Influenza (3)-Leah

Question 1

Influenza

• Virus family:
• genome type:
• shape

Answer 1

• orthomyxovirus
• negative SS RNA (8 segments)
• enveloped helical nucelocapsid

Question 2

Important proteins on influenza viral membrane (3)

Answer 2

hemagglutinin (HA; Neuramidase (NA); M2

Question 3

Components of influenza nucelocore (3)

Answer 3

1. the 8 RNA segments
2. nuclear matrix protein (M1)
3. nucleoprotein (NP)

Question 4

How many types of influenza are there?

Which are clinically relevant?

Answer 4

A,B,C

*C does not cause human illness

Question 5

How are influenza viruses grouped into classes?

Subtypes?

Answer 5

Classes based on nucleocore proteins (M1, NP)

Subtypes based on membrane proteins (HA, NA)

Question 6

Two recent major flu strains:

Answer 6

H1N1; H2N3

Remember: 1,1,2,3

Question 7

In both epidemics and pandemics, what proteins are altered?

Answer 7

HA, NA- membrane proteins

subtypes change; classes do not– always A,B,C

Question 8

How does antigenic drift occur?
How does shift occur?
What is the result of each?

Answer 8

drift: gradual change via point mutations= epidemic
shift: sudden change via reassortment= pandemic

Question 9

Which influenza virus classes undergo shift/ drift?

Answer 9

shift: seen in both A and B
drift: has only been seen in influenza A

Question 10

When and why does flu peak?

Answer 10

Dec- March

*low temp and humidity

Question 11

How is flu transmissed?

Answer 11

• respiratory droplets

- contaminated surfaces

Question 12

What are the very basic functions of hemagglutinin and neuramidase?

Answer 12

HA- mediates viral ENTRY by binding sialic acids

NA- mediates RELEASE of virus progeny after replication

Question 13

What determines the anatomical location of influenza infection?

Answer 13

HA type! – HA mediates entry

*Multiple sialic acid receptors exist in body; HA type determines what cells the virus can enter (& therefore location of infection)

Question 14

Human influenza virus has a hemagglutinin capable of binding what sialic acid type? What is the implication?

Answer 14

-binds a2,6 sialic acid =

infection of tracheobronchial epi/ type 1 pneumos

Question 15

Avian influenza virus has a hemagglutinin capable of binding what sialic acid type? What is the implication?

Answer 15

-binds a2,3 sialic acid=

infection of distal bronchiole/ type 2 pneumos

Question 16

Role of birds in the spread of influenza

Answer 16

• act as RESOVOIRS for all flu strains

- rarely spread infection to humans directly

Question 17

Role of pigs/ swine in the spread of influenza

Answer 17

can be infected by both human/ avian viruses; can be the site of REASSORTMENT= MIXING VESSELS

Question 18

Does “swine” flu infect humans?

Does “avian” flu infect humans?

Answer 18

• swine flu can infect pigs + birds + humans

- avian flu can infect humans, but it usually does not

Question 19

Specifically, what determines an influenza subtype’s ability to disseminate (vs remaining in the respiratory tract)?

Answer 19

-number of amino acids in the HA cleavage site

Question 20

A single basic amino acid in the HA cleavage site implicates what for a certain strain of influenza?

Answer 20

• extracellular cleavage only

- virus stays in respiratory tract

Question 21

Multiple basic amino acids in the HA cleavage site implicates what for a certain strain of influenza?

Answer 21

-can be cleaved intracellularly
-can spread systemically
more amino acids –> able to bind more than one sialic acid receptor

Question 22

2 exact functions of neuroamidase?

How are these functions carried out?

Answer 22

1. facilitates release of virion progeny
2. prevents aggregation of virus in extracellular space

*cleaves sialic acid from glycoproteins

Question 23

Typical incubation period for influenza?

Is it assc with viremia?

Answer 23

1-3 days; NO assc viremia

Question 24

4 complications of influenza

Answer 24

1. otitis media
2. sinusitis
3. primary viral pneumonia (rare)
4. secondary bacterial pneumonia (common)

Question 25

Influenza patients are susceptible to infection by what other bugs?

Answer 25

``` #1 strep pneumo also: staph aureus, H. flu ```

Question 26

What drug do you AVOID when treating influenza in kids?

Answer 26

Aspirin + fever in kids = Reyes | rash & puking --> encephalopathy & fatty liver

Question 27

Four drugs for treating influenza: | Which 2 are the better 2?

Answer 27

If you shoot AROZ (arrows) laced with medicine into the lungs of someone with the flu, theyll get better! - Amantadine - Rimantadine - Oseltamivir - Zanamavir Dr. OZ are the two actually being used. AROZ aren't logical.

Question 28

Amantadine and Rimantadine: MOA Flu class is treats Why it isn't used

Answer 28

M2 inhibitors; prevent viral uncoating - only treats type A! - prevents symptoms and titers if given w/in 48 hours of symptom onset BUT it PROMOTES RESISTANCE!

Question 29

Oseltamavir and Zanamavir MOA Flu class it treats Why is it used?

Answer 29

NA inhibitor treats type A & B good for preventing secondary bacterial infection; less likely to promote resistance

Question 30

Two types of immuno responses to flu?

Answer 30

neutralizing antibodies; cytotoxic T cells (CD8)

Question 31

Flu Ab's: 1. What type of Ig are produced? 2. what are they targeted against? 3. What is their function? 4. How long do they last? 5. are they strain specific?

Answer 31

1. IgA (nasal) and IgG/ IgM (serum) are produced 2. Targeted against HA 3. block infection 4. last ~ 6 mos 5. strain specific; immune to one straight doesn't = immune to others

Question 32

Flu CD8+ cells: 1. What are they targeted at? 2. What is their function 3. How long do they last? 4. Are they strain specific?

Answer 32

1. targeted against any of the 5 key proteins (HA, NA, M2// M1, NP) 2. Terminate replication; aid in disease recovery 3. Half life= 4 years 4. Can cross react if specific for M, NP proteins

Question 33

2 reasons of immunization against influenza must be annual

Answer 33

drift/ shift; protective immunity is short lived

Question 34

What strains do flu vaccines contain?

Answer 34

Those that circulated at the end of the previous season | Types A and B

Question 35

Two ADRs to flu vaccines

Answer 35

egg allergy; Guillan Barre

Question 36

Three types of flu vaccine

Answer 36

1. whole virus (fixed/ inactivated) 2. Split viruses (subvirons) 3. purified glycoproteins

Question 37

I had a test question on this somewhere: | Why specifically can influenza virus cause pandemics? What part of its structure makes this possible?

Answer 37

The fact that it is SEGMENTED makes it easier for genome exchanges.