To investigate the ability of the SERA assay to detect early Lyme disease, we compared the performance of the validated IgG and IgM panels and STTT in an additional set of clinically defined Lyme disease specimens (n = 119) of which a subset of these subjects are Lyme positive by culture, PCR, or additional clinical criteria, including EM (9). The gene discussed is CD40LG; the disease is Lyme disease.