Summary: Passive immunization
Groups of mice were injected twice weekly through the intraperitoneal route with 2 mg
(unless otherwise stated) ICSM 18, ICSM 35, IgG1 isotype control (BRIC 222 recognizing
CD44; ref. 27) or IgG2b isotype control (BRIC 126 recognizing CD47; ref. 28) antibodies
in PBS. Animals were monitored daily for clinical symptoms of scrapie29
weekly from 17 weeks after i.c. inoculation or 22 weeks after i.p. inoculation. Clinical signs
in untreated mice were first observed approximately 4 weeks before terminal illness (day of
death) and included coat ruffling/discoloration, progressive weight loss, bradykinesia
(slow movement), tail rigidity, dystonia (clasp foot), kyphosis (hunched back), ataxia and
stupor. Weights of scrapie-infected (untreated) mice decreased before terminal illness
from 3 and 4 weeks in i.c.- and i.p.-inoculated mice, respectively (Supplementary Fig. 1).
Confirmation of scrapie disease was performed by western blot analysis of PrPSc
tissue and in some cases by standard PrP immunohistochemistry.
Immunoprecipitation of PrP from murine brain tissues using ICSM and BRIC antibodies
was performed as described11