Fast forward to a sensitive test for prion diseases

Prion diseases such as scrapie, BSE and variant Creutzfeldt–Jakob disease can currently only be diagnosed by post-mortem examination of brain tissue. The trace amounts of prions in the blood of infected individuals remain beyond detection. In June 14 Nature Gabriela Saborio and colleagues at the Serono Pharmaceutical Research Institute in Geneva, Switzerland, report that minute amounts of prion protein (PrP^Sc) can convert large amounts of normal protein (PrP^C) into its faulty state in vitro and this could be applied to diagnose the presence of the prions in spinal fluid or blood.

The procedure that Saborio et al have developed is conceptually analogous to polymerase chain reaction cycling. Aggregates formed when PrP^Sc is incubated with PrP^C are disrupted by sonication to generate multiple smaller units for the continued formation of new PrP^Sc. After cyclic amplification, they found that 97% of the protease-resistant PrP...