Introduction Purpose to identify proteins by separating those protein molecules in a sample via electrophoresis can be used as a confirmatory test for a positive HIV ELISA test Example HIV antigens (e.g., p24, gp41, and gp120) are separated by electrophoresis and then blotted onto nitrocellulose paper the patient's serum (which contains produced antibodies) is added where the antibodies can bind to the antigens it recognizes anti-human antibodies conjugated to an enzyme or radioactive label is then added these anti-human antibodies can bind to the patient's antibody which produces bands