5. Influenza virus (flu)

Question 1

Genome of influenza?

Answer 1

8x segmented (-)ssRNA

Question 2

Family that influenza belongs to?

Answer 2

Orthomyxoviridae

Question 3

What are the glycoproteins on flu viruses?

Answer 3

Hemagglutinin (HA) and neuraminidase (NA)

Question 4

Influenza viruses are grouped type A, B, and C based on _______ differences in matrix proteins and NP

Answer 4

antigenic

Question 5

Types of hosts influenza A acts on? B and C?

Answer 5

Human AND non-human (birds, pigs)

B and C = only humans

Question 6

Which type of influenza causes seasonal epidemics?

Answer 6

Influenza B

Question 7

How many different HA subtypes are there? NA?

Answer 7

18 HA, 11 NA

Question 8

What disease/problems can influenza lead to?

Answer 8

Pneumonia by virus itself = rare

Opportunistic bacteria = more common

Question 9

Example of an influenza drug?

Answer 9

Tamiflu (antiviral)

Question 10

H1N1/09 may have infected as much as ____% of the world’s population

Answer 10

24%

Question 11

What does neuraminidase do?

Answer 11

Cleave sialic acid

Question 12

How do new influenza strains form?

Answer 12

2 diff flu viruses co-infect single cell and their gene segments reassort to make new combinations

Question 13

Of the total number of HA and NA subtypes, only ___HA and ___ NA have ever been found in truly-human adapted viruses

Answer 13

3 HA, 2 NA

Question 14

2 mechanisms that can result in highly virulent an pathogenic flu?

Answer 14

Adaptive mutation => genetic drift (acquire ability to bind human cells)

Reassrotment even => genetic shift (increase specificity/virulence)

Question 15

2 reasons why flu genome is unstable?

Answer 15

Error-prone viral RNA polymerase

Segmented genome

Question 16

How many copies of HA on flu virus?

Answer 16

3x HA1, 3x HA2

Question 17

Flu binds to host cells containing what?

Answer 17

Sialic acid

Question 18

Fusion of flu viral membrane is induced by what?

Answer 18

Mildly acidic pH

Question 19

What is contained in the ribonucleoprotein complex (RNP)?

Answer 19

Viral (-)RNA, RNA pol (PB1/PB2/PA), NP

Question 20

Which part of the HA trimer binds sialic acid on host receptors?

Answer 20

HA1

Question 21

Function of RNP?

Answer 21

Transport viral RNA into nucleus

Question 22

Which terminal of HA2 is intracellular?

Answer 22

C-terminal

Question 23

pH change causes what part of the HA trimer to be exposed? What does it do?

Answer 23

HA2 fusion peptides

Inserts into endosomal membrane

Question 24

What is formed as the HA intermediate collapses after pH change? What gets inserted into the host cell?

Answer 24

6-helix bundle

RNP complex

Question 25

Difference between avian and human flu virus sialic acid linkage recognition?

Answer 25

Avian - alpha2,3
Human - alpha2,6

(Sialic acid at pos 3/6)

Question 26

Alpha linkages are found between sialic acid and..?

Answer 26

Galactose