Purified Toxoplasma antigen is coated on the surface of microwells. Diluted patient serum is added to the wells,and the Toxoplasma IgM-specific antibody, if present, binds to the antigen. All unbound materials are washedaway. HRP-conjugate is added, which binds to the antibody-antigen complex. Excess HRP-conjugate is washed offand a solution of TMB Reagent is added. The enzyme conjugatecatalytic reaction is stopped at a specific time. The intensity of the color generated is proportional to the amount ofIgM-specific antibody in the sample. The results are read by a microwell reader compared in a parallel manner withcalibrator and controls.