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HEPATOBILIARY SYSTEM 303 > Hepatitis Viruses (Microbiology) > Flashcards

Hepatitis Viruses (Microbiology) Flashcards

1
Q

What is hepatitis?

A

Inflam of liver

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2
Q

Causes of hepatitis?

A

Infectious

  • Viral
  • Bacterial
  • Fungal
  • Parasitic

Non-infectious:

  • Alcohol
  • Drugs
  • Autoimmune
  • Metabolic diseases
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3
Q

Signs and symptoms of hepatitis?

A 
Malaise 
Jaundice
Dark urine
Pale fatty stools
Serum and urine biochemistry - serology tests for HepA, B, C, D and A antibodies for viral hepatitis
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4
Q

Virus structure?

A

Strand of nucleic acid (DNA or RNA, surrounded by a protective coat (Capsid)
Sometimes have an envelope surrounding the protein

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5
Q

Name the major hepatitis viruses

A

HAV - RNA - Non-enveloped - Spread by faecal-oral

HBV - DNA - lipid envelope - parenteral spread

HCV - RNA - lipid envelope - parenteral spread

HDV - RNA - lipid enveloped - parenteral spread

HEV - RNA - Non-enveloped - faecal oral spread

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6
Q

Features of hepatitis A?

A

RNA, belongs to group Picornavirus
Genotypes I-VII (most being I)
2 week incubation, then 4-10 day prodrome, resolves in few weeks
vaccine - formalin-killed virus

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7
Q

How does hepatitis A travel?

A

Enters stomach by ingesting contaminating food = small intestine = blood = liver = bile to faeces = further spread

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8
Q

Hepatits A virus vaccine?

A

Formalin-killed virus

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9
Q

Hepatitis A epidemiology?

A

1.5 million cases worldwide
Children 3-5 yrs old often symptomatic
Severity increases with age

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10
Q

When is IgM produced? When will it eventually do?

A

The 1st time a host is exposed to an antigen

Will eventually decline, then host produces IgG = lasts longer

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11
Q

What does the detection of IgM indicate?

A

Acute or primary infection

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12
Q

What does IgG’s presence indicate?

A

Past infection or immunity

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13
Q

Hepatitis B is caused by?How is it transmitted?

A

Hep B virus (HBV)

Parenteral role of transmission

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14
Q

Hep B features?

A

dsDNA virus, resides and multiplies in hepatocytes
Most pts recover in few weeks
2-5% develop chronic carrier state
- Chronic persistent hepatitis (healthy carrier)
- Chronic active hepatitis

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15
Q

What particles make up the structure of the hepatitis B virus?

A 
Dane particle (complete infective virus) 
Spherical = (non-infective)
Tubular forms (non-infec)
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16
Q

What is the central core of HBV made up of?

A

dsDNA, DNA polymerase enzyme and core antigen HBcAg

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17
Q

What is HBeAg?

A

Marker of active infection

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18
Q

What are the HBV genes?

A 
S = preS1, preS2, surface antigen
C = preC, core protein
P = polymerase
X = regulatory
19
Q

Why are the HBc and HBe antigens important?

A

Hbe antigen = soluble component released by virus core, targeted by host immune system

20
Q

Possible courses of HBV infection?

A

Low viral replication = elimination of viruses; immunity and low HBsAg

Strong viral replication = acute hepatitis and persistent viraemia (chronic hep)

21
Q

How is Hep B diagnosed by serology?

A

Detection of hep B surface antigen HBsAg

22
Q

How is an acute HBV infec diagnosed by serology?

A

Acute HBV infec = presence of HBsAg and IgM antibody to the core antigen, HBcAg

23
Q

What indicates the initial phase of a HBV infection in serology?

A

Initial phase of infec = seropositive for HBeAg = marker of high levels of replication of the virus = blood and body fluids are highly contagious

24
Q

How is chronic HBV infec diagnosed by serology?

A

Persistence of HBsAg for at least 6 months

Persistence of HBsAg = risk for developing chronic liver disease and liver cancer (hepatocellular carcinoma)

25
Q

Hep B epidemiology?

A

UK carriage approx. 0.1%
Carriage in Africa and Asia approx. 5%
Transmission; vertical, parenteral, sexual
>108 HBV/ml; 0.000001-0.00001ml blood;
Infection early in life > increased chance of chronicity
10% of chronic infection progress to chronic liver disease

26
Q

Hep B vaccine?

A

Genetically engineered HBsAg

27
Q

Hep D causes?

A

Defective RNA virus which coexists with HBV

Outer coat derived from HBsAg - cannot survive without HBV

28
Q

How to diagnose Hep D virus?

A

Detection of delta antigen

29
Q

Features of Hep D?

A

Infection co-incident with HBV:

  • HDV influenced by replication of HBV
  • Rarely progressive or chronic

Superinfection on HBV disease:

  • Ideal for rapid HDV replication
  • commonly chronic
30
Q

Hep D epidemiology?

A

15 million cases worldwide - mainly IV drug users in UK

31
Q

Hep C structure?

A

Small enveloped SSRNA virus
RNA surrounded by an icosahedral capsid
2 viral envelope glycoproteins, E1 and E2 = embedded in the liquid envelope
10 genes - transcribed as a polyprotein

32
Q

How is the Hep C virus released?

A

By budding

33
Q

What is E2 in hep C responsible for?

A

Attachment via host cells scavenger receptor B1 and CD81

34
Q

HCV epidemiology?

A

180 million carriers worldwide
5 million in Western Europe
UK carriage ~0.08% (~40,000)

35
Q

How is HCV transmitted?

A

IV drug abuse needle sticks, tattoos, ear piercing
Previously - blood products, haemodialysis, transplantation
Minor routes - saliva, sexual, vertical

36
Q

What occurs if hep C is chronic?

A

50% fatigue (10y); 25% cirrhosis (20y); 5% HCC(30y)

350 000 to 500 000 people die each year from hepatitis C-related liver diseases.

37
Q

How persistent is Hep C?

A

Relavively low replication rate
No RNA repair mechanism
Variants selected by non-reactivity with antibody

38
Q

How to treat Hep C?

A

Inferferon α and ribavirin

39
Q

Prospects for HCV vaccine?

A

11 major genotypes, ~ 40 subtypes

  • multiple types in same individual
  • types 1a & 1b in UK

Re-infection can occur (with same type)
- lack of neutralising antibody

40
Q

What is Hep E virus?

A

An RNA hepevirus; 4 genotypes

41
Q

Who does Hep E commonly infect?

A

Young-middle aged adults

42
Q

How does each hepatitis spread?

A 
A = contaminated food/water
B = infected blood, sexual contact
C = infected blood
D = infected blood, sexual contact
E = contaminated water
43
Q

Which virus has a DNA genome? (The rest are RNA)

A

HBV

HEPATOBILIARY SYSTEM 303 (2 decks)

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