Hepatitis

Question 1

What is hepatitis?

Answer 1

• ‘inflammation of the liver’

Question 2

Explain the difference between acute and chronic hepatitis?

Answer 2

• Acute disease: weeks to months
  
  • non-specific, flu-like symptoms
  • jaundice, dark urine, pale faeces
• Chronic disease: years to lifetime
  
  • general malaise
  • cirrhosis, liver cancer

Question 3

Where do hepatitis viruses replicate?

Answer 3

Hepatitis viruses replicate in hepatocytes in the liver

Question 4

What causes the damage in hepatitis?

Answer 4

Hepatitis viruses replicate in hepatocytes in the liver

• the immune response to hepatitis viruses causes liver damage
  
  • -> Jaundice from hyperbilirunemia
  • -> Cirrhosis from chronic liver damage
  • -> Hepatocellular carcinoma

Question 5

What is the pathogenesis of hepatitis?

Answer 5

• Hepatitis viruses are not cytolytic; they replicate in the liver but do not kill the liver cells and the disease is caused by the immune response to the replicating viruses.
• Age-related outcomes depending upon the age of the individual at infection
• Exposure early in life results in
  
  • less severe acute disease
  • higher rates of chronic infection

Question 6

What are some types of viral hepatitis? Which of these causes acute and chronic infections?

Answer 6

Hepatitis A (HAV) --> “infectious hepatitis” 
Hepatitis B (HBV) --> “serum hepatitis” 
Hepatitis C (HCV) --> serum non-A, non-B 
Hepatitis D (HDV) --> dependent on HBV 
Hepatitis E (HEV) --> enteric non-A, non-B

• unrelated to each other and so consequently there is no cross-protection
• HBV & HCV cause chronic infection
• A and E are examples of Acute viruses.

Question 7

What are some features of Hepatitis A Virus?

Answer 7

- Picornaviridae family - Hepatovirus 
	– (other relatives = polio, rhinoviruses) 
- Non-enveloped (+) ssRNA virus 
	– 30nm particle resistant to stomach acid 
	– 7500nt coding a single polyprotein 
- Single serotype worldwide 
- Infects man, many higher primates 
- Replicates in cell culture

Question 8

Explain the significance of the location of replication for Hep A.

Answer 8

The initial site where the virus invades and replicates is the intestinal epithelia; but the primary replication site is in the liver.