An ultrastructural and immunohistochemical study on the δ antigen associated with the hepatitis B virus

Abstract

Thirteen liver biopsies in which the delta antigen was detected by immunofluorescence were studied by electron microscopy and immune electron microscopy with peroxidase labelled IgG and F(ab1)2 fraction obtained from a human antiserum containing high-titre anti-delta antibodies. The findings were compared with those obtained in 11 HBcAg positive and in two HBsAg negative controls. Neither unique particulate morphology nor any HB virus ultrastructural component were visualised in the delta positive specimens; 20-23 nm naked core particles were observed in 10 of 11 biopsies displaying the HBcAg in immunofluorescence. Delta positive nuclei frequently contained dense round structures of diameter varying between 20 and 30 nm with a soft indistinct edge. These granules did not exhibit characteristic ultrastructural features which enabled them to be distinguished from other granular material observed occasionally in nuclei of normal and diseased livers. However, their association with the delta antigen has been proved by the deposition on identical structures of peroxidase labelled anti-delta antibody. These results suggest that the delta antigen is unrelated to the Dane particle, the putative HB virus. The granules observed in the delta positive nuclei are composed of an amorphous matrix, possibly insoluble aggregates of the delta antigen.

delta Agent: association of delta antigen with hepatitis B surface antigen and RNA in serum of delta-infected chimpanzees.

“…The standard anti-3-Ag antiserum was obtained from a patient with chronic persistent type B hepatitis and contained a high titer of anti-3-Ag [1:1000 by immunofluorescence (1); 1:105 by a blocking radioimmunoassay (3)], a low titer of antiHBc (1:600 by radioimmunoassay), and no HBeAg, anti-HBs, or anti-HBe activity by radioimmunoassay. The optimal dilution of the standard anti-3-Ag serum (1:1000) was previously established by checkerboard titration against a preparation of b-Ag extracted from a b-Ag-positive human liver (2). Serum samples were tested before and after treatment with different concentrations of Nonidet P-40.…”

“…After extraction from hepatocyte nuclei with guanidine hydrochloride, b-Ag was characterized as a protein with a molecular weight of approximately 68,000 (2). Although b-Ag has not been detected in the sera of patients with intrahepatic b-Ag, such individuals develop high titers of anti-3-Ag which might interfere with the available solid-phase radioimmunoassay for b-Ag.…”

“…The 3 antigen (6-Ag), a relatively new specificity, first was detected by immunofluorescence in the liver of human subjects with chronic hepatitis B surface antigen (HBsAg) hepatitis (1). Ultrastructural studies have failed to demonstrate components of hepatitis B virus (HBV) in b-Ag-positive nuclei (2) and the b-Ag-anti-b-Ag system is distinct from the known antigenantibody systems of HBV (3). Prevalence studies of b-Ag-anti-3-Ag in human populations (4,5) and transmission experiments in chimpanzees (6) indicate that b-Ag is associated with a transmissible pathogenic agent, 3 agent, that is either a HBV mutant with characteristics of a defective interfering particle or a new agent which requires helper functions of HBV for its expression.…”

Delta hepatitis: molecular biology and clinical and epidemiological features

“…The tubular and reticular abnormalities were coincident with the reexpression of HDAg in liver biopsies and abnormal ALT levels. Canese et al (26) reported identical ultrastructural abnormalities in chimpanzees infected with the same inocula.…”

“…Subsequently, human sera containing high titers of anti-HD and low titers of anti-HBc activity were labeled with horseradish peroxidase and used for the direct detection of HDAg by immunoperoxidase staining of frozen sections and paraffin-embedded sections from patients with chronic liver disease (26,82,194 (95,179). In the assay described by Shattock and Morgan (179), Tween 20 is used to release the antigen from the HBsAg envelope.…”