The virus which causes chickenpox and shingles may help re-awaken the dormant herpes virus, another common virus that triggers the early stages of Alzheimer’s disease, according to a study published in the Journal of Alzheimer’s Disease.
Previous studies have implicated the Varicella zoster virus (VZV) in Alzheimer’s disease (AD). In addition, vaccination against shingles caused by VZV has been found to reduce the risk of AD/Dementia.
To test the effect of active VZV on inactive HSV-1, researchers at Tufts University and the University of Oxford infected human-induced neural stem cell (hiNSC) cultures with Herpes Simplex (HSV-1) and/or VZV to check for the presence of phenotypes associated with AD, such as amyloid-(A) and P-tau buildup, gliosis, and neuroinflammation.
The researchers found that HSV-1, one of the main variants of the virus, which usually lies dormant, causes a buildup of tau and amyloid beta proteins as well as a loss of neuronal function, which are distinguishing symptoms of Alzheimer’s disease. The researchers also found that the link between HSV-1 and Alzheimer’s disease only occurs when HSV-1 has been reactivated.
Furthermore, researchers discovered that infecting the brain tissue with VZV cells alone did not lead to the formation of the signature Alzheimer’s proteins tau and beta-amyloid that form in Alzheimer’s patient’s brains. However, for brain neurons with already dormant HSV-1, exposure to VZV caused HSV to become active again, causing a sharp rise in tau and beta-amyloid proteins and slowing the neuronal signals.
“Our results are consistent with the suggestion that shingles cause reactivation of HSV1 in the brain and with the protective effects against AD of various vaccines, as well as the decrease in herpes labialis reported after certain types of vaccination”, the authors said
Source: Science Daily
Journal Source: Journal of Alzheimer’s Disease