[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Microbiology](https://durgical.com/en/microbiology/) › [Other DNA viruses](https://durgical.com/en/microbiology/groups/other-dna-viruses/) › Hepatitis B virus [Microbiology](https://durgical.com/en/microbiology/) · [Other DNA viruses](https://durgical.com/en/microbiology/groups/other-dna-viruses/) # Hepatitis B virus - Virus - Enveloped - Exam priority: high A virus that infects the liver; it may clear or become chronic and lead to cirrhosis and liver cancer. A vaccine is given from birth. Updated 2026-11-01 Also called: HBV ## Key points - Quick read: HBsAg = current infection; IgM anti-HBc = acute; anti-HBs = immunity; HBeAg = replication and high infectivity. - Vaccinated: anti-HBs only. Resolved infection: anti-HBs plus total anti-HBc. - Chronic infection is almost the rule when infection happens at birth and rare in adults: hence the birth dose. - A DNA virus that replicates with reverse transcriptase; hepatocellular carcinoma can appear without cirrhosis. ## At a glance **Shape** Spherical (Dane particle) with an HBsAg-bearing envelope **Genome** Circular, partially double-stranded DNA (replicates with reverse transcriptase) **Envelope** Enveloped **Family** Hepadnaviridae **Size** About 42 nm ## Morphology - Complete particle (Dane particle): envelope with HBsAg and nucleocapsid with HBcAg - Infected blood also holds many empty HBsAg particles without genome - HBeAg is a secreted protein that goes with active replication ## Transmission - Perinatal, mother to child at birth (the main route in endemic areas) - Sexual - Parenteral: shared needles, unsafe injections, needlestick injuries in health care - Close household contact in childhood (wounds, sharp objects) **Reservoir:** Humans ### Isolation precautions What the care team adds to standard precautions. - Standard ## Life cycle - The virus enters the hepatocyte through the bile-salt receptor NTCP. - The genome reaches the nucleus and is repaired into covalently closed circular DNA (cccDNA), which persists. - Messenger RNAs and a pregenomic RNA are transcribed. - Inside the capsid, reverse transcriptase copies the pregenomic RNA into DNA. - Nucleocapsids are enveloped in the endoplasmic reticulum and leave without killing the cell. ## Virulence factors - Liver damage comes mainly from cytotoxic T cells attacking infected hepatocytes, not from the virus itself - Nuclear cccDNA explains why antivirals control but rarely cure - Integration of viral DNA and chronic inflammation favour hepatocellular carcinoma, even without cirrhosis - The HBx protein disturbs cell regulation and adds to oncogenesis ## Diseases it causes - Acute and chronic hepatitis B [Viral hepatitis →](https://durgical.com/en/conditions/viral-hepatitis/) - Liver cirrhosis [Cirrhosis →](https://durgical.com/en/conditions/cirrhosis/) - Hepatocellular carcinoma [Hepatocellular carcinoma →](https://durgical.com/en/conditions/hepatocellular-carcinoma/) - Extrahepatic disease: polyarteritis nodosa and membranous glomerulonephritis ## Clinical picture - Acute infection may be silent or cause jaundice, dark urine, fatigue and very high transaminases - The chance of chronic infection depends on age: the rule in newborns, the exception in adults - Co-infection or superinfection with hepatitis delta virus (HDV), which only replicates when HBsAg is present and worsens disease ## Diagnosis - HBsAg positive: current infection (acute or chronic), the person is infectious - IgM anti-HBc positive: recent or acute infection; it can also appear in severe flares - Total anti-HBc positive with HBsAg negative and anti-HBs positive: past, resolved infection - Anti-HBs positive alone (anti-HBc negative): immunity from vaccination - HBeAg positive: active replication and high infectivity; conversion to anti-HBe usually marks lower replication - Window period: HBsAg has gone and anti-HBs is not yet detectable; IgM anti-HBc is the key marker (anti-HBe may also be present) - Viral load (HBV DNA) by PCR to decide on and follow treatment ## Treatment Acute infection is usually managed with supportive care. Chronic infection is treated with high-barrier nucleoside or nucleotide analogues (tenofovir, entecavir), which suppress but rarely eliminate the virus; pegylated interferon alfa is another option. Lamivudine is no longer preferred because resistance is common. Drug class only; doses and regimens are set by the clinician from the current guideline. In Pharmacology: - [Entecavir](https://durgical.com/en/pharmacology/entecavir/) ## Prevention - Recombinant HBsAg vaccine, with the first shot within hours of birth - HBsAg screening in every pregnancy - Newborn of an HBsAg-positive mother: vaccine plus hepatitis B immune globulin within 12 hours - Screened blood, sterile equipment, condoms and post-exposure prophylaxis at work **Vaccine:** Recombinant vaccine (HBsAg). In Colombia's PAI: a birth dose, then within the combined vaccine of the first year of life. ## In Colombia Hepatitis B is a notifiable SIVIGILA event (hepatitis B, C and B-Delta co-infection). Historically the Amazon region and the Sierra Nevada de Santa Marta have had higher endemicity, with cases of hepatitis delta. ## Memory aid The e in HBeAg is for extra-infectious, IgM anti-core is for current (recent) infection, and anti-surface means safe (immune). ## Test yourself Think of the answer, then tap the question to see it. ## Which serologic pattern fits a vaccinated person with no past infection? HBsAg negative, total anti-HBc negative and anti-HBs positive. ## Which marker shows infection during the hepatitis B window period? IgM anti-HBc: HBsAg has disappeared and anti-HBs is not yet detectable. ## What does a positive HBeAg mean in chronic hepatitis B? Active viral replication, a high viral load and greater infectivity, including perinatal transmission. [Add to my cards (3)](https://durgical.app/estudiar/?add=/en/microbiology/hepatitis-b-virus/) ## Related - [Human papillomavirus](https://durgical.com/en/microbiology/human-papillomavirus/) ## Related conditions - [Viral hepatitis](https://durgical.com/en/conditions/viral-hepatitis/) - [Cirrhosis](https://durgical.com/en/conditions/cirrhosis/) - [Hepatocellular carcinoma](https://durgical.com/en/conditions/hepatocellular-carcinoma/) ## What the colours mean **Gram-positive** Thick peptidoglycan wall: stains purple. **Gram-negative** Thin wall with an outer membrane: stains pink. **Acid-fast** Lipid-rich wall (mycobacteria): Ziehl–Neelsen stain. [← Back to the group: Other DNA viruses](https://durgical.com/en/microbiology/groups/other-dna-viruses/) Educational content on microorganisms; not a treatment guide and no substitute for a health professional's advice. No doses are given. Sources: [Hepatitis B](https://www.who.int/news-room/fact-sheets/detail/hepatitis-b) (WHO, 2025); [Clinical Testing and Diagnosis for Hepatitis B](https://www.cdc.gov/hepatitis-b/hcp/diagnosis-testing/index.html) (CDC, 2025); [Recommendations for Identification and Public Health Management of Persons with Chronic Hepatitis B Virus Infection](https://cdc.gov/mmwr/preview/mmwrhtml/rr5708a1.htm) (CDC (MMWR), 2008); [Clinical Overview of Perinatal Hepatitis B](https://www.cdc.gov/hepatitis-b/hcp/perinatal-provider-overview/index.html) (CDC, 2025). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/microbiology/hepatitis-b-virus/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/microbiology/hepatitis-b-virus/