Species differences in the blood content of the normal cellular isoform ofprion protein, PrPc, measured by time-resolved fluoroimmunoassay

Background and Objectives The concern that variant Creutzfeldt-Jakob diseas e could be transmitted via blood transfusion has prompted studies of blood infectivity in animal models. As normal prion protein acts as a substrate f or conversion to the abnormal form associated with infectivity, we have qua ntified its distribution in mice and hamsters, the most commonly used anima l models. Materials and Methods A time-resolved fluoroimmunoassay was used to measure normal prion protein in hamster and mouse tissues, including blood. Results Levels of prion protein in hamster blood were remarkably low compar ed with human blood. In contrast, levels in mouse blood were quite similar to human blood; however, there were differences in the distribution of norm al prion between cellular and cell-free fractions. Conclusion Differences between levels of normal prion in blood of animal mo dels and humans should be considered as a possible contributor to infectivi ty study outcomes in these models.