Microbiology 14: Pandemic Flu Flashcards
Which 2 factors could allow bird flu to cross into humans?
Mutation in polymerase protein PB2 627k
Reassortment (when a cell is infected with human influenza and bird influenza they shuffle their RNA)
Name 3 antiviral therapies that could be used to treat flu ?
Amantadine
Neuraminidase inhibitors- oseltamivir (tamiflu)
Polymerase inhibitors- favipiravir
What is contained in the seasonal flu vaccine in the UK ?
Purified fraction containing HA and NA of an inactivated virus
Why does influenza only cause respiratory pathology ?
The virus requires activation by host cell proteases that are only expressed in the respiratory tract.
Outline the 7 steps in the influenza replication cycle ?
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.
Which protein of the Influenza virus needs to be cleaved ?
Which enzyme cleaves the protein ?
HA (haemaglutinin)
Tryptases in the lungs
How can an avian influenza that crosses into humans cause death ?
First there is a massive cytokine storm.
This can cause ARDS.
Which people should get the seasonal flu vaccine ?
Adults >65
Asthmatics
Diabetics
Healthcare workers
What type of vaccine is given to children ?
Intra nasal Live attenuated virus
Which enzyme in the lungs cleaves HA giving influenza a tropism for the lungs ?
Clara tryptase
list flu pandemics in the 20th/21st century
spanish flu
asian flu
hong kong flu
swine flu
what is the natural reservoir for influenza A viruses
ducks
why can flu viruses only replicate in the lungs
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
how can appropriate genes be incorporated into a virus to infect humans
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
what 2 steps are needed for an animal virus to become a human pandemic
1 - require the ability to infect human cells (ether by PB2 627K or reassortment)
2 - develop the ability to transmit between humans
