Ultrastructural Localization of Pre-S2 Polypeptides in the Liver Tissues of Patients with Chronic Hepatitis B Virus Infection

Pre-S2 polypeptides in the liver tissue were investigated by immunoperoxidase staining in 26 patients with chronic hepatitis B virus (HBV) infection positive for HBeAg. Pre-S2 polypeptides were detected in the liver of 25 patients, in 17 of whom Pre-S2 polypeptides were localized both on the hepatocyte membrane and in the cytoplasm, and in eight of whom only in the cytoplasm. The localization pattern of Pre-S2 polypeptides was not correlated with the histological findings but with the replicative status of HBV. In cases with a high level of DNA-polymerase in the serum or with both nuclear and cytoplasmic expression of HBcAg in the liver, Pre-S2 polypeptides were more frequently expressed both on the hepatocyte membrane and in the cytoplasm (P less than 0.05). Membranous expression of Pre-S2 polypeptides was speculated to be linked to active replication of HBV in the hepatocytes. Under immune electron microscopy, Pre-S2 polypeptides were observed on the plasma membrane, membranes and cisternae of endoplasmic reticulum (ER), or perinuclear space. Moreover, Pre-S2 polypeptides were detected on the tubular structures and the intracisternal particles about 40 nm in diameter considered to represent HBV. These findings suggest that the immunoreactions of Pre-S2 polypeptides in the liver tissue are similar to those of HBsAg, indicating that Pre-S2 polypeptides play an important role in the immunocharacteristics of HBsAg.