Lecture 23 - Influenza

Question 1

What type of genome does influenza virus have?

Answer 1

8 segments of (-)ssRNA

Question 2

What viral family does influenza virus belong to?

Answer 2

Orthymyxoviridae

Question 3

What can change your immunity to a type of influenza?

Answer 3

when it mutates

Question 4

What are the 2 types of mutations?

Answer 4

antigenic shift and antigenic drift

Question 5

What are the characteristics of the influenza viral capsid?

Answer 5

enveloped containing hemagglutinin (HA) and neraminidase (NA) antigenic glycoprotein spikes on the surface

Question 6

What helps us name the influenza viruses? What is it based on?

Answer 6

HA and NA proteins

Question 7

What are the 4 influenza viral capsid proteins?

Answer 7

HA, NA, M1 and M2

Question 8

What are M2 influenza viral proteins?

Answer 8

ion channel proteins

Question 9

What species is influenza A H1 found in?

Answer 9

human, swine, bird

Question 10

What species is influenza A N1 found in?

Answer 10

human, swine, bird

Question 11

What species are most of the H and N subtypes of influenza A are found in?

Answer 11

birds

Question 12

What is the issue with the influenza A H1N1?

Answer 12

it is in 3 different species including humans

Question 13

What does HA protein bind to?

Answer 13

sialic acid

Question 14

Where is sialic acid found?

Answer 14

present on glycoproteins of ciliated cells lining the sinuses and airways

Question 15

How does the influenza virus enter the cell?

Answer 15

receptor-mediated endocytosis

Question 16

In order for the influenza viral genome to exit the endosome, what must happen?

Answer 16

drop the pH from 7 to 5 to expose fusion peptide proteins = triggers fusion with endosomal membrane and viral membrane to deliver the viral RNPs (ribonucleoproteins)

Question 17

What is the function of M2 proteins?

Answer 17

the ion channels allow hydrogen ions to penetrate virion

Question 18

Where does the influenza virus replicate its genome?

Answer 18

cytoplasm

Question 19

What is the function of the M1 protein?

Answer 19

matrix proteins that holds the vRNPs together

Question 20

How are the M1 proteins dissociated from the vRNPs?

Answer 20

increase in hydrogen ions weakens the matrix proteins association from the vRNPs

Question 21

What happens to the vRNPs once released into cytoplasm?

Answer 21

is directed towards the nucleus and enters it

Question 22

What helps initiate genome replication?

Answer 22

the proteins on the end of the genome

Question 23

What are 2 things that will be synthesized from copying the (-)ssRNA genome?

Answer 23

the viral mRNA and the (+)ssRNA template (antigenome)

Question 24

In order for the viral mRNA to be translated by the host cell ribosomes, what modification must the virus do its viral mRNA?

Answer 24

snatch a 5’ cap to put on it

Question 25

What is the function of the influenza viral protein NS1?

Answer 25

prevents nuclear export of cellular pre-mRNAs by trapping them in the nucleus

Question 26

What is the 5' cap used/beneficial for the influenza virus?

Answer 26

as a primer to initiate transcription of viral RNA

Question 27

What intermediate is formed during influenza viral replication?

Answer 27

double-stranded RNA (dsRNA)

Question 28

Which influenza viral protein binds and sequesters the dsRNA intermediate?

Answer 28

NS1

Question 29

Where does assembly of the progeny influenza virion occur in the cell?

Answer 29

cell membrane

Question 30

How are new influenza virions released?

Answer 30

budding off

Question 31

Which organ does influenza virus initially enter the body through?

Answer 31

respiratory tract

Question 32

In the lungs, what does influenza virus infect?

Answer 32

pneumocytes lining alveoli of the lungs

Question 33

What do the pneumocytes release as the influenza virus replicates?

Answer 33

cytokines and chemokines

Question 34

What mediates genetic variation that causes new strains of influenza to appear more often than yearly?

Answer 34

antigenic shift and antigenic drift

Question 35

What is antigenic drift responsible for?

Answer 35

localized/seasonal influenza epidemics caused by types A or B

Question 36

Where do the mutations in the influenza virus occur in the antigenic drift process?

Answer 36

in the HA and/or NA genes

Question 37

What is antigenic shift responsible for?

Answer 37

pandemic strains

Question 38

In which genetic variation process are new influenza virions produced?

Answer 38

antigenic shift

Question 39

Which genetic variation process allows for influenza viruses to move from animals to birds in order to infect humans?

Answer 39

antigenic shift

Question 40

Why was the H1N1 Swine flu pandemic alarming?

Answer 40

traced to an antigenic shift resulting in triple reassortment of bird, human, and pig viruses

Question 41

What is a consequence of a single mutation within the H5N1 strain?

Answer 41

allow the influenza virus spread more efficiently

Question 42

What was significant of the H5N1 influenza virus strain?

Answer 42

jumped directly to infecting humans which never observed before; same strain was killing chickens

Question 43

What animal reservoir does the H5N1 infleunza virus strain infect?

Answer 43

birds

Question 44

What type of genetic variation process did the H5N1 strain undergo?

Answer 44

antigenic drift – did not combine with human strain

Question 45

What happens when the M2 ion channels are inhibited?

Answer 45

prevents uncoating step

Question 46

What is the issue with using antivirals that inhibit the M2 ion channels?

Answer 46

the virus develops drug resistance

Question 47

What happens with the NA capsid protein is inhibited?

Answer 47

prevents NA from cleaving sialic acid during budding

Question 48

What is the most effective way to prevent influenza?

Answer 48

vaccines

Question 49

Why does recombination occur within influenza?

Answer 49

due to segmented genome

Question 50

What are 3 distinguishing characteristics about the H7N9 strain?

Answer 50

in birds and humans | combo of 3 viruses fromwild birds and domesticated ducks and chickens | short lived