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14 Cards in this Set
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- Back
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lecture objectives: describe structure/organization/genome of A and B
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it's RNA, negative sense, helical, SEGMENTED GENOME (which is how it generates all its diversity).
orthomyxovirus. comes in A B C varieties. Note that A and B are subdivided into numbers. H types 1, 2 and 3 are epidemic potential N types 1 and 2 have epidemic potential |
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Know the key steps and the role of individual viral proteins in the influenza replication cycle
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know entry protein is HA (hemaglutenin), which binds sialic acid, then endocytosis. Know that HA has to be cleaved BY HOST PROTEASES for infection to happen.
Lowered pH causes confirmational change in HA to cause endosome fusion, uncapping. NA is for release. Uncoating drugs attack M2 KNOW THAT IT TRANSPORTS TO THE NUCLEUS FOR REPLICATION (HIV is the only other RNA virus that replicates in the nucleus). Virus carries its own RNA-dependent RNA polymerase that makes mRNAs and templates for new genomic RNA. Maybe know PB1 and PB2 are required for stealing the 5' caps off normal cellular proteins. |
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Be able to explain the mechanisms of ANTIGENIC DRIFT and ANTIGENIC SHIFT and the role these play in epidemics
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short - drift is random mutation that causes yearly epidemics.
shift is the trading of segments that leads to super pandemice drift has to do with slight mutations in the HA and NA protein, which is a major antigenic target of host antibodies. Rna-dependent RNA polymerase are error prone, gradually the virus becomes able to dodge host antibodies. ANTIGENIC SHIFT - this only happens within species (A interchanges with A, B interchanges with B). Because it's segmented, different segments can get packaged in the same virion - this makes a new subtype (get new A and new B parts). Comes from super infection by different subtypes. |
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Know the clinical presentation of Influenza A infection in humans
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acute infection = abrupt onset fever, chills, cough, headache, sore throat, malaise
probably only replicates in the respiratory tract, so systemic effects are likely due to inflammation cytokines. |
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what animals might act as mixing pots and what strains should we associate with them?
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pigs - think H1N1, serving as an intermediate between human and water foul virus.
H5N1 - think of terestrial foul, usually in bird markets in china. |
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what's our other segmented virus that can reassort?
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Rotovirus! which is a reovirus, which is double-stranded RNA and nekkid.
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which influenza are filamentous?
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all of them.
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alpha 2,3 linkages are preferentially attacked by...?
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avian viruses - H5N1. Avian can bind both 2,6 and 2,3...but prefer 2,3. This is why we have bad transmission between birds, generally.
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what's cap snatching?
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PB1 and PB2 steak 5' caps from host mRNA and put them on the new viral particles.
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how many segments do the influenza viruses have?
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A and B have 8 segments.
C has 7. |
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What's usually found in Swine? Birds?
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H1N1, H3N2, H1N2
Birds is H5N1 |
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what's the big mixing vesseL?
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Pig acts as MIXING VESSEL - avian viruses infect birds, human viruses infect humans preferentially, BOTH infect pigs with NO PREFERENCE - reassort in the pigs, acts as a mixing vessel.
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where are bird infected?
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the GI tract - so they pass virus out their asses.
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swine vs. avian - which is more dangerous? what parts do you want from each?
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you'd want the HA/NA from a swine, and the rest of the genes from birds. Avian flu is more dangerous but hard to transmit.
Pig stuff is more easily transmitted but not as bad as a bird. So, HA/NA from pigs, the rest from avian. |
