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

Abstract

Liver biopsies (13) in which the .delta.-antigen [Ag] was detected by immunofluorescence were studied by EM and immune EM with peroxidase-labeled Ig[immunoglobulin]G and F(ab1)2 fractions obtained from a human antiserum containing high titer anti-.delta. antibodies. The findings were compared with those obtained in 11 HBcAg[hepatitis B core Ag]-positive and in 2 HBsAg[HB surface Ag]-negative controls. Neither unique particulate morphology nor any HB virus ultrastructural component were visualized 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 20-30 nm in diameter 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. Their association with the .delta.-Ag was proved by the deposition on identical structures of peroxidase labeled anti-.delta. antibody. .delta.-Ag may be 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.-Ag.