Microbiology 14: Pandemic Flu

Question 1

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

Answer 1

Mutation in polymerase protein PB2 627k

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

Question 2

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

Answer 2

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

Question 3

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

Answer 3

Purified fraction containing HA and NA of an inactivated virus

Question 4

Why does influenza only cause respiratory pathology ?

Answer 4

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

Question 5

Outline the 7 steps in the influenza replication cycle ?

Answer 5

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.

Question 6

Which protein of the Influenza virus needs to be cleaved ?

Which enzyme cleaves the protein ?

Answer 6

HA (haemaglutinin)

Tryptases in the lungs

Question 7

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

Answer 7

First there is a massive cytokine storm.

This can cause ARDS.

Question 8

Which people should get the seasonal flu vaccine ?

Answer 8

Adults >65
Asthmatics
Diabetics
Healthcare workers

Question 9

What type of vaccine is given to children ?

Answer 9

Intra nasal Live attenuated virus

Question 10

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

Answer 10

Clara tryptase