Influenza virus

Question 1

When were the 3 influenza pandemics?

Answer 1

1918-1919, 1968-1969, 2009-2010

Question 2

What type of virus is influenza?

Answer 2

RNA virus that is an enveloped virus and has a membrane

Question 3

How many genes does the influenza virus have?

Answer 3

8

Question 4

What are the 2 coat proteins of influenza?

Answer 4

Hemagglutinin and neuraminidase

Question 5

What is the structure of hemagglutinin?

Answer 5

A trimer attached to the viral membrane

Question 6

What does hemagglutinin do?

Answer 6

Is a lectin and is responsible for getting the viral RNA into the host cell

Question 7

What is the target on the host cell surface for hemagglutinin?

Answer 7

Sialic acid

Question 8

How does influenza get into the host cell?

Answer 8

HA binds to sialic acid on the host cell surface, and gets brought in by endocytosis. When the endosome gets acidified like usual, HA is refolded and exposes the fusion peptide. The fusion peptide is hydrophobic and sticks itself into the membrane where it causes the viral and endosome membranes to fuse, and the viral RNA gets released into the host cell to reproduce

Question 9

How does influenza determine host specificity?

Answer 9

Which carbon on the galactose the sialic acid is linked to

Question 10

Which galactose carbon is sialic acid linked to in human tracheal epithelium cells?

Answer 10

Carbon 6. Uses alpha2-6 linkages

Question 11

Which galactose carbon is sialic acid linked to in bird tracheal epithelium cells?

Answer 11

Carbon 6. Uses alpha2-3 linkages

Question 12

Which carbon on sialic acid is the anomeric carbon?

Answer 12

Carbon 2

Question 13

Why are humans able to be infected by bird viruses?

Answer 13

We also have some of the sialic acid with the alpha2-3 linkages, so we can get infected

Question 14

What animal can be infected by both human and bird viruses and acts as an intermediate?

Answer 14

Pigs

Question 15

What happens if a pig is infected by both a human and bird virus?

Answer 15

The viruses can reassort and mix up their RNA, and you can get a virus with fragments of bird virus RNA and human virus RNA. They have the virulence of a bird virus and are able to infect humans, so are extremely deadly

Question 16

What is RNA segment reassortment?

Answer 16

Two viruses that infect different hosts swapping different segments of their genome

Question 17

What is the structure of neuraminidase?

Answer 17

Tetramer that is attached to the viral membrane

Question 18

What is the function of neuraminidase?

Answer 18

Cleaves sialic acid off the host cell to allow the newly made virus to leave and infect other cells

Question 19

Why does neuraminidase need to be there on the virus?

Answer 19

It can’t leave the host cell without it and can’t infect other cells

Question 20

How do anti-viral drugs work?

Answer 20

They are sugar analogs and mimic a sialic acid. They inhibit neuraminidase and prevent new viruses from leaving the host cell

Question 21

What defines the influenza strain?

Answer 21

The HA/NA combination

Question 22

What is H1N1?

Answer 22

Swine flu

Question 23

What is H5N1?

Answer 23

Avian flu

Question 24

What part of the virus elicits an immune response in the host?

Answer 24

HA and NA

Question 25

Why do we need a flu vaccine every year?

Answer 25

RNA is copied as perfectly as DNA and mutates a lot

Question 26

What is in a seasonal flu vaccine?

Answer 26

Whole viruses. They create antibodies for the head portions of HA, which mutates a lot

Question 27

What would be in a universal flu vaccine, if we could make one?

Answer 27

Only the stem of HA, which doesn’t mutate as much