Infectious Causes of Hepatitis 2 Flashcards Preview

Gastrointestinal > Infectious Causes of Hepatitis 2 > Flashcards

Flashcards in Infectious Causes of Hepatitis 2 Deck (65):
1

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

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

2

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

chronic

3

For which hepatitis virus is there perinatal transmission?

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

4

What proportion of regular IV drug users have hepatitis C?

50-60%

5

What is the structure of the hepatitis B virion?

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

6

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


* 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)

7

What restricts the level of mutation capable?

There is more than one reading frame

8

How does the hepatitis B virus replicate?

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

9

Does hepatitis B replicate in intestinal mucosa?

No - only penetrates

10

What is the incubation period of hepatitis B?

on average 60-90 days

11

What percentage of patients under 5 will develop acute jaundice?

under 10%

12

What percentage of patients over 5 will develop acute jaundice?

30-50%

13

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

30-90%

14

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

15-25%

15

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

resolution or chronic carrier state

16

What is the outcome of patients who are chronic carriers?

Can further progress to cirrhosis or can stabilise

17

What is the outcome of patients who develop cirrhosis?

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

18

What is a possible outcome of cirrhosis?

liver cancer

19

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

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

20

What is the initial immune response?

IgM against the core protein

21

What is the immune response that develops?

IgG against the core protein

22

When do symptoms appear?

when the immune response begins

23

What demonstrates an immune response against the virus?

surface antibody

24

What stays at a sustained high level in chronic infection?

surface antigen and e antigen and core antibodies

25

What does a chronic infection lack?

antibodies to the surface and antibodies to the e antigen

26

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

positive for surface antigen

27

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

The core antibody

28

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

cytokines (interferon) and antivirals (target replication)

29

What treatment is often required at end stage liver disease?

transplant

30

What causes hepatocellular carcinoma in hepatitis B infected patients?

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

31

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

a general marker of infection

32

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

recovery and or immunity to HBV and also successful vaccination

33

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

marker of acute infection (rising titre)

34

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

marker of past or chronic infection (steady titre)

35

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

indicates active replication - used to see if treatment is effective

36

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

that the virus is no longer replicating

37

What does the HBV-DNA in serological tests show?

active replication - more accurate than hepatitis B e antigen

38

What antiviral drugs are available for HBV?

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

39

What does the pegylated mean?

better bioavailability

40

How do nucleoside and nucleotide analogues work?

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

41

What is the difference between nucleoside and nucleotide analogues?

nucleotides have a phosphate added already to increase activity

42

What are 3TC and entecavir?

nucleoside analogues

43

What are adefovir and tenofovir?

nucleotide analogues

44

Is there a successful vaccine for hepatitis B?

yes - also works for hepatitis D

45

Can the vaccine be used post exposure?

yes

46

What is the hepatitis D virus?

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

47

What type of genome is hepatitis D?

single stranded RNA

48

What is the core antigen for hepatitis D?

delta antigen

49

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

less severe acute disease with a low risk of chronic infection

50

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

a chronic HDV infection with high risk of chronic liver disease

51

What family does the hepatitis C virus belong to?

flavivirus family

52

Is there a vaccine for hepatitis C?

No - instigates poor immune response

53

What is the genome of the hepatitis C virus?

single stranded linear + sense RNA

54

How does the hepatitis C virus make proteins in replication?

Protein encoded as a polyprotein which is cleaved by a protease

55

How does hepatitis C virus enter hepatocytes?

by associating with lipid

56

What happens after the hepatitis C enters the hepatocyte?

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

Why do a lot of mutations occur in hepatitis C?

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

58

What is the incubation period of hepatitis C?

6 weeks

59

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

70%

60

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

70-90%

61

What are the outcome of a chronic hepatitis C infection?

cirrhosis, liver failure and carcinoma

62

What are the older drugs used to treat hepatitis C?

interferon alpha and ribavirin (a nucleoside inhibitor)

63

What are the disadvantages of the older drugs?

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

64

What are teleprovir and boceprevir?

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

65

What other HCV specific life cycle inhibitors are available?

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