Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025
Definition
Direct fluorescent antibody (DFA) tests use fluorescent-labeled antibodies to directly detect the presence of specific antigens in a sample. They are commonly used in microbiology to identify pathogens quickly and accurately.
5 Must Know Facts For Your Next Test
DFA tests involve the use of antibodies labeled with a fluorescent dye that binds directly to the target antigen.
These tests are highly specific, as they rely on antigen-antibody binding for detection.
DFA tests can provide rapid results, often within hours, which is crucial for timely diagnosis and treatment.
They are commonly used to diagnose infections caused by bacteria, viruses, and fungi.
The fluorescence can be observed under a fluorescence microscope, allowing for visual confirmation of the presence of the pathogen.
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Related terms
Indirect Fluorescent Antibody (IFA) Tests: Tests where the primary antibody binds to the target antigen and a secondary fluorescent-labeled antibody binds to the primary antibody.
Fluorescence Microscope: A specialized microscope used to observe specimens that fluoresce under ultraviolet light.
Antigen-Antibody Binding: The specific interaction between an antigen and an antibody that allows for targeted detection in immunological assays.