7.1. ELISA (Enzyme Linked Immuno Sorbent Assay)
The enzyme-linked immunosorbent assay (ELISA) is a common serological test for particular antigens or antibodies. There are two forms of the test: i. the direct ELISA employs antibodies to detect presence of a particular antigen in a samples and; ii. the indirect ELISA is usually used to detect specific antibodies in a specimen such as blood serum. However, the indirect ELISA method can also be applied for detection of antigens as described in section 7.1.3. The ELISA method described by Pinnock and Featherstone (1984) is unable to detect bacterial levels less than 105 cells per ml.