Both Western Blot and ELISA measure the immune system’s response to an infectious agent rather than looking for the components of the agent itself.

Western Blot is an antibody detection procedure where a mixture of proteins is separated based on molecular weight through gel electrophoresis. These results are then transferred to a membrane producing a band for each protein. The membrane is then incubated with labeled antibodies specific to the protein of interest.

In an ELISA, an antigen must be immobilized on a solid surface and then complexed with an antibody that is linked to an enzyme. Detection is accomplished by assessing the conjugated enzyme activity via incubation with a substrate to produce a measureable product. The most crucial element of the detection strategy is a highly specific antibody-antigen interaction.

Columbia Biosciences manufactures and sells both secondary antibody conjugates and streptavidin conjugates for use in both Western Blot and ELISA.