Demonstration of pre‐S polypeptides of hepatitis B virus in infected livers

The large (pre‐S1), middle (pre‐S2) and major (P24) polypeptides of HBsAg have been defined in detail, but their role in hepatitis B virus infection is not known. Therefore, we studied the expression of pre‐S1, pre‐S2 and P24 in the liver of 15 patients with acute or chronic hepatitis B virus infection using monoclonal and polyclonal antibodies in a double staining immunofluorescence method. The pre‐S and major HBsAg polypeptides were co‐expressed in the hepatocyte cytoplasm of all patients except for one case of chronic active hepatitis and cirrhosis. HBcAg was present in hepatocyte nuclei of nine patients suggestive of active hepatitis B virus replication. These studies support the hypothesis that the pre‐S polypeptides represent essential components of the envelope of hepatitis B virus.