<prompt> Antigen-antibody reaction is detected byELISASouthern blotNohern blotWestern blot  <response>: An enzyme-linked immunosorbent assay, also called ELISA or EIA, is a test that detects and measures antibodies in your blood. This test can be used to determine if you have antibodies related to ceain infectious conditions. Antibodies are proteins that your body produces in response to harmful substances called antigens. An ELISA test may be used to diagnose:HIV, which causes AIDSLyme diseasepernicious anemiaRocky Mountain spotted fever RMSFRotavirusSquamous cell carcinomaSyphilisToxoplasmosisVaricella-zoster virus, which causes chickenpox and shinglesRef: DM Vasudevan, 7th edition, page no: 453 