Hepatitis Delta Virus: HDV-HBV Interactions

The hepatitis delta virus (HDV) is a subviral agent that utilizes the envelope proteins of the hepatitis B virus (HBV) for cell to cell propagation. In infected human hepatocytes, the HDV RNA genome can replicate and associate with multiple copies of the delta protein to assemble a ribonucleoprotein (RNP). However the RNP cannot exit the cell because of the lack of an export system. This is provided by the HBV envelope proteins, which are capable of budding at an internal cellular membrane to assemble mature HDV virions when RNPs are present. This review covers advances in the molecular aspects of the HDV-HBV interactions, with an emphasis on the HBV properties that are instrumental in HDV maturation, in particular the central role of the small HBV envelope protein.