Hepatitis B Virus
One-Sentence Definition
Hepatitis B virus (HBV) is a partially double-stranded DNA hepadnavirus causing acute and chronic hepatitis, cirrhosis, and hepatocellular carcinoma — preventable by highly effective subunit vaccination.
Taxonomy & Morphology
- Hepadnaviridae; small enveloped DNA virus
- Replicates via RNA intermediate (reverse transcriptase) — not a retrovirus
Virulence Highlights
- cccDNA persistence in nucleus → chronicity
- HBsAg, anti-HBc, anti-HBs serologic patterns define infection phase
- High chronicity risk if acquired perinatally
Clinical Syndromes
- Acute hepatitis (± fulminant)
- Chronic hepatitis → cirrhosis, HCC
- Occult HBV (low-level DNA, complex serology)
Diagnosis
| Marker | Meaning |
|---|---|
| HBsAg | Active infection |
| anti-HBc IgM | Acute/recent |
| anti-HBs | Immunity (vaccine or recovery) |
| HBV DNA PCR | Viremia; treatment monitoring |
Treatment / Prevention
- Vaccine (HBsAg) — neonatal schedule cornerstone (Vaccination)
- PEP: HBIG + vaccine after exposure
- Chronic: antivirals (tenofovir, entecavir) — long-term suppression
Related Notes
- Hepatitis C Virus · Gastrointestinal Infections · MOC - Virology
- Serology in Clinical Microbiology · Adaptive Immunity
Active Recall
- Which serology pattern indicates vaccine immunity?
- Why is perinatal acquisition high risk for chronicity?
- HBV DNA vs HBsAg roles?