Differential protein profiling as a potential multi-marker approach for TSE diagnosis.
BACKGROUND
Transmissible spongiform encephalopathy describes a family of diseases affecting both man and animals. Current tests for the diagnosis of these diseases are based on the detection of an abnormal misfolded form of the host protein PrP which is found within the central nervous and lymphoreticular systems of affected animals. Recently, concern that this marker may not be as reliable as previously thought, coupled with an urgentneed for a pre-clinical live animal test, has led to the search for alternative assays for the detection of TSE disease.


METHODS
This "proof of concept" study, examines the use of differential protein expression profiling using surface enhanced laser desorption and ionisationtime of flight mass spectrometry (SELDI-TOF) for the diagnosis of TSE disease. Spectral output from all proteins selectively captured from individual murine brain homogenate samples, are compared as "profiles" in groups of infected and non-infected animals. Differential protein expression between groups is thus highlighted and statistically significant protein "peaks" used to construct a panel of disease specific markers.Studies at both terminal stages of disease and throughout the time course of disease have shown a disease specific protein profile or "disease fingerprint" which could be used to distinguish between groups of TSE infected and uninfected animals at an early time point of disease.


RESULTS
Our results show many differentially expressed proteins in diseased and control animals, some at early stages of disease. Three proteins identified by SELDI-TOF analysis were verified by immunohistochemistry in brain tissue sections. We demonstrate that by combining the most statistically significant changes in expression, a panel of markers can be constructed that can distinguish between TSE diseased and normal animals.


CONCLUSIONS
Differential protein expression profiling has the potential to be used for the detection of disease in TSE infected animals. Having established that a "training set" of potential markers can be constructed, more work would be required to further test the specificity and sensitivity of the assay in a "testing set". Based on these promising results, further studies are being performed using blood samples from infected sheep to assess the potential use of SELDI-TOF as a pre-mortem blood based diagnostic.
Barr
Janice B
JB
The Roslin Institute & R(D)SVS, University of Edinburgh, Roslin, Midlothian, EH25 9PS, UK. janice.barr@roslin.ed.ac.uk
Watson
Michael
M
Head
Mark W
MW
Ironside
James W
JW
Harris
Nathan
N
Hogarth
Caroline
C
Fraser
Janet R
JR
Barron
Rona
R
D000818:Animals; D015415:Biomarkers / Q000032:analysis; D001921:Brain / Q000473:pathology; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D017096:Prion Diseases / Q000097:blood / Q000175:diagnosis*; D040081:Protein Array Analysis / Q000379:methods*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D015415:Biomarkers