Fig 1.

Intracranial inoculation of FFPE sCJD brain tissue causes clinical or subclinical prion infection in Tg66 mice. (A) H&E (left panel)- and 3F4 (right panel)-stained sagittal sections from a clinically positive Tg66 mouse 167 days after inoculation with control CJD^Froz brain homogenate. Spongiosis and PrP^Sc deposition (brown stain) are present in the pons. Scale bar, 100 μm. (B) Section of cortex stained with the anti-PrP monoclonal antibody 3F4 from a patient diagnosed with sCJD in 1979 (CJD1^FFPE) or 1981 (CJD2^FFPE). Both samples are positive for spongiosis and PrP^Sc (red stain). The arrow in the right panel indicates a unicentric PrP^Sc plaque. Scale bar, 100 μm. (C) Western blot analysis of brain homogenates from Tg66 mice inoculated with homogenates made from FFPE sCJD brain samples CJD1^FFPE and CJD2^FFPE. Each lane represents 0.7-mg brain equivalents of an individual mouse brain, except for the lane labeled CJD^Froz, which represents brain homogenate from the sCJD MM type 1-positive control sample. The CJD1^FFPE sample lanes 1 to 3 represent three mice that were euthanized for non-prion-disease-related causes at 113, 127, and 131 days postinfection. The blot was developed with the anti-PrP mouse monoclonal antibody 3F4 and the ECL development system. Molecular mass markers are indicated on the left. (D) H&E-, 3F4-, or Thioflavin S (ThioS)-stained sagittal brain sections from a Tg66 mouse at 234 (CJD1^FFPE) or 648 (CJD2^FFPE) days postinoculation with brain homogenate derived from FFPE sCJD brain samples. Spongiosis and PrP^Sc deposition (brown stain) are present in the midbrain in CJD1^FFPE-inoculated mice and in the pons in CJD2^FFPE-inoculated mice. The arrows in the top two right panels indicate a plaque visible in both the H&E- and 3F4-stained sections. ThioS-positive plaques were present only in animals inoculated with the CJD2^FFPE sample. Scale bar, 100 μm.