Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Virology > Exam 2 - Influenza > Flashcards

Exam 2 - Influenza Flashcards

1
Q

when is flu season in temperate/cold regions?

A

winter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

when is flu season for tropical regions?

A

througout the year

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

why do influenza epidemics become unmanageable rapidly?

A
  • short incubation period (1-4 days)
  • one droplet has up to 1 million particles
  • symptomatic people do not stay home
  • lack of herd immunity
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

why is influenza more prevalent during the winter?

A
  • aerosol spread
  • humidity drives spread in temperate regions
  • more indoor gatherings
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Reye’s syndrome (rare)

A
  • risk increased with aspirin use
  • affects all organs
  • most harmful to brain and liver
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

the flu has very similar symptoms to _______

A

a cold

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

influenza is spread by ________ and enters the _______________ via ____________

A

droplets; respiratory tract; inhalation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

primary site of influenza infection

A

tracheobronchial tree, nasopharynx

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

influenza viral replication destroys __________ and causes _____________________________

A

cilia; mucus to clog the airways –> coughing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

influenza is part of the ______________ family

A

orthomyxoviridae

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

clinical features of influenza A

A
  • may cause pandemics with significant mortalities in affected young people
  • antigenic shift and antigenic drift
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

clinical features of influenza B

A
  • severe disease in elderly and high risk patients
  • no pandemics
  • antigenic drift
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

clinical features of influenza C

A
  • mild disease
  • common in children
  • not seasonal
  • antigenic drift
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

influenza A structure

A
  • segmented -ssRNA genome
  • enveloped
  • filamentous, helical virions after isolation
  • spherical virions after cell culture
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

influenza virion structure

A
  • 500 glycoproteins
  • 8 segments of -ssRNA
  • M2 ion channel protein
  • M1 is most abundant
  • NS2 = nuclear export protein
  • NP = nucleoprotein
  • transcriptase complex associated with each segment
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

role of influenza nucleoprotein

A

covers RNA and acts as a capsid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

which 2 influenza virion segments produce 2 proteins?

A

7 (M1, M2) and 8 (NS1, NS2)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

10 steps of influenza replication

A
  1. attachment - H binds sialic acid (receptor)
  2. entry - endocytosis
  3. uncoating - vRNPs released into cytoplasm and transported to nucleus
  4. viral mRNA synthesis - cap snatching
  5. mRNA splicing - viral mRNA segments 7 & 8
  6. genome replication
  7. translation
  8. maturation - H0 is cleaved so virus becomes infectious
  9. assembly - at cell surface
  10. release - exocytosis, N protein destroys sialic acid receptors on cell surface
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

H0 protein subunit is _________ during ___________ for virus to be infectious

A

cleaved; maturation

20
Q

H protein has ____ subunits

A

2 (H1 and H2)

21
Q

NS1 protein

A
  • enhances cap snatching
  • most abundant
  • inhibits CPSF (involved in making polyA tail) and PABP
  • prevents cellular mRNA export to cytoplasm
  • decreases translation of cellular proteins
22
Q

NS1 suppresses ________ response

A

IFN (interferon)

23
Q

how does NS1 suppress IFN response?

A

NS1 binds to dsRNA to block the activation of PKR (kinase)
- allows for translation of viral proteins

24
Q

to gain immunity against influenza, what antibodies must be developed?

A

antibodies against N and H

25
cytokine storm or SIRS (systemic inflammatory response syndrome)
- provides immunity to influenza - immune system overreacts - stuck in pos. feedback loop - overproduction of pro-inflammatory cytokines - recruit macrophages - causes tissue damage and organ failure - death
26
what specimen is needed for influenza laboratory diagnosis?
respiratory specimen, nasal swab
27
3 tests for laboratory diagnosis of influenza A and B
- viral RNA detection (molecular assays) - antigen detection tests - isolation/detection in cell culture (used for research)
28
3 types of influenza antivirals
- M2 inhibitors - N inhibitors - PA inhibitors
29
how do M2 inhibitors prevent influenza?
prevents the uncoating step of replication, blocks production of pores for protein entry
30
how do N inhibitors prevent influenza?
prevents cleaving of sialic acid for budding, causes virions to clump at surface
31
how do PA inhibitors prevent influenza?
prevents cap-snatching, blocks viral RNA transcription (no caps present)
32
influenza vaccination is based upon _____________________
prediction of circulating strains
33
why is influenza vaccination recommended in Oct/Nov
allows for stabiliation before cases start appearing
34
how is influenza virus named?
type/ species isolated from (unless human)/ place of isolation/ strain designation/ year of isolation/ (H#N#)
35
4 reasons for genetic variation of influenza
- H and N subtypes - RNAP lacks proofreading --> mutations - antigenic drift - antigenic shift
36
antigenic drift
lack of proofreading ability causes random mutations - localized or seasonal epidemics - influenza A & B
37
antigenic shift
reassortments of 2 viruses affecting the same organism - pandemic strains - influenza A
38
H5 and H7 can cause _________________
epizootics - epidemic among animal species
39
highly pathogenic avian influenza A viruses (HPAI)
- H5 and H7 viruses - severe disease - high mortality in infected poultry - H5N1 - no person to person spread - A(H5) - spillover to humans
40
1918 Spanish Flu
- 25x more deadly than previous influenza A viruses - spread faster than any plaque in history - unique: 20-40 year olds, killed in 2-3 days, hemorrhagic symptoms
41
1957 Asian Flu
- H3N2 - identified in northern China - spread to US - 70k deaths - vaccine
42
1968 Hong Kong Flu
- H2N2 - spread to US - 33,800 deaths
43
2009 Swine Flu
- mexican town - sample from southern CA - 12,500 deaths in US - age 10-19 most affected - <3% cases over age 65
44
why were those over age 65 thought to have better protection against the 2009 Swine Flu?
protected from circulating virus that they had already had OR this strain was a similar strain to previous vaccination
45
interferon (IFN)
signals and warms cell of foreign invador/virus

Virology (12 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions