Immunology and Immunodiagnosis of Cystic Echinococcosis: An Update

Figure 1

Schematic of ELISA and immuno-PCR for detecting circulating antigen in serum. (a) Sandwich ELISA. (1) Plate is coated with a capture antibody; (2) serum sample is added, and any antigen present in the serum binds to the capture antibody; (3) detecting antibody conjugate is added and binds to the antigen; (4) substrate is added, and is converted by the enzyme to a detectable form. (b) Direct ELISA. Plate is coated with diluted serum containing antigen; (2) detecting antibody is added, and binds to antigen; (3) enzyme-linked secondary antibody is added, and binds to detecting antibody; (4) substrate is added and is converted by the enzyme to a detectable form. (c) Capture immuno-PCR. (1) Plate is coated with capture antibody; (2) serum sample is added; (3) biotinylated detecting antibody is added and binds to antigen; (4) Streptavidin and biotinylated reporter DNA are added, and the biotinylated antibody and biotinylated reporter DNA are linked by streptavidin; (5) Primers and PCR components are added and PCR or real-time PCR undertaken to quantify antigen. (d) Non-capture immuno-PCR. Serum sample is coated on the plate and the remainder of the steps are as for the capture-immuno-PCR (C).