In this type of ELISA format, antigen (or the protein) is coated on the surface of the wells of the microtitration plates (solid phase). The antigens are detected by addition of the specific antibody labelled with an enzyme. Following washing unbound components, a substrate specific to the the enzyme is added. This results in a color formation that is proportional to the amount of antigen in the sample.
In this type of ELISA format, antigen (or the protein) is coated on the surface of the wells of the microtitration plates (solid phase). The antigens are detected by addition of the specific antibody labelled with an enzyme. Following washing unbound components, a substrate specific to the the enzyme is added. This results in a color formation that is proportional to the amount of antigen in the sample.
This test format is similar to direct ELISA but, this time, a secondary antibody labelled with an enzyme is used. Primary antibody is bound to the antigen coated on the surface of the microtiter plate (solid phase) but detection is done by a secondary antibody specific to the primary antibody. Substrate is added and color formation is measured by a microplate reader spectrophotometer. In some indirect ELISA formats, primary antibody is replaced with antibodies in the serum of a patient. Thus, presence of specific antibodies to the antigen can be detected in that sample. In serologic studies, bacterial, viral or parasitic antigens are coated on the surface the plate and presence of specific antibodies are determined.
In this type of ELISA, the antigen is sandwiched between two antibodies specific to different epitopes of that antigen. To do that, capture antibody is coated on the surface of the microtiter plate. Then sample solution is added. Antigen is bound to the capture antibody. Following washing away the unbound particles, labelled detection antibody is added to determine antigen presence.
In this type of ELISA, the antigen is sandwiched between two antibodies specific to different epitopes of that antigen. To do that, capture antibody is coated on the surface of the microtiter plate. Then sample solution is added. Antigen is bound to the capture antibody. Following washing away the unbound particles, labelled detection antibody is added to determine antigen presence.
All previous test formats can be converted to the competetive type.In competetive ELISA format , labelled antigen or unlabelled antigen in the sample compete for the antibody binding sites. Quantification is made by adding suitable substrate. Color formed is inversely correlated with antigen levels in the sample.
All previous test formats can be converted to the competetive type.In competetive ELISA format , labelled antigen or unlabelled antigen in the sample compete for the antibody binding sites. Quantification is made by adding suitable substrate. Color formed is inversely correlated with antigen levels in the sample.
Alternatively, antigen coated on the surface of the solid phase (immobilized) competes with antigen (free competing antigene) in the liquid phase (sample) to bind to the specific antibody added. Following washing, the color formed is negatively correlated with the antigen in the liquid phase.
Alternatively, antigen coated on the surface of the solid phase (immobilized) competes with antigen (free competing antigene) in the liquid phase (sample) to bind to the specific antibody added. Following washing, the color formed is negatively correlated with the antigen in the liquid phase.
