This ELISA kit uses Indirect-ELISA as the method to qualitatively detect the Monkeypox Virus (MPXV) IgG in the sample. The micro ELISA plate provided in this kit is pre- coated with purified MPXV antigen, after adding samples to wells, the MPXV IgG in the samples will combine with the pre-coated MPXV antigen. After washing completely, add Horseradish Peroxidase (HRP) conjugated goat anti human IgG to develop the antigen- antibody-HRP conjugated secondary antibody complex. Free components are washed away, then the substrate solution is added to each well. Only those wells that contain MPXV IgG and HRP conjugated anti-human IgG will appear blue in color. The enzyme- substrate reaction is terminated by the addition of stop solution and the color turns yellow. The optical density (OD) is measured spectrophotometrically at a wavelength of 450 ± 2 nm. Compared with the CUT OFF value to judge whether MPXV IgG exists in the tested samples or not