TABLE 2.
Incubation period of VRQ/VRQ TSE-free recipient sheep inoculated with PG127 classical scrapie isolatea
| Blood population and volume or cell no. | Incubation periodb (dpi) and presence of PrPSc |
|||||||
|---|---|---|---|---|---|---|---|---|
| D1 |
D2 |
D3 |
D4 |
|||||
| Incub | PrPSc | Incub | PrPSc | Incub | PrPSc | Incub | PrPSc | |
| Whole blood | ||||||||
| 10 ml | 183 | + | 177 | + | 207 | + | 184 | + |
| 1 ml | 213 | + | 190 | + | 274 | + | 215 | + |
| 0.1 ml | >450 | − | 232 | + | >450 | − | >450 | − |
| 0.01 ml | >450 | − | >450 | − | >450 | − | >450 | − |
| WBC | ||||||||
| 106 cells | >450 | + | 230 | + | 218 | + | 220 | + |
| 105 cells | >450 | − | 254 | + | >450 | − | >450 | − |
| 104 cells | >450 | − | >450 | − | >450 | − | >450 | − |
| 103 cells | >450 | − | >450 | − | >450 | − | >450 | − |
| CD4+/CD8+ | ||||||||
| 106 cells | >450 | − | 195 | + | >450 | + | >450 | − |
| 105 cells | >450 | − | >450 | − | >450 | − | >450 | − |
| 104 cells | >450 | − | >450 | − | >450 | − | >450 | − |
| CD45R+ | ||||||||
| 106 cells | 305 | + | 224 | + | >450 | + | 240 | + |
| 105 cells | >450 | − | >450 | − | >450 | − | >450 | − |
| 104 cells | >450 | − | >450 | − | >450 | − | >450 | − |
| CD14+ | ||||||||
| 106 cells | >450 | − | >450 | − | >450 | − | >450 | − |
| 105 cells | >450 | − | >450 | − | >450 | − | >450 | − |
| 104 cells | >450 | − | >450 | − | >450 | − | >450 | − |
Shown are the incubation periods of VRQ/VRQ TSE-free recipient sheep that received, by the intravenous route, whole blood or one of the WBC or cell-sorted PBMC subpopulations collected from four VRQ/VRQ sheep orally inoculated with PG127 classical scrapie isolate.
The four susceptible VRQ/VRQ sheep between 6 and 10 months of age (identified as D1, D2, D3, and D4) were orally challenged with 2 g of brain homogenate (106.6 50% infectious doses [ID50]/g intracranially in tg338 mice). The sheep were euthanized at 207, 219, 217, and 196 dpi, respectively. At 180 dpi, whole blood was collected from each donor, and a 200-ml volume was transfused into scrapie-free VRQ/VRQ recipients within the 6 h following collection. Recipient sheep were observed until the occurrence of clinical signs of scrapie. The incubation periods (Incub) of recipients are presented (in days). Recipient sheep that apparently were still healthy 450 days posttransfusion were killed. The occurrence of scrapie was confirmed by histopathology (vacuolar change in central nervous system) and the detection of abnormal PrP deposits (PrPSc) in the central nervous system and lymphoid tissues.