Herpesvirus Flashcards
3 Things all viruses have
nucleic acid
protein coat
some can have extra material (glycoproteins)
Virion
infectious virus particle
Enveloped virus
has a tegument between the capsid and lipid bilayer
Properties of herpes viruses
- Infections last a lifetime in latency stage
- They do not integrate into host cell genomes (tethering event)
- Herpes can reactivate
Explain the tethering event
Proteins that mediate genome persistance in host cells are made that bind to the viral genome and ensure that as the host cell divides, the viral genome is copied
What two molecules control the virus?
Natural killer cells
CD8 T cells
Alphaherpesviruses
HSV1
HSV2
varicella zoster virus
latent in neurons
Betaherpesviruses
humany ctomegalovirus (HCMV) latent in T cells
Gammaherpesviruses
Epstein barr virus
Kaposi sarcoma associated herpes virus (KSHV)
latent in B cells
Tropism
Which host cells are susceptible by which particular particles
How do viruses pick a host cell?
Glycoproteins have the ability to attach to particular host proteins
How does herpes infect a cell?
Attaches and enters
- Tegument proteins released
- capsid translocates to nucleus
- DNA injected
- Transcription of genome
- goes through rough ER and Golgi
- Goes out of cell
Steps of viral replication
- attachment
- penetration/absorption
- synthesis
- assembly
- release
3 mechanisms of disease for viruses
- cytopathic effect (disrupts normal cell physiology)
- host immune response
- tumorigenesis: viral infection promotes uncontrolled proliferation of infected cells
Process by which VZV infection occurs
- infection of upper respiratory mucosa with virus containing droplets
- virus spreads to region lymph nodes and replicates
- virus spreads to liver and spleen
- Infection of skin leads to appearance of rash and fever may occur
- virus enters neurons and migrates to ganglia
Process by which HSV infection occurs
- Virus penetrates into skin where it replicates
- Virus enters cutaneous neurons and migrates to ganglia where it remains in latency
- Virus can be reactivated and travel through sensory neurons to epidermis
- REcurrent infection results
What causes ulcers to form in HSV-1
CD8+ cytoxic effect
What causes the chickenpox response?
CD8 T cell response
How can we treat Alphaherpesvirus?
Acyclovir
How does acyclovir work?
Tricks viral polymerase into thinking it’s a guanine base
Once it’s incorporated, it’ll terminate the chain since it’s missing the sugar group with the 3’ OH.
How is acyclovir activated?
Thymidine kinase
What do betaherpesviruses infect?
fibroblasts
Example of betaherpesvirus
HCMV
HCMV
most infections asymptomatic
Can be a problem in organ transplants and newborns
transmitted through close contact
