The hidden connection between herpes and Alzheimer’s

A new study has uncovered a surprising link between Alzheimer’s disease and Herpes Simplex Virus-1 (HSV-1). Researchers found HSV-1 proteins embedded in Alzheimer’s brains, revealing how the virus is inhibited by tau protein—a key player in the disease. These insights could pave the way for innovative treatments targeting viral activity and the brain’s immune response to slow or even stop Alzheimer’s progression.

New study led by Dr. Or Shemesh from the School of Pharmacy at the Hebrew University of Jerusalem has uncovered a surprising connection between Alzheimer’s disease and the Herpes Simplex Virus-1 (HSV-1). The research team used advanced techniques to identify 19 HSV-1-related proteins in the brains of people with Alzheimer’s, across all stages of the disease. This discovery strengthens the growing evidence that infections like HSV-1 might play a role in the development and progression of Alzheimer’s.

One key finding was the increased activity of a herpesvirus protein called ICP27, which became more prominent as the disease advanced. This protein was found to occupy the same space as tau, a brain protein that becomes harmful when it undergoes changes in Alzheimer’s disease, but it did not appear near amyloid plaques, another hallmark of the illness. This suggests that HSV-1 may directly affect tau and contribute to the changes seen in Alzheimer’s.

The team’s experiments with human brain organoids derived from stem cells revealed that HSV-1 infection can increase tau modifications at specific sites linked to Alzheimer’s disease. Remarkably, these modifications seem to help protect brain cells early on by reducing the amount of virus and preventing cell death. However, as the disease progresses, these same processes may contribute to the brain damage associated with Alzheimer’s. The study also highlighted the role of Alzheimer’s pathologies as part of the brain’s natural immune system in this process, focusing on a pathway called cGAS-STING, which influences tau changes.

Dr. Shemesh explained, "Our research shows how HSV-1 interacts with the brain and influences the pathologies of Alzheimer’s disease. Early on, the changes in tau may protect brain cells by limiting the virus, but as the disease advances, these same changes could lead to more harm and accelerate neurodegeneration."

This study provides new insights into how infections and the brain’s immune response may be involved in Alzheimer’s disease. It suggests that targeting viral activity or modifying the immune system’s response could offer new treatment possibilities. While more research is needed to fully understand these processes, these findings open the door to innovative ways to slow or stop the progression of this devastating disease.