Viruses lecture 2

Question 1

Are ribosomes a feature of viruses?

Answer 1

no

Question 2

Describe positive-strand RNA virus genomes

Answer 2

• simple open reading frame
• cassette their proteins into structural and non-structural
• 5’UTR and 3’UR
• sometimes Cap
• sometimes Poly(A)
• 1 start
• 1 stop

Question 3

Which direction do negative strand RNA viruses get read?

Answer 3

right to left

Question 4

What do negative strand RNA proteins do first when they invade a cell?

Answer 4

begin by replicating (must contain a polyerase in its capsid)

Question 5

What are the four types of negative-strand RNA genomes?

Answer 5

• simple
• multiparte, simple
• multiparte, simple, ambisense
• multiparte, complex, ambisense

Question 6

What does ambisense mean?

Answer 6

some bits of RNA translate n both directions

Question 7

What is a mononegavirale?

Answer 7

single-stranded, single pieces of anti-sense viral RNA (must have a RNA polymerase as cells don’t have one)

Question 8

Can viruses make a two codon translation?

Answer 8

yes

Question 9

What does para mean?

Answer 9

correct/normal

Question 10

What does ortho mean?

Answer 10

similar

Question 11

Meta?

Answer 11

following after

Question 12

Name the segmented viruses (BOARing)

Answer 12

bunyavirus, orthomyxovirus, arenavirus and reovirus

Question 13

What makes it possible for reassortment of genetic information?

Answer 13

segmented genomes

Question 14

What does reassortment achieve?

Answer 14

rapid generation of genetic diversity

Question 15

What must all viruses contain at some point in their life cycle?

Answer 15

double stranded RNA as they have to replicate

Question 16

What triggers an innate response?

Answer 16

the replication intermediate double stranded rNA which is normally never seen

Question 17

In retroviruses where is the nucleocapsid protein found?

Answer 17

on the left, near 5’ end

Question 18

Where is the envelop protein in retroviruses?

Answer 18

right

Question 19

Where is the polymerase in retroviruses?

Answer 19

middle

Question 20

How do retroviruses replicate?

Answer 20

make DNA from RNA and then RNA from the DNA that has been made

Question 21

Are retroviruses nuclear?

Answer 21

yes always because they are DNA viruses half of the time

Question 22

Why do viruses spread so quickly?

Answer 22

once a cell is infected it defends the virus inside it to avoid superinfection. It pushes the other virus away causing other cells to become infected (this occurs via A33 and A36 proteins)

Question 23

What does VEHCS stand for?

Answer 23

Virally Encoded Host Cell Shutoff

Question 24

How does polio produce viral proteins?

Answer 24

1. Removes the cap binding complex on mRNA so that translation can’t occur
2. Polio can bind directly to the ribosome using the internal ribosome entry site so it can produce proteins

Question 25

How does HSV work?

Answer 25

to remain hidden it stays silent
-turns off everything other than a series of micro RNAs that control the host cell (not antigens) (immosilent and invisible)

Question 26

What makes a virus more likely to spread?

Answer 26

by keeping host cells alive (more chance for transmission than if host cells are dying) (need to be less virulent)

Question 27

What is the role of the HERV-W virus?

Answer 27

mediates the cell-cell fusion which forms the synciotrophoblast forming the fetal-parent barrier

Question 28

Do all viruses contain RdR polymerases?

Answer 28

no HIV has a RdD polymerase (RNA dependent DNA polymerase)