Table 2. Intracerebral inoculation of blood components collected from 1 vCJD and 4 sCJD cases (MM1) in transgenic mice expressing the bovine or human prion protein gene*†.
| Mouse model | Donor | Specimen | Inoculated mice | Positive mice | Incubation period, d | ID/mL (95%CI)‡ |
|---|---|---|---|---|---|---|
| tgBov | vCJD | Leukocyte | 24 | 3 | 476, 567, 576 | 2.23 (0–4.87) |
| Plasma | 24 | 1 | 453 | 2.12 (0–6.52) | ||
| Erythrocyte | 24 | 1 | 433 | 2.12 (0–6.52) | ||
| tgHu | sCJD case 1 | Plasma | 14§ | 1 | 338 | 3.70 (0–11.65) |
| Brain | 6 | 6 | 216 ± 2 | NA | ||
| sCJD case 2 | Plasma | 24 | 0 | >700 | 0 (0- 6.24) | |
| brain | 6 | 6 | 217 ± 5 | NA | ||
| sCJD case 3 | Plasma | 24 | 1 | 233 | 2.12 (0–6.52) | |
| Brain | 6 | 6 | 205 ± 5 | NA | ||
| sCJD case 4 | Plasma | 24 | 0 | >700 | 0 (0–6.24) | |
| Brain | 6 | 6 | 207 ± 3 | NA | ||
| tgHu | Control human | Plasma | 12 | 0 | >650 | NA |
| tgBov | Control human | Plasma | 12 | 0 | >650 | NA |
| tgHu | Control human | PBS | 12 | 0 | >700 | NA |
| tgBov | Control human | PBS | 12 | 0 | >700 | NA |
| tgHu | Control human | Brain | 24 | 0 | >700 | NA |
| tgBov | Control human | Brain | 24 | 0 | >700 | NA |
| tgHu | Control human | None | 24 | 0 | >750 | NA |
| tgBov | Control human | None | 24 | 0 | >750 | NA |
*vCJD, variant Creutzfeld-Jakob disease; sCJD, sporadic Creutzfeld-Jakob disease; dpi, days postinfection; ID, infectious dose; tgBov, bovine prion protein; tgHu, human prion protein;; PBS, phosphate-buffered saline. †The leukocyte(s) from a single vCJD case corresponding to a starting volume of 3 mL of blood were suspended in 1 mL of 5% glucose solution. The leukocyte suspension and the crude erythrocytes were homogenized by using a high speed cell disrupter. The leukocyte and erythrocyte homogenates (vCJD case) and crude plasma (vCJD and sCJD cases) were intracerebrally injected into mice (20 µL per mouse). For the 4 sCJD MM1 cases, brain homogenate (10%, temporal cortex) were also inoculated in tgHu. Mice were euthanized when they showed clinical signs of infection or after 650 or 750 dpi. Mice were considered infected when abnormal protease-resistant prion protein; deposition was detected in brain tissue by using Western blot analysis with Sha31 monoclonal antibody: epitope amino acids 145–152 (YEDRYYRE) of the sheep PrP sequence. For samples showing 100% attack rate, incubation periods are reported as mean (± SD). For other samples, individual incubation period of CJD-positive mice are presented; their infectious titers were estimated by using limiting dilution titration method (application of Poisson model) described by Brown et al (13). ‡Leukocyte titer is expressed as ID/mL of the starting whole blood. Plasma and erythrocyte titers are expressed as ID/mL of inoculum. §24 mice were inoculated; 10 died because of the acute toxicity of the sample.