Polyoma, Papilloma, Adeno Flashcards
Which virus families are oncoviruses (cause cancer)?
- Polyomaviridae
- Papillomaviridae
- Adenoviridae
- Herpesviridae
What are the 2 tumor suppressor genes that prevent cancer?
- Rb
- p53
How does Rb work?
Binds to E2F and prevents activation of cell cycle genes
-cell cycle stops
How does p53 work?
Responds to DNA damage by doing apoptosis or stops cell cycle
True or false: Only Papillomavirade and Polyomaviridae have proteins that disrupt Rb and p53
False
1. Polyoma
2. Papilloma
3. Adeno
all have proteins that encode proteins that disrupt Rb & p53
What pathogens are in polyomaviridae?
- Human polyomaviruses (10 types, only 1 causes cancer) 10 to 70% of people are infected
- Merkel Cell polyomavirus (causes cancer)
What pathogens are in papillomaviridae?
- Human papillomaviruses (nearly everyone has been infected, causes warts)
- HPV16 and HPV18 (cause mostly cervical cancer)
Why did identifying HPV causes cervical cancer win a nobel prize?
Identifying that a virus causes cervical cancer we could prevent cancer with a vaccine
What group are Polyoma and Papilloma in?
Group 1–>dsDNA
True or false: Polyoma and Papilloma are small LINEAR genomes
False
-small
-circular
What kind of polymerase do Polyoma and Papilloma use?
HOST DNA dep RNA pol–>Trancscription
HOST DNA dep DNA pol–>replication
Where do Polyoma and Papilloma replicate?
Nucleus
Are polyoma and papilloma enveloped or non enveloped?
Non enveloped
True or false: Polyoma and papilloma have their genome wrapped by host histone proteins
true
Life cycle of Polyoma and Papilloma
- Entry: Endocytosis
- Capsid disassembly: (+) protein into nucleus –>Early genes
- Genome Replication–>Late genes
- Exit: Cell lysis
What transcribes early genes (non structural) in Polyoma and Papilloma
Host DNA dep RNA pol
What transcribes late genes (structural) in Polyoma and Papilloma
Host DNA dep DNA pol
What are the early proteins in Polyoma and Papilloma and 2 function
- DNA binding and helicase activity
-Polyoma: T antigen
-Papilloma: E1 & E2 - Drives cell cycle progression & transcription
-Polyoma: T antigen
-Papilloma: E6 & E7
What is an advantage of early proteins driving cell cycle for virus?
-Drive cell cycle so cells get out of G1 phase
-At G1 phase no replication happens
-Progresses cell cycle so polymerase is active & replicates genome
What are the late proteins and function function in Polyoma and Papilloma?
-Polyoma: VP1, VP2, VP3
-Papilloma: L1 & L2
-Make capsid proteins
Why is it important that Polyomavirus does bidirectional transcription?
So strands do not overlap and make dsRNA
-will cause an immune response
Which virus have large T antigen what does it do?
-Polyoma
-host dependent genome replication
-Binds p53 and Rb
True of false: Papilloma is studied well in lab
False
-only replicates well in tissues
-causes warts on outer layers–>hard to work with
True or false: Polyoma and Papilloma cause cancer frequently
False
-Cancer is off target effect
-Only happens if there is linear integration (mostly E6 & E7 for Papilloma)
True or false: Driving cell cycle forward causes cancer
False
-it allows for replication
-Cancer cells are dead end–>can no longer replicate
What group are Adenoviridae in
Group 1–>dsDNA
What polymerase does Adenoviridae use?
-Host DNA dep RNA pol (Gene transcription)
-Viral DNA dep DNA pol (Gene replication)
What type of genome does Adenoviridae have (circular or linear)
Linear
Are adenoviridae enveloped/non what is their capsid shape?
-Non enveloped
-Icosahedral
What pathogens are in Adenovirdae?
Human adenoviruses–> does NOT cause cancer
-causes cancer in non humans–>integration not necessary
Why are adenovirdae useful?
Broad range of tissue tropism and genes
-Gene therapy vectors
-oncolytic viruses –> can kill cancer cells
-vaccine delivery vectors –> J & J vaccine
Adenovirdae life cycle
- Entry: Endocytosis
- Capsid dissasembly–>(+) protein into nucelus–>Early genes (HOST DNA dep RNA pol)
- Genome replication (VIRAL DNA dep DNA pol)–>Late genes
- Exit by cell lysis
Where does protein assembly occur in Adeno
Nucleus
Adenoviridae have linear genomes, what problem does this cause when genome replicates?
-Ends can get degraded
-Humans solve w/ telomerase
-Adeno solves by terminal repeats and is primed by protein TP
What 2 proteins do Adeno have that drive transcription forward/manipulate cell and interacts with Rb p53?
-E1A
-E1B
Adeno have late stage mRNAs that do what?
-Cap independent translation
-allows virus to translate when host shuts off cap-dependent translation