This assay employs a two-site sandwich ELISA to quantitate MHB in samples. An antibody specific for MHB has been pre-coated onto a microplate. Standards and samples are pipetted into the wells and any MHB present is bound by the immobilized antibody. After removing any unbound substances, a biotin-conjugated antibody specific for MHB is added to the wells. After washing, Streptavidin conjugated Horseradish Peroxidase (HRP) is added to the wells. Following a wash to remove any unbound avidin-enzyme reagent, a substrate solution is added to the wells and color develops in proportion to the amount of MHB bound in the initial step. The color development is stopped and the intensity of the color is measured.