INTERACTION BETWEEN HEPATITIS-DELTA VIRUS-ENCODED PROTEINS AND HEPATITIS-B VIRUS ENVELOPE PROTEIN DOMAINS

Hepatitis delta virus (HDV) packaging requires prenylation of the HDV large protein (p27), as well as a direct protein-protein interaction b etween HDV proteins and hepatitis B virus (HBV) envelope protein domai ns. To investigate this interaction, we have analysed the binding capa city of baculovirus-expressed delta p24 and p27 proteins to synthetic peptides specific for the HBV envelope. Although a higher degree of bi nding was observed with p27, both p24 and p27 could bind HBV envelope peptides. One such peptide corresponded to residues 56-80 located in t he cytosolic loop of the small HBV envelope protein, and another corre sponded to 23 carboxy-terminal residues of the pre-S1 specific to the large HBV envelope protein. This indicates that in addition to p27, p2 4 may contribute to packaging of HDV through a protein-protein interac tion with HBV envelope domains, and that an interaction between the pr e-S1 polypeptide and delta proteins may play a role in infectivity.