This kit detects Measles virus IgG antibody (MV-IgG) in human serum or plasma samples, polystyrene microwell strips are pre-coated with Measles virus antigen. After first adding serum or plasma specimens to be examined, corresponding specific antibodies (MV-IgG-Ab & some IgM-Ab) present in patient specimens bind to the antigens at the solid phase, and other unbound components will be removed by washing. In the second step, the HRP(horseradish peroxidase)-conjugated anti-human IgG will specifically react only with MV IgG antibodies. After washing to remove the unbound HRP-conjugate, chromogen solutions are added into the wells. In presence of (MV Ag) - (MV-IgG) - (anti-human IgG-HRP) immunocomplex, after washing the plate, the TMB substrate was added for color development, and the HRP connected to the complex catalyzes the color developer reaction to generate the blue substance, add 50μl of Stop Solution, and turn yellow.The presence of the absorbance of the MV-IgG antibody in the sample was determined by a microplate reader.