In AD+ mice, intranasal Chlamydia pneumoniae inoculation establishes brain infection and is accompanied by upregulation of Nlrp3, Il1β, and Il6 transcripts, amplified IBA1+ microgliosis and GFAP+ astrogliosis, and increased cortical and hippocampal Aβ plaques. This evidence concerns the gene AIF1 and Alzheimer disease.