Beads improve the amplification efficiency of SSLOW.

SSLOW scrapie brain material was diluted 10³-fold (lanes 1–8) or 10⁴-fold (lanes 9–15) into 10% NBH, subjected to serial PMCA in the absence or presence of 3 small beads, as indicated, and digested with PK. Each PMCA round consisted of 48 cycles; the material amplified in each round was diluted 10-fold into 10% NBH for the next PMCA round. Undigested 10% NBH (lane 1) loaded at 1/10^th the amount of the digested samples is provided as a reference.