Herpes virus Flashcards
How long does the Herpes infection last?
All your life
Why do Herpes viruses not have the capacity to mutate?
DNA-based genome
Proof-reading error correcting is better than in RNA
How many species can Herpes infect?
Every species known to man
How many Herpes strains infect humans?
8
What strain is known to cause cold sore?
HS1
What strain is known to cause genital sore?
HS2
What strain is known to cause chickenpox?
Varicella Zoster
Why is the Herpes virus lifelong?
Due to its latency
What is latency?
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
What are the inactive and active stages called?
Latent
Lytic
Why is the active stage called lytic?
Because activation causes cell lysis
Why is it not optimal that Herpes viruses are latent
They need to transmit
Why do Herpes viruses stay latent?
The viral population has to grow in number in order to combat the host immune system
Encode a repertoire of immune evasion factors
What is the pathogenesis of the primary infection?
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
What is retrograde expasion?
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
How does recurrent infection occur?
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
Who is at risk for Herpes reactivation?
Immunocompromised patients
What is shingles?
Reactivation of varicella zoster virus in later life
How does shingles present?
As localised rashes where the nerves containing latent virus innervates
Circumscription
What is the Fc region
The opposite end of the antigen-binding domains of the antibody
Communicates with
Complement system
Macrophages
Natural Killer Cells
How does the Herpes virus mantain latency?
Evades antibodies
Evades immune system
How does Herpes Virus evade antibodies?
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
How does Herpes Virus evade immune system?
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
What is IPC47?
Protein made by Herpes virus that blocks the action of TAP from transporting peptides from proteasome to the ER
What does the Fc region do?
Recruits macrophages
FIxes complement
Recruits NK cells
