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General Virology- Exam 3 > Influenza > Flashcards

Influenza Flashcards

1
Q

Pathogenesis

A

causes 3 diseases:

  1. URI (upper respiratory illness) or cold
  2. Bacterial Pneumonia
  3. Viral Pneumonia
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2
Q

(1) Upper Respiratory Illness (URI) or cold

A

occurs by sneezing: spectrum of particle sizes released
Incubation period: 1-2 days
fever, muscle aches
1 week in adults vs. 1.5 weeks in kids
kids who have virus for the 1st time have it longer and get more sick- more virus produced (cell mediated immunity helps adults recover faster since we’ve had it before)

cilia beat/move mucus up the tract
“bald” cells put out the mucus
– non specific response –

3 days post infection= epithelium covered in basal cells (hole between cells=runny nose)
7-10 days post infection= basal cells regenerate to become ciliated and mucus cells (mucus cells come back faster)

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3
Q

What flu diseases will hand washing prevent?

How effective do you think surgical masks are?

A

Hand washing would prevent contact transfer

Surgical masks traps particles

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4
Q

Diagnosis of URI

A

influenza like illness (ILI)
- fever >100, cough/sore throat

proven flu (PCR or viral isolation)

acute onset of profound malaise

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5
Q

(2) Bacterial Pneumonia

A

start to get sick again on day 4 or 5 (unlike URI)
inflammatory response within the pulmonary alveoli
- become solid due to build and debris
- walls of alveoli infected

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6
Q

(3) Viral Pneumonia

A

drastically high severity very quickly
walls of pulmonary alveoli become extremely thin
fluid leaks out

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7
Q

Prior Flu Infection

A

NO:
Nasal= N –> T –> L–> Survival
Total= N+T+L –> Death

YES (has cell mediated immunity):
Nasal= N -//->
Total= N+T+L –> Survival

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8
Q

Given a non-immune animal, how would you prove that antibody to a germ could prevent infection by that germ?

A

Give antibodies to one group of mice, then infect both groups
One group lives and the other dies of viral pneumonia

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9
Q

Host Defense Against Influenza

A

IgG prevents viral pneumonia, but not URI

  • in blood serum (specific)
  • speeds recovery from viral infection
  • antibody leaks out into fluid film so when the virus comes in, it meets the antibody and can’t infect the cells
  • doesn’t leak across membrane in the URI

IgA prevents viral infection of the upper respiratory tracts
- in mucus and snot (general)

Cell mediated immunity (CMI) promotes recovery
- deters spread down the respiratory tract

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10
Q

Components of immune system

Host Defense

A

Cell Mediated Immunity (CMI)
Kills virus infected cells
Not live virus

Antibody “kills” virus

       1. IgG in blood and tissues
       2. IgA in mucus secretions
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11
Q

Immunization

A

2 vaccines
Shots: Quadrivalent Inactivated Vaccine (QIV)
Spray: Live Attenuated Influenza Vaccine (LAIV)

both contain:
H1N1, H3N2
B (Victoria), B (Yamagata) - 2 strains of the B virus

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12
Q

Influenza virus

A

named by strain/city/isolate/year

8 (-)ssRNA segments encode 11 proteins of the virus

Error prone polymerase results in accumulation of mutations that select for hemagglutinin (HA) and to a lesser extent neuraminidase (NA) proteins present on external surface of virus
RNA makes sloppy replications = lots of mutation

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13
Q

how does HA function in virus attachment?

A

HA grabs hold of the cell enabling the virus to stick and then penetrate

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14
Q

CDC Vaccine Recommendation

A

all children 6 months and up should be immunized against flu with either the spray or shot

Shots only give antibodies in blood stream (IgG)
Spray gives antibodies in mucus secretions (IgA)

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15
Q

Which vaccine is better for most children?

A

Live Attenuated Influenza Vaccine (LAIV)

why doesn’t it work for older people? Elderly have enough IgA

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16
Q

Live Attenuated Influenza Vaccine (LAIV)

A

Induces:

  • serum IgG antibody (drift sensitive) –specific
  • secretory IgA antibody (cross protective) –grabs hold of virus
  • CMI (cross protective)

has no mercury in it

Live virus induces cell mediated and the other 2 antibodies

17
Q

Quadrivalent Inactivated Vaccine (QIV)

A

Induces only serum IgG antibody (drift sensitive)
cannot cause the flu
- injected in arm & virus only grows in epithelium

18
Q

which vaccine is more effective for adults?

A

Trivalent influenza vaccine (dead virus)

Although in theory LAIV should be better than TIV;
TIVs have been shown to be more effective for adults

19
Q

Vaccine: Shots induce…

A

serum antibody (drift sensitive)

20
Q

Vaccine: Spray induces…

A 
serum antibody (drift sensitive)
secretory antibody  (cross protective)
CMI (cross protective)
21
Q

M2SR Vaccine

A

flu vaccine of the future
M gene codes for 2 proteins.
M2 is a trans membrane protein
SR stands for Single Replication

Membrane through the channel of the virus that allows protons to go through

22
Q

Issue with M2SR

A

Vaccine given by spray infects the nasal epithelium but can’t replicate or spread

Grown in tissue culture

23
Q

How do you grow a vaccine that can’t replicate?

A

grow the virus in tissue culture and put the M2 gene into the tissue culture cells, so the virus can grow (bad gene, but good M2)

Insert the normal M gene into the cells of the tissue culture

24
Q

Why do vaccines change each year?

A

shifts & drifts

mutations in HA and NA

25
Q

Orthomyxoviruses

A

Negative strand RNA viruses
Segmented genome
16 Hemagglutinin (HA) subtypes
9 Neuraminidase (NA) subtypes

26
Q

Types of Orthomyxoviruses

A

Influenza A, B and C

Avian – wild birds, domesticated birds
Influenza A – All 16 HA and 9 NA subtypes

Swine
A H1,H2,H3 & N1,N2 Influenza C

Equine
A H7N7, H3N8

Human
A H1,H2,H3, N1, N2, influenza B &C

27
Q

shift

A

Gene reassortment leading to new surface glycoproteins

ex: H2N2 to H3N2

28
Q

drift

A

Point mutations leading to antigenic drift

small changes

29
Q

Influenza A & Seasonal Epidemiologic Patterns

A

Seasonal influenza:
minor genetic changes (e.g., point mutation)
in limited alterations in the HA or NA
Minority of the population is susceptible
Annual mortality rate in the USA 3,000- 49,000/yr
Higher mortality usually occurs with H3N2 compared to H1N1 or B

30
Q

Influenza A Virus & Pandemic Epidemiologic Patterns

A

Pandemic influenza:
major genetic changes (e.g., reassortment from 2 different animal influenza viruses ) result in substantial alterations of HA or NA
Majority or entire population is susceptible to the virus

31
Q

Two major hypotheses regarding what strains can cause a pandemic:

A
  1. only H1N1, H2N2 and H3N2 can cause pandemics and do so when a strain has not circulated for several generations
  2. Many strains can do this if their genetic makeup allows easy transmission between people
32
Q

Difference between human and non-human viruses

A

Sialic acid (host receptor) difference on Human and non-human viruses’ respiratory epithelial cells

33
Q

Pneumonia- Influenza Reported Deaths

A

More deaths occur in the winter than in the summer

Only the flu raises that curve

34
Q

H5N1 Drift Mutations

A

Major concern

  • tamiflu resistance
  • respiratory- systemic (encephalitis)
35
Q

Influenza Host Receptors Sialic Acid

A

Bird= alpha 2-3 gal

Human= alpha 2-6 gal

36
Q

Prevent pandemic if H5N1 human-human by…

A

Delay spread till vaccine becomes available
Social Distancing
Protected/Isolated Groups

37
Q

Influenza Treatment

A

Drink lots of fluids
Rest
Stay in a warm room

38
Q

Treatment (OTC Drugs)

A

Acetaminophen (Tylenol) for pain (not low grade fever)

Cough suppressors

39
Q

How to control the flu?

A

Schools!
School Located Influenza Vaccination (SLIV)

70% immunization rate in kids can protect an entire community

General Virology- Exam 3 (6 decks)

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