Intravenous immunoglobulin reduces β amyloid and abnormal tau formation caused by herpes simplex virus type 1.

Intravenous immunoglobulin (IVIG) treatment of Alzheimer's disease (AD) has been encouraging. Its mechanism of action might be via anti-β-amyloid (Aβ) antibodies which facilitate Aβ clearance. However, IVIG's benefits might result from its antiviral activity, particularly against herpes simplex virus type 1 (HSV1), a virus implicated in AD. We investigated IVIG's effect on HSV1, specifically on the accumulation of Aβ and abnormally phosphorylated tau which it causes. We show that IVIG is effective at reducing the accumulation of these abnormal molecules and that it acts synergistically with the antiviral acyclovir, suggesting that their combined use would be beneficial for treating AD.