Hepatitis -

Hepatitis B Virus

ds DNA virus
Infective “Dane“ particle consists of inner core & outer coat
- Inner core contains DNA & DNA Polymerase
  - Replicates within nuclei of infected hepatocytes
- surface coat added in the cytoplasm as the Hep B s Ag

Hep B s Ag
Australia antigen
Associated with surface coat
First evidence of infection & implies infectivity of blood
- Incubation period appears 1-6 weeks prior to biochemical or clinical illness
- Disappears during convalescence
Anti HBs (antibody) appears weeks or months later
- It implies past infection & relative protection in future
- 10% will not have the antibody & they become chronic carriers

Core antigen
Found in infected hepatocytes
Not detectable in serum except using techiques that disrupt the Dane particle
Antibody to it (Anti HBc) reflects active viral replication & appears early in illness
- Gradually reducing titre for years after
- Usually indicates past infection only
Maybe only positive test in window period between HB s Ag disappearance & appearance of Anti HBs

Constituent of the core
Found only in Hep B s Ag positive serum
Indicates greater infectivity & greater chance of progression to chronic hepatitis
Presence of antibody (Anti HBe) indicates less infectivity & more benign outcome

HBsAg
- Currently infected & Infectious
Anti HBs
- Vaccinated or Post-Infection Immunity
Anti HBc
- Post-Infection Immunity useful in window period between HBsAg disappearance & appearance of Anti HBs
Others
- HBeAg
  - Older marker of infectivity with greater chance of chronic hepatitis
- Anti-HBe
  - Indicates less infectivity
- HBVDNA
  - Direct marker infectivity
  - Acute & Chronic Hepatitis

Parenteral spread
- Blood or blood products
High risk groups
- IV drug users
- Homosexuals
- Haemophiliacs
- Renal dialysis patients
Extremely infectious groups
- IV drug abuse
- Homosexual
- Neonatal infection
Transmission via sweat described through intact gloves from surgeon
1 million infective doses/ ml blood

First recognised 1974
ss RNA virus
Usually presents in chronic form or as serological diagnosis
Transmission
- Mainly IV Drug abuse
- Also in multiple transfusions (haemophilia)
- Little evidence for sex spread
Commonest transmitted hepatitis via blood transfusions
- 0.5% blood donors positive
Anti HCV within 3-6/12 of exposure
Usually subclinical infection
20% patients no obvious source
40% proceed to chronic liver disease
- 20% carriers get cirrhosis at 20 years
- 5% get hepatocellular carcinoma
Reduce by 25% the liver disease with Interferon usage