Immune electron microscopy of hepatitis delta-antigen in hepatocytes.

Immune electron microscopic examination of hepatitis delta delta-antigen (HDAg) was carried out on liver biopsies from seven patients with chronic type B hepatitis and delta-infection. HDAg was mainly found in the nucleus, but in some scattered hepatocytes it was found in the cytoplasm also, either in association with ribosomes or in the hyaloplasm. The association of HDAg with ribosomes may be the result of translation from delta-messenger RNA on the same ribosomes. In the nucleus, delta-antigen was present in the chromatin area as irregular granular structures, and there was staining of aggregates of 20 to 30-nm particulate structures, similar to those first described in non-A, non-B hepatitis. However, similar particulate structures were also present in HDAg negative nuclei. The delta-particles which have been described in blood could not be identified in hepatocytes.