RNA editing at adenosine 1012 (amber/W site) in the antigenomic RNA of hepatitis delta virus (HDV) allows two essential forms of the viral protein, hepatitis delta antigen (HDAg), to be synthesized from a single open reading frame. Editing at the amber/W site is thought to be catalyzed by one of the cellular enzymes known as adenosine deaminases that act on RNA (ADARs). In vitro, the enzymes AD...

Hepatitis delta antigen (HDAg) was first described by Rizzetto et aL. (1977). Hepatitis D virus (HDV), also known as the 'delta agent', is a satellite agent of hepatitis B virus (HBV). HDV does not synthezise its own coat; it is enveloped by hepatitis B surface antigen (HBsAg), which occurs as large (L), middle (M) and smaII or major (S) surface proteins, differing in the length of the amino-te...

A host-mediated RNA-editing event allows hepatitis delta virus (HDV) to express two essential proteins, the small delta antigen (HDAg-S) and the large delta antigen (HDAg-L), from a single open reading frame. One or several members of the ADAR (adenosine deaminases that act on RNA) family are thought to convert the adenosine to an inosine (I) within the HDAg-S amber codon in antigenomic RNA. As...

None of the mutations so far discovered in several hepatitis delta virus (HDV) isolates appears to determine important changes in HDV specific protein (HDAg) expression, except for a putative mutation at nucleotide 1012 converting an amber stop codon (TAG) to a codon for tryptophan (TGG). Here we present the characterization of an HDV obtained from the liver of a woodchuck inoculated with sera ...

Human hepatitis delta virus (HDV) is the only animal virus known to replicate its RNA genome using a host polymerase because its only virally encoded proteins, the small and large hepatitis delta antigens (HDAg-S and HDAg-L), lack polymerase activity. Although this makes HDV an ideal model system to study RNA-directed transcription in mammalian cells, little is known about the host factors invo...

The hepatitis delta virus genome is a small circular RNA, similar to viroids. Although HDV contains a gene, the protein produced (HDAg) is encoded by less than half the genome and possesses no RNA polymerase activity. Because of this limited coding capacity, HDV relies heavily on host functions and on structural features of the viral RNA-very much like viroids. The virus' use of host RNA editin...

Hepatitis delta virus (HDV) contains two RNA species (HDV-S and HDV-L), which encode the small and large forms of hepatitis delta antigens (S- and L-HDAg), respectively. HDV-L RNA is a result of an RNA editing event occurring at an amber/W site of HDV-S RNA. RNA editing must be regulated to prevent premature and excessive accumulation of HDV-L RNA in the viral life cycle. In this study, we used...

Hepatitis delta virus (HDV) is a distant relative of plant viroids in the animal world. Similar to plant viroids, HDV replicates its circular RNA genome using a double rolling-circle mechanism. Nevertheless, the production of hepatitis delta antigen (HDAg), which is indispensible for HDV replication, is a unique feature distinct from plant viroids, which do not encode any protein. Here the HDV ...

Hepatitis delta antigen (HDAg) consists of two species, large (LHDAg) and small (SHDAg), which are identical in sequence except that the large form contains 19 extra amino acids at the C terminus. The large form is prenylated on the Cxxx motif. The small form can trans activate HDV RNA replication, while the large form inhibits it. To determine the molecular basis for their differential functio...

Hepatitis delta virus (HDV) is a small RNA virus that contains one 1.7-kb single-stranded circular RNA of negative polarity. The HDV particle also contains two isoforms of hepatitis delta antigen (HDAg), small (SHDAg) and large HDAg. SHDAg is required for the replication of HDV, which is presumably carried out by host RNA-dependent RNA polymerases. The localization and the HDAg and host RNA pol...