Most sensitive test for antigen detection is -
RIA is a competitive binding assay in which fixed amounts of antibody and radiolabelled antigen react in the presence of unlabeled antigen. The labeled and unlabeled antigens compete for the limited binding sites on the antibody. This competition is determined by the level of the unlabelled antigen present in the patient's serum sample. Reference : Anathanarayan & paniker's 9th edition, pg no:113 <\p>
RIA
Elisa
Immunofluorescence
Passive hemagglutination
Immunology