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Gastrointestinal > Infectious Causes of Hepatitis 2 > Flashcards

Infectious Causes of Hepatitis 2 Flashcards

1
Q

What is the transmission of hepatitis B, C and D?

A

blood and blood derived body fluids - sexually transmitted and IV drug use

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2
Q

What type of infection is caused by hepatitis B, C and D?

A

chronic

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3
Q

For which hepatitis virus is there perinatal transmission?

A

hepatitis B - can be reduced but not eliminated with drug treatment

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4
Q

What proportion of regular IV drug users have hepatitis C?

A

50-60%

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5
Q

What is the structure of the hepatitis B virion?

A

virus particles have suface antigens, outer envelope (lipid bilayer) and inner capsid (the core structure) and contain an incomplete double strand of DNA - there are also not infectious particles made up purely of surface antigen

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6
Q

What are the different messenger RNAs that can be transcribed from the hepatitis B genome?

A
  • the pregenomic RNA which codes for the core protein, the precore (HBeAg) and an enzyme for reverse transcription
    • an RNA which codes for surface proteins
    • another RNA which codes for non structural proteins involved in immune evasion and pathogenesis (protein X)
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7
Q

What restricts the level of mutation capable?

A

There is more than one reading frame

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8
Q

How does the hepatitis B virus replicate?

A

infects hepatocytes, DNA goes into nucleus where replication completes the gap to make a closed circular DNA episome, pregenomic RNA is transcribed, pregenomic RNA goes to the cytoplasm and forms a nucleocapsid which serves as a template for the genome via reverse transcription, produce core particles which can either re-enter the nucleus or leave the cell

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9
Q

Does hepatitis B replicate in intestinal mucosa?

A

No - only penetrates

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10
Q

What is the incubation period of hepatitis B?

A

on average 60-90 days

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11
Q

What percentage of patients under 5 will develop acute jaundice?

A

under 10%

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12
Q

What percentage of patients over 5 will develop acute jaundice?

A

30-50%

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13
Q

What percentage of patients under 5 will go on to develop a chronic infection?

A

30-90%

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14
Q

What percentage of patients over 5 will go on to develop a chronic infection?

A

15-25%

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15
Q

What are the two outcomes of an initial infection of hepatitis B?

A

resolution or chronic carrier state

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16
Q

What is the outcome of patients who are chronic carriers?

A

Can further progress to cirrhosis or can stabilise

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17
Q

What is the outcome of patients who develop cirrhosis?

A

Cirrhosis can maintain as compensated or can go into a decompensated cirrhosis

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18
Q

What is a possible outcome of cirrhosis?

A

liver cancer

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19
Q

In an acute infection what marks replication and presence of viral particles?

A

hepatitis B surface antigen and the presence of hepatitis B e antigen

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20
Q

What is the initial immune response?

A

IgM against the core protein

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21
Q

What is the immune response that develops?

A

IgG against the core protein

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22
Q

When do symptoms appear?

A

when the immune response begins

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23
Q

What demonstrates an immune response against the virus?

A

surface antibody

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24
Q

What stays at a sustained high level in chronic infection?

A

surface antigen and e antigen and core antibodies

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25
Q

What does a chronic infection lack?

A

antibodies to the surface and antibodies to the e antigen

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26
Q

What serological test shows that a patient is a chronic hepatitis B carrier?

A

positive for surface antigen

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27
Q

Which antibody to hepatitis B is present first - the core or the surface antibody?

A

The core antibody

28
Q

What treatments can be used to prevent chronic hepatitis B from going to end stage liver disease?

A

cytokines (interferon) and antivirals (target replication)

29
Q

What treatment is often required at end stage liver disease?

A

transplant

30
Q

What causes hepatocellular carcinoma in hepatitis B infected patients?

A

partial integration of HBV genome disrupting normal DNA, repeated destruction and regeneration of hepatocytes accumulates mutations, and possible role of HBV-X gene

31
Q

What is the surface antigen used to show in serological tests?

