FIGURE 1.

The most promising techniques for the quantitation of tau seeding activity in human biofluid. (A) In cell-based assay, seed-containing sample is incubated on a biosensor cell line overexpressing tau linked to either a CFP or YFP fluorescent protein. Upon aggregation, energy transfers between CFP and YFP allows for the detection of FRET signal using flow cytometry. Signal is quantified as integrated fret density which is the product between the percentage of FRET-positive cells and the median fluorescence intensity in the FRET channel. (B) In RT-QuIC, seed-containing material is incubated with recombinant tau substrate with thioflavin T in optimized conditions. Seed-competent material induces the aggregation of the substrate which generate ThT fluorescence that is measured over time.