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HDV is a
blood-borne pathogen that causes fulminant hepatitis and liver cancer. It has the same symptoms as Hep B, but it causes worse problems.
It is not really a full virus--more like a viroid or satellite virus--it can't even replicate on its own and requires Hep B. It may have evolved from a primitive viroid-like RNA
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How does HDV function?
it infects the cell, gets in, replicates DNA in the nucleus via a symmetric rolling circle mechanism.
It replicates in the liver and causes fulminant hepatitis, using Hep B envelope protein (S antigen) to package its RNA genome
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RNA editing generates __
two forms of hepatitis delta antigen
- small delta antigen is needed for replication
- large delta antigen is part of the virion
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Two different celular RNA polymerases are used to replicate.
- cellular RNA polymerase I is used to produce the antigenome
- Genome replication may use cellular RNA pol II
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Genome of Hep D
- One open reading frame, complementary to genome RNA
- - a polyadenylated mRNA is synthesized by cellular RNA polymerase
There are self-cleaving motifs used on both genome andcomplementary antigenome RNAs
can be folded into a rod-like structure through extensive internal base pairing
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Prognosis
1) Why we care?
2) What three things can happen?
1) it is really important clinically
- By itself: nothing
- Infected with both B and D at the same time
- Infected with Hep B, cleared and later exposed to HDV: bad
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What happens with a simultaneous infection of B and D
not that terrible; you're still at the 90%: 10% level where 90% are cleared; 10% get fulminant hepatitis
You don't really go chronic. You can either recover or go straight to the really bad stuff
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What happens with an infection of Hep B, clearance, and then later exposure to HDV?
This is when you go from an asymptomatic to a chronic disease
This is a super infection
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