What can properly executed ELISA tests determine?

The correct answer identifies the primary function of Enzyme-Linked Immunosorbent Assay (ELISA) tests, which is to detect the presence of specific antigens or antibodies in a sample. ELISA works by using enzyme-linked antibodies that bind to the target antigen or to specific antibodies in the presence of the sample. This binding produces a measurable signal, often a color change, that indicates the concentration of the target molecule.

ELISA tests are highly specific, making them suitable for diagnosing various conditions, including infections, autoimmune diseases, and allergies by identifying the specific proteins or antibodies present in the sample. The high specificity of these tests ensures that they do not simply indicate the presence of all bacteria or provide a general overview of the immune response, aspects that fall outside the scope of what ELISA is designed to measure. Unlike options that suggest identifying all types of bacteria, classifying infections broadly, or assessing overall immune response, ELISA's focus remains on particular antigen-antibody interactions, allowing for precise diagnostic capabilities.