ELISA and RIA are two different types of immunoassays used in research and diagnosis.
Their principle is similar but their methods of detection and analysis are different.
ELISA is a method wherein color is produced out of an immune reaction and the color is estimated for qualitative analysis and quantitative analysis.
While RIA is also an immune reaction, it involves the presence of radiation after the reaction.
Also, read the ELISA and western blot similarities and differences.
So the radiation is measured as a function of the quality and quantity of the sample under test.
For more details read our detailed articles on the ELISA principle and also the RIA principle.
First, we will see the similarities.
ELISA and RIA similarities
| Characters | ELISA | RIA |
| Principle | Immunoassay type | Immuno assay type and involves the formation of antigen and antibody. |
| Factors involved | Antigen and antibody reaction | Antigen and antibody reaction by immune methods. |
| Uses and applications | For research and diagnosis | Also useful in diagnosis and research. |
| Cost of experimentation | Expensive and one has to rely on ready made industry kits and elisa plate reader | Expensive and one may need to procure radioisotopes and also radio film |
ELISA VS RIA differences
| Character | ELISA | RIA |
| The measurement relies largely | On development of color. | Production of radiation. |
| The key molecule is | Enzyme linked to antigen or antibody. | The radioactive isotope. |
| The types of reacting substance to produce detectable change | Many enzymes like horse raddish peroxidase | Mostly a single iodine isotope. |
| Time duration of experimental procedure | Is very short and one can measure very fast. | It is very time taking |
| Skill requirement | Minimal skill and knowledge required. | An efficient and highly skilled handler is needed to minimize the risk of exposure to radiation. |
| Permissions | No special permissions required. | Permissions or license required for use of radioactive material |
| Disposal | Disposal of waste is simple and can be done along with medical waste if used in hospital. | Disposal requires special care to avoid radiation exposure by other people. |
| Applications | Disease diagnosis due to rapid experimentation | Largely for receptor binding studies and also to a small extent for diagnosis. |
Also, the Elisa protocol has different types like direct ELISA, indirect ELISA, sandwich ELISA. Even there are multiple bindings like antigen-antibody-antigen or antibody-antigen-antibody.
The detection of color generated due to ELISA reaction is done by a simple photometer (visible spectrophotometer). In an RIA, the measurement of the radioactive emission is done by using a gamma counter.
Both have different roles in research and also diagnosis. But currently, the use of RIA is declining in Health care while the ELISA technique has gained wide popularity. Especially for infectious disease, serum diagnosis by ELISA is too frequent as it is cheap and very rapid.
On the other hand, RIA has got limited use due to safety issues and legally binding rules. Yet, it is an indispensable tool in medical research as it helps in the study of drug-receptor binding and other microstructural imaging.