MAPT and dementia: Hyperphosphorylation of tau, caused byHSV-1 (Figure 2), leadsto the formation ofpaired helical filaments (PHFs) and NFTs (Figure 3) whose density correlates with disease severityand dementia.63 Alvarez et al. used immunostainingto show hyperphosphorylated tau inside the nucleus of SK-N-MC cellsto be caused by HSV-1 VRCs.