Transmission of Scrapie by Steel-surface-bound Prions

Table 1 Infectivity of steel or gold wires after exposure to intact brain or to brain homogenate of scrapie-infected mice

Inoculation	Sick/Total	Incubation Time ± s.d. (days)
Experiment 1
Wire transiently inserted for 5 min	5/5	68 ± 2
for 30 min	6/6	65 ± 4
for 120 min	6/6	69 ± 5
Wire exposed to 10% brain homogenate⁺	7/7	75± 5
Brain homogenate⁺ (1%, 0.03 ml)	4/4	68± 8
Experiment 2
Wires exposed to homogenate
Steel wire (10%, w/v)	4/4	85± 4
Gold wire (10%, w/v)	3/3	74± 2
Steel wire (1%, w/v)	4/4	86± 8
Gold wire (1%, w/v)	4/4	81± 6

For experiment 1, two C57BL/6 mice were culled 87 days after i.c. inoculation with RML, that is, about 2 months before appearance of clinical symptoms. Wires were inserted into brain for the time indicated or exposed to centrifuged 10% brain homogenate for 16 h and processed as described in the Methods section. For experiment 2, wire segments were exposed to centrifuged brain homogenate of RML-infected, terminally sick CD1 mice as described in Methods.
⁺6.8 logLD₅₀ units/ml 10% homogenate, as determined by end point titration (23) in Tga20 mice.

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