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'''Hepatitis D''' is a [[disease]] caused by a small circular [[RNA virus]] ('''Hepatitis delta virus''' or '''hepatitis D virus''', '''HDV'''); this virus is |
'''Hepatitis D''' is a [[disease]] caused by a small circular [[RNA virus]] ('''Hepatitis delta virus''' or '''hepatitis D virus''', '''HDV'''); this virus is a [[subviral satellite]]. In a natural infection, it can only propagate in the presence of of another virus, the [[Hepatitis B|hepatitis B virus (HBV)]]. When this transmission occurs simultaneously, it is called [[coinfection]]. When the hepatitis D virus infects cells previously infected with hepatitis B, it is called [[superinfection]]. |
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Either superinfection or coinfection can seriously worsen the damage to the [[liver]] caused by hepatitis B, causing [[cirrhosis]] or [[hepatocellular carcinoma]] (liver [[cancer]]). |
Either superinfection or coinfection can seriously worsen the damage to the [[liver]] caused by hepatitis B, causing [[cirrhosis]] or [[hepatocellular carcinoma]] (liver [[cancer]]). |
Revision as of 08:30, 8 September 2006
Template:Taxobox begin Template:Taxobox begin placement virus Template:Taxobox group v entry Template:Taxobox genus entry Template:Taxobox species entry Template:Taxobox end placement Template:Taxobox end Hepatitis D is a disease caused by a small circular RNA virus (Hepatitis delta virus or hepatitis D virus, HDV); this virus is a subviral satellite. In a natural infection, it can only propagate in the presence of of another virus, the hepatitis B virus (HBV). When this transmission occurs simultaneously, it is called coinfection. When the hepatitis D virus infects cells previously infected with hepatitis B, it is called superinfection.
Either superinfection or coinfection can seriously worsen the damage to the liver caused by hepatitis B, causing cirrhosis or hepatocellular carcinoma (liver cancer).
The tropical fever called Lábrea fever, detected in the Amazon for the first time, has been identified as a type of hepatitis D.
The hepatitis D virus genome consists of a negative sense single strand of RNA which forms a circular structure such that around 70% is Watson Crick base paired. With only 1700 nucleotides this virus has the smallest genome of any known to infect animals. It appears to have originated from a viroid which at some point acquired a cellular gene; the delta antigen.
Replication, using an RNA dependant RNA polymerase, first requires the formation of a positive sense RNA template from which a negative sense genome can be produced and part of this positive sense strand is cleaved to produce mRNA encoding the delta antigen.
There are two different forms of this antigen, which differ by 19 amino acids at the c-terminal, and the larger of the two associates with the RNA genome of the hepatitis B virus preventing its replication. It also directs packaging of HDV genomes into HBV particles.