Viruses Flashcards
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
- attachment
- penetration
- uncoating
- genome replication, RNA synthesis, protein synthesis
- assembly
- 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:
- fuse with host cell membrane
2. endocytosis
Do fusing with cell membrane viruses have envelopes?
yes
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?
togavirus
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?
mRNA
What are early viral proteins?
non structural
What are late viral proteins?
structural (capsids)
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?
Pox
Hepadna
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
Why glycosylation?
for budding of enveloped viruses
