Flashcards in Viruses Deck (40)
How do viruses differ in their replication cycle?
Viruses have an eclipse/latent period then burst
Bacteria just linearly replicate from the get go
6 stages in viral replication
4. genome replication, RNA synthesis, protein synthesis
6. RELEASE THE KRAKKEN!
Viral attachment to specific receptors on hosts does what?
limited the host species/type of cell
2 kinds of receptors for viruses to attach?
protein (ICAM-1 for rhinoviruses)
Carbohydrate (sialic acid for influenza)
HIV uses two receptors to attach: explain
on initial CD4
then CCR5 locks it in
2 ways to penetrate a cell as a virus:
1. fuse with host cell membrane
Do fusing with cell membrane viruses have envelopes?
Do endocytosis viruses have envelopes?
Yes and they don't need them either.
HIV penetrates how?
Fusion of region gp41
What's an example of a virus that is endocytosed?
DNA viruses replicate where? exception?
nucleus except for influenza(RNA)
RNA viruses replicate where? exception?
cytoplasm except for poxvirus(DNA)
What's vital for viral protein transcription initially?
What are early viral proteins?
What are late viral proteins?
How does an RNA virus replicate?
needs RNA dependent DNA polymerase
Poliovirus is a plus sense ssRNA, how does it replicate?
goes right to translation to make proteins
auto cleavage of parts
one is a RNA polymerase to make more copies
What happens with a -ve sense ssRNA virus?
need to bring your own polymerases (BYOP)
Why would a retrovirus want to go back to DNA?
It needs to be DNA to insert itself in the host genome
2 viruses that need their own polymerase?
Translation is done how and by whom?
Host cell ribosomes in cytoplasm
when do you need virus coded proteases?
post-translational cleavage of viral polyproteins
What's glycosylation in viral replication?
envelope glycoproteins in RER and golgi get deposited on underside of cell surface
for budding of enveloped viruses
T/F? All non-enveloped viruses are helical?
Assembly of non-enveloped viruses happen 2 ways:
1. spontaneous assembly
2. proteolytic cleavage to induce assembly
Do non-enveloped viruses bud?
Two viruses that bud?
Besides budding and lysing out, is there another way viruses can exit the cell?
Elementary Watson. some enveloped viruses use the golgi vesicles' secretary pathway
Example of a virus that uses the secretory pathway?
4 virus induced changes in cells?
What' s the difference between chronic and latent viral infection?
Chronic is slow release, no cell death
latent is dormant, emerges later as lytic
What are cytopathic effects?
changes in virus infected cells you can SEE on light microscope
What are inclusion bodies re: viruses
viral proteins visible at site of virus assembly
The goal of a virus isn't to turn a cell cancerous, how does it happen?
The virus oncogenes are growth promoting genes that 'accidentally' lead to uncontrolled proliferation of infected cell
What kind of inhibition do cancer cells lack?
3 ways viral genetics change?
recombination (DNA viruses)
reassortment (swapping of segments e.g.. flu/rota)
4 ways to halt viruses
2. kill infected cell via CD8, NK
4. antiviral drugs
do antivirals work on classes of viruses?
NOPE. very specific