RNA Viruses 1 Flashcards
How is RNA made from RNA?
RNA-dependent RNA Pol
In an RNA virus, what is the + stand?
sense strand
= synthesized mRNA
In an RNA virus, what is the - strand?
antisense strand
= template for mRNA
where does RDRP perform replication?
Cytoplasm
Can happen on cell membranes
What is the advantage of having RDRP work at cell membranes (endosomes, lysosomes, ER)?
concentrates all components
increases efficiency
What is the fidelity of RDRP? does it proofread?
low fidelity
does not proofread
What is responsible for the rapid evolution of RNA viruses?
recombination
What can happen to segmented genomes in RNA viruses? What does this produce? What are examples of segmented RNA viruses?
rearrangement –> different strains
reo, retro, bunya, arena, orthomyxo
Influenza
What are consequences of RNA virus genetic diversity
QUASISPECIES mutants arise frequently new variants, new diseases drugs and vaccines lose effectiveness not pure populations
What sense and strandedness is the Poliovirus?
+ sense ssRNA
What is the transmission of Poliovirus? What are its hosts?
fecal-oral (water)
humans only
What is the mechanism of entry for the Poliovirus?
binds receptor, changes conformation
capsid proteins become hydrophobic
capsid proteins form pore through membrane
RNA genomes enter cell at PM or endosome membrane
Which enzyme copies the + strand (mRNA) in the Polyovirus? Which copies the -?
Both RDRP
In Poliovirus, what triggers the stop of translation and the packaging of mRNA?
capsid (tln products) proteins accumulate
What are three problems with + sense RNA
Collisions between RDRP and ribosomes
Tln happens first when RDRP is scarce
- RNA synthesis happens later when RDRP is abundant
Which type(s) of RNA viruses MUST package RDRP in the virion?
- RNA
dsRNA
Which type(s) of RNA viruses don’t need to package RDRP in the virion?
+ RNA
What is the diagnosis of Poliovirus?
monitor neuron involvement
serology and culture
What is the Treatment for Poliovirus?
control any symptoms
breathing support if needed
What is the prevention of Poliovirus?
vaccine
sanitation
What % of Poliovirus infections become paralytic?
1%
What % of Poliovirus infections are asymptomatic acute GI infections?
95%
