Importance of the C terminus of the hepatitis B virus precore protein in secretion of HBe antigen.

The hepatitis B virus (HBV) e antigen (HBeAg) is a 15 kDa soluble antigen derived from a precursor protein (precore protein) by two processing events, cleavage of the N-terminal signal peptide and cleavage of the C-terminal 34 amino acids. So far, the role of the C-terminal sequences in secretion has not been analysed in full. In this study deletion of the last 60 amino acids was found to abrogate HBeAg secretion whereas deletions of the last 10, 25 or 39 amino acids decreased its secretion rate. These data demonstrate that C-terminal precore protein sequences are crucial for HBe secretion and determine its secretion rate.