• Journal Article

A sensitive and quantitative assay for normal PrP in plasma

Citation

Gregori, L., Gray, B. N., Rose, E., Spinner, D., Kascsak, R. J., & Rohwer, R. G. (2008). A sensitive and quantitative assay for normal PrP in plasma. Journal of Virological Methods, 149(2), 251-259. DOI: 10.1016/j.jviromet.2008.01.028

Abstract

Transmissible spongiform encephalopathies can be transmitted by blood transfusion. The risk of spreading the disease among the human population could be mitigated with the implementation of a blood screening assay. We developed a two-antibody assay for PrP detection in plasma using the ORIGEN technology with a protocol modification to improve the limit of detection and to increase the sample volume assayed. In the standard 200 ?L format, the assay had a detection limit of 7–10 pg of recombinant PrP and 3 pg in 1 mL final volume implementation. PrP concentration measured in normal and scrapie-infected hamster brains was 7.5 ± 0.9 and 57.3 ± 9.6 ?g/g, respectively. After a concentration step with an immuno-affinity resin, plasma PrPc was detected by Western blot and its concentration was measured at 3.5 ± 0.8 ng/mL. From these data and assuming that blood has the same specific infectivity as brain, we estimated the concentration of abnormal PrP in hamster-infected plasma to be 32 fg/mL. The assay also detected abnormal brain PrP spiked into plasma although the limit of detection was affected. This is a novel and sensitive assay for the detection of PrP in plasma that could be developed into a platform for a plasma-based TSE test.