Influenza (3)-Leah Flashcards Preview

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

Flashcards in Influenza (3)-Leah Deck (37)
Loading flashcards...
1

Influenza
-Virus family:
-genome type:
-shape

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

2

Important proteins on influenza viral membrane (3)

hemagglutinin (HA; Neuramidase (NA); M2

3

Components of influenza nucelocore (3)

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

4

How many types of influenza are there?
Which are clinically relevant?

A,B,C
*C does not cause human illness

5

How are influenza viruses grouped into classes?
Subtypes?

Classes based on nucleocore proteins (M1, NP)
Subtypes based on membrane proteins (HA, NA)

6

Two recent major flu strains:

H1N1; H2N3

Remember: 1,1,2,3

7

In both epidemics and pandemics, what proteins are altered?

HA, NA- membrane proteins
(subtypes change; classes do not-- always A,B,C)

8

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

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

9

Which influenza virus classes undergo shift/ drift?

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

10

When and why does flu peak?

Dec- March
*low temp and humidity

11

How is flu transmissed?

-respiratory droplets
-contaminated surfaces

12

What are the very basic functions of hemagglutinin and neuramidase?

HA- mediates viral ENTRY by binding sialic acids
NA- mediates RELEASE of virus progeny after replication

13

What determines the anatomical location of influenza infection?

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)

14

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

-binds a2,6 sialic acid =
infection of tracheobronchial epi/ type 1 pneumos

15

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

-binds a2,3 sialic acid=
infection of distal bronchiole/ type 2 pneumos

16

Role of birds in the spread of influenza

-act as RESOVOIRS for all flu strains
-rarely spread infection to humans directly

17

Role of pigs/ swine in the spread of influenza

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

18

Does "swine" flu infect humans?
Does "avian" flu infect humans?

-swine flu can infect pigs + birds + humans
-avian flu can infect humans, but it usually does not

19

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

-number of amino acids in the HA cleavage site

20

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

-extracellular cleavage only
-virus stays in respiratory tract

21

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

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

22

2 exact functions of neuroamidase?
How are these functions carried out?

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

*cleaves sialic acid from glycoproteins

23

Typical incubation period for influenza?
Is it assc with viremia?

1-3 days; NO assc viremia

24

4 complications of influenza

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

25

Influenza patients are susceptible to infection by what other bugs?

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

26

What drug do you AVOID when treating influenza in kids?

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

27

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

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

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

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

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

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

30

Two types of immuno responses to flu?

neutralizing antibodies; cytotoxic T cells (CD8)