Ultrastructural localization of Pre‐S2 polypeptides in the liver tissues of patients with chronic hepatitis B virus infection

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Abstract
— 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 < 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.