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Table 3 Infectivity of prion-coated wire after exposure to brain homogenate, PBS or brain of uninfected mice

From: Transmission of Scrapie by Steel-surface-bound Prions

Inoculation Sick/Total Incubation Time ± s.d. (days)
Infectious wire 3/4 62 ± 3
Experiment 1: In vitro exposure of infectious wire to:   
(a) Prnp 0/0 brain homogenate   
Wire 4/4 89 ± 3
Homogenate 1/4* 108
(b) PBS   
Wire 3/3 85 ± 6
PBS 0/4 >260
Experiment 2: In vivo exposure of infectious wire to:   
(a) Brain of Prnp +/+ mice, 1 day   
Wire 3/3 104 ± 20
Surrounding tissue 0/8 >260
(b) Brain of Prnp +/+ mice, 5 days   
Wire 2/3 86 ± 4
Surrounding tissue 0/8 >260
(c) Brain of Prnp 0/0 mice, 1 day   
Wire 3/3 79 ± 4
Surrounding tissue 1/8,* 101
(d) Brain of Prnp 0/0 mice, 5 days   
Wire 3/3 91 ± 5
Surrounding tissue 0/8 >260
  1. Infectious wires were prepared with centrifuged 10% brain homogenate from terminally sick CD1 mice (11). For the in vitro assay (expt.1), 20 wires were shaken in Eppendorf tubes for 24 h at 37°C, either with 0.2 ml freshly prepared brain homogenate (10% w/v in PBS) of uninfected Prnp0/0 mice or with 0.2 ml PBS/0.1% albumin, on a thermomixer (1400 rpm). After washing with 0.2 ml of the cognate solution, wires were assayed for infectivity. Thirty-µl samples of each preparation (0.4 ml) were assayed for infectivity in Tga20 indicator mice. For the in vivo experiment (expt.2), infectious wires were implanted into the brain of uninfected Prnp+/+ (C57Bl6) or Prnp0/0 mice. After 1 and 5 days, respectively, the mice were culled and the brain tissue immediately surrounding the wire was dissected out. Wires were washed in 1 ml PBS and assayed. The brain samples (each about 80 mg) were homogenised in PBS to give a 10% homogenate and centrifuged samples were injected i.c. into 3 indicator mice each.
  2. *Scrapie diagnosis was confirmed by histopathology or histoblotting (24)
  3. One of 9 mice died during or after injection.