Herpes virus

Question 1

How long does the Herpes infection last?

Answer 1

All your life

Question 2

Why do Herpes viruses not have the capacity to mutate?

Answer 2

DNA-based genome

Proof-reading error correcting is better than in RNA

Question 3

How many species can Herpes infect?

Answer 3

Every species known to man

Question 4

How many Herpes strains infect humans?

Answer 4

8

Question 5

What strain is known to cause cold sore?

Answer 5

HS1

Question 6

What strain is known to cause genital sore?

Answer 6

HS2

Question 7

What strain is known to cause chickenpox?

Answer 7

Varicella Zoster

Question 8

Why is the Herpes virus lifelong?

Answer 8

Due to its latency

Question 9

What is latency?

Answer 9

Latency is the maintenance of the viral genome in the absence of the full viral gene expression

Some genes are expressed but do not produce viral proteins

Question 10

What are the inactive and active stages called?

Answer 10

Latent

Lytic

Question 11

Why is the active stage called lytic?

Answer 11

Because activation causes cell lysis

Question 12

Why is it not optimal that Herpes viruses are latent

Answer 12

They need to transmit

Question 13

Why do Herpes viruses stay latent?

Answer 13

The viral population has to grow in number in order to combat the host immune system

Encode a repertoire of immune evasion factors

Question 14

What is the pathogenesis of the primary infection?

Answer 14

At site of inoculation the virus causes a lesion

This is controlled and removed by the immune system

Virus travels along the sensory neurons that innervate the site of innoculation

Reaches the cell body and this is were latency is established

Silent - no immune response is triggered

Retrograde spread happens

Question 15

What is retrograde expasion?

Answer 15

The viral particles move from the dendrites to the cell body to establish latency

This is opposite to the flow of information through a neuron

Question 16

How does recurrent infection occur?

Answer 16

No known stimulus

Gene expression initiates and transcription kicks off

New viruses are produced in the cell body of the neuron

Assembly forms in vesicles at distal end of a neuron and contacts cells from the initial site of inoculation

Cells replicate at distal end and cell death and lesion occurs

Anterograde expansion

Question 17

Who is at risk for Herpes reactivation?

Answer 17

Immunocompromised patients

Question 18

What is shingles?

Answer 18

Reactivation of varicella zoster virus in later life

Question 19

How does shingles present?

Answer 19

As localised rashes where the nerves containing latent virus innervates

Circumscription

Question 20

What is the Fc region

Answer 20

The opposite end of the antigen-binding domains of the antibody

Communicates with

Complement system
Macrophages
Natural Killer Cells

Question 21

How does the Herpes virus mantain latency?

Answer 21

Evades antibodies

Evades immune system

Question 22

How does Herpes Virus evade antibodies?

Answer 22

Making their binding irrelevant

Encode glycoproteins that prevent the antibody from contacting the immune defeces mediated by the Fc region

Antibody can no longer

Fix complement
Recruit macrophages

Question 23

How does Herpes Virus evade immune system?

Answer 23

Normally, the antigens are chopped up into peptides in the proteasome and transmitted to the ER via TAP transporter proteins until MHC I presents them on their surface

Herpes stops this from working by making a protein called IPC47 that binds to TAP

Question 24

What is IPC47?

Answer 24

Protein made by Herpes virus that blocks the action of TAP from transporting peptides from proteasome to the ER

Question 25

What does the Fc region do?

Answer 25

Recruits macrophages
FIxes complement
Recruits NK cells