The research program has the overall objective of combining the techniques of electron microscopy, ultracentrifugation, column chromatography, tissue culture and serology to identify, isolate and characterize the etiologic agent of infectious hepatitis, to propagate it in cell cultures and to develop in vitro immunodiagnostic assays capable of detecting the presence of the hepatitis A virus and its antibody both in the patient and the environment. Through the program, it was possible morphologically and serologically to relate this agent to those isolated from other geographically separated hepatitis A epidemics. Employing hepatitis A antigen detected by radioimmunoassay (RIA) screening and isolated from stool specimens collected from patients with both clinical and subclinical hepatitis, a radioimmunoassay and an immune adherence hemagglutination assay were developed for the detection of antibody to hepatitis A. Using these assays, the protective effect of circulating anti-HA against reinfection and the prophylactic effect of commercial immune serum globulin (ISC) containing anti-HA were established. A survey of a commercial plasma donor population showed that approximately 37% of the tested donors had anti-HA with the frequency varying directly with age. All attempts to propagate the hepatitis A virus in tissue culture have been unsuccessful.

"EPA-600/1-77-049." "This report was submitted in fulfillment of Grant No. R-804003 by Electro-Nucleonics Laboratories, Inc." Includes bibliographical references (p. 34-38).