Class #6 - Infection (part2) - Influenza Flashcards
Affinity of influenza virus is to ….cells?
Tracheobronchial epithelial cells, specifically the ciliated epithelial cells
Difference between influenza and cold?
Influ: resp and systemic Sx, with sudden onset
Cold only throat and nose Sx, gradual onset
Common complication of influenza in child?
Otitis media
Sx of influenza?
Headaches, fever, myalgia, sore throat, runny nose.
Biggest influenza pandemic?
1918:Spanish flu, 50 millions died
Most recent influenza pandemic?
H1N1 209
20th century flu Pandemics?
1918, 1957 (asian flu 1-2millions), 1968 (hong-kong flu, 700 000), 2009 (Swine flu, 280 000)
Influenza DNA or RNA virus?
RNA
What are the types of flu virus?
A,B,C
What allows flu virus to recognize epithelial cells?
Hemagglutinin
Influenza type A and B difference with type c?
A/B: 8 RNA, neurominidase and hemagglutinin
C: 7 RNA and no neurominidase. Once you get infected you retain immunity, which is not true of A/B
What is RNP?
Ribonucleoprotein that contains coiled RNA in flu virus
What make influenza virus special and dangerous?
Potential for cross species connection
Different type of antigenic variations?
drift and shift
Antigenic drift?
Small mutation in RNA of virus overtime as virus replicates, happens all the time. This can make Ig less effective with time
Antigenic shift?
Different RNA strains inside a cell recombine resulting in abrupt major change resulting in new hemagglutinin or neuraminidase or both, rare.
Difference between influenza A/B, which is more dangerous?
A: Drift and Shift, more dangerous.
B: Drift
Influenza life cycle? + complete time?
1) Absorption: H binds to sialic acid on epithelial cells
2) Endocytosis
3) Fusion: M2 p+ proton ion channel acidify interior, weakening bond between cell and virus
4) Replication/transcription of RNA
5) Assembly
6) Release: Neuraminidase frees the new virus by breaking bond with sialic acid on cell membrane
- > 4-6 hours
Hemagglutinin recognize…..linkage in human and ….linkage in birds?
human: alpha 2-6
birds: alpha 2-3
Specificity of virus is due to?
sialic acid uniqueness in the epi. cell of upper airways
Why can birds spread virus in their feces?
Because they have sialic acid bonding site in their GIT
Drugs blocking (M2p+) release of virus from endosomic vesicule?
A”mantadine” and Ri”mantadine”
But, virus can be resistant
Drugs blocking release of virus from cell?
Oselt”amivir” and Zan”amivir”
Influenza nomenclature?
type/geographic origin/isolate #/year discovered/HA:NA
Eg: A/Fujian/411/2002/H3N2
