Hepatitis B virus Flashcards
Genome of Hepatitis B
- circular
- double stranded
- DNA
Capsid of Hepatitis B
- icosahedral
- core protein: Hepatitis B core antigen(HBcAg)
- soluble core protein: HBeAg
Detection of HBeAg is an indicator of
HBV replication phase
Envelope of Hepatitis B
Hepatitis B surface antigen(HBsAg)
S: large HBsAg protein
S2: medium HBsAg protein
S1: small HBsAg protein
Unique aspect of replication of Hepatitis B
Even though DNA, encodes a reverse transcriptase and replicates through an RNA intermediate.
Replication process of Hepatitis B
- ds DNA enters into the nucleus
- transcription to produce 4 mRNAs
- mRNA moves to cytoplasm
- core proteins assemble around larger mRNA
- sense DNA synthesized by a reverse transcriptase activity in the core
- RNA degraded as a positive sense DNA
- Core is enveloped, released by exocytosis.
Incubation of acute hepatitis B
- period of 1-6 months
Symptoms of acute hepatitis B
- icteric(Jaundice) hepatitis
- anorexia, nausea, vomiting, low grade fever, myalgia
- fatiguability, right upper quadrant and epigastric pain
- jaundice
Rare symptoms of acute hepatitis B
- fulminant hepatitis
- risk of developing GI bleeding
- coma, hepatic encephalopathy, ascites, coagulopathy
Results following acute hepatitis B
- complete recovery with life immunity
- will not develop “chronic” hepatitis
Chronic hepatitis B infection
-individuals who can’t fight off virus will develop “chronic” hepatitis
Chronic carriers
-patients with chronic hepatitis B can be healthy carriers
Designation to become a chronic carrier
- chronic hepatitis B infection for longer than 6months
Symptoms of chronic active hepatitis B
-fatigue, anorexia, nausea, mild upper quadrant pain
Hepatitis B and risk to infants
-contract hepatitis B during birth, and turn into chronic
Risks of chronic hepatitis B infection
- liver damage
- liver failure
- liver diseases like cirrhosis and cancer
Pathogenesis of chronic hepatitis B infection
- HBV infection does not directly cause the issue
- cell mediated immune lysis of infected cells produces symptoms
Insufficient immunity of hepatitis B can lead to what
Chronic hepatitis B infection
Typical hepatitis B disease progression
Acute infection => chronic infection => liver cancer, cirrhosis, liver failure => death
Typical immunology response to Acute hepatitis B
HBsAg : peaks 4-24wks
IgM anti-HBc : peaks 7-32wks
IgG anti-HBs : peaks 32wks and on
Total anti-HBc : begins after 7wks, rises, constant
Immunology response that leads to chronic hepatitis B?
- lack of the IgG anti-HBs development
- constant presence of HBsAg
Epidemiology of Hepatitis B
- blood, sex, direct contact
- in utero or birth
Occurrence of chronic hepatitis B infection
- not prevalent in N. A., western europe
- more common everywhere else
Treatment for hepatitis B
- Acute : no treatment
- Chronic: reverse transcriptase inhibitor, polymerase inhibitor ( Lamivudine, Adefovir)
Control of hepatitis B
- screening donated blood
- passive or active immunizations
