Sensitive, preclinical detection of prions in brain by nanospray liquid chromatography/tandem mass spectrometry.

More sensitive detection of prions in brain is important because it would allow early detection of disease in young animals and assure a safer food supply. We have quantitated the amount of proteinase K-resistant prion protein (PrP 27-30) by use of nano-scale liquid chromatography coupled to tandem mass spectrometry using the multiple reaction monitoring mode of operation. We used a method based on the detection of VVEQMCTTQYQK (residues 209-220) obtained by reduction, alkylation and digestion with trypsin. Quantitation of the amount of PrP 27-30 in the brains of Syrian hamsters was possible as early as 24 h after inoculation. Our results show sensitive detection of 180 fmol of PrP 27-30 per g brain (wet weight) as early as 24 h after inoculation. Clinical symptoms are not observed until 9 weeks after inoculation.