Infectious - Viral - Bacterial - Fungal - Parasitic Non-infectious: - Alcohol - Drugs - Autoimmune - Metabolic diseases

Hepatitis Viruses (Microbiology) Flashcards by Soph 1

What is hepatitis?

Inflam of liver

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Causes of hepatitis?

Infectious

Viral
Bacterial
Fungal
Parasitic

Non-infectious:

Alcohol
Drugs
Autoimmune
Metabolic diseases

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Signs and symptoms of hepatitis?

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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Virus structure?

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

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Name the major hepatitis viruses

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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Features of hepatitis 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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How does hepatitis A travel?

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

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Hepatits A virus vaccine?

Formalin-killed virus

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Hepatitis A epidemiology?

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

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When is IgM produced? When will it eventually do?

The 1st time a host is exposed to an antigen

Will eventually decline, then host produces IgG = lasts longer

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What does the detection of IgM indicate?

Acute or primary infection

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What does IgG’s presence indicate?

Past infection or immunity

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Hepatitis B is caused by?How is it transmitted?

Hep B virus (HBV)

Parenteral role of transmission

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Hep B features?

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

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

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What is the central core of HBV made up of?

dsDNA, DNA polymerase enzyme and core antigen HBcAg

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What is HBeAg?

Marker of active infection

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What are the HBV genes?

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

Why are the HBc and HBe antigens important?

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

Possible courses of HBV infection?

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

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

How is Hep B diagnosed by serology?

Detection of hep B surface antigen HBsAg

How is an acute HBV infec diagnosed by serology?

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

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

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

How is chronic HBV infec diagnosed by serology?

Persistence of HBsAg for at least 6 months

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

Hep B epidemiology?

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

Hep B vaccine?

Genetically engineered HBsAg

Hep D causes?

Defective RNA virus which coexists with HBV | Outer coat derived from HBsAg - cannot survive without HBV

How to diagnose Hep D virus?

Detection of delta antigen

Features of Hep D?

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

Hep D epidemiology?

15 million cases worldwide - mainly IV drug users in UK

Hep C structure?

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

How is the Hep C virus released?

By budding

What is E2 in hep C responsible for?

Attachment via host cells scavenger receptor B1 and CD81

HCV epidemiology?

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

How is HCV transmitted?

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

What occurs if hep C is chronic?

50% fatigue (10y); 25% cirrhosis (20y); 5% HCC(30y) | 350 000 to 500 000 people die each year from hepatitis C-related liver diseases.

How persistent is Hep C?

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

How to treat Hep C?

Inferferon α and ribavirin

Prospects for HCV vaccine?

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

What is Hep E virus?

An RNA hepevirus; 4 genotypes

Who does Hep E commonly infect?

Young-middle aged adults

How does each hepatitis spread?

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

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

HBV