A sol-particle immunoassay for determination of anti-rubella antibodies; development and clinical validation

A sol-particle immunoassay (SPIA) was developed for determination of anti-rubella antibodies. The test is based on antibody-coated gold sol particles, which may agglutinate in the presence of rubella haemagglutinin antigen. The agglutination which gives a decrease in optical density can be inhibited by specific antibodies present in sera incubated with the immunochemical reagents. The test is performed in microtitration plates and results can be read in a plate-reader. Clinical validation studies were performed comparing the anti-rubella SPIA with the haemagglutination inhibition test and with the latex agglutination test. The sensitivity of the SPIA was calculated to be 99%; the specificity of the test was at least 99.5%. The anti-rubella SPIA is highly suitable for large-scale screening to determine the rubella immune-status.