Nine herpes viruses infect humans and all of them establish life-long latency after infection. Several herpes viruses including herpes simplex virus-1 (HSV-1), establish latency in the peripheral nervous system. Herpes simplex virus-1 directly induces intracellular and extracellular Aβ production in cultured neuronal and glial cells. Herpes simplex virus-1 DNA was present in 90% of Aβ plaques in the post-mortem brains of Alzheimer’s disease patients. Herpes viruses trigger the main hallmarks of Alzheimer’s disease in the human brain. Herpes virus-induced interferon signalling can trigger Aβ production and APOE4 increases the effect of herpes-viral reactivation on Alzheimer’s disease risk.
