Microbiology 14: Pandemic Flu Flashcards

1
Q

Which 2 factors could allow bird flu to cross into humans?

A

Mutation in polymerase protein PB2 627k

Reassortment (when a cell is infected with human influenza and bird influenza they shuffle their RNA)

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2
Q

Name 3 antiviral therapies that could be used to treat flu ?

A

Amantadine
Neuraminidase inhibitors- oseltamivir (tamiflu)
Polymerase inhibitors- favipiravir

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3
Q

What is contained in the seasonal flu vaccine in the UK ?

A

Purified fraction containing HA and NA of an inactivated virus

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4
Q

Why does influenza only cause respiratory pathology ?

A

The virus requires activation by host cell proteases that are only expressed in the respiratory tract.

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5
Q

Outline the 7 steps in the influenza replication cycle ?

A

1- The virus binds to sialic acid receptors on the host cell surface
2- The virus enters the cell via thew endosome
3- The Ph of the endosome triggers a fusion event causing the viral genome to be released.
4- The genome travels to the nucleus and takes over host factors to drive its transcription and replication.
5- new viral products are produced.
6- The viral products assemble into a new virus at the cell surface
7- The virus buds of and is released from the host cell.

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6
Q

Which protein of the Influenza virus needs to be cleaved ?

Which enzyme cleaves the protein ?

A

HA (haemaglutinin)

Tryptases in the lungs

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7
Q

How can an avian influenza that crosses into humans cause death ?

A

First there is a massive cytokine storm.

This can cause ARDS.

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8
Q

Which people should get the seasonal flu vaccine ?

A

Adults >65
Asthmatics
Diabetics
Healthcare workers

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9
Q

What type of vaccine is given to children ?

A

Intra nasal Live attenuated virus

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10
Q

Which enzyme in the lungs cleaves HA giving influenza a tropism for the lungs ?

A

Clara tryptase

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11
Q

list flu pandemics in the 20th/21st century

A

spanish flu
asian flu
hong kong flu
swine flu

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12
Q

what is the natural reservoir for influenza A viruses

A

ducks

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13
Q

why can flu viruses only replicate in the lungs

A

haemaglutinin (HA) protein must be cleaved for virus to fuse with the endosome membrane and release its genome into host cells
human airway tryptase in lung lining can cleave HA

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14
Q

how can appropriate genes be incorporated into a virus to infect humans

A

reassortment
when a single cell is infected by both a human virus and bird virus - shuffles their RNA resulting in the production of a bird virus capable of infecting a human

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15
Q

what 2 steps are needed for an animal virus to become a human pandemic

A

1 - require the ability to infect human cells (ether by PB2 627K or reassortment)
2 - develop the ability to transmit between humans

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