Extended Data Fig. 2 |. Serial propagation of α-syn aggregates derived from patients with MSA and patients with PD.

For serial propagation of α-syn aggregates, an aliquot of the final product of the first α-syn-PMCA reaction (starting from CSF samples) was diluted 100-fold into a solution containing fresh α-syn monomers (1 mg ml⁻¹). A second round of amplification was done in the same buffer (100 mM PIPES, pH 6.5 containing 500 mM NaCl) at 37 °C with intermittent shaking for 1 min every 30 min at 500 rpm. The extent of aggregation was monitored by the increase in ThT fluorescence. The maximum fluorescence value at the plateau of aggregation was recorded and plotted in the graph as the second round of amplification (R2). Similarly, the third and fourth rounds of amplification (R3 and R4) were performed by diluting the product 100-fold on amplification each time into fresh α-syn monomer substrate and repeating the α-syn-PMCA assay. The results shown are from one patient with PD and one patient with MSA. The experiment was carried out in duplicate, each dot represents an individual technical replicate and data are mean ± s.e.m.