This kit is comprised by HRP conjugate, other reagents, ELISA Microtiter plate pre-coated with the Avian Influenza Virus H9 (AIV-H9) antigen. Apply the principle of enzyme-linked immunoassay (ELISA) to detect AIV-H9-Ab in serum, plasma and yolk of poultry animals. During the experiment, add control, samples, and antibody working solution into the ELISA microtiter plate, AIV-H9-Ab will compete with the antibody working solution to bind with the antigen pre-coated on the ELISA Microtiter plate. Then horseradish peroxidase (HRP) conjugate is added to each ELISA microtiter plate well, and substrate reagent is added for color development. There is a negative correlation between the OD value of samples and the concentration of AIV-H9-Ab. Measure the absorbance value of each well by using a microplate reader with 450 nm (630 nm) wavelength, then we can judge whether AIV-H9 antibody exist in the sample.