A radioimmunoassay for hepatitis A antigen and anbtiody

Progress in the field of hepatitis A research has been hindered by a lack of standard reagents, mainly the difficulty of finding convenient sources of virus. In spite of this, several tests for virus and antibody have been described by various workers. These include immune electron microscopy, the test used successfully in finding the causative agent in faeces from patients with hepatitis A (Feinstone et al., 1973) and complement fixation and immune adherence haemagglutination, which were developed in an attempt to provide a more sensitive and less laborious diagnostic test (Krugman et al., 1975). However, radioimmunoassay promises to be the most useful as it is relatively quick and easy to perform and is very sensitive (Hollinger et al., 1975; Purcell et al., 1976). We have been trying for some time to develop a diagnostic test for this infection; at first we used immune electron microscopy. In samples from some of our patients small virus particles resembling those of hepatitis A and reacting with anti-MSI serum obtained from the National Institutes of Health have been observed and described (Skidmore and Boxall, 1977). However, the interpretation of results has been particularly difficult since stool samples often contain many types of small particles, and no hepatitis A virus has been available for reference. Recently, however, Abbott Laboratories have introduced a commercial radioimmunoassay kit for the detection of antibody to hepatitis A. This has provided us with an opportunity to study samples from our 'infectious hepatitis' patients using standard reagents.