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MM- Viruses > Hepatitis Recap > Flashcards

Hepatitis Recap Flashcards

1
Q

What is hepatitis?

A

Inflammation of the liver, destruction of hepatocytes

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2
Q

What are symptoms of hepatitis?

A

Jaundice- due to a build-up of bilirubin

Elevated levels of trans-aminases in the blood

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3
Q

What happened in 2017?

A

HBV vaccine was added to the routine vaccination programme in the United Kingdom

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4
Q

Which types of hepatitis are food-borne?

A

A and E

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5
Q

Developing chronic HCV?

A

The majority of people infected with HCV go on to develop chronic HCV infection= 60-80%

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6
Q

Developing chronic HBV?

A

The likelihood of developing chronic HBV decreases with age

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7
Q

HCV family?

A

Flaviviridae

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8
Q

HBV family?

A

Hepadnaviridae

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9
Q

HCV E1 function?

A

Fusion

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10
Q

HCV E2 function?

A

Attachment

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11
Q

HCV virion structure?

A

Lipoviroparticle
Contains lipids
Enveloped with embedded E1 and E2 glycoproteins
Contains an icosahedral capsid

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12
Q

IRES binds to?

A

40S ribosomal subunit

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13
Q

What is p7?

A

Ion channel which is involved in viral assembly and release

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14
Q

HCV is so genetically diverse that there are?

A

7 distinct genotypes

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15
Q

The HCV tropism is defined by?

A

Presence of miR-122

Post-entry regulation of tropism

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16
Q

Function of miR-122?

A

Binds to two regions in the 5’ NTR of the genome

Stabilises the genome

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17
Q

miR-122 can only be found expressed in?

A

Hepatocytes

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18
Q

What determines the tropism of HBV?

A

Presence of NTCP receptor

Pre-entry determination of tropism

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19
Q

NTCP receptor stands for?

A

Sodium co-transporting polypeptide

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20
Q

NTCP receptor can only be found on?

A

Hepatocytes

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21
Q

HCV entry?

A

Binding to low affinity receptors such as LDLR- low density lipoprotein receptors
Binding of E2 to SR-B1 scavenger receptor causes a conformational change in E2 allowing it to bind to CD81
CD81 forms a complex with tight junction proteins: claudin and occludin. This allows the receptor mediated endocytosis of HCV
Acidification of the endosome facilitates fusion

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22
Q

SR-B1 is what type of receptor?

A

Scavenger receptor

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23
Q

Do host cell receptors determine HCV tropism?

24
Q

What determines HCV tropism?

A

Tropism is determined post-entry

Determined by presence of miR-122 micro RNA

25
Q

Where does replication occur?

A

In the cytoplasm in association with membranous web

26
Q

Formation of the membranous web is induced by?

27
Q

Membranous web is made up of?

A

The membranous web is made up of double membrane vesicles containing non-structural proteins e.g. NS3, NS4A, NS4B etc…

28
Q

Which protein functions as the RNA polymerase?

29
Q

What is the function of the membranous web?

A

It is thought to function in protecting the viral genome from immune recognition

30
Q

How does assembly and release occur?

A

The core protein is transported from the ER where it has been translated to lipid droplet organelles present in the cell. The newly made genome is also trafficked to the lipid droplets where it is encapsidated. Some of the lipid droplet may be incorporated which creates the lipoviroparticle.

31
Q

Subgenomic replicon is made out of?

A

5’ HCV IRES which drives expression of neomycin phosphotransferase
EMCV IRES drives the expression of NS3-NS5B

32
Q

What does the subgenomic replicon not contain?

A

The structural proteins: E1, E2, core, NS1 or even NS2

33
Q

As the subgenomic replicon lacks structural proteins it is?

A

Non-infectious and can be worked on in biosafety level 2

34
Q

The subgenomic replicon replicates in which cell line?

A

Huh-7

Human hepatoma cell line

35
Q

What medium is the Huh-7 cell line grown on and why?

A

Medium containing G418 which is an antibiotic

36
Q

Why is antibiotic added?

A

G418 is an antibiotic and will kill cells that do not contain RNA or where RNA has not replicated. Only cells containing a self-replicating replicon will have a high enough copy number of gene encoding neomycin phosphotransferase which allows survival in presence of antibiotics

37
Q

Why does the replicon replicate better in the cell line over time?

A

Accumulation of mutations

38
Q

Hepatitis B family?

A

Hepadnaviridae

39
Q

Hepatitis B dane particle size?

40
Q

HBV genome size?

A

Very small

3.2 kb

41
Q

How many ORFs in HBV encoding how many proteins?

A

4 overlapping ORFs encoding 7 proteins

42
Q

Why is HBV not very genetically diverse?

A

Due to the overlapping open reading frames

Each nucleotide is coding

43
Q

5’ end of -ssDNA is covalently linked to?

44
Q

Replication occurs in the?

45
Q

RC-DNA stands for?

A

Relaxed circular DNA

46
Q

Removal of HBX leads to?

A

Rapid silencing of cccDNA

47
Q

Pregenomic RNA is known as?

48
Q

pgRNA encodes?

A

HBcAg

P protein

49
Q

Pre-core RNA encodes?

50
Q

Subgenomic RNAs encode?

51
Q

What triggers encapsidation?

A

Binding of the P protein to the RNA structural element in the 5’ region of pgRNA known as epsilon

52
Q

Which strand of RC-DNA is incomplete?

53
Q

Repair of RC-DNA occurs where and forms?

A

Occurs in the nucleus and forms cccDNA

54
Q

What receptor does HBV rely on for entry which also defines its tropism for hepatocytes?

A

NTCP receptor is only located on hepatocytes

55
Q

cccDNA is transcribed into what by what?

A

pgRNA
Precore RNA
Subgenomic RNAs
All by cellular RNA Pol-II

MM- Viruses (13 decks)

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