Hepatitis Recap

Question 1

What is hepatitis?

Answer 1

Inflammation of the liver, destruction of hepatocytes

Question 2

What are symptoms of hepatitis?

Answer 2

Jaundice- due to a build-up of bilirubin

Elevated levels of trans-aminases in the blood

Question 3

What happened in 2017?

Answer 3

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

Question 4

Which types of hepatitis are food-borne?

Answer 4

A and E

Question 5

Developing chronic HCV?

Answer 5

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

Question 6

Developing chronic HBV?

Answer 6

The likelihood of developing chronic HBV decreases with age

Question 7

HCV family?

Answer 7

Flaviviridae

Question 8

HBV family?

Answer 8

Hepadnaviridae

Question 9

HCV E1 function?

Answer 9

Fusion

Question 10

HCV E2 function?

Answer 10

Attachment

Question 11

HCV virion structure?

Answer 11

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

Question 12

IRES binds to?

Answer 12

40S ribosomal subunit

Question 13

What is p7?

Answer 13

Ion channel which is involved in viral assembly and release

Question 14

HCV is so genetically diverse that there are?

Answer 14

7 distinct genotypes

Question 15

The HCV tropism is defined by?

Answer 15

Presence of miR-122

Post-entry regulation of tropism

Question 16

Function of miR-122?

Answer 16

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

Stabilises the genome

Question 17

miR-122 can only be found expressed in?

Answer 17

Hepatocytes

Question 18

What determines the tropism of HBV?

Answer 18

Presence of NTCP receptor

Pre-entry determination of tropism

Question 19

NTCP receptor stands for?

Answer 19

Sodium co-transporting polypeptide

Question 20

NTCP receptor can only be found on?

Answer 20

Hepatocytes

Question 21

HCV entry?

Answer 21

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

Question 22

SR-B1 is what type of receptor?

Answer 22

Scavenger receptor

Question 23

Do host cell receptors determine HCV tropism?

Answer 23

No

Question 24

What determines HCV tropism?

Answer 24

Tropism is determined post-entry

Determined by presence of miR-122 micro RNA

Question 25

Where does replication occur?

Answer 25

In the cytoplasm in association with membranous web

Question 26

Formation of the membranous web is induced by?

Answer 26

NS5A

Question 27

Membranous web is made up of?

Answer 27

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

Question 28

Which protein functions as the RNA polymerase?

Answer 28

NS5B

Question 29

What is the function of the membranous web?

Answer 29

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

Question 30

How does assembly and release occur?

Answer 30

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.

Question 31

Subgenomic replicon is made out of?

Answer 31

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

Question 32

What does the subgenomic replicon not contain?

Answer 32

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

Question 33

As the subgenomic replicon lacks structural proteins it is?

Answer 33

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

Question 34

The subgenomic replicon replicates in which cell line?

Answer 34

Huh-7 | Human hepatoma cell line

Question 35

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

Answer 35

Medium containing G418 which is an antibiotic

Question 36

Why is antibiotic added?

Answer 36

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

Question 37

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

Answer 37

Accumulation of mutations

Question 38

Hepatitis B family?

Answer 38

Hepadnaviridae

Question 39

Hepatitis B dane particle size?

Answer 39

42nm

Question 40

HBV genome size?

Answer 40

Very small | 3.2 kb

Question 41

How many ORFs in HBV encoding how many proteins?

Answer 41

4 overlapping ORFs encoding 7 proteins

Question 42

Why is HBV not very genetically diverse?

Answer 42

Due to the overlapping open reading frames | Each nucleotide is coding

Question 43

5' end of -ssDNA is covalently linked to?

Answer 43

P protein

Question 44

Replication occurs in the?

Answer 44

Cytoplasm

Question 45

RC-DNA stands for?

Answer 45

Relaxed circular DNA

Question 46

Removal of HBX leads to?

Answer 46

Rapid silencing of cccDNA

Question 47

Pregenomic RNA is known as?

Answer 47

pgRNA

Question 48

pgRNA encodes?

Answer 48

HBcAg | P protein

Question 49

Pre-core RNA encodes?

Answer 49

HBeAg

Question 50

Subgenomic RNAs encode?

Answer 50

HBX | HBsAg

Question 51

What triggers encapsidation?

Answer 51

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

Question 52

Which strand of RC-DNA is incomplete?

Answer 52

+ssDNA

Question 53

Repair of RC-DNA occurs where and forms?

Answer 53

Occurs in the nucleus and forms cccDNA

Question 54

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

Answer 54

NTCP receptor is only located on hepatocytes

Question 55

cccDNA is transcribed into what by what?

Answer 55

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