Hepatitis B
Virus (HBV)
Epidemiology and
Etiology:
- Hepatitis
B virus:
- hepadnavirus
- Enveloped
dsDNA – circular
- Replication
via a RNA intermediate template
- Transmission:
- Parenteral
- Close
contact
- Hardy
virus – can be spread by contact with body secretions
- Vertical
through breast milk
- 4-26wk
incubation
- Primary
Risk factors:
- Blood
transfusion
- Blood
products
- Dialysis
- Needle-stick
accidents
- IV
drug abuse
- Homosexual
activity
- Endemic
areas:
Common sites:
- Present
in all physiologic and pathologic body fluids EXCEPT stool
-
Gross features:
Histologic
features:
Immunophenotype:
Marker:
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Sensitivity:
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Specificity:
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Molecular features:
Other features:
- Clinical
features:
- Acute
hepatitis following incubation period
- Many
weeks to months
- Fulminant hepatitis
(complicating <1% of acute hepatitis)
- Carrier
state (5-10% become healthy carriers)
- Defined
by HBsAg in serum > 6mo
- Chronic
hepatitis in 5-10% of acute infections
- 10-30%
of persistent infections will lead to chronic hepatitis
- Cirrhosis
– 20-50% of chronic hepatitis patients
- Vertical
transmission – carrier for life
- 2 Phases
of infection:
- Proliferative
Phase:
- Integrative
Phase:
- Complications:
- HCC
(10% of cirrhotic HBV patients)
- HDV
- Serology:
- Vaccination
is effective
- HBeAg
- Similar
to core antigen
- Secreted
into the blood
- HBcAg
- Remains
In hepatocytes for assembly of complete virions
- HBsAg
- Envelope
glycoprotein
- Infected
hepatocytes synthesize and secrete massive
quantities of mostly non-infective surface protein
- Spheres
/ tubules 22nm diameter
- HBVDNA
- EM:
- Spherical,
double layered “Dane particle” – 42nm
- Outer
surface envelope of protein, lipid, and carbohydrate
- Electron-dense,
28nm, slightly hexagonal core
-
References:
- Robbins
& Cotran Pathologic Basis of Disease (2005)