What is common to PCR and ELISA?
 

Polymerase Chain Reaction (PCR) and Enzyme Linked Immuno-sorbent Assay (ELISA) are some of the techniques that serve the purpose of early diagnosis. Using conventional methods of diagnosis (serum and urine analysis, etc.) early detection is not possible. Both are used in the diagnosis of HIV (not typhoid). Only ELISA is based on the principle of antigen-antibody interaction.