Influenza Virus and Vaccine

Question 1

What are the 3 proteins in the influenza envelope

Answer 1

Hemagluttinin (HA)
Neuraminidase (NA)
Matrix protein 2 (MP2)

Question 2

What does NA do

Answer 2

cleaves sialic acid which allows virus to leave the cell

Question 3

WHat does MP2 do?

Answer 3

forms ion channel in endosome allowing the fusion domain of HA to fuse endocytic vesical with viral membrane

Question 4

Which influenza strains ahve drift and whoch shift?

Answer 4

B, C: only drift

A = drift and shift

Question 5

What two populations does strain B infect

Answer 5

humans and seals

Question 6

Which strains cause epidemics

Answer 6

both A and B

Question 7

WHich strains cause pandemics

Answer 7

A

Question 8

Strain A infects what types of animals

Answer 8

humans, swine, birds (also marine mammals, bats, horses)

Question 9

Which strains have NA (thus are susceptible to NA inhibitors

Answer 9

A and B are susceptible

C is not

Question 10

What are the implications fo being negative sense

Answer 10

it has to package it’s own RNA-dependent viral protease

Question 11

What populations are more at risk for complicatinos from (7)

Answer 11

DM
Obesity
Renal Dz
Pregnancy
Chronic lung dz
CVD
ASthma

Question 12

What are the rates of hospitalizations for children who get the flu?

Answer 12

50% are hospitalized w/no comorbidity

Question 13

Who dies most often from flu

Answer 13

80-90% of deaths are usually people > 65 years old

Question 14

When is flu season and when is the peak?

Answer 14

Flu season –November through March-peak usually Dec/Jan in U.S.

Question 15

5 sx of lu

Answer 15

i. Abrupt fever
ii. Myalgia (affecting upper back)
iii. Vomiting/diarrhea- mostly in children
- Non-productive cough (thought to be dt epithelial cell destruction)
- sore throat

Question 16

How long are adults infectious before and after symptoms appear?

Answer 16

Adults are infectious for 24 hours before symptoms and about 5 days after symptoms

Question 17

How long are children infectious before and after sx appear?

Answer 17

Children can be infectious for several days before symptoms and shed for 10 days after symptoms.

Question 18

what 3 cells are destroyed in influenza infx

Answer 18

Productively infects epithelial cells of the respiratory tract (also macros and neutros but non-productive)

Question 19

why a person is more at risk of bacterial secondary infections with influenza infections. (4)

Answer 19

1. ↓ velocity of ciliated clearance = more attachment sites
2. viral neuraminidase cleavage of sialic acid–> ↓ bacterial receptor decoy
3. ↓ in alveolar macrophages by influenza killing–> decreased clearance of bacteria
4. Cells killed by virus provide a rich source of nutrients for bacterial growth!!!

Question 20

how many deaths in influenza are from bacterial pneumonia?

Answer 20

20-30% of

Question 21

WHat is the most important Ab to make in influenza infx and why/how?

Answer 21

HA ab- it blocks infx of new cells by neutralizing the virus

Question 22

Also what viral protein is most important in antigenic shift and drift? and why/how?

Answer 22

HA- can change epitope or mask epitope by glycosylation; this is antigenic drift.

Question 23

antibodies to NA can also help in infection how?

Answer 23

by blocking the production of infectious particles (block budding and release of the virus).

Question 24

How does the test detect the flu?

Answer 24

tests for presence of Virus not antibody

Question 25

What are the limitations of the test

Answer 25

doesn’t work well out of flu season because low prevalence= low predictive value

Question 26

where does the CTL act?

Answer 26

act on the conserved domains in the virus (not the HA ad NA because these change so much)

Question 27

What is in the Trivalent vaccine? (2)

Answer 27

1) Two strains of Influenza A: one H1N1 and one H3N2

2) The most prevalent Influenza B, either Yamamoto or Victoria

Question 28

WHat is in the Quadravalent vaccine?

Answer 28

has trivalent Influenza A strains: H1N1, H3N2

plus has both strains of the B influenza

Question 29

How is vaccine picked

Answer 29

WHO convenes all of the 5 major testing centers every February for the Northern Hemisphere vaccine (again in spetmeber for southern hemisphere)

Question 30

who is recommended (1) and who is “hihgly” recommended (4) for the vaccine

Answer 30

recommended: all over the age of 6 months
Highly recommended:
1) Comorbidities: cancer, HIV, pregnancy (and the ppl who care for them)
2) Healthcare workers
3) >65
4) Kids <5

Question 31

Who is the vaccine contraindicated for (3)

Answer 31

1) <6mo

2) Anyone who has ever had Guillian-Barré syndrome, 3) allergic rxn to vaccine or eggs

Question 32

Who is contraindicated for just the Live-attenuated Influenza vaccine

Answer 32

contraindicated for people with asthma, immunodeficiency, and pregnancy every year.

Question 33

Amantidine is only useful for one strain of vaccine- which is it?

Answer 33

Strain A

“A”mantidine = “A”

Question 34

which flu tx is only useful early in infection, and which is not useful for currently circulating strains

Answer 34

NA inhibitors are only useful in early infection

Amantidine is not useful ini current circultating strians

Question 35

What vaccine is contraindicated in ashtma, pregnancy, immunodeficiency

Answer 35

LAIV4) quadrivalent = live attenuated influenza vaccine