To quantitatively assess tau misfolding and multimerization, we first developed three AlphaLisa assays to analyze tau in protein homogenates from the mouse forebrain. The assays were conceived using the human-specific HT7 monoclonal antibody as capture antibody. For the first assay, we used MC1 as reporter antibody for early conformational changes of tau (Fig. 4b,c). Already at 1.5 months after injection, we detected a significantly higher MC1 signal in the mice injected with the tau-expressing vectors as compared with mice injected with the control vector (Fig. 4b). These data indicate that human tau protein rapidly acquires a pathology-prone conformation when overexpressed in the mouse forebrain. In order to effectively compare the misfolding of tau between animals, the signal obtained with the HT7/MC1 assay was normalized to the total amount of human tau, determined for each sample in a parallel AlphaLisa with the HT7/TAU-13 monoclonal antibody pair. As shown in Fig. 4c, the normalized MC1-positive tau remained constant over time in the AAV-WT mice. In contrast, the injection of the AAV-P301S vector induced a progressive increase in the amount of misfolded MC1-tau, which was increased by 4.6- and 5.9-fold compared to AAV-WT at 3 and 7 months post-injection, respectively.