Indirect ELISA

Indirect ELISA is a laboratory technique used to detect specific antibodies in a blood sample. It involves first attaching an antigen (a substance that antibodies recognize) to a surface. When the patient’s sample is added, any matching antibodies will bind to the antigen. A secondary antibody, linked to an enzyme, is then added; it binds to the patient’s antibodies. When a substrate is added, the enzyme produces a measurable color change. This color indicates the presence and amount of specific antibodies, helping to determine if someone has been exposed to a particular pathogen or has an immune response.