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Micro - Influenza
Terms in this set (25)
What virus family comprises the influenza virus?
What is the virology of Orthomyxoviridae?
- ssRNA- (7-8 segments each coding for one chromosome)
What are the possible reservoirs for influenza A?
only human beings!
What does the nomenclature H1N1 stand for?
The subtypes of hemagglutinin (HA) and
neuraminidase (NA) that present in a specific strain
How many possible subtypes are there for HA and NA?
HA - 16
NA - 9
What are the only subtypes that are considered to be human for HA and NA?
(thus 6 possible strains that can be transfered human to human)
What is a likely subtype of a influenza that is passed from chicken to human?
any combinations of HA and NA that involve numbers outside of the 6 possible human subtype combinations
What is the replication cycle of Influenza?
1. virus binds sialic acid on surface of cell using HA
2. enters through endocytosis
3. M2 ion channel increases acidity inside vacuole so that hemagglutinin gets cleaves and exposes fusion protein
4. fusion protein interacts with endosomal membrane so that through fusion, RNA will be free
5. viral RNA replicates within nucleus and is used to transcribe protein
6. to avoid destruction with lysis of cell, neuraminidase cleaves sialic acid so HA can be freed from glycocalyx and virus is free to infect other cells
Where do epidemics of influenza occur?
in temperate regions, originating in southeast asia
What is the seasonality of influenza?
- October to April
What is the host rang of influenza
very wide - from birds to swine to humans
Who is most susceptible to influenza?
- infants and children
- pregnant women (especially influenza pneumonitis)
- elderly ( but with different symptoms - lassitude lethargy, anorexia and inc chance of bacterial pneumonia)
How is influenza transmitted?
- droplets and contact
What is the Human target for influenza subtypes that are considered human subtypes?
sialic acid-a2,6 - galactose on the surface of epithelial cells of the upper respiratory tract
What is the Human target for influenza subtypes that are considered non-human subtypes?
sialic acid-a2,3-galactose on the surface of the epithelial cells of the lower respiratory tract
What is the pathophysiological mechanism of non-human subtypes of influenza?
- intra-alveolar and intra-bronchiolar hemorrhage, as well as interstitial edema and hemorrhage due to inflammation
What is the pathophysiological mechanism of human subtypes of influenza?
- destruction and inflammation of respiratory epithelium in the nasopharynx and bronchi with edema and cellular infiltration
What is the M2 ion channel used for by the influenza virus?
entry & uncoating*
What is NA protein used for by the influenza virus?
maturation* & release
- NOT EXIT
What is the pathogenesis of the influenza virus that leads to the "flu", tracheobronchitis and pulmonary inflammation?
- proinflammatory cytokines & chemokines - IFN-alpha, IFN-y, TNF-a, IL-6
- direct viral damage - replicative cycle; NSA1 & NA-induced apop.
- TNF-a & MIP-2
What is the issue with progression of the influenza virus symptoms untreated?
influenza infections sets the stage for bacterial infections particularly in the elderly
What is antigenic drift?
- stepwise accumulation of point mutation in the HA and NA proteins
What is antigenic shift?
When RNA segments reassort (genetic recombination), like would happen if a single cell were infected by 2 separate strains.
What are the possible vaccines created today?
Inactivated and LAIV:
What are the possible treatments for the influenza virus?
1. Amantadine and Rimantindine
- M2 ion channel protein inhibitors (stops fusion and uncoating)
2. Zanamavir and Oseltamivir
- influence A and B - NA inhibitors (inhibits budding)
THIS SET IS OFTEN IN FOLDERS WITH...
Pharm: - Anti-viral therapies
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Path - disease of head and neck 1&2
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