RNA Viruses 1

Question 1

How is RNA made from RNA?

Answer 1

RNA-dependent RNA Pol

Question 2

In an RNA virus, what is the + stand?

Answer 2

sense strand

= synthesized mRNA

Question 3

In an RNA virus, what is the - strand?

Answer 3

antisense strand

= template for mRNA

Question 4

where does RDRP perform replication?

Answer 4

Cytoplasm

Can happen on cell membranes

Question 5

What is the advantage of having RDRP work at cell membranes (endosomes, lysosomes, ER)?

Answer 5

concentrates all components

increases efficiency

Question 6

What is the fidelity of RDRP? does it proofread?

Answer 6

low fidelity

does not proofread

Question 7

What is responsible for the rapid evolution of RNA viruses?

Answer 7

recombination

Question 8

What can happen to segmented genomes in RNA viruses? What does this produce? What are examples of segmented RNA viruses?

Answer 8

rearrangement –> different strains
reo, retro, bunya, arena, orthomyxo
Influenza

Question 9

What are consequences of RNA virus genetic diversity

Answer 9

QUASISPECIES
mutants arise frequently 
new variants, new diseases
drugs and vaccines lose effectiveness
not pure populations

Question 10

What sense and strandedness is the Poliovirus?

Answer 10

+ sense ssRNA

Question 11

What is the transmission of Poliovirus? What are its hosts?

Answer 11

fecal-oral (water)

humans only

Question 12

What is the mechanism of entry for the Poliovirus?

Answer 12

binds receptor, changes conformation
capsid proteins become hydrophobic
capsid proteins form pore through membrane
RNA genomes enter cell at PM or endosome membrane

Question 13

Which enzyme copies the + strand (mRNA) in the Polyovirus? Which copies the -?

Answer 13

Both RDRP

Question 14

In Poliovirus, what triggers the stop of translation and the packaging of mRNA?

Answer 14

capsid (tln products) proteins accumulate

Question 15

What are three problems with + sense RNA

Answer 15

Collisions between RDRP and ribosomes
Tln happens first when RDRP is scarce
- RNA synthesis happens later when RDRP is abundant

Question 16

Which type(s) of RNA viruses MUST package RDRP in the virion?

Answer 16

• RNA

dsRNA

Question 17

Which type(s) of RNA viruses don’t need to package RDRP in the virion?

Answer 17

+ RNA

Question 18

What is the diagnosis of Poliovirus?

Answer 18

monitor neuron involvement

serology and culture

Question 19

What is the Treatment for Poliovirus?

Answer 19

control any symptoms

breathing support if needed

Question 20

What is the prevention of Poliovirus?

Answer 20

vaccine

sanitation

Question 21

What % of Poliovirus infections become paralytic?

Answer 21

1%

Question 22

What % of Poliovirus infections are asymptomatic acute GI infections?

Answer 22

95%