Virus-like particles in Australia antigen-associated hepatitis. An immunoelectron microscopic study of human liver

IN A PREVIOUS REPORT (HUANG SN: Hepatitis-associated antigen hepatitis: an electron microscopic study. Am J Pathol 64:483-500, 1971) liver biopsies of renal transplant patients who developed chronic progressive viral hepatitis associated with persistence of Australia antigenemia [Au(1)] while under immunosuppressive therapy were studied. Predominantly intranuclear 210-250 A spherical, virus-like particles were revealed in 12 of 13 biopsies examined by electron microscope. No such particles were found in biopsies from Australia antigen negative patients. To investigate the relationship of these virus-like particles to Australia antigen, 2 of the Au(1) hepatitis renal transplant patients were restudied 6 to 8 months later. Liver biopsy material was prepared for light microscopy, immunofluorescent microscopy, electron microscopy and immunoelectron microscopy. The specificity of the anti-Au(1) serum used in this study was ascertained by immunodiffusion and immunoelectrophoresis, and by immunoelectron microscopic studies of the antigen-antibody complex prepared in vitro by mixing the ferritin-conjugated anti-Au(1) reagent with the purified Au(1) particles. Electron microscopy of biopsies from liver not treated with antibody showed that virus-like particles persisted in liver cells. Immunofluorescent microscopy of teased liver biopsy suspensions showed nuclear and some cytoplasmic fluorescence, indicating the cellular localization of Au(1). The immunoelectron microscopic preparations showed agglutination of the virus-like particles and the presence of antibody coupled ferritin in the intranuclear and cytoplasmic particle agglutinates. No virus-like particles were seen in the biopsy from a control patient without Au(1) antigenemia, and results of the immunoelectron microscopic procedure were negative. Our observations that massive amounts of Au(1)-associated particles are located in liver cell nuclei of individuals with chronic active hepatitis strengthen the hypothesis of Blumberg et al that Au(1) is an infectious agent and/or the antigenic determinant of a hepatitis virus.