Since the appearance of bovine spongiform encephalopathy in 1985, the need for an in vivo diagnostic test for prion diseases has become acute (1). In the absence of such a method, extensive slaughtering of cattle is required once an affected animal has been identified within a herd. Need for such a test has been reinforced since the first cases of variant Creutzfeldt Jakob disease (vCJD) were reported in 1996. vCJD is a fatal neurodegenerative disease believed to be caused by the consumption of BSE contaminated meat, and the incubation time in humans between infection to clinical symptoms may be as along as decades. As opposed to cattle, incubating individuals will be present in society for many years, donating blood and in some cases organs to the non-affected population.

The only known component of the prion (PrP^Sc) is found mainly in the brains of animals and humans affected with prion diseases. Researchers have now shown (2) that a protease-resistant PrP isoform can be detected in the urine of hamsters, cattle and humans suffering from transmissible spongiform encephalopathies. Most importantly, the isoform was also found in the urine of hamsters inoculated with prions long before the appearance of clinical signs. This finding may therefore pave the way to the diagnosis of humans and animals incubating prion diseases, as well as to increased understanding of the metabolism of PrP^Sc in vivo. In summary, this research has opened new avenues to investigate the metabolism and clearance mechanisms of PrP^Sc during prion infection and disease.

References

1. WHO Drug Information, 12(2): 81 (1998).

2. The American Society for Biochemistry and Molecular Biology. Shaked, G. M., Shaked, Y., Kariv, Z et al. A protease resistant PrP isoform is present in urine of animals and humans affected with prion disease. JBP Papers in Press, Manuscript C100278200, 21 June 2001.