Enzyme linked protein-A: an ELISA for detection of amoebic antibody.

Enzyme linked protein-A was used to develop an enzyme linked immunosorbent assay (ELISA) system for the detection of circulating antibodies to amoebic antigen. The specificity of protein-A to bind IgG only through Fc receptors, makes the test more specific for the detection of IgG antibodies to amoebic antigen. The ELISA system was used to detect amoebic antibody in control subjects (56), patients with amoebic liver abscess (79) and Entamoeba histolytica cyst-passers (10) and the results compared with those of indirect haemagglutination assay (IHA). The ELISA was more sensitive and detected 74.7% of cases with amoebic antibody in amoebic liver abscess compared with 66.7% detected by IHA. The test was more specific, sensitive and easy to perform and is recommended as a test of choice for the serological diagnosis of amoebic liver abscess.