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Infection > Influenza > Flashcards

Influenza Flashcards

1
Q

Orthomyxovirus

A

Enveloped
Spherical
Contains segmented negative strand RNA genome

Surface antigens:
Haemagglutinin
Neuraminidase

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2
Q

Haemagglutinin

A

Binds to host cells

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3
Q

Neuroaminidase

A

Release the virus from host cells surface

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4
Q

Influenza A natural hosts

A

Animals and humans

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5
Q

Influenza B natural host

A

Humans

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6
Q

Influenza C natural host

A

Humans

Pigs

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7
Q

Influenza A spread

A

Antigenic drift
And antigenic shift

Large pandemics

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8
Q

Replication of orthomyxovirus

A
  1. Negative SsRNA invades host cell and transcribed to mRNA and coverted to positive SsRNA
  2. Positive ssRNA replicates and RNA dependent RNA polymerase is used from the infected virus to translate to viral proteins
  3. Using viral proteins and negative ssRNA nucleocapsids are assembled
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9
Q

Viral entry

A
  1. Virion binds to NANA residues on the host receptors cell via haemagglutinin antigens
  2. Receptor mediated endocytosis in upper respiratory cells
  3. Endocytic vescile formed
  4. Virion released from vesicle into cytoplasm a neurominidase cleaves glycoprotein from haemagglutinin
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10
Q

Antigenic shift

A

New subtype
Pandemics
Rapid

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11
Q

Transmission

A

Respiratory route

  • small particle aerosols
  • large particle aerosols
  • indirect contact - particles land on surface
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12
Q

Barriers to entry

A

Upper respiratory mucous - trap virus particles
Cilia
Immunoglobulins in the lung - IgA
Macrophages and natural killer T cells

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13
Q

How does influenza leave cells

A

Neuraminidase cleavage sites therefore cleaved at sialic acid

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14
Q

Symptoms

A

Fever, headache
Sore throat, cough, nasal congestion
Nausea and vomiting and diarrhoea
Myalgia, fatigue

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15
Q

Incubation

A

1 - 5 days

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16
Q

Who is at risk for more serious complications

A 
Children under 6
Older people 
Underlying health issues 
Pregnant women
Morbid obesity
17
Q

Treatment

A

Influenza A
- Antivirals - rimantadine

Influenza A and B
- Neuraminidase inhibitors - oseltamivir

18
Q

Vaccine

A

Formalin inactivated vaccine
- quadrivalent or trivalent

Or

Live attenuated cold adapted vaccine - nasal spray (used in children)

19
Q

Why is antigenic drift seen in influenza

A 
Life cycle of 6 hours 
RNA Polymerase error rate is high 
Lack of proof reading 
Genetic variation and resistance 
Seen in H and N proteins
20
Q

Antigenic shift

A

Only seen in influenza A
Surface antigens hemagglutinin and neuraminidase from different species
When 2 or more strains combine

Infection (10 decks)

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