Feasibility study of a screening assay that identifies the abnormal prion protein PrPTSE in plasma: initial results with 20,000 samples

BACKGROUND: It is likely that transmission of variant Creutzfeldt-Jakob disease (vCJD) occurs by transfusion and that the candidate infectious agent (PrP(TSE)) is present in small concentrations in the blood of infected donors in the asymptomatic phase of the disease. A new blood screening assay has been developed to detect PrP(TSE) in citrated plasma samples. STUDY DESIGN AND METHODS: Three regional Blood Transfusion Establishments (ETS) in France (ETS Alsace, ETS Bourgogne Franche-Comte, and ETS Pyrenees-Mediterranee) will screen 60,000 plasma samples (20,000 in each ETS) over a time period of approximately 9 to 12 months. RESULTS: Results provided in this report are those of the first testing site in Strasbourg, Alsace. The preliminary results have demonstrated an initial specificity of 97.60%. Upon repeat testing the specificity rate achieved 99.90% (20 repeat-positive samples). Based on the known epidemiology of vCJD in France, it is likely that the repeat-reactive samples are not true-positives. CONCLUSION: The screening assay was studied in terms of specificity and practicality and was found to be suitable for use in routine testing of blood donations. However, throughput must be enhanced by automation of the assay, and traceability would be improved if automated systems were used to distribute and identify samples.