(A–D) EBNA-specific IgG antibody responses were assessed in n = 270 MS patients and n = 270 healthy controls using indicated (A) EBNA_381–452–derived peptides or (B) individual EBNA_386–405–,EBNA_393–412–,EBNA_409–428–,EBNA_426–445–, or corresponding CNS-derived GlialCAM_370–389–,CRYAB_2–21–,MBP_205–224-,or ANO2_135–154 peptides. IgG antibody responses were assessed at the time point of MS diagnosis or a matched time point for controls (T1; A and B) and during primary EBV infection (T0; A). The dashed black line indicates the cut-off for detection. (C and D) High-level EBNA-specific or CNS-specific antibody levels were first defined by receiver operating characteristic (ROC) analysis (Supplemental Table 2) and then compared between MS patients and controls. (E) Distribution of high-level EBNA-specific or CNS-specific CD19⁺ B cell (Figure 1B), CD4⁺ T cell (C), and CD8⁺ T cell (D) levels was defined by ROC analysis (Supplemental Table 2) and then compared between n = 20 MS patients and n = 80 healthy controls. Statistical differences were assessed by (A) Kruskal-Wallis and Dunn’s multiple-comparison test, (B) Mann-Whitney U test, (C–E) and χ² test. ABs, antibodies; HC, healthy control; T, timepoint.