Laboratoire de génétique des virus, CNRS UPR 9053, avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex
The HBe antigen is a secreted protein detected in the sera of infected patients when active HBV replication occurs. As HBV variants that cannot synthesize HBe are detected, this antigen is dispensable both for infectivity and replication of the virus. However, circumstantial evidences suggest that it could play an important role in the establishment of a persistent infection. HBe derives from the precore protein, which contains at its N-terminal extremity a signal-peptide that directs the protein into the secretory pathway, before its cleavage. Along its intracellular transport, the C-terminal domain of the resulting protein P22 is removed, then the mature HBe antigen is secreted. Interestingly, some P22 molecules are detected in the cytosol. In this review, we will first present the biosynthetic pathway of the HBe antigen and focus on the recently described interactions of P22 with some cellular proteins and then speculate on the biological function of these proteins.