Subsequently, a plenitude of biological evidence has emerged for a relationship between HSV-1 and AD, all supporting the association of HSV-1 in the brain with AD in APOE4 carriers: pathology correlations using neural stem cells (beta-amyloid production and tau phosphorylation), the preventive effects of HSV-1 with antivirals before the onset of dementia, the decreased risk of dementia following vaccination with a variety of vaccines and the association with a decreased frequency of HSV-1 reactivation shown in some vaccine studies, and anti-HSV serum antibodies [25,56,57,58,59]. The gene discussed is APOE; the disease is Alzheimer disease.