When the cold sore virus (HSV-1) infects brain cells in a lab dish, it seems to turn up the volume on two proteins that help make a sticky substance linked to Alzheimer’s disease.

When the cold sore virus (HSV1) infects brain cells in a lab dish, it causes more of a sticky protein (beta-amyloid) to build up inside the cells and less of the protein that normally makes it — which might help explain why this virus could be linked to Alzheimer’s-like brain changes.

When mice get a common cold sore virus in their brains, scientists see more of a sticky protein buildup that’s linked to Alzheimer’s disease—so maybe the virus helps cause that buildup.