MODEL RELEASED. Semi-automated ELISA blood test. Samples being prepared for an enzyme-linked immunosorbent assay (ELISA) blood analysis. Use of multi-channel pipettes and other semi-automated methods make it possible to run an analysis on a number of samples simultaneously. In the ELISA test, the amount of a substance can be detected by the use of antibodies that bind to the substance (such as a virus). The amount of the antibody complex that is formed can then be measured by the use of an enzyme that binds to the complex. These levels of analysis amplify the sensitivity of the ELISA test, allowing small amounts of the original substance to be detected. Photographed at Clinique St Pierre, a biological laboratory in Ottignies, Belgium.