ABSTRACT
The ability of hepatitis A virus (HAV) to agglutinate human erythrocytes was used to develop IgM and IgG antibody capture haemadherence tests (MACHAT and GACHAT). Haemadherence was dependent on the pH of the red cell suspension and was best in the pH range 5.4 to 5.8. The tests were applied to serum, urine, and saliva specimens from individuals susceptible to, or with recent or past infection with HAV. Haemadherence test reactivities were compared with results obtained with IgM and IgG antibody capture radioimmunoassay (MACRIA and GACRIA) and competitive radioimmunoassay (COMPRIA). For 339 serum specimens examined, the sensitivity and specificity of MACHAT were 98.2% and 99.6%, respectively, and of GACHAT 99.1% and 100.0%. For 303 urine specimens, the sensitivity and specificity of MACHAT were 99.1% and 100.0%, and of GACHAT 100% for both. On initial testing, accuracy on saliva specimens was considerably less. For 2,819 saliva specimens, the sensitivity and specificity of MACHAT were 85.7% and 97.2% and of GACHAT 90.4% and 94.7%. The haemadherence test is a simple, inexpensive method which is satisfactory for use on serum and urine specimens. MACHAT and GACHAT can be used for epidemiological investigations, e.g., hepatitis A outbreaks and, in conjunction with a confirmatory test, for clinical diagnostic testing.
