Table 2.
Direct ELISA | Competitive ELISA | Indirect ELISA | Indirect competitive ELISA | Sandwich ELISA | |
---|---|---|---|---|---|
Advantage | Simple because only one antibody is used | Higher sensitivity and versatility than direct methods owing to usage of PAb that recognizes different epitopes of primary antibody | High specificity as two antibodies possessing different epitopes are used | ||
Disadvantage | Labeling antibody is necessary for each ELISA, which may result in inactivation of antibody | Nonspecific signal is induced through cross-reactivity of secondary antibody | To prepare two different antibodies is labor-intensive and expensive | ||
Target | Macromolecules | Macromolecules (Hapten) | Macromolecules | Macromolecules (Hapten) | Generally macromolecules |
Signal (as target antigen increase) | Increase | Decrease | Increase | Decrease | Increase |