Hepatitis B

Question 1

How is hepatitis B transmitted?

Answer 1

Percutaneous (IVDU)
Permucosal (sexual transmission)
High rate (30-50%) of perinatal transmission if mother is HBeAg+

Question 2

Describe the structure of hepatitis B

Answer 2

Outer envelope and inner capsid with dsDNA

There are also incomplete particles with only envelope proteins (HBsAg particles)

Question 3

How does hepatitis B replicate and what is the significance of this?

Answer 3

Pregenomic RNA undergoes RT to make dsDNA of the EC virion

High error rate means mutants are produced

Question 4

Describe the life cycle of hepatitis B

Answer 4

Acquired from blood, semen or other secretions via injection or sexual contact
Penetrates intestinal mucosa
Enters blood
Replicates in liver
Shed in bodily fluids

Question 5

What is the incubation period for hepatitis A?

Answer 5

~60-90 days

Question 6

In what demographic does hepatitis B most commonly cause chronic illness?

Answer 6

<5 years

Question 7

In what demographic does hepatitis B most commonly produce acute symptoms?

Answer 7

> 5 years

Question 8

What markers are measured in hepatitis B serology and what do they mean?

Answer 8

HBsAg: surface protein, general marker of infection
Anti-HBs: document recovery and/or immunity/successful vaccination
Anti-HBc IgM: to core protein, marker of acute infection
Anti-HBc IgG: to core protein, marker of past or chronic infection
HBeAg: variant of core protein, indicates viral replication (can be used to monitor therapy)
Anti-HBe: virus no longer replicating (can still be HBsAg+, made by integrated HBV)
HBV-DNA: indicates viral replication (more accurate than HBeAg, used to monitor therapy)

Question 9

What are the possible sequelae of chronic hepatitis B?

Answer 9

Cirrhosis
Liver failure
HCC (most common cause)

Question 10

How does hepatitis B cause HCC?

Answer 10

Partial integration of HBV genome within hepatocyte at random
Accumulation of chromosomal mutations

Question 11

How is chronic hepatitis B treated?

Answer 11

Pegylated IFN-a

Nucleoside/nucleotide analogues

Question 12

3TC

Answer 12

Nucleoside analogue

Question 13

Adefovir

Answer 13

Nucleotide analogue

Question 14

Limitation of nucleoside/nucleotide analogues

Answer 14

Low rate of viral clearance, relapse after stopping therapy

Question 15

What is the hepatitis B vaccine used for?

Answer 15

Pre-exposure prevention of HBV and HDV

Post-exposure for healthcare workers

Question 16

How can perinatal transmission of hepatitis B be prevented?

Answer 16

With treatment of infected mother (lower rates of transmission to 1-2%)
Vaccination of baby immediately postnatally