Hepatitis Flashcards
HAV class
Picornaviridae
HBV class
Hepadnaviridae
HCV class
Flaviviridae
Hep D class
Satellite, coinfect with B
Hep F class
???
Hep G class
Flaviviridae
HAV genome and structure
ss+RNA
Icosahedral capsid of 4 polypeptides (VP1-4)
Non-enveloped
HAV genome distinguishing feature:
VPg (protein) on 5’ end
HAV inactivated by (5 things)
Chlorine
Formalin
Peracetic acid
Beta-propiolactone
UV
Replication of HAV (6 steps)
Receptor binding
Uncoating (+RNA)
Translation/Proteolytic processing
Replication
Assembly
Maturation and release
HAV produces _____ infection
acute
HAV incubation period length
2-6 weeks
2 phases of HAV infection
1. Prodrome (flu-like, immune mediated hepatic damage)
2. Icteric (billirubinemia, jaundice, abdominal pain)
- symptoms wax/wane
- complete recovery in 99% cases
Immunogically, acute HAV infection results in
lifelong immunity
icterus is an increase in
unconjugated bilirubin
What happens to conjugated bilirubin?
Water soluble, renal excretion
HAV replication occurs in __________ (in body)
Oropharynx or GI tract
HAV is shed in the _______
bile and feces
Does HAV cause viremia?
Yes
Brief
HAV can be detected…
in the stool before symptoms occur
Three serological peaks during HAV infection
ALT at 2 months
IgM anti-HAV at 3 months (recent infection)
Total anti-HAV (immunity
HAV transmission routes (3 categories)
Close personal contact
Contaminated food
Blood exposure (rare)
Seroprevalence of HAV antibodies
40-70% of adults
Serological distinction between acute and past HAV infection
IgM = Acute
IgG = Past
IgM and IgG are detected by
ELISA
Is RT PCR useful in detection of HAV?
It may detect earlier than serology, but it is rarely performed
HAV vaccines
HAVRIX
VAQTA
TWINRX
Who is TwinRx not recommended for? What’s the dosing schedule?
All patients under 18 years of age.
3 doses @ 0, 1, 6 months
HBV genome and structure
Genome: Circular dsDNA
Capsid: Icosahedral
Enveloped
HBV capsid proteins
- Core Protein
(HBcAG) - Soluble core protein
(HBeAG)
What is HBeAG?
Indicator of active HBV replication phase
(it is a variant of the core protein that was modified within the cell)
HBV envelope proteins
Surface antige (HBsAG)
3 forms:
- S = large
- S2 = medium
- S1 - small
Unique feature of the DNA virus HBV
Encodes a RT enzyme
replicates through RNA intermediate
The first weird step of HBV replication cycle
Second and third steps?
- After uncoating, partially double stranded DNA genome is completed by host enzymes – becomes CCCDNA (Covalently Closed Circular DNA)
- Four mRNAs are made (one giant one)
- Goes to cytoplasm where the mRNAs assemble around the big one, and NEGATIVE DNA is made by Reverse Transcriptase
What happens after DNA is synthesized in HBV replication?
RNA Degrades, and the POSITIVE counterpart to the negative DNA is synthesized.
The envelope forms before this completes
HBV released from cell via ______ after assembly
Exocytosis
HBV causes what kinds of infections?
Acute or chronic
Acute HBV incubation time
1-6 months