This assay is based upon the two-step capture method. In the first step, the sample and mouse monoclonal Anti-human IgM coated micro plate are combined. During the incubation, IgM antibodies present in the sample bind to the Anti-human IgM coated on the wells. After the washing, in the second step, HAV antigens and Enzyme Conjugate are added to the wells. During the incubation, HAV antigens are allowed to react with the Anti-HAV IgM bound to the micro plate and enzyme labeled antibodies, then a complex is generated among the solid phase, HAV antigens and enzyme-linked antibodies by immunological reactions. After a second washing, Substrate A and Substrate B are then added and catalyzed by this complex, resulting in a chromogenic reaction. The resulting chromogenic reaction is measured as absorbance. The color intensity is proportional to the amount of Anti-HAV in the sample.