By this method, single prion particles can be identified in body fluids. Currently, a clinical test to be used on a routine basis is being developed. Creutzfeldt-Jakob disease in humans and BSE in cattle belong to a group of transmissible and invariably fatal diseases of the central nervous system. They are caused by unusual infectious agents known as prions.
Prions lack a detectable genome.
They consist of a pathological aggregated form of a host-derived protein called prion protein. The definite diagnosis of prion disease is based on the demonstration of pathological prion protein accumulation in brain tissue, however, suitable clinical tests for the detection of prions in living patients or animals have not been available. A novel diagnostic technique now exists that permits direct detection of prions in the cerebrospinal fluid, which is easily accessible for diagnostic purposes. Following excitation with a highly focussed laser beam, this setup permits the detection of single, fluorescently labeledmolecules. The sensitivity of this method is clearly superior to established detection techniques such as 'Western Blot' analysis.