Fig. 4.

Efficient purification of tau seeds from CSF. a 10 ng of protein from frontal cortex of case AD1 was spiked into control CSF or PBS. FRET positivity resulting from IP followed by seeding assay of spiked samples did not differ between CSF and PBS, or with volume of IP. b 1 ml aliquots of control CSF were spiked with a serial dilution of protein from brain AD1. c 1 ml aliquots of control CSF were spiked with a serial dilution of recombinant tau fibrils. Seeding was detected from these spiked samples down to 31.6 pg of total AD brain protein and 100 attomoles of recombinant fibrils (monomer equivalent). Pre-IP shows FRET positivity from direct treatment with the same amount of protein spiked into the corresponding sample. Error bars are SEM of 3 technical replicates over which each sample was divided