Viruses

Question 1

Host cell specificity

- what it is and what determines it (viruses)

Answer 1

Virus interact with one or more host cell molecule/receptor

Spike projections determine where have access to, the cells, which may determine symptoms

Question 2

Examples of viral host cell specificity

Answer 2

Rabies
Influenza
HIV 
Epstein-Barr
Human rhinoviruses

Question 3

Rabies - host cell specificity

Answer 3

Rabies - neuronal cells acetylcholine receptor Neuronal cell adhesion molecule

Question 4

Influenza - host cell specificity

Answer 4

Influenza - sialic acid receptor on lung epithelial cells and upper respiratory tract

Question 5

Human rhinoviruses - host cell specificity

Answer 5

Human rhinoviruses - lots of different cells, because general targets
iCAM-1 - intracellular adhesion molecule
VLDL-R = very low density lipoprotein receptor

Question 6

Differences in viral replication steps between types

Answer 6

DNA viruses use host machinery for translation

RNA viruses

Negative-sense strands must be converted to positive-sense then used as mRNA

Positive-sense strands can be used directly as mRNA

Retro-viruses ssRNA+->ssRNA- ->dsDNA->mRNA

Question 7

Outcomes of viral host cell infection (with examples)

Answer 7

Lytic - e.g. influenza
Persistent infection - e.g. hep B
Latent infects - e.g. herpes virus

Question 8

Features of a latent viral infection

Answer 8

Remain in cell cytoplasm (e.g. herpes virus)

Is incorporated into host genome

Question 9

The 7 Ebola proteins in the Ebola genome

Answer 9

Glycoprotein, part of spike (GP/sGP)

Matrix protein (VP24) - INHIBITS NORMAL ANTIVIRAL RESPONSES (INF-β & INF-INDUCED EXPRESSION OF ALPHA-STAT-1)

Nucleoprotein, associated with RNA genome (NP)

Polymerase cofactor (VP35)

Transcription activator (VP30), encourage transcription of viral RNA over host RNA 
(preference)

Nucleocapsid proteins (VP30, VP24, VP35)

Question 10

How many strains of Ebola are there?

Answer 10

5

Question 11

Lifecycle of the Ebola virus

Answer 11

Attached to TIM-1 (T-cell immunoglobulin and mucin domain 1)

Membrane comes round and wraps up ebola and takes in to cell in endosome

Binding to NPC1 (Niemann-Pick C1, endosomal/lysosomal cholesterol transporter)

Release from endosome, release of capsid into cell

Virion constructed, release from cell through lysis (takes membrane of cell as coating)

Question 12

Key receptors in Ebola life cycle for targeting

Answer 12

Ebola

TIM-1 (T-cell immunoglobulin and mucin domain 1)

NPC1 (Niemann-Pick C1)

Question 13

TIM-1

Answer 13

T-cell immunoglobulin and mucin domain 1

Question 14

NPC1

Answer 14

Ebola

Niemann-Pick C1, endosomal/lysosomal cholesterol transporter

Question 15

DNA viruses (all icosohedral)

Answer 15

Hepatitis B
Epstein Barr Virus
Poxviruses (inc. smallpox)
Papilloma Virus

Question 16

RNA viruses (icosahedral)

Answer 16

Rubella
HIV
Norovirus

Question 17

RNA viruses (helical)

Answer 17

Mumps
Marburg
Influenza

Question 18

Viral replication steps

Answer 18

Attachment and entry
Uncoating of virion
Migration of genomic nucleic acid to nucleus
Transcription/replication
Biosynthesis
Assembly of virion
Release - some retain parts of host membrane (hiding)

Question 19

Viral replication

Answer 19

Usually one polycistronic RNA (all open reading frames together) - one mRNA

Use host ribosomes for mRNA-> single large protein THEN cleavage with specific proteases

• Viral capsid
• Polymerase
• Protease - for large protein cleavage

Question 20

Features of a lytic viral infection

Answer 20

Immune response (sometimes severe)

Question 21

Features of a persistent viral infection

Answer 21

Slow release of viral particles (under detection levels for immune system of host)

Question 22

HPV viruses that cause cancer

Answer 22

HPV - 18
HPV - 16
HPV - 45
HPV - 31

Question 23

Viruses linked with cancers

Answer 23

Hepatitis B
Epstein-Barr 
Herpesvirus
HPV
Merkel cell polyomavirus
Human T-cell leukaemia lymphoma virus

Question 24

What is Ebola?

Answer 24

Filovirus
single-stranded, negative-sense
19k nucleotides (RNA)
Helical structure

Question 25

How does Ebola enter the cell?

Answer 25

Niemann-Pick C1 receptor

T-cell immunoglobulin and mucin domain 1 (TIM-1)

Question 26

What does TIM-1 do?

Answer 26

T-cell immunoglobulin and mucin domain 1 (TIM-1)

Receptor for mucosal surfaces - how Eboli is initially contracted? (hand->eye)

Question 27

What does NPC1 do?

Answer 27

Niemann-Pick C1 receptor

Access to dendritic and other cells.

Question 28

How Ebola inhibits viral response?

Answer 28

VP24 (viral protein 24)

-> INF-beta & STAT-1 expression

Question 29

VP24

Answer 29

Ebola Matrix protein

INHIBITS NORMAL ANTIVIRAL RESPONSES (INF-β & INF-INDUCED EXPRESSION OF ALPHA-STAT-1)

Question 30

NP

Answer 30

Ebola, Nucleoprotein, associated with RNA genome

Question 31

VP35

Answer 31

Ebola, Polymerase cofactor

Question 32

VP30

Answer 32

Ebola, Transcription activator, encourage transcription of viral RNA over host RNA
(preference)

Question 33

VP30, VP24, VP35

Answer 33

Ebola nucleocapsid proteins

Question 34

HIV - host cell specificity

Answer 34

CD4

CCR5 or CXCR4 chemokine receptors

Question 35

Epstein-Barr

Answer 35

C3d recpetor on B cells

Question 36

What does the Ebola virus seem to affect in particular (cells)?

Answer 36

Immune system

- dendritic cells - high amount of Nieman-Pick C1 receptors