Fig. 6.

Serial passage of vCJD prions in Tg22372 mice. Each box represent a single mouse, with its incubation period in days and strain type indicated in color: type 1 (blue), type 2 (red), types 1 and 2 (purple), not determined (white). From center, inner ring shows the first passage with human vCJD brain homogenate, second ring shows second passage, third ring shows third passage, outer ring shows fourth passage. For first and second serial passage, brain homogenates from the respective ill Tg22372 mice were prepared and inoculated into other hemizygous Tg22372 mice. For third and fourth passage, inoculations were performed in homozygous Tg22372^+/+ mice.