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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
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
RNA editing generates __
two forms of hepatitis delta antigen
- small delta antigen is needed for replication
- large delta antigen is part of the virion
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
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
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
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
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