Transferred Tau species are mainly in a dephosphorylated state. LVs encoding V5-hTau46WT were bilaterally injected into the CA1 layer (IS; bregma -5.3) of rat brains (n = 3). Five months later, the animals were sacrificed, and the rostral areas of the brain were processed for immunofluorescence analysis using a rabbit polyclonal anti-V5 antibody to detect total Tau and a mouse monoclonal antibody to pTau (AT8). The V5-Tau proteins were visualised in green using the corresponding secondary antibody Alexa Fluor-488 labelled goat anti-rabbit IgG (a and e) and the phospho-Tau in red using Alexa Fluor-568 labelled goat anti-mouse IgG (b and f). The scale bars are indicated on the figure. Adjacent brain slides from the rostral areas were assessed by immunohistochemistry using an antibody directed against the N-terminal portion of Tau containing a dephosphorylated tyrosine 18 residue (ADx215) (c) or an antibody to total V5-Tau (d). Most of hTau46WT Tau species found in secondary neurons are dephosphorylated.