A

a general marker of infection

32
Q

What is the surface antibody used to show in serological tests?

A

recovery and or immunity to HBV and also successful vaccination

33
Q

What is the IgM core antibody used to show in serological tests?

A

marker of acute infection (rising titre)

34
Q

What is the IgG core antibody used to show in serological tests?

A

marker of past or chronic infection (steady titre)

35
Q

What is the e antigen used to show in serological tests?

A

indicates active replication - used to see if treatment is effective

36
Q

What is the e antibody used to show in serological tests?

A

that the virus is no longer replicating

37
Q

What does the HBV-DNA in serological tests show?

A

active replication - more accurate than hepatitis B e antigen

38
Q

What antiviral drugs are available for HBV?

A

pegylated interferon alpha, nucleoside and nucleotide analogues and some new generation drugs

39
Q

What does the pegylated mean?

A

better bioavailability

40
Q

How do nucleoside and nucleotide analogues work?

A

they target polymerase function - but have low rates of viral clearance and get relapse after therapy stops

41
Q

What is the difference between nucleoside and nucleotide analogues?

A

nucleotides have a phosphate added already to increase activity

42
Q

What are 3TC and entecavir?

A

nucleoside analogues

43
Q

What are adefovir and tenofovir?

A

nucleotide analogues

44
Q

Is there a successful vaccine for hepatitis B?

A

yes - also works for hepatitis D

45
Q

Can the vaccine be used post exposure?

A

yes

46
Q

What is the hepatitis D virus?

A

It is an infectious virus particle encased in hepatitis B surface antigen which allows it to be taken up by hepatocytes

47
Q

What type of genome is hepatitis D?

A

single stranded RNA

48
Q

What is the core antigen for hepatitis D?

A

delta antigen

49
Q

What is the clinical presentation of a co-infection of hepatitis B and D?

A

less severe acute disease with a low risk of chronic infection

50
Q

What is the clinical presentation of a hepatitis B infection followed by a hepatitis D infection?

A

a chronic HDV infection with high risk of chronic liver disease

51
Q

What family does the hepatitis C virus belong to?

A

flavivirus family

52
Q

Is there a vaccine for hepatitis C?

A

No - instigates poor immune response

53
Q

What is the genome of the hepatitis C virus?

A

single stranded linear + sense RNA

54
Q

How does the hepatitis C virus make proteins in replication?

A

Protein encoded as a polyprotein which is cleaved by a protease

55
Q

How does hepatitis C virus enter hepatocytes?

A

by associating with lipid

56
Q

What happens after the hepatitis C enters the hepatocyte?

A

the RNA molecule goes to the ER where it is translated to structural and non structural proteins and then non structural proteins replicate the template to produce a lot of DNA

57
Q

Why do a lot of mutations occur in hepatitis C?

A

because the replication machinery is error prone - an evasion strategy of the virus

58
Q

What is the incubation period of hepatitis C?

A

6 weeks

59
Q

What percentage of hepatitis C infections will lead to a chronic infection?

A

70%

60
Q

What percentage of those infected with hepatitis C become chronic carriers?

A

70-90%

61
Q

What are the outcome of a chronic hepatitis C infection?

A

cirrhosis, liver failure and carcinoma

62
Q

What are the older drugs used to treat hepatitis C?

A

interferon alpha and ribavirin (a nucleoside inhibitor)

63
Q

What are the disadvantages of the older drugs?

A

They have lots of side effects and are ineffective in many patients

64
Q

What are teleprovir and boceprevir?

A

direct acting antivirals that inhibit proteases that cleaves up the polyprotein in the active forms

65
Q

What other HCV specific life cycle inhibitors are available?

A

viral entry inhibitors, RNA translation inhibitors, replication inhibitors, assembly and release inhibitors

Gastrointestinal (40 decks)

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