The diagnosis of Lyme disease is aided by detection of antibodies to B. burgdorferi using the standard two-tier testing (STTT) algorithm, which incorporates a first-tier enzyme immunoassay (EIA) and second-tier IgG and/or IgM immunoblotting (7) or a variation of this algorithm known as modified two-tier testing (MTTT), replacing the second-tier immunoblot with a second enzyme-linked immunosorbent assay (ELISA) (8). This evidence concerns the gene CD40LG and Lyme disease.