Table 2.
Summary of mouse bioassays of non-central core soil samples taken from the lysimeter containing sandy soil with buried boluses of 301V brain homogenate
| Depth (cm) | 25 cm distance from central core | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Month: | 1 | 3 | 7 | 9 | 12 | 18 | 14 | 36 | 48 | |
| 40 | X | X | X | X | 0/4 | 0/4 | 0/4 | 0/4 | 0/4 | |
| 50 | 0/3# | 0/4 | 0/4 | 0/4 | 0/4 | 0/4 | 0/4 | 0/4 | 0/4 | |
| 60 | 0/4 | 0/4 | 0/4 | 0/4 | 1/4 | 0/4 | 0/4 | 0/4 | 0/4 | |
| 70 | 0/4 | 0/4 | 0/4 | 0/4 | 0/4 | 0/4 | 0/4 | 0/4 | 0/4 | |
| Depth (cm) | 50 cm distance from central core | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Month: | 1 | 3 | 7 | 9 | 12 | 18 | 14 | 36 | 48 | |
| 40 | X | X | X | X | X | X | X | X | X | |
| 50 | X | X | X | X | 0/4 | 0/4 | 0/4 | 0/4 | 0/4 | |
| 60 | 0/4 | 0/4 | 0/4 | 0/4 | 0/4 | 0/4 | 0/4 | 0/4 | 0/4 | |
| 70 | X | X | X | X | 0/4 | 0/4 | 0/4 | 0/4 | 0/4 | |
Samples were taken at 25 cm and 50 cm from central cores at different depths as indicated. Samples were taken repeatedly from 1 to 48 months and on four radii around the central core. X = not tested, samples stored (N.B. samples at 10, 20, 30, 80, 90 and 100 cm depths were also taken and stored). Each sample that was tested was inoculated into four mice (#1 mouse died of intercurrent disease), and results are presented as the number of TSE-positive animals/total injected. Samples with any sign of infectivity are in bold. The bolus level in the central core was 50 cm