Comparative neuropathology in Tga20 and C57BL/6 mice infected with three prion strains.

The severity of spongiform changes, astrogliosis and PrPSc deposition are indicated as follows: ?, none; +, slight; ++, moderate; +++, severe; ++++, very severe. PrPSc is defined as PrP immunoreactive material which is not observed in similarly processed sections from uninfected mice, and its overall intensity was visually assessed regardless of the morphology of the deposits (described in Table 4).