Virology1

Question 1

What s the Baltimore classification

Answer 1

1 - dsDNA - herpes
2 - ssDNA - parvo
3- dsRNA - reo
4 - ssRNA +sense - polio
5 - ssRNA -sense - influenza, measles 
6 - ssRNA +sense DNA intermediate - HIV
7 - dsDNA, RNA intermediate - HBV

Question 2

Which viruses use viral DNA polymerase?

Answer 2

Herpesvirus

Question 3

Which virus uses host DNA polymerase?

Answer 3

Parvo

Question 4

which virus uses viral RNA dependent RNA polymerase?

Answer 4

Rota, polio, influenza

Question 5

which virus uses viral RNA dependent DNA polymerase?

Answer 5

HIV, HBV

Question 6

What type of virus is influenza?

Answer 6

Class 5, Orthomyxovirus, segmented genome

Question 7

Draw a diagram of an influenza virus

Answer 7

picture lol

Question 8

what are the segments of influenza in order - largest to smallest?

Answer 8

1. PB2
2. PB1, PB1-F2
3. PA, PA-X
4. HA
5. NP
6. NA
7. M1, M2, M3
8. NS1, NS2

Question 9

What is the active form of HA

Answer 9

trimer

Question 10

How is sialic acid linked to galactose in humans?

Answer 10

a-2, 6 linkage

Question 11

How is sialic acid linked to galactose in ducks?

Answer 11

a-2,3 linkage

Question 12

What are the 3 stages in influenza virus mRNA synthesis?

Answer 12

1. Cap snatching
   2 Cleavage
2. Elongation

Question 13

What is the function of NP

Answer 13

• Associates with - strand genome RNA

Question 14

What is the function of NP

Answer 14

• Associates with - strand genome RNA

- Binds to cRNA and allows antitermination at polyA site so it can make a vRNP once it has been stabilised by NP

Question 15

What is the function of PB2

Answer 15

• Binds cap of host mRNA

Question 16

What is the function of PA

Answer 16

• Cleaves capped mRNA to produce cap and 10-12 nucleotides

Question 17

where does polyadenylation occur in mRNA synthesis of influenza?

Answer 17

17-22 bases from the 5’ end of the genome at a poly U tract

Question 18

where does polyadenylation occur in mRNA synthesis of influenza?

Answer 18

17-22 bases from the 5’ end of the genome at a poly U tract

Question 19

Describe the timing of influenza synthesis

Answer 19

1. mRNA –> cytoplasm
2. viral proteins made. Pol and NP enter nucleus
3. cRNA stabilised as cRNP
4. many copies of vRNA can be made from each cRNP
5. vRNA stabilised as vRNP and exported into cytoplasm for assembly.

Question 20

How is segment 2 translated in influenza?

Answer 20

Different start codons in different reading frames via leaky scanning

Question 21

How is segment 3 translated in influenza?

Answer 21

Proteins have common N terminus, diff C terminus via ribosomal frameshifting

Question 22

How is segment 7 translated in influenza?

Answer 22

Splicing to give 3 different mRNAs coding for different proteins

Question 23

How is segment 8 translated in influenza?

Answer 23

Splicing to give 2different mRNAs coding for different proteins

Question 24

What is the role of PB1-F2?

Answer 24

virulence factor, increases inflammation in the host

Question 25

What is the role of PA-X?

Answer 25

Host cell shut off gene expression, non-specific mRNA cleavage protein, dampens host antiviral response - anti-inflammation

Question 26

What is the role of NS1?

Answer 26

• Promote translation of viral mRNA
• IFN antagonist
• Inhibit nuclear export of cellular mRNA

Question 27

How does RNP export occur?

Answer 27

Via Crm1
M1 binds vRNP
NS2 binds M1 and interacts with Crm1 - part of the nuclear pore complex
vRNPs can be exported through the nuclear pore into the cytoplasm

Question 28

What is the role of NA?

Answer 28

Removes sialic acid from HA and prevents aggregation of new virions with each other and with the surface of the infected cell. allows viruses to leave the cell.