Hepatitis B

Question 1

Hepatitis B was discovered before?

Answer 1

Hepatitis C

Question 2

Hepatitis B is more likely to cause chronic infection in?

Answer 2

Younger individuals

Question 3

Family?

Answer 3

Hepadnaviridae

Question 4

Genus?

Answer 4

Orthohepadnavirus

Question 5

Genome?

Answer 5

dsDNA-RT
RC-DNA= Relaxed circular DNA
Partially dsDNA

Question 6

RC-DNA stands for?

Answer 6

Relaxed circular DNA

Question 7

Baltimore classification?

Answer 7

VII

Question 8

100 times more infectious than?

Answer 8

HIV

Question 9

Does integration into the host genome occur?

Answer 9

No

Question 10

Replication occurs where?

Answer 10

Cytoplasm within the nucleocapsid

Question 11

Stages of HBV infection?

Answer 11

Immune tolerant
Immune active
Inactive

Question 12

What is associated with the immune tolerant stage?

Answer 12

Immune system not yet active
High levels of viral replication- active infection
High levels of HBeAg present in the blood

Question 13

A person can remain in the immune tolerant stage for?

Answer 13

Decades

Question 14

Immune active stage is usually entered in?

Answer 14

When children who were infected reach their thirties

Question 15

Immune tolerant stage is associated with?

Answer 15

Inflammation, liver damage

Anti HBeAg antibody presence

Question 16

Immune inactive stage is associated with?

Answer 16

Anti HBeAg

The infection can re-activate

Question 17

Why is there less genome diversity in HBV?

Answer 17

Overlapping genomes
There are 4 ORFs which are overlapping
Each nucleotide is coding, sometimes for multiple proteins. Therefore mutations are rare as it is highly likely a mutation will lead to a dysfunctional protein

Question 18

What antigens are associated with HBV?

Answer 18

HBsAg
HBcAg
HBeAg

Question 19

The e in HBeAg stands for?

Answer 19

Early

Question 20

High levels of HBeAg are indicative of?

Answer 20

Active infection

Question 21

HBcAg?

Answer 21

This is not secreted
It is at the surface of the nucleocapsid
Remains associated with the viral particle at all times

Question 22

HBsAg?

Answer 22

This is the surface antigen

Also known as the Australia antigen

Question 23

Infectious HBV particle is called what and is what size?

Answer 23

Dane particle 42nm

Question 24

HBsAg can form non-infectious particles known as?

Answer 24

Subviral particles

Question 25

What types of subviral particles are there?

Answer 25

Filamentous and spheres

Question 26

What size are subviral particles?

Answer 26

22nm

Question 27

Describe the virion structure?

Answer 27

Envelope made up of HBsAg | Icosahedral capsid

Question 28

What is the purpose of subviral particles?

Answer 28

May be to sequester antibodies to allow the infectious Dane particles to go undetected

Question 29

Why are subviral particles non-infectious?

Answer 29

Made up of solely HBsAg | Contain no nucleocapsid/core, no genome and no P protein

Question 30

P protein functions?

Answer 30

RT- RNA dependent DNA polymerase DNA dependent DNA polymerase function Ribonuclease H- RNase H activity

Question 31

How large is the viral genome?

Answer 31

3.2kb

Question 32

HBV genome is very?

Answer 32

Small, one of the smallest viral genomes

Question 33

What DNA is found in the virion?

Answer 33

RC-DNA

Question 34

RC-DNA structure?

Answer 34

Relaxed circular DNA Incomplete +ssDNA P protein attached to -ssDNA

Question 35

The RC-DNA enters the nucleus and is rapidly repaired to form?

Answer 35

cccDNA

Question 36

cccDNA?

Answer 36

Covalently closed DNA

Question 37

How is cccDNA formed?

Answer 37

Repair of RC-DNA Covalent ligation Required the removal of P protein, ssDNA flap and RNA

Question 38

Does cccDNA integrate?

Answer 38

No

Question 39

cccDNA is transcribed by?

Answer 39

RNA pol-II

Question 40

cccDNA is transcribed into?

Answer 40

Long and short RNAs

Question 41

Long RNAs include?

Answer 41

pre-core RNA | pre-genomic pgRNA

Question 42

pre-core RNA encodes?

Answer 42

HBeAg

Question 43

pgRNA is used for?

Answer 43

Replication

Question 44

pgRNA encodes?

Answer 44

P protein | HBcAg

Question 45

Subgenomic RNAs encode?

Answer 45

HBsAg | HBX

Question 46

How many proteins are encoded by HBV?

Answer 46

7 proteins

Question 47

Which 7 proteins are encoded by HBV?

Answer 47

``` HBsAg= small, medium and large HBcAg HBeAg HBX P protein ```

Question 48

cccDNA is present as what in the nucleus?

Answer 48

Minichromosome

Question 49

How does the minichromosome form?

Answer 49

Due to histone and non-histone proteins

Question 50

What allows the expression of the cccDNA genes?

Answer 50

HBX

Question 51

Without HBX?

Answer 51

cccDNA is rapidly silenced

Question 52

What triggers encapsidation?

Answer 52

Binding of P protein to the 5' RNA structural element epsilon of pgRNA

Question 53

Reverse transcription is triggered by?

Answer 53

Encapsidation

Question 54

Priming for reverse transcription in HIV is mediated by?

Answer 54

Cell derived tRNA

Question 55

Priming for reverse transcription in HBV is mediated by?

Answer 55

Novel protein priming mechanism

Question 56

Why is the +ssDNA of RC-DNA incomplete?

Answer 56

Due to the limited dNTP pool present in the nucleocapsid

Question 57

How is exit mediated?

Answer 57

Budding of the nucleocapsid through the ER and golgi