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DT3- EXAM 2 > Influenza (3)-Leah > Flashcards

Influenza (3)-Leah Flashcards

1
Q

Influenza

  • Virus family:
  • genome type:
  • shape
A
  • orthomyxovirus
  • negative SS RNA (8 segments)
  • enveloped helical nucelocapsid
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2
Q

Important proteins on influenza viral membrane (3)

A

hemagglutinin (HA; Neuramidase (NA); M2

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3
Q

Components of influenza nucelocore (3)

A
  1. the 8 RNA segments
  2. nuclear matrix protein (M1)
  3. nucleoprotein (NP)
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4
Q

How many types of influenza are there?

Which are clinically relevant?

A

A,B,C

*C does not cause human illness

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5
Q

How are influenza viruses grouped into classes?

Subtypes?

A

Classes based on nucleocore proteins (M1, NP)

Subtypes based on membrane proteins (HA, NA)

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6
Q

Two recent major flu strains:

A

H1N1; H2N3

Remember: 1,1,2,3

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7
Q

In both epidemics and pandemics, what proteins are altered?

A

HA, NA- membrane proteins

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

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8
Q

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

A

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

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9
Q

Which influenza virus classes undergo shift/ drift?

A

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

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10
Q

When and why does flu peak?

A

Dec- March

*low temp and humidity

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11
Q

How is flu transmissed?

A
  • respiratory droplets

- contaminated surfaces

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12
Q

What are the very basic functions of hemagglutinin and neuramidase?

A

HA- mediates viral ENTRY by binding sialic acids

NA- mediates RELEASE of virus progeny after replication

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13
Q

What determines the anatomical location of influenza infection?

A

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)

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14
Q

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

A

-binds a2,6 sialic acid =

infection of tracheobronchial epi/ type 1 pneumos

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15
Q

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

A

-binds a2,3 sialic acid=

infection of distal bronchiole/ type 2 pneumos

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16
Q

Role of birds in the spread of influenza

A
  • act as RESOVOIRS for all flu strains

- rarely spread infection to humans directly

17
Q

Role of pigs/ swine in the spread of influenza

A

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

18
Q

Does “swine” flu infect humans?

Does “avian” flu infect humans?

A
  • swine flu can infect pigs + birds + humans

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

19
Q

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

A

-number of amino acids in the HA cleavage site

20
Q

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

A
  • extracellular cleavage only

- virus stays in respiratory tract

21
Q

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

A

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

22
Q

2 exact functions of neuroamidase?

How are these functions carried out?

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

*cleaves sialic acid from glycoproteins

23
Q

Typical incubation period for influenza?

Is it assc with viremia?

A

1-3 days; NO assc viremia

24
Q

4 complications of influenza

A
  1. otitis media
  2. sinusitis
  3. primary viral pneumonia (rare)
  4. secondary bacterial pneumonia (common)
25
Q

Influenza patients are susceptible to infection by what other bugs?

A 
#1 strep pneumo
also: staph aureus, H. flu
26
Q

What drug do you AVOID when treating influenza in kids?

A

Aspirin + fever in kids = Reyes

rash & puking –> encephalopathy & fatty liver

27
Q

Four drugs for treating influenza:

Which 2 are the better 2?

A

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.

28
Q

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

A

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!
29
Q

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

A

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

30
Q

Two types of immuno responses to flu?

A

neutralizing antibodies; cytotoxic T cells (CD8)

31
Q

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?
A
  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
32
Q

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?
A
  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
33
Q

2 reasons of immunization against influenza must be annual

A

drift/ shift; protective immunity is short lived

34
Q

What strains do flu vaccines contain?

A

Those that circulated at the end of the previous season

Types A and B

35
Q

Two ADRs to flu vaccines

A

egg allergy; Guillan Barre

36
Q

Three types of flu vaccine

A
  1. whole virus (fixed/ inactivated)
  2. Split viruses (subvirons)
  3. purified glycoproteins
37
Q

I had a test question on this somewhere:

Why specifically can influenza virus cause pandemics?
What part of its structure makes this possible?

A

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

DT3- EXAM 2 (19 decks)

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