The possible link between herpes simplex virus type 1 infection and neurodegeneration

Abstract

Herpes simplex virus type 1 and type 2 (HSV-1 and HSV-2) are ubiquitous, neurotropic, and the most common pathogenic cause of sporadic acute encephalitis in humans. Herpes simplex encephalitis is associated with a high mortality rate and significant neurological sequelae, which afflict patients for life. HSV-1 has been suggested as an environmental risk factor for Alzheimer's disease. However, the link between HSV-1 infection and neurodegenerative processes is still unclear. It has been proposed that the innate immune response to the virus particularly the activation of Toll-like receptor pathways in astrocytes and microglia could lead to neurodegeneration. Finally, we have also shown that in vitro HSV-1 neuronal infection triggers a change in the hyperphosphorylation state of tau and also results in marked neuritic damage and neuronal death. © Springer Science + Business Media, LLC 2009.