Influenza Flashcards
What is the clinical presentation of season influenza?
Fever, chills, cough, headache, muscle aches, fatigue and loss of appetite
What does the CXR of patients with seasonal influenza look like?
Clear
How long does acute influenza infection last?
7 days or longer.
What groups of people are at risk of severe influenza infection?
Young
Elderly
Those with underlying heart, lung, renal, metabolic disease
Pregnant women
Obese people
What is the incubation period of influenza?
1-5 days depending on the size of the innoculation
What receptors do viruses bind to? Where are they located in the body?
Sialic acid containing receptors in non-cilia cells on the respiratory tract
They are also present throughout the body
What causes headaches, muscle aches and malaise in influenza?
IFN
Which type of influenza is only in humans?
B
How are influenza type differentiated?
Antibodies to internal antigens differentiate them
What type of genome does influenza have?
- sense RNA genome
What is the function of NS1?
Inhibit interferon
What does HA do?
Gripper
It binds to sialic acid
What does NA do?
It’s the snipper
Cuts sialic acid
What do all type A subtypes share?
Internal proteins
How many subtypes of HA and NA are there?
17 and 9 respectively
What enzyme is required for new virion to be infectious?
tryptase Clara
What is the function of tryptase Clara
Cleave HA after viral budding
What two aspects of the immune system are important in influenza?
CD8+ T cell response
Antibodies
How does antigen shift work in influenza?
Single amino acid mutations occur do to error in replication. If these change HA (or NA) so they they are no longer recognised by antibody then they will be selected for.
What does the influenza vaccine contain?
Inactivated virus with H1N1, H3N2 and influenza B
What type of immune response does the influenza vaccine stimulate?
Antibody (not cytotoxic T cell)
What are the targets of anti-viral drugs?
Ion channel blockers to prevent endosome escape by RNPs
NA inhibitors to block efficient release of virus
What is the difference between avian and human HA?
Human recognises SA alpha 2-6 galactose while avian recognises 2-3
What is antigenic shift?
Sudden appearance of new HA subtype from birds due to gene segment swapping in a co-infected host
T/F Swine HINI and Avian H5N1 are both susceptible to NA inhibitors?
True
