Hepatitis B Virus Flashcards
Classification
Family: Hepadnaviridae
Genus: Hepadnavirus
Species: hepatitis B
(Hints: occurs with double layered blue clothes)
Characteristics
- enveloped virus
- incomplete circular dsDNA
- Virion DNA polymerase
- one serotype
> it replicates both inside and outside the nucleus:
- intranuclear replication
- cytoplasmic replication
Three important antigens:
- surface antigen
- core antigen
- e-antigen
Transmission
> Blood borne
During birth —> vertical transmission = “ TORCH infection”
> By sexual intercourse
Pathogenesis
Hepatocellular injury due to immune attack by cytotoxic (CD8) T cells
About 5 - 10% of HBV in adults result in a chronic carrier state
About 90 - 95% of newborns develop chronic carrier state
Disease
Hepatitis B
Polyarthritis nodosa (PAN) -> can lead to -> glomerulonephritis
Implicated as a cause of hepatocellular carcinoma
- chronic hepatitis —> cirrhosis —> hepatocellular carcinoma
Microbiological diagnosis
- HBV has not been grown in cell culture
- serological tests:
Presence of e antigen indicates a chronic carrier who is making infectious virus —> transmissibility
Detection of s antigen for more than 6 months indicates a chronic carrier state
An HBV-infected person who has neither detectable HBs antigen nor HBs antibody is said to be in the [Window Phase]
—> diagnosis of this patient is made by detecting HB core antibody
There is an increased level of ALT in patients with hepatitis B
Compared with hepatitis of alcoholism which has increased AST
Treatment and prevention
Treatment:
Inflammation of chronic hepatitis can be reduced (not cured) by:
Pegylated Alpha interferon
Lamivudine (a reverse transcriptase inhibitor)
minimize the damage by inhibiting replication
Prevention:
Three approaches:
1) VACCINE that containing surface antigen
2) Hyperimmune immunoglobulin with surface antibody
3) Education of chronic carriers regarding precautions
