TSE occurrence in VRQ/VRQ TSE free sheep transfused with frozen plasma and plasma fractions prepared from Scrapie infected sheep.

Whole blood pool was constituted by mixing 600–700 mL from 3 VRQ/VRQ sheep orally inoculated with PG127 classical scrapie isolate. Aliquots of blood were processed as described in Figure 1. For each pool, plasma obtained from Inoculum 7 and 8 preparation lines were stored at −30°C. Decreasing amount of plasma (200 mL, 20 mL and 2 mL) were then transfused to VRQ/VRQ recipients. In parallel, 200 mL of plasma were submitted to standard cryoprecipitation procedure. Both supernatant and cryoprecipitate were intravenously administered to VRQ/VRQ recipient sheep. Recipients were monitored for clinical TSE occurrence. Clinically affected animals were culled when displaying locomotor difficulties that could impair their abilities to feed. The remaining apparently healthy recipients were killed 450 days after transfusion. Systematic detection of abnormal PrP (using both immunohistochemistry and western-blot) in lymphoid tissues (LRS) and central nervous system (CNS) was carried out in recipients as to establish their status.