Infleunza Flashcards
Which influenza strain can affect animals like pigs birds and humans and is most severe
A
What does B and C cause
Milder disease in humans
How is influenza transmitted
Respiratorily
Which types of cells are killed by influenza
Ciliated epithelial cells
What happens to mucus because of lysed ciliated cells
It can’t get dislodged and there’s a build up of mucus in the respiratory tract (upper)
What is the first thing that happens due to lysed ciliated cells (our immune response)
Macrophages phagocytose the infected cell
This release cytokines which cause inflammation
What symptom do cytokines cause and why
Leaky nose
Because they act on endothelial cells in the nose
What causes fever
Pyrogens which cause cytokines to act on hypothalamus and increase temperature
Why is a cough a symptom
Build up of mucus
What are the 2 innate responses to influenza
Natural killer NK cells
And
Type 1 interferons IFN which allow resistance of other cells around infected
What are the 2 adaptive responses to influenza
B cells which produce antibodies
T cells which produce CD8 cytotoxic and CD4 helper cells
What is the difference between mucosal and system immunity
Mucosal-
Causes production of IgA antibody
Systemic -
Causes production of igG to protect mucosal surfaces
When is igG produced to protect mucosal surface in the systemic immunity
When cytokines cause leaky nose by acting on endothelial cells
What is the type of immunity the systemic and mucosal immunity produce via iga and igG
Waning immunity
Explain the genome of influenza
8 ss rna (-) (antisense)
Which 2 proteins are within the genome of influenza
Nucleoproteins
Rna dependant rna polymerase (for rep and transcription)
What are the 3 types of proteins which produces rna dep rna pol
PA
PB1
PB2
How many matrix protein types are there
2
M1 and M2
Which protein forms pores in the envelope
M2
What are the 2 types of glycoproteins on surface of influenza
Haemogglutinin
Neuraminidase
What does gp haemogglutinin bind to on ciliated epithelial cells for entry
Sialic nana acid
How does haemogglutinin binding to nana cause entry
Receptor mediated endocytosis into a vesicle
How does fusion of envelope with vesicle occur
Endosomes with Protons fuse with vesicles
H moves in via the M2 pores
Causes a conformational change which causes fusion
What happens when rna dep rna pol and rna genome released
Rna is transcribed into mrna +
Via rna dep rna pol
What are rna + copies used for other than translation of structural proteins
Produce new rna - strand copies for the new genome
What happens once the GP Neuraminidase and haemogglutinin are glycosylated at Golgi
Transfer to the cell membrane where all other proteins and new rna - strands assemble to form and bud off a new virus
How is budding off allowed by neuraminidase
It cleaves sialic acid to stop the binding of haemogglutinin in the new virions
What catalyses the production of new rna (-) from mrna +
Rna dep rna polymerase
What is the difference between antigenic shift and drift
Antigenic drift is gradual mutation causing an epidemic
Antigenic shift is complete reassortment of genome causing a pandemic
What 2 things change in antigenic shift and drift
Haemogglutinin and neuraminidase
How does reassortment occur (antigenic shift)
If another host becomes infected with 2 diff strains eg bird and human strain infect pig
The strains then mix in genome to produce new sets of proteins eg new gp
Why was the 1918 strain prominent in young people
Because they have higher immune response they produce more cytokines which cause bad effects like fever
What 2 types of vaccines are there
Killed : where the killed virus is a administered
Live attenuated : live but non infectious
What 2 types of therapies are there for influenza
Amantidine - M2 pore channel blocker which stops fusion with vesicles
Tamiflu- inhibit neuraminidase so budding can’t occur
