Hepatitis B virus

What is hepatitis?

Inflammation of the liver

How long does acute hepatitis last?

It resolves within 6 months

What are the possible outcomes of acute hepatitis?

It can be self-limiting chronic or rarely cause acute liver failure

How long does hepatitis need to last to be considered chronic?

More than 6 months

What are possible complications of chronic hepatitis?

Carrier state cirrhosis liver failure or liver cancer

What are the symptoms of hepatitis?

Fatigue headaches anorexia fever nausea vomiting hepatomegaly abdominal pain jaundice and dark-colored urine

How severe can hepatitis be?

It can be asymptomatic mild severe chronic or fatal

What is primary hepatitis?

Hepatitis that affects the liver without affecting other organ systems

What are the complications of primary hepatitis?

Cirrhosis liver failure and hepatocellular carcinoma

What percentage of primary hepatitis cases are caused by hepatitis viruses?

More than 80%

What are noninfectious causes of hepatitis?

Autoimmune hepatitis alcoholism and medications

What connects hepatitis viruses as a group?

Their ability to cause inflammation of the liver

Which hepatitis virus has a DNA genome?

Hepatitis B virus (HBV)

Which hepatitis viruses have RNA genomes?

Hepatitis A C D and E viruses

What is secondary hepatitis?

A secondary infection of the liver following a disseminated infection (viremia)

Which viruses can cause secondary hepatitis?

Epstein-Barr virus (EBV) cytomegalovirus (CMV) and varicella-zoster virus (VZV)

What is direct liver injury?

Damage to hepatocytes caused directly by a substance

What commonly causes direct liver injury?

Medications or toxins such as ethanol

What is the first-pass effect in the liver?

Metabolism that occurs as substances pass through the liver

How do AST and ALT change during direct liver injury?

They increase rapidly

What is indirect liver injury?

Liver damage caused by the immune response to viruses toxins medications or other substances

Which innate immune components are involved in indirect liver injury?

Natural killer (NK) cells and interferons (IFNs)

Which adaptive immune cells are involved in indirect liver injury?

T cells

Who is at greater risk of chronic infection?

Individuals with impaired immunity

How do AST and ALT change during indirect liver injury?

They rise gradually

What family does hepatitis A virus (HAV) belong to?

Picornaviridae

What family does hepatitis B virus (HBV) belong to?

Hepadnaviridae

What family does hepatitis C virus (HCV) belong to?

Flaviviridae

What family does hepatitis D virus (HDV) belong to?

It has no assigned family

What family does hepatitis E virus (HEV) belong to?

Hepeviridae

What type of genome does HAV have?

Single-stranded RNA (ssRNA)

What type of genome does HBV have?

Double-stranded DNA (dsDNA)

What type of genome does HCV have?

Single-stranded RNA (ssRNA)

What type of genome does HDV have?

Single-stranded RNA (ssRNA)

What type of genome does HEV have?

Single-stranded RNA (ssRNA)

How is HAV transmitted?

Fecal-oral transmission

How is HBV transmitted?

Parenteral exposure sexual contact and vertical transmission

How is HCV transmitted?

Through the same routes as HBV

How is HDV transmitted?

Through the same routes as HBV

How is HEV transmitted?

Fecal-oral transmission

Can HAV cause a carrier state or chronic hepatitis?

No

What mortality rate is listed for HAV?

0.1–0.2%

Can HBV cause a carrier state and chronic hepatitis?

Yes

What mortality rate is listed for HBV?

5–10%

Can HCV cause a carrier state and chronic hepatitis?

Yes

What mortality rate is listed for HCV?

0.5–2.0%

When can HDV cause chronic hepatitis?

With HBV infection

What mortality rate is listed for HDV?

Up to 30%

Can HEV cause chronic hepatitis?

Rarely

What mortality rate is listed for HEV?

1–3%

What family does HBV belong to?

Hepadnaviridae

What is the complete infectious HBV particle called?

The Dane particle

Is HBV enveloped?

Yes

What shape is the HBV nucleocapsid?

Icosahedral

What is the HBV genome like?

Circular and partially double-stranded DNA

How are the two strands of HBV DNA different?

One strand is full-length and bound to DNA polymerase while the other is incomplete

What templates can HBV DNA polymerase use?

Both DNA and RNA

What special activity does HBV DNA polymerase have?

Reverse transcriptase activity

What other enzyme activity does HBV DNA polymerase have?

Ribonuclease H (RNase H) activity

What does HBsAg stand for?

Hepatitis B surface antigen

What is HBsAg?

An envelope protein

What does HBcAg stand for?

Hepatitis B core antigen

What is HBcAg?

A nucleocapsid protein

What does HBeAg stand for?

Hepatitis B envelope antigen

Where is HBeAg found?

It is a soluble antigen found between the nucleocapsid and envelope

How is HBV transmitted parenterally?

Through blood or other infected body fluids

How many infectious HBV virions can be present per mL of blood?

Up to 1 million

Which body fluids can contain HBV?

Blood and most body fluids including breast milk

Which body fluids are less infectious for HBV?

Tears urine and sweat

What activities can transmit HBV through contaminated blood?

Sharing contaminated needles and blood transfusions

How else can HBV be transmitted besides parenteral exposure?

Sexual contact and vertical transmission

Which groups are at high risk for HBV infection?

IV drug users people with multiple sex partners healthcare personnel hemodialysis patients and infants born to HBV-positive mothers

Do all HBV-infected patients have known risk factors?

No

What determines HBV pathogenesis?

The viral infectious dose and the host's immune competence

What is the approximate incubation period of HBV?

Approximately 90 days

What is the HBV incubation period range?

60–150 days

How does HBV reach the liver?

It travels through the blood and infects hepatocytes

How is HBV infection slowly cleared?

Through an activated immune response

What is the most frequent form of HBV infection?

Asymptomatic infection

Approximately what percentage of HBV infections are asymptomatic?

About 50%

What happens to hepatocytes during asymptomatic HBV infection?

Infection causes minimal cytopathic effects and little to no inflammation

How does the immune response to HBV differ between adults and children?

Adults generally have a robust immune response while children have a weaker response

Which immune cells respond initially to HBV infection?

Natural killer (NK) cells

What do NK cells do during HBV infection?

Kill infected cells and recruit T cells

Which cells are responsible for hepatocellular damage and viral clearance in HBV infection?

Cytotoxic T lymphocytes (CTLs)

What immune complexes can form during HBV infection?

HBsAg and anti-HBs antibody immune complexes

What conditions can HBV immune complexes cause?

Vasculitis arthralgia and glomerulonephritis

What percentage of adults develop acute self-limited hepatitis after HBV infection?

About 20–30%

What are the symptoms of acute HBV hepatitis?

Fatigue headaches anorexia fever nausea vomiting abdominal pain jaundice and hepatomegaly

What is the outcome of acute self-limited HBV hepatitis?

Complete resolution

What percentage of people with acute HBV develop fulminant hepatitis?

Less than 1%

What is fulminant hepatitis?

Acute liver failure

What percentage of infants with HBV develop chronic infection?

About 90%

What percentage of children aged 1–5 with HBV develop chronic infection?

About 25–50%

What percentage of adults with HBV develop chronic infection?

About 5–10%

What is cirrhosis?

Fibrosis and scarring of liver tissue

What does HCC stand for?

Hepatocellular carcinoma

What is the prognosis for HBV-associated HCC according to the notes?

Poor; it is typically fatal within less than one year

What percentage of HCC cases worldwide are caused by HBV and HCV combined?

Approximately 80%

How can hepatocellular carcinoma be treated?

Surgery or liver transplantation