Table 2. Prion detection in tissue harvested from a mouse dilutional bioassay of CWD+ cervid brain.
| Mouse cohort (average dpi to terminal disease ± SD) n+/total n |
||||||||
|---|---|---|---|---|---|---|---|---|
| Tissue tested | Assay | 10−2 CWD (203±36) | 10−3 CWD (239±46) | 10−4 CWD (232±54) | 10−5 CWD (372±133) | 10−6 CWD (423±108) | 10−7 CWD (>450) | Neg (NA) |
| Brain | WB | 6/6 | 6/6 | 5/6 | 2/5 | 2/5 | 0/6 | 0/12 |
| IHC | 6/6 | 6/6 | 5/6 | 3/5 | 2/5 | 0/6 | 0/12 | |
|
sPMCA/ WB |
5/5 | 6/6 | 5/6 | 2/5 | 2/5 | 0/6 | 0/12 | |
| RT-QuIC | 5/5 | 6/6 | 5/6 | 3/5 | 2/5 | 0/6 | 0/12 | |
|
sPMCA/ RT-QuIC |
5/5 | 6/6 | 6/6 | 3/5 | 2/5 | 0/6 | 0/12 | |
| Spleen | RT-QuIC | 5/5 | 6/6 | 5/6 | 3/5 | 2/5 | 0/6 | 0/12 |
Comparison of in vitro conventional (WB, IHC) and amplification (RT-QuIC, sPMCA/WB and sPMCA/RT-QuIC) assays. Prions were detected in the brains of mice inoculated with CWD+ cervid brain (CBP6) dilutions 10−2–10−6 (300 μg-30 ng) by all assays. sPMCA/RT-QuIC detected prions in brain tissue of one additional mouse in the 10−4 cohort (3 μg seed material). In the 10−5 cohort, IHC, RT-QuIC, sPMCA/RT-QuIC and RT-QuIC of spleen tissue revealed one additional prion+ mouse than WB and sPMCA/WB. Prions were not detected in mice inoculated with the 10−7 CBP6 dilution (3 ng) nor in n = 12 negative control mice inoculated with naïve cervid brain homogenate.