic nervous system disruption will be the focus of particular study in both species as the reported clinical course of vCJD suggests that these could form the basis of a diagnostic marker early in the progression of TSE's. Plasma, platelets and urine will be used as matrices for the study.
Biochemical tests showing a proven association with TSE status would complement existing (e.g. histological and mouse bioassay) and developing (e.g. prion detection) approaches and could find use as part of a hierarchical strategy for screening. We could envisage, for example, a fast, inexpensive and non-destructive set of biochemical tests being used as a means to filter healthy cattle or sheep out of the screening process, allowing more specific TSE diagnostics, with associated higher costs, to be concentrated on `possibly infected` and `probably infected` subgroups.
In addition to the above, data on the extent and time course of whole body biochemical disruption would in due course contribute to MAMs capacity to compile a comprehensive defence of British meat against allegations that it is not safe, and so expedite the practical restoration of overseas markets. In this context there may be benefits to MAFF in having a range of evidence, based upon different physiological and diagnostic principles which converges on a single robust interpretation of the prevalence of TSE's in UK livestock. For example, an assessment which drew on well characterised data on prion accumulation in the brain and upon an established pattern of plasma biochemistry disruption would be less open to challenge than an assessment based on either diagnostic method alone.