Relative swa resistance of various prion populations.

a<p>Prion samples were assayed by the Standard Scrapie Cell Assay (SSCA) on PK1 cells in the absence or presence of swainsonine (swa, 1 µg/ml).</p>b<p>as shown in <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1003158#ppat-1003158-g002" target="_blank">Figure 2</a> (cell-derived samples) or <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1003158#ppat-1003158-g008" target="_blank">Figure 8</a> (brain-derived samples).</p>c<p>Q_rel = Q_sample/Q_RML where Q = RI_PK1/RI_PK1+swa and RI_cell = reciprocal of the dilution required to yield specified designated number of PrP^res positive cells per 20000 cells.</p><p>nid = no infectivity detected; nrd = no ratio determinable.</p>*<p>Q_RML was exceptionally high in the experiments of <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1003158#ppat-1003158-g004" target="_blank">Figures 4C</a> and <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1003158#ppat-1003158-g005" target="_blank">5B</a> (about 2.7 rather than 1.5–2 logs), resulting in what may be misleadingly low values for Q_rel in the associated samples.