Hepatitis Flashcards
Which form of chronic hepatitis is most prevalent in the US?
Hepatitis C.
Hepatitis A
Describe its structure, shape, and genome.
How many serotypes are there?
How is it spread?
Hepatitis A
It is a simple picornavirus–naked, icosahedral, with a simple RNA genome (encodes 1 polypeptide).
Only 1.
Fecal-oral transmission; contaminated food, daycare, etc.
Hepatitis A
What is the cause of pathology?
How long is the incubation period? Virulent period?
Describe the vaccine. Who is recommended to receive it?
Hepatitis A
Usually immune response creates the disease symptoms.
Roughly 1 month, but the virus is shed prior to that.
A formalin-inactivated vaccine conjugated to aluminum hydroxide. Indicated only for those at high risk (infants, travelers, people with liver disease).
Hepatitis __E
Describe its structure, shape, and genome.
How many serotypes are there?
How is it spread?
Hepatitis E
It is a calicivirus; simple, naked, icosahedral with +ssRNA genome (Type IV).
Four.
Fecally contaminated drinking water, in endemic regions like Africa and Asia.
Hepatitis B
Describe its structure, shape, and genome.
How many serotypes are there?
Describe what occurs following viral fusion.
Hepatitis B
It is a hepadnavirus; enveloped with a circular DNA (partially ds) genome.
A-H, so 8.
The DNA genome is extended (full ds), an mRNA transcript is created, from which new virion DNA is formed via reverse transcriptase. Kinda weird.
Hepatitis B
Why do electron micrographs display a heterogeneous mix of viral particles?
How is it spread?
Describe the course of illness.
Hepatitis B
Some of these are sub-viral particles, which contain only surface antigens (“decoy”).
Sexual contact, shared needles, neonatal transmission.
Incubation is ~2 months, then symptoms emerge including jaundice, fever, malaise. Immunity takes months to develop. Infection may become chronic.
Hepatitis B
What are some possible outcomes?
What determines if chronic infection will develop?
How are adults affected differently than infants?
Hepatitis B
Most cases resolve. If the infection becomes chronic, there is risk for hepatic cell carcinoma and extrahepatic disease.
How robust the cell-mediated response is.
Adults are less likely to develop chronic illness.
What is the significance of Hepatitis D (delta)?
Hepatitis Delta is a “viroid” that coinfects with hepatitis B. It encodes a peptide that packages in the hep B surface antigen, and results in a more serious disease course–higher chance of liver failure and fulminant hepatitis.
Can also cause “superinfection” in those chronically infected with B.
Hepatitis B
How is it treated?
Describe the vaccine.
Hepatitis B
Certain inferferons and NRTIs can treat them, but resistance has been observed.
A recombinant particle of surface antigen (HBsAg), presumably inspired or taken from the viral subparticles.
Hepatitis C
Describe its structure, shape and genome.
How many serotypes are there?
How is it spread?
Hepatitis C
It is a flavivirus; enveloped with +ssRNA genomes.
There are many, many “quasi-species” which are highly variable.
Primarily by IVDU, but also sexually and previously via transfusion.
Contrast these traits of illness between Hepatitis B and C:
Incubation period
Cause of pathology
Outcome of illness
Longer incubation in B (1mo vs 2mo)
Same; mostly due to immune response.
Same negative outcomes (hepatocarcinoma, liver failure) but much higher incidence of persistent infection in C (85% vs 10%).
How do the following Hep C viruses contribute to hepatocellular carcinoma:
Core protein
Envelope protein 2 (E2)
Non-structural proteins (NS3/5)
Core affects tumor suppressors (p53, Rb) and induces steatosis.
E2 inhibits natural killer cells.
Non-structural proteins affect p53.
What factor, expressed in the liver, facilitates HCV infection? How?
How can this be targeted for HCV treatment?
Are there any other host factors that affect HCV infection?
miRNA-122, which enhances expression of the HCV genome. Crucial to expedient replication.
Targeting this microRNA for deletion may treat illness.
The IL28B gene appears to be implicated (new research…)
Hepatitis C
What are some targets of treatment?
What is “SVR”?
Hepatitis C
Entry, translation, replication–not dissimilar to other viral infections.
SVR (sustained viral response) is a measure of viral treatment efficacy. Appears to only apply to hepatitis C…
