After 28 days of treatment with GSI + Qa, rPrPSc levels remain low for an additional 21 days after treatment is ceased. Estimates of rPrPSc concentration (n = 3 mice) in the neocortex (A) and thalamus (B) are given. Relative PrPSc levels from untreated infected mice at 78, 85, 92 and 99 dpi were estimated by using data from an earlier study . Adapted from Spilman et al. .