Case Study Comparison Chart: Influenza Flashcards
describe the structure of the influenza virus
- lipid envelope
- NA
- HA
- SS(-)RNA
- replicase
- M2 ion channel
what is the role of HA?
aids in attachment to sialic acid on ciliated epithelial cells
what is the role of NA?
aids in release
what is responsible for antigenic drift?
mutations
what is responsible for antigenic shift?
recombination of viral genome
which is the only class of influenza virus to experience antigenic shift?
A
what is the responsibility of the M2 ion channel in an influenza infection?
M2 ion channel mediates release of viral genome nucleic acid into cytoplasm
why is it significant that influenza is an RNA virus?
high mutation rate
describe the genome of an influenza virus. why is that significant?
segmented. errors can occur during recombination of viral genome, causing antigenic shift
what are the types of influenza virus that matter?
A, B, C
which influenza types cause an illness in humans?
A, B, C
which influenza types are responsible for seasonal epidemics?
A and B
which influenza types cause minor illnesses?
C
how are influenza A types named?
after the H and N types that are involved ex. H1N1
how are influenza B types named?
based on where they were isolated ex. B/Victoria
wide host range for different strains?
A
influenza A host range: wide or narrow?
wide
examples of influenza type A hosts?
birds, pigs, humans
which influenza type is responsible for pandemics?
A
influenza type A is responsible for
pandemics
influenza type B is responsible for
NOT pandemics
influenza B host range: wide or narrow?
narrow
higher mutation rate: influenza type A or influenza type B?
A
lower mutation rate: influenza type A or influenza type B?
B
what is the incubation period for influenza?
roughly two days
describe some symptoms of influenza:
headache, fever, sore throat, dry/tight cough, chest pain, muscle aches, weakness, extreme fatigue
how is influenza spread?
via droplets or fomites
what is the most telling symptom of flu?
extreme fatigue
what are some symptoms of flu?
headache, fever, sore throat, dry/tight cough, chest pain, muscle aches, weakness
flu can sometimes lead to… (2)
Reye’s syndrome or Guillain-Barre syndrome
what treatment exists for influenza? how do they help? (4)
influenza-specific medicine:
- interfere with uncoating process, act on M2
- NA inhibitors
- replicase inhibitors
- antibiotics for secondary infections (like bacterial pneumonia)
who is most at risk for secondary infections because of the flu?
- 65+ or younger than 5
- immunocompromised
- pregnant
why is there no immunity to a flu pandemic when it occurs? (3) how often does it occur?
in a storm, the escalator drifts.
- antigenic drift
- mucociliary escalator is destroyed
- cytokine storm
occurs periodically.
how is the mucociliary escalator destroyed as a result of the flu?
infected epithelial cells die and slough off, destroying the mucociliary escalator
when does a cytokine response occur?
extreme immune response
antigenic drift vs. shift:
DRIFT:
- slow, constant changes aka mutations during viral replication
- seasonal flu
SHIFT:
- change in H&N type
- pandemics
what prevention methods are available against influenza?
VACCINES!
what can you tell me about flu vaccines? for instance, how many types are there, what are they, and what are their characteristics?
inactivated
- grown in chicken eggs/cell cultures
- quadrivalent
live attenuated
- nasal flu mist
- only for ages 2-49
- cannot be given to immunocompromised
- effectiveness varies
what can you tell me about influenza vaccine production?
- new vaccine each year
- start production in Jan to distribute in the fall
- try to predict strains that are circulating and that previous vaccines don’t protect against
what are the steps of an influenza infection?
- get infected (fomite or droplets)
- attachment of virus
- enter cell via receptor-mediated endocytosis
- M2-mediated release of viral nucleic acid into cytoplasm
- host cell protein and DNA synthesis stopped
- viral RNA and protein synthesis
- HA and NA embedded in host cell membrane
- mature virions bud from host cell via NA
how does an influenza virion exit the cell?
budding
how does an influenza virion enter the cell?
receptor-mediated endocytosis
