We then performed an epitope‐level analysis focused on HCMV and identified 24 unique epitopes that were over‐represented among the IgG4 repertoires of CD83(+) microglia AD subjects (FDR < 0.05, Table S3), with the “QLRHALELQ” motif contained within the UL35 protein emerging as the most strongly enriched (Z‐score: 7.5, FDR 4.1e‐10). Here, CD83 is linked to Alzheimer disease.