Characterized syphilis sera n = 129 Overall agreement with characterized syphilis sera: Architect CLIA 98.4%, Murex immune capture enzyme 86.0%, TPPA 98.4%, IgM EIA 86.8%, VDRL 83.7% Agreement with primary syphilis: Architect CLIA 97.5%, Murex immune capture enzyme 77.2%, TPPA 97.5%, IgM enzyme immunoassay 93.7%, VDRL 78.5% Prospective study n = 1107 Overall agreement between Architect and TPPA was 98.9% (1095/1107) Architect CLIA: sensitivity 100% and specificity 99.1% Murex immune capture enzyme: sensitivity 97.9% and specificity 99.9% Here, CD40LG is linked to syphilis.