Exogenous cellular co-factors do not modify the efficiency of M1000 infection in vitro or in vivo. (A) Representative cell blot showing PrPres levels produced by recipient MoRK13 cells exposed to M1000 brain homogenate diluted to three different final concentrations (as indicated) with either 1:4 lysis buffer (LB):medium or 1:4 MoRK13 fraction:medium mix. (B) Quantification of PrPres produced by MoRK13 cells exposed to M1000 brain homogenate diluted in subcellular fraction relative to the equivalent % M1000 brain homogenate diluted in lysis buffer; data is from M1000 spiked into three independent fractionations of MoRK13. For quantification purposes, the three different % M1000 spikes into the same MoRK13 fractionated lysate were considered a triplicate of the same experiment. Fractions enriched in lipid raft (LR), endoplasmic reticulum (ER), mitochondrial (MT) and early endosome (EE) marker proteins are highlighted. Analysis of relative levels of PrPres produced after infection was by one-way ANOVA with Tukey's multiple comparison test; no significant differences found comparing subcellular fractions. (C) Survival of Tga20 mice inoculated with M1000 brain homogenate diluted to 0.01% with either PBS, selected fractions from an empty Nycodenz gradient, or selected subcellular fractions from MoRK13 cells. Each data point represents the number of days post-inoculation (PI) which mice were sacrificed because of terminal prion disease. Statistical analysis was by one way ANOVA, with no significant differences in survival seen between any inocula.