Antigenic determinant

An antigenic determinant, also known as an epitope, is a specific part of a foreign substance, like a virus or bacteria, that the immune system recognizes and targets. Think of it as a unique "fingerprint" on the surface of the pathogen. When the immune system detects this fingerprint, it can produce antibodies to neutralize or destroy the invader. Multiple antigenic determinants can exist on a single pathogen, each recognized by different antibodies, helping the immune system identify and respond effectively to a wide variety of microbes.