HBV-associated ultrastructures in the chimpanzees' livers with experimental hepatitis B.

An electron-microscopic study was carried out using chimpanzees' livers infected with experimental hepatitis B for the elucidation of intracellular development of HBV-associated ultrastructures and extracellular release of HBV. Core particles were first detected in the nucleus of liver cells at around the time of the first seropositiveness for HBsAg, and then in the cytoplasm. Subsequently, their budding into endoplasmic reticular cisterna was seen together with other core particles in the surrounding cytoplasm. Dane-like particles were seen in the cisterna, and also extracellularly nearby a liver cell with a marked proliferation of microvilli at the onset of liver cell injury. Thereafter, core-like particles were seen within electrondense amorphous material at the site of the contact between liver cell and lymphocyte. The above sequence of features suggested us the assembly of core particles and surface envelope at the cisternal membrane of endoplasmic reticulum, and a reversed pinocytosis whereby Dane or HBV particles were released extracellularly. The filamentous structures within endoplasmic reticular cisternae, which were thought to be HBsAg, were never detected.