Influenza Flashcards
What are the FOUR types of influenza virus?
- Influenza A - many strains, some infect humans
- Influenza B
- Influenza C - mild human infections - non pandemic
- Influenza D - infect cattle
What is the main reservoir of influenza viruses?
Wild birds
What THREE virus types can infect humans?
A, B and C
Is the influenza virus:
A) Naked
OR
B) Enveloped?
RNA Enveloped
What is the size of an influenza virus?
80 - 200nm
(0.08 - 0.12microns)
What are the surface antigens on an influenza virus?
H (haemaglutinin)
N (neuraminidase)
What viral family does influenza virus belong to?
Orthomyxoviridae
What classification of virus is influenza?
ssRNA(-)
How many genomic units make up the Influenza A virus?
8
Which surface protein allows the influenza virus to bind to the host cell and is recognised by the immune system?
H (Haemaglutinin)
How many H types are there?
16
H1 - H16
What surface enzyme allows the virus to exit from the host cell?
N (Neuraminidase)
How many N types are there?
9
N1 - N9
Which receptor on the host cell does the H surface protein on the influenza virus bind to?
alpha-2-3 sialic acid
or
alpha-2-6 sialic acid
What causes ANTIGENIC DRIFT?
Small mutations on the surface proteins that make antibodies less able to bind to the virus
What causes ANTIGENIC SHIFT?
Major changes to surface proteins on virus that enables it to completely bypass the immune system.
e.g. switching from H1 to H2
What TWO influenza strains make up seasonal flu?
- H1N1
- H3N2
What THREE influenza strains are transmissible human to human?
- H1N1
- H2N2
- H3N2
What THREE influenza strains are non-transmissible human to human?
- H5N1
- H9N2
- H7N